Calories or kilojoules?

by John Q on January 21, 2013

Like many of us, I’m engaged in a constant struggle to maintain a healthy weight and fitness level, and being an economist, I naturally like to think about this in quantitative terms (I’m not alone in this).

The basic equation is simple[1]: Energy used – energy consumed = fat burnt. But to make sense of this equation, we need units, and that raises the immediate questions:

Calories or kilojoules? and
How much do I have to burn to lose 1kg of fat?

The short answers are: Calories and 9000 Cal[2]

More over the fold

Calories (more precisely, kilogram calories, Cal in SI) are familiar and widely used, but Kilojoules are the Standard International Unit, and are more prominently displayed on food. 1 calorie is approximately equal to 4 kilojoules, which is discouraging, because Australian food labels report kilojoules (calories in small print) while most exercise programs only give you calories. Looking at how the unit are derived, this is the wrong way around.

A calorie is a unit of heat: the amount required to raise the temperature of a kilogram (or litre) of water by 1 degree Kelvin (or Celsius). That makes sense as a measure of food energy, since we burn it. A Kilojoule is a measure of work done: it’s what’s needed to generate one kilowatt of power for one second. So, if you’re concerned with running or cycling, the question of interest is how many kilojoules you can generate in torque, overcoming resistance and so on.

So, we might say that Calories are input and Kilojoules are output. If you want to lose weight, it’s calories burnt that matter. But it turns out, quite by chance, that calories are also a pretty good output measure. That’s because, considered as engines, our bodies are only about 25 per cent efficient, which roughly cancels the ratio of kilojoules to calories. So, one calorie (= 4Kj) consumed translates to about 1Kj of useful work.

That makes sense to me. At top pace, I burn around 1000 Cals an hour. At 25 per cent efficiency, that amounts to an output of 250 watts, which is about right, given that I weigh 70kg, am travelling at 3.5m/s and would decelerate to zero in a couple of seconds if I stopped pushing. (The efficiency figure is just for conversion of food to mechanical energy – there’s a whole lot more to consider in terms of the mechanical efficiency of running. Measurement is much easier in the case of cycling).

On the second question, the energy content of fat is around 37Kj/g, or 9Cal/g. Exercise will also result in fluid loss, but since fat doesn’t contain much water, this is all temporary.

So far, I’ve talked only about the difference between calories in and out, but what about the levels? It’s surprisingly hard to get good estimates, but it appears that a moderately active man of my age should be consuming 2000-2500 Cals/day. I’d say I’m burning an extra 1000/day, but on the other hand, I’d like an energy deficit of 500/day at the moment, since I’m trying lose a few kilos I put on at the end of last year. However, I’m not measuring calorie intake with any precision, relying for the moment on more activity and cutting down on a few obvious items, like alcohol.

fn1. Exploiting it is not so simple. I’m not an expert, but it seems pretty clear that, if you have been at a given weight for a long time, your body will try to keep you there, by slowing down metabolism, sending hunger signals to your brain and so on. Still, having lost 15 kilos over a couple of years, and kept all but 2 or 3 off for a couple of years more, I don’t accept the fatalist view that there’s nothing to be done about this.

fn2. My earlier understanding was 7500, and since posting, I’ve seen some sources to support this. YMMV



hardindr 01.21.13 at 3:08 am


hardindr 01.21.13 at 3:09 am

I should comment that I have been able to lose weight by lowering calorie intake and increasing exercise.


JanieM 01.21.13 at 4:11 am

I come at this from a different angle. Growing up I was skinny as a rail. As an adult I gradually gained about 25 pounds and was, from my mid-20s onward, at a pretty healthy weight for my height. I exercised regularly but not obsessively, mostly basketball, some bicycling.

Then I had two kids. I gained 50 pounds with my first pregnancy (at age 35), lost all but 10 pounds of it, got pregnant again, ditto. When my 2nd child was about 3 I decided to lose that excess 10 lb., so I counted calories (in, not out) for six months and kept myself at a strict limit of 2000 a day. I lost the 10 pounds, quit counting calories, and promptly gained 20 pounds back. Then, gradually, 10 more.

Eventually I developed an auto-immune skin condition, and when the conventional dermatologist said he could do nothing for me but monitor the situation, I went to an alternative practioner whose major piece of advice (there was quite a lot of it, mostly dietary) was to stop eating wheat.

It took me a year to get serious about that, because I love good bread (hey, I’m half Italian), and bread and pasta are the easiest foods in the world, not to mention relatively cheap. But when I did get serious I lost 30 pounds effortlessly (except for: no bread! no pasta!) in a year and a half, back to my original steady state adult weight, and I’ve stayed there ever since, about 15 years. I get none of the strenuous exercise of old; I walk a lot and I stretch, but my knees are wrecked so there’s no more basketball or cycling for me.

And — my skin condition and several other chronic and annoying symptoms cleared up as well.

My admittedly unscientific conclusion is *not* that avoiding wheat would help everyone, but rather that if we could each figure out which foods “agree with” us (as my old grandma used to say) and which don’t, maintaining a healthy weight wouldn’t be as much of an issue for a lot of us.

I think what happened for me was that when I stopped eating what didn’t agree with me, my weight stabilized along with my health. (Aging does a number regardless, it seems, but that’s a separate phenomenon.) Before I stopped eating wheat it had gotten so that I was naggingly hungry all the time. I suspect this was because my gut was constantly irritated, so I wasn’t absorbing nutrients properly, and when the irritation stopped, the nagging hunger stopped too. (For the record, I have tested negative for celiac disease.)

Having glanced for half a minute at hardindr’s links, I’ll repeat/emphasize that I don’t think one size fits all is a good approach to diet, except in the most general way (Michael Pollan quote from the second link: “Eat food. Not too much. Mostly plants”). I eat some of this and some of that, not much meat, some fish, a lot of rice-based stuff, vegies, olive oil, cheese (I’m trying now to switch to sheep’s milk cheese, the price of which will limit my intake if nothing else does).


anon 01.21.13 at 4:21 am

This article describes an applied mathematician in the US National Inst. of Health studying obesity. They have developed an approach very much in the spirit of what you are doing here:

The best part, a link to a java applet that will model your weight (gain/loss) over long periods of time given amount of activity done and calories consumed:

They key, just as you suggest, is that body weight is regulated like a stable dynamical system. It requires either sustained effort, permanent change, or a major shock to get the body out of its “equilibrium” weight.


Glen 01.21.13 at 4:36 am

I had a thermo professor that calculated that he could bath in ice water for ten minutes every day and never have to worry about his weight until he realized that for diet and food, kilo calories are always used so he was off by 3 orders on magnitude. That’s a much longer time in the ice water bath tub.


KJM 01.21.13 at 4:52 am

As a physicist/engineer, I one small quibble: the distinction between units of calories and kilojoules as heat and work, respectively, is rather artificial and is probably only still around for historical reasons. Neither is more fundamentally “correct” than the other. Heat and work are both energy! And calories, or kilojoules, are units of energy.


Trevor 01.21.13 at 5:13 am

To gain knowledge about manipulating one’s body composition, it seems pretty clear that one ought to turn to the people who devote their entire being to body composition manipulation, who stay rigorously abreast of whatever relevant scientific knowledge exists, and who minutely track their own relevant behaviors and personal outcomes. These people are, of course, body builders and fitness models. However existentially repellent you might find their vocation, it’s clear that, when it comes to reducing one’s body fat percentage, they know of what they speak. And, in my experience, what they speak lines up much more closely with Gary Taubes @1 than with the competing “calories in minus calories out” argument. Specifically, what sort of calories you consume and when you consume them matters a great deal, as our bodies’ various hormonal responses have a great deal to do with fat and muscle loss and gain. For example, you should only ever allow your blood sugar to spike in the brief window surrounding intense exercise.


RobW 01.21.13 at 5:16 am

Recommend anyone that find this post pursuasive consult Gary Taubes on the subject. Links to two interviews on EconTalk here and here. Bottom line, beware the calorie counters.


George D 01.21.13 at 6:25 am

Use the metric system, you nation of troglodytes.


John Quiggin 01.21.13 at 6:44 am

@Trevor I don’t see why my personal experience is less valid than theirs, and I’m confident about the laws of physics. Whatever the effects of hormones etc, they must work in a way that is consistent with energy balance. Of course, if you want specific effects on muscles, you may need a specific strategy. I just want to lose weight and run faster.

@RobW hardindr @1 links to Taubes and a rebuttal, which I find convincing.


Mr Art 01.21.13 at 7:11 am

15kg weight loss is quite an achievement! Congratulations.


Alan 01.21.13 at 7:21 am

“Energy used – energy consumed = fat burnt” is true but not particularly helpful. What makes you want to eat more than you burn? If you eat 1000 Calories worth of starchy food (e.g. bread, rice, pasta, potatoes) you will feel hungry again much sooner than if you ate 1000 Calories worth of nuts, fruit, meat or fish. If the food is also crunchy, chewy, slow to digest or highly spiced (or all four) the feeling of satiation lasts even longer.

I have kept my weight under control for several years by eating a diet based on fruit, vegetables, nuts, beans, fish, a little meat. I eat bread and/or pasta most days. I don’t feel as hungry as I did when I was eating more calories per day.


K 01.21.13 at 7:23 am

It’s not “kilogram calories”. It’s kilo-calories, i.e. 1000 calories.
For some stupid reason people say calorie when they mean kcal, which
is equivalent to saying 1000=1.


John Quiggin 01.21.13 at 7:56 am

@K You would think so, but you would be wrong


Naadir Jeewa 01.21.13 at 7:57 am

I don’t think there’s much alternative to calorie counting in order to lose weight. Fortunately, new mobile apps make this a lot easier. Plenty of good recommendations in the National Institute of Clinical Excellence guidance:

Unfortunately, I’m one of those who needs to calorie count for life, so I promptly put on a whole load of weight as soon as I stopped.


Hidari 01.21.13 at 8:24 am

Here is a link to a somewhat less contemptuous review of the Taube book. He does admit ” I’m quite low-carb friendly and that I readily agree that science has proven that saturated fat has been wrongly demonized by the medical establishment for decades , including somewhat by me when I co-wrote my book in 2006/7 (a guy’s allowed to learn, and it was in this spirit that I approached reading Taubes’ book). Furthermore, I also agree that carbohydrates, more specifically the refined highly processed ones, contribute dramatically to both obesity and chronic disease and their reduction may well have a role to play in most folks’ weight management efforts, and that a myopic view of dietary fat as causal to chronic disease and obesity has likely in and of itself, by means of a consequent dietary shift to carbohydrates, contributed dramatically to the rise in the societal prevalence of chronic disease and obesity.”

I listened to the whole skeptic podcast and Taube did make a good point about fruit, which is that the fruit our great grandparents ate is not the same as the fruit (or “fruit”) we eat today, which has been systematıcally bred for centuries to be “sweeter” (ı.e. have more sugar). So it probably is better for you than, say, eating a Mars Bar but it’s probably not as much better for you as you think. Also back in neolithic times fruit was seasonal: our bodies don’t adapt well to having the huge apples and bananas we have available nowadays all the year round (and our teeth fare even less well). So while fruit is on balance good for you, we probably eat too much.

He also makes a good point (implicitly) about amounts. From my own experience my own partner sometimes presents me with a gigantic plate of food with a pile of wholemeal rice bigger than my head which I feel duty bound to eat. The point of course is that, yes, it’s wholemeal rice (or pasta) but it’s still food and if you eat gigantic amounts of it it will still make you fat(fn1). He doesn’t make this point as clearly as he could have done but his point is about portions (same with fruit) and so in that sense I agree with him. We undeniably eat too much processed carbs and probably too much unprocessed carbs as well.

BUT having said, that the basic thrust of his argument seems bizarre. His basic argument so far as I can see is that you shouldn’t exercise as exercise makes you hungry. So basically what he is saying is that if you run a marathon and then go out and eat 10 pizzas you won’t lose weight. But of course you won’t!! Whoever said anything else? Diets don’t work. “Fitness plans” on their own don’t work. You have to exercise AND restrict the amount you eat. Isn’t that common sense?

Also his basic point is also false. Exercise doesn’t make you hungry (or at least it doesn’t make me hungry). It suppresses your appetite which only comes back about 1 hour later. I hate going for a meal immediately after (say) going to the gym.

His point about being fat making you lazy also seems bizarre. Isn’t sumo wrestling a fairly intense sport?

fn1; This goes double for the modern potato which has been bred for generations to look and taste like nothing. I can’t believe it has much nutritional value either. CF also modern “brown” bread which is frequently white bread with (effectively) dye added to it.


K 01.21.13 at 8:27 am

@JQ. Oops, I would indeed.
“In an attempt to avoid confusion, the large calorie is sometimes written as Calorie.”
Sure, that really helps.


Hidari 01.21.13 at 9:10 am

One more thing. For a skeptical podcast, called Skepticality, on behalf of the Skeptics society…..the presenter wasn’t very skeptical was she?


John Quiggin 01.21.13 at 9:19 am

@K Certainly I’m confused enough that I had to look this up for about the fifth time to make sure I had it right before I posted. That’s a point in favor of joules/kilojoules I guess.


Trevor 01.21.13 at 10:32 am

@John 10: I think the experience of body builders is especially informative given the extent to which 1) their eating habits tend to be very tightly regimented and tracked, 2) they keep careful (less charitably: psychotically narcissistic) track of the outcomes of their eating habits, 3) they experiment with different eating habits in attempts to gain competitive advantage, 4) they tend to communicate among themselves what works particularly well, meaning that promising nutritional strategies get tried and evaluated quite a bit.

Obviously, if you’re not trying to be 250 lbs and veiny, you’d want to modify some of their approaches. But there’s almost certainly quite a lot you could learn by paying attention to people who are very good at taking themselves down to very low body fat percentages.


krippendorf 01.21.13 at 11:45 am

The experience of body builders and the like is NOT especially informative for the 99% of us who have (a) average genetics, (b) an aversion to performance-enhancing drugs, and (c) jobs, kids, activities we enjoy other than being in a gym, etc. Also, bodybuilders/fitness folks allow their weight and bodyfat levels to fluctuate enormously throughout the year, cutting fat for shows and then gaining fat back while they try to build more muscle between them; most of us don’t want our weight to fluctuate by 10-15%+ over the course of months.

Even assuming correct calculation of calories in (people tend to underestimate intake by about 50%, on average with a large standard deviation), actual losses will nearly always fall short of calculated losses. The most notable reason is that non-exercise activity tends to drop when people diet and exercise.

It’s not just a “oh, I read a magazine whilst on the recumbent bike for a half hour this morning, I can sit on the couch all day” effect, although that’s some of it. Unconscious energy-burning activity — e.g., fidgeting — also goes down during a diet, which can be a very large part of the “calories out” side of the equation. Just your body’s way of saying, “I love you.”

I recommend Lyle McDonald’s site if you want a “scientific” approach to losing weight (meaning one that’s based in the scientific literature on nutrition and exercise, not just the fad of the day). Aside from a couple of books, he’s not selling anything or doing the morning talk show circuit thing to sell junk science (ahem, Taubes, cough).


sanbikinoraion 01.21.13 at 11:45 am

And the exercise you choose will make a difference too. Just running won’t develop muscles that need feeding all day; weightlifting will.


genauer 01.21.13 at 1:39 pm

my 2 cents worth of wisdom:

1. a carrot is a carrot, but raw or steamed makes a lot of a difference, and the experience / constitution of the body you feed it to, too.

The simple equation delta fat = energy in – energy consumed does not work that simple.

2. when you take a closer look at the data, people live longer with BMIs > 27, and age 70 I would be fine with BMI = 30.1, when the hunger horder boohooos “obese”.
But that is OK, they will die earlier, and I get a slightly higher pension : – )

When you take a look at how much physical exercise helps you how much, something like 15 – 20 min per day are actually the BROAD maximum Utility point, ……, IF you hate the time spend on workout, and “account” for it versus your lifetime.
If you do this, because you walk anyway to work or shopping, or actually enjoy it, seeing some seasonal change, think about some stuff, without the need to focus on traffic ….., well, then 60 min dont hurt, obviously.

I believe, the increased mortality for that supposedly “ideal” weight BMI < 25 does not really come from being intrinsically "unhealthy", but that too many folks, desperately trying to keep up with some supposed social norms, do not listen to their bodies, do unhealthy things to stay that way, and in general enjoy life a lot less.

Can I "prove" that? No.


Don A in Pennsyltucky 01.21.13 at 2:36 pm

I tried the “informal” approach that you describe using and was able to reduce my total body mass by about 2 kg (5 lb) in a year’s time. I started logging my food intake and consciously trying to stay below 1800 “Calories” increased my activity by about 10% and dropped 40 lb in 6 months. I also reduced my waist size by 4″. Losing weight is a simple matter of 4 little words.
Eat Less
Move More


geo 01.21.13 at 3:20 pm

You might try clinical depression. I find it generally results in a roughly 10 percent weight loss.


andrew adams 01.21.13 at 3:25 pm


Also his basic point is also false. Exercise doesn’t make you hungry (or at least it doesn’t make me hungry). It suppresses your appetite which only comes back about 1 hour later. I hate going for a meal immediately after (say) going to the gym.

I’m not sure about this – I personally do find that increasing my level of exercise does make me more hungry, maybe not immediately but the effect certainly kicks in at some point, and it’s something that comes up a lot when reading about this subject so it’s not a particularly controversial claim (though to be fair this is an area where a lot of “received wisdom” is probably dubious). And it does make sense – your body is doing extra work so it wants extra fuel, it’s not necessarily going to immediately start eating into your fat reserves. Of course it would be silly to use this as an argument against doing exercise, but it’s right to warn people – even they don’t do obviously wrong things like thinking that they can eat 10 pizzas without consequences they might well find themselves unconsciously snacking more or having larger portions.


Christiaan 01.21.13 at 4:21 pm

I fully agree with KJM that Cal and kJ are just units, and your reasons for Cal over kJ are irrelevant. This means that one should use kJ, because Cal is not SI and outdated, it’s a bad unit (there’s a reason it’snt SI). Moreover, the confusion between Cal and cal is a very good second reason why one should avoid using either. (And it’s kJ, not Kj, as the symbol for joule is J and the symbol for 1000 is k.)


JW Mason 01.21.13 at 4:41 pm

I agree with others that actual weight loss or gain is more complicated than a simple calculation of calories in vs calories out. The body has many self-regulatory mechanisms and other feedback loops — there’s a reason many adults remain at the same weight, give or take a few pounds, for decades.

This may be the first time since he’s appeared here that I agree with genauer.


Bruce Wilder 01.21.13 at 5:10 pm

I am happy to say that I can keep up my perfect record of antagonism to genauer.

The paradox that being somewhat overweight does not reduce life expectancy significantly should not be confused with the idea that being overweight is “healthy”. Being somewhat overweight does correlate, unfortunately, with many chronic disease conditions, which, though they don’t kill you, do reduce the quality of life lived.


Hidari 01.21.13 at 5:16 pm


Yeah I should have said I hate going for a HEAVY meal after going to the gym (or whatever). And it’s true that some people probably eat more after exercise (in a “oh I have earned it”) kinda way. On the other hand some people (as someone points out above) probably feel that they have done half an hour on the bike so they can sit about the house watching TV all day.

But having said that….I stıll find the Gary Taubes argument in its totality bizarre although as I stated above there is unquestionably “something in it”.


Anderson 01.21.13 at 5:19 pm

You might try clinical depression. I find it generally results in a roughly 10 percent weight loss.

Depends on whether you’re self-treating with whiskey.


Hidari 01.21.13 at 6:38 pm

@31 If you self-medicate with cocaine the pounds just fall off.


primedprimate 01.21.13 at 7:11 pm

While the law of conservation of mass and the law of conservation of energy are both true in the context of the weight of the human body, the following post (also by an economist) is definitely worth reading.


genauer 01.21.13 at 9:36 pm


according to my records, I left just one comment a year ago on the blog “crooked timber”, in response to niam.
And then, recently, just a few, on just one entry “home truth”.

The more it impresses me, that I left with that an impression
Bruce Wilder @ 29 here
“I am happy to say that I can keep up my perfect record of antagonism to genauer.”

Just one issue, and then it is extented to the whole rest.


genauer 01.21.13 at 9:50 pm

@ JW Mason & Bruce Wilder,

if I would be wrong with what the ECB and Bundesbank,
and the folks I elected to do, what they are doing now (Merkel, Schäuble, Weidmann, Asmussen), just speaking theoretically : – )
you could argue, that it hurts you and your people.

If I would be wrong with my assessment of those health myths, it should only hurt me, or ? And vice versa. It is not a win/lose.

This could be a good opportunity, to learn more about each others approaches to common (individual) problems.

“crooked timber, upright walk” was, 30 years ago, a significant turning point in my life.
Krummes Holz, Aufrechter Gang
The point I became an adult, not fearing to be in a small minority, taking responsibility, not just for me, my family.


sam 01.21.13 at 10:11 pm

My (anecdotal) experience is that it really isn’t as simple as calories in/out. In fact I’m skeptical of almost all orthodox dietary advice given that obesity has continued to rise despite ‘everyone knowing’ about the Food Pyramid, etc, and our ever-increasing obsession with our bodies. (A parallel with economics, perhaps?) I’ve read Taubes’ book, and while some of his claims don’t make much sense to me (a lot of circular reasoning about the relationship between diet and exercise), I think his empirical case (I can’t judge the chemistry) against carbohydrates and in favour of fats is pretty strong.

I’ve also come to think that the role of exercise in weight loss is really overstated. My parents were both very overweight, and both exercising a lot. They continued putting on weight while doing plenty of cycling, jogging, weights etc. Only moving to fairly rigorous low-carb regime made a difference (and quickly.) Despite unhelpful genes, I’ve stayed in reasonable shape (and lost an incipient belly) by following in a lax way the same principles of avoiding sugar, wheat foods and potato in favour of meat and veg. That said, I’m also convinced that there are genetic variables that make it impossible to be prescriptive and that those battling weight gain need to experiment on themselves.


Joshua Holmes 01.21.13 at 10:40 pm

Calories in, calories out is a bad model: the body is not a wood stove. Rats fed yogurt with calorie-free artificial sweetener gained weight when rats fed yogurt with no sweetener gained none, though they consumed the same number of calories. In my personal experience, and the experience of a lot of other people, replacing diet soda with water caused a significant weight loss even though there was no calorie change. Studies show that high-fructose corn syrup tends to cause more weight gain than an equivalent number of table sugar calories.

The best thing you can do is replace your fluids with water, sleep restfully and enough, don’t eat your emotions, avoid HCFS, and fast 16-18 hours twice a week. That will get you within 4kg/10 lbs./a half-stone of where you should be. That last bit requires intensive exercise and dieting beyond the scope of what you’re looking for here.


dsquared 01.21.13 at 10:51 pm

I am not sure that those bastions of common sense and sensible regard for health consequences, bodybuilders should be our lodestone here.


lestin 01.21.13 at 10:52 pm

By “maintain a healthy weight,” I take it you mean you’re struggling to put yourself in the overweight or slightly obese range?

Because that is, in fact, far healthier than being “normal,” with a mortality rate about 5% lower.

I don’t debate the merits of exercise, but it seems likely that losing weight is bad for you:

Obligatory qualification about correlation and causation, of course, but these are exactly the opposite of the results you would expect if the enormous time and energy people pour into losing weight were worthwhile.


lestin 01.21.13 at 11:00 pm

Bruce Wilder, incidentally, is incorrect. Sandy Szwarc’s series on the “Obesity Paradox” is a good place to start for information on fat and health:


Chaz 01.21.13 at 11:27 pm

JQ: “Whatever the effects of hormones etc, they must work in a way that is consistent with energy balance.”

Yes, but what was your energy balance? It was:

(Baseline energy consumption + Extra exercise – Food energy intake) * (kg fat to store 1 kJ energy) = kg of weight lost

All your calculations are done at the margin. You assume baseline energy consumption is constant and look at exercise and changes in food intake. But baseline energy consumption (amount of energy your body burns just by sitting around) is not constant. It depends on your metabolism, not to mention things like how cold it is, how stressed you are, etc. If your body adjusts its metabolism in response to what it perceives as starvation or other factors, as people here allege (I can’t vouch for this, but I hear it a lot), then that could reduce the baseline amount of energy you consume. That change could be enough to overwhelm changes in food intake or exercise.

One other thing: You say your exercise guides give energy burned in calories, and the efficiency of your body means it actually takes 4 food calories to produce 1 calorie of work. But beware that your exercise guides have probably already taken this into account! When they say running for x minutes burns y calories, what they are really trying to tell you is that it compensates for y calories of food intake. They are measuring exercise in calories because Americans label food in kilogram calories (unforgivably written as just “calories”). So it’s probably all sorted out for you already, and if you try to adjust by 4x you’ll just end up eating 4x too much. And then when you try to come to America to yell at us for our confusing exercise guides, you won’t be able to, because you won’t fit through the airplane door. Catch-22!

When you keep track of your food intake and exercise in terms of energy (Americans call this “counting calories” or just “Weight Watchers”), most of the effort involved comes from having to count the energy in every bagel, apple, and pasta supper you eat. So you should use whatever units are written on your food, which I guess for you is kJ. You can sum up your exercise amounts in calories, horsepower-hours, or whatever you want and convert at the end. Or better yet, get an Austrian exercise guide which I presume will give you estimates in kJ.

And finally, while I share your general feeling that K is wrong and should have read Wikipedia before posting, he is actually right. As Wikipedia says, the real calorie, used by chemists, is the gram calorie. Then there is also the kilogram calorie, which equals exactly 1000 gram calories. Therefore, even though Wikipedia defines it slightly differently, 1 kilogram calorie is exactly the same thing as 1 kilocalorie. And at some point long ago, some idiot in the U.S. Government decided to measure food energy in kilogram calories but label it as calories.


bianca steele 01.21.13 at 11:30 pm

Like JanieM, I started out adulthood underweight. I was 5-10 pounds over my best weight by the time I had a baby, and now 5-10 pounds over what I’d like to be. (I finally got a scale that seems to track the doctor’s–after it seemed suspicious that my cheap spring-powered scale showed my weight go up 6 pounds when the weather turned humid, and drop back as soon as it cooled off.)

I’ve finally decided that I interpret acid-reflux as the munchies, or eat to get rid of the bad taste in my throat, or something, and started trying to drink something, or chew some sugarless gum, instead. Cutting back on gluten didn’t seem to make a difference, but switching from high-fiber cold cereal to oatmeal a few days a week does.


JimV 01.22.13 at 1:07 am

Losing 60 pounds (okay, 27.3 kilograms) is easy. I’ve done it twice in my life so far, and may do it again. (As Mark Twain would say – but it’s the truth.) Both times I decreased my food intake and increased my exercise. Speaking of the effects of depression, the first time seemed quite easy because I was, as they say, heart-broken, and I often couldn’t tell if I was hungry or not because my stomach hurt all the time.

I disagree with this statement (although I could of course be wrong): “Exercise will also result in fluid loss, but since fat doesn’t contain much water, this is all temporary.”

As I see it, the basic chemical equation used by our cells is:

C6H12O6 (simple sugar) +6O2 –> energy + 6CO2 + 6H2O

So after I’ve walked five or six miles, despite swearing through my clothes, I also have to urinate. I’ll replace a lot of that water, but not necessarily the part which came from burning the sugar (which may have been reduced from fat).


John Quiggin 01.22.13 at 2:14 am

@krippendorf “oh, I read a magazine whilst on the recumbent bike for a half hour this morning, I can sit on the couch all day”

I use the opposite self-talk, reinforced by spouse-talk, namely “if you’ve got the energy to run 10k, you’ve got the energy to go for an evening walk/take the garbage out/ride to work instead of driving.

As regards fidgeting, I’m sure this happens (my footnote 1 anticipated a lot of the discussion in this thread), but can it really be that important as a negative feedback? Can you burn even 100 extra calories/day by fidgeting? I’d be interested in a link on this.


JW Mason 01.22.13 at 3:16 am

according to my records, I left just one comment a year ago on the blog “crooked timber”, in response to niam. And then, recently, just a few, on just one entry “home truth”.

You also made a brief but pungent intervention on one of the Aaron Swartz threads.

So I even disagree with you about your posting history here. :-)


eg 01.22.13 at 4:37 am

It’s not like we’re bomb calorimeters, so the direct correlation between calorie consumption and fat deposition is probably simplistic.

In my n=1 exercise is rounding error; caloric reduction, a lot of rest, and avoidance of both processed and carbohydrate foods are crucial. I have found that avoiding carbohydrates and processed foods (which are mostly carbohydrate) helps particularly with appetite suppression. A lot of water also helps fill you up and flush out the byproducts of lypolysis. Gum can help with oral fixation. YMMV


mark 01.22.13 at 6:12 am

I’ve read a lot that fidgeting is a big deal, don’t know how robust the studies really are. One example:

Given that it seems impossible to consciously balance inputs and outputs completely accurately, and some people (not including me) maintain reasonably constant weights, there have to be decent negative feedbacks somewhere.


JW Mason 01.22.13 at 6:21 am

Given that it seems impossible to consciously balance inputs and outputs completely accurately, and some people (not including me) maintain reasonably constant weights, there have to be decent negative feedbacks somewhere.

This seems like the dispositive point to me.

My father, a doctor, always said he saw patients come in year after year with their weight not varying more than a pound or two. Sometimes they were trying to lose weight, sometimes not, all kinds of things changed in their circumstances, but their weight never moved. You just can’t explain that without some strong feedback mechanism. The post linked to by Hidari makes this point well.


John Quiggin 01.22.13 at 6:49 am

@JWM But equally, given that some people do change their weight greatly and sustain that change for a long time, these negative feedbacks can’t guarantee that you will stay at any particular equilibrium.

And, as I said in the footnote, if you lose weight and keep it off for a while, the feedbacks start working in your favor.


John Quiggin 01.22.13 at 6:55 am

The fidgeting study gives evidence that fidgeting makes a surprisingly big difference between individuals, but the discussion of feedbacks is just speculation.

Also, and probably inevitably, the energy use attributed to fidgeting is just a residual. They don’t seem to have observed any actual fidgets.


garymar 01.22.13 at 7:23 am

Saibikinoraion, how’d you pick your handle? “3 lions”.


hidflect 01.22.13 at 7:55 am

I calculated that if you drank 14L of zero deg. C water a day you’d consume all your daily calories just heating it up. OK, so you don’t have to drink 14L but even 2L would be a great weight saver.


Mao Cheng Ji 01.22.13 at 8:23 am

I would like to endorse the notion that this is all about how much you eat. The rest is BS.


eg 01.22.13 at 11:44 am

While I said I have found exercise to be rounding error in my weight control experience, I should hasten to add that it has other benefits — muscular and cardiovascular fitness, and mental health chief among them.


faustusnotes 01.22.13 at 1:54 pm

Since I have lived in Japan for five years, I am now amazed by the way westerners eat. On my last overseas holiday in Germany, my partner ordered the smallest schnitzel in the pub (“M” size – what’s that about?) and it was clearly big enough to feed a whole Japanese family for two nights running. Why? When I’m in London I have to argue with cafe staff to get a small (i.e. normal) size coffee – many chains start their sizes at basically what to any sane person is a large. Australian food servings are easily twice what an adult needs to eat. Why? Also, you can’t get cheap, healthy fast food anywhere: in Japan the standard cheap food is onigiri (100 yen) and oden (80 yen a pop) at any convenience store – for 3 or 4 US dollars you get a full meal of calories with zero fat or sugar. The equivalent in the west would be – a bag of chips.

I think it’s a combination of straight out gluttony (much of it related to a colonial notion of “rights”) and a pernicious view that if you’re paying for food, the only measure of value is the amount you get – even if 50% of it is going to be wasted as fat you don’t need.

Of course, all of this is structural. You can’t change it individually (well, you can, but it’s a huge effort). Basically, we in the west need to change our food culture and the way we design our cities. We also need to return to a cultural expectation of thinness, rather than a culture of passive-aggression about fat. But that’s not going to happen. Which is why everyone is getting fat.


Metatone 01.22.13 at 2:32 pm

Others have noted this, but in the interests of science, I think it’s worth repeating:

The body is not a wood stove. Excretion is a real effect and we have far too little research into how it works. Base energy usage by the body tends to dwarf the amount of exercise you do unless you’re training for some kind of serious sport/activity.

Still, naive calorie counting is better than nothing, but don’t be surprised if the maths gets tricky. It works a lot better if you’re training serious amounts, because then your expenditure is more on par with base energy usage.


Shining Raven 01.22.13 at 3:08 pm

Incidentally, 250 Watts sustained output are quite a bit of power, and not something a normal person can sustain for longer periods of time. For professional cyclists, peak output for short periods can be as much as 300-400 Watts, but that’s pretty much it for humans.

Sustained output for running etc. is probably more on the order of 100 Watts, not 250 Watts, I’d say.


Jeffrey Davis 01.22.13 at 3:54 pm

From childhood to early adulthood, I tended to be gaunt. At my wedding, I stood well over 6′ but weighed only around 145 lbs. Marriage, however, agreed with me, and I quickly increased my weight to 170 lbs. Which is where things stood for years and years.

Recently, our daughter shamed me out of my teenager eating habits and in less than a month, I’ve dropped almost 10 of those lbs. (My fear of diabetes helped.) A doctor who only sees me once a year was worried until I told him the loss was intentional. People over 60 don’t tend to lose weight except via disease.

I’ve no miracle plan. I quit drinking soft drinks (substituting water) and my portion sizes have looked like something passed around in the movie “King Rat” rather than an American “super size” meal. Those two things worked. I’ve tried exercise in the past, but exercise stimulates appetite and proved ineffective at getting me back into my old 32″ waist pants. I don’t count calories and eat what I want. Just less of it. Much less of it. I imagine/hope when I switch to actually eating healthier foods that the little pot belly I’ve sported for years (a python after a meal) will melt away. Maybe not. Everybody’s body is different.


Trader Joe 01.22.13 at 5:17 pm

I’ve used the ‘pants size’ approach for 3+ decades and it works for me. I only buy one size waist in clothing and I refuse to go up (there is a cheap-skate factor invovled as well).

When the pants get a little snug the feeling of ‘snug-ness’ is the positive reinforcement I need to eat less/eat better or exercise more as time and opportunity allow. The more I do, the quicker my pants fit right. By the same token, sometimes I find the pants getting a little loose and that lets me know its ‘ok’ to have dessert.

My exercise is mostly walking/treadmill. I have only 2 diet rules 1) is “no snacking” when I feel a little hungry between meals, a small handful of lightly or un-salted nuts or chewing gum suffices and:
2) portion management (Faustnotes was dead-on above)…stop eating when you’re full, not when the plate is empty. People are raised on “cleaning their plate” and “not wasting food because of the starving kids in China”…if you can’t eat it, throw it out and send money to UNICEF (or whomever) for your soul.

In scientific terms – I’ve established my equilibribum body weight around my clothing size and the positve/negative reinforcements are registered every time I need to buckle my belt.


Yarrow 01.22.13 at 5:20 pm

Shining Raven @ 57: Incidentally, 250 Watts sustained output are quite a bit of power, and not something a normal person can sustain for longer periods of time

Hmm… I’m 61 and, erm, not buff, and I regularly sustain 200 watts on an exercise bike for 40 minutes or so. So 250 doesn’t seem out of reach for normal people. Admittedly, you’d have to work up to it, and it would be work.


GU 01.22.13 at 6:20 pm

Figures that a Keynesian would believe “Energy used – energy consumed = fat burnt.”

(It’s just a joke, people).


shah8 01.22.13 at 8:04 pm

Every thread remotely related to body weight ends up like this.

Generally is pretty simple folks. It only gets complicated at the margins for people who have special circumstances. Eat less, move more. It generally always works. If you ain’t on drugs that mess with appetite or metabolism… If you don’t have thyroid issues, depression, or some other disease… Well, people trying to lose weight generally fail for the usual reasons, especially the fact that they are unreliable narrators of their own life histories.

So, wanna lose weight?

1) It’s gotta be something you tolerate or even enjoy. No pain, no gain is a horrible slogan, because the only thing that works is a lifestyle change, on a permanent basis. Permanent pain and deprivation? No way. Some dietary changes work because they make things more comfortable, like avoiding micro-allergies. Some exercises work because it’s your big chance to “read” via some audiobook. Or just being alone.

2) It also has to be something you constantly monitor. Keep a food diary, keep notes of just how much you’re exercising. This helps keeps you on the wagon, and lets you know when you need to adjust your daily life.

The primary issues with obesity has to do with control. People are not generally allowed to maintain regular schedules that is inclusive of the need for people to take care of themselves. If you can’t give yourself a day off with the flu, how do you expect to find a regular hour for exercise, or fixing a tasty and nutritious meal for the later lunch? People are also bombarded with ads for unhealthy foods, scam diets, and body image expectations that are totally unrealistic. This tends to mess with expectations and sense of rewards. If you’re a big-boned woman, you’ll never look like that slim model, but society sets the disapproval decibel level at 11!! Why even try to be healthy if no approval will be forthcoming? Thus the tub of emergency sweet and creamy stuff in the freezer.


Bruce Wilder 01.22.13 at 8:22 pm

In the spirit of human beings are not wood stoves, the regulatory functions, which keep a person’s weight to some “norm”, sometimes malfunction, and this can be a factor in weight gain/weight loss.

I think the anomaly (or “paradox”) of a statistical correlation between life expectancy and being somewhat overweight may be due to the frequency with which chronic disease conditions call on the body to gain weight in defense. Emphysema (or more generally, COPD) is particularly dramatic. At the outset of emphysema, weight loss is quite a common response, and correlates strongly with dramatically reduced life expectancy — we’re talking about something close to a decade of life, compared to similarly situated person, who gains weights or remains somewhat “overweight” (by a BMI standard, which standard is, of course, stupid applied prescriptively in such a case).

Hypothyroidism, untreated, can cause rapid and dramatic weight gain. Chronic hypothyroidism is debilitating enough that it eventually gets diagnosed and treated, but the weight gain is not reversed, just by the administration of synthetic thyroid hormones. Transitory hypothyroidism may be quite common and rarely diagnosed or treated.

There are medical regimens, which could, logically, be used to reverse the weight gain induced by hypothyroidism, but they are never prescribed. The hormone, hcg, is used in a popular diet promoted by parts of the the multi-billion-dollar diet industry, to create an almost mirror-image of the processes that drive the weight gain in hypothyroidism. (The marketing of fraudulent, homopathic “hcg” has attracted FDA attention, which is just one of hundreds of examples of how the free market works to confuse everyone and everything.)

I would echo some of what other comments have highlighted, concerning the subversive effects of some food choices, on the body’s regulatory mechanisms. The body does not do a good job of registering calories in drinks — they don’t reduce appetite as much as calories in solid food. Sugars and starches should probably be reduced dramatically as a proportion of diet, especially as calories consumed per day dip below 3000; too much sugar in the diet is hard on the insulin system, which is one of the principal regulators of metabolism and appetite. The huge excess of hfcs in American diets, as activity levels declined, certainly has a lot to do with weight gain across the population, as well as rising levels of Type 2 diabetes. Many people adopting even modest long-term weight-loss goals would be well-advised to familiarize themselves, less with calorie-counting, and more with the glycemic index. For people, consuming less than 2000 calories a day, eliminating bread from their diets might be a highly effective strategy for losing a modest amount of excess weight.


Grincheuse 01.22.13 at 8:33 pm

Primary care doc here. I’ve seen people lose weight all sorts of ways and fail all sorts of ways. Taubes does a good job of pointing out that the anti-saturated fat theory is mostly speculative, but then he goes on to speculate that carbohydrates are the real problem. IMHO cheap, tasty, readily available carbs are the problem but not because they are carbs per se. I’ve had good luck with what I call “the skinny husband diet”. My skinny husband has not much interest in food, but I’ve calculated that he needs nealy twice the calories that I do, so I use that as my guide for serving size. On the rare occasion that he wants more, I rejoice. My weight is at its lowest whenever I live someplace that lends itself to walking for transportation, too even though I have a pack of dogs that get daily walks.


Shining Raven 01.22.13 at 9:13 pm

@Yarrow: I probably should have said “not well trained person”.

I looked up my comparisons again: If you are well-trained, you can indeed sustain 250 W, but above that even well-trained people go into the anaerobic regime which you cannot sustain continuously. Even for well-trained people the maximum short-time power tops out at at most 500 W.

I really only wanted to make the point that 250 W is already quite a bit of power, and not the output that you need to for normal running, which John seemed to suggest.


John Quiggin 01.22.13 at 10:27 pm

A few points relating to various things said above
1. If you want anecdotal evidence from a group with evident success in reducing weight to a healthy level and sustaining it, I suggest looking at runners/triathletes. From my experience, most subscribe to the straightforward energy balance approach. Of course, there may be some selection bias in the sense that people who start out overweight and stay that way are less likely to persevere in a sport like running where this is a big handicap.

2. The best single study appears to be that of Foster et al (2010), a two-year randomized trial that concluded “Successful weight loss can be achieved with either a low-fat or low-carbohydrate diet when coupled with behavioral treatment.” That seems like both an endorsement of energy balance and a suggestion for a ceasefire in silly wars about low-fat vs low-carb.

2a Transfats (which don’t occur in nature at all) are still bad. Also from what I can see, the evidence that replacing saturated fats with polyunsaturated reduces LDL doesn’t seem to be have been seriously challenged.

3. @metatone and others: everything I’ve seen suggests that the standard deviation in non-exercise metabolism is below 500cals/day, and (with less evidence) I’d claim that feedback effects from a change in energy balance are unlikely to be larger than that. So, if you add 500 cals/day in exercise (about 40 minutes of moderately vigorous work) and don’t offset with any increased food energy (easier to say than to do, I know), metabolic feedback effects will be swamped. The really problematic feedback is the one driven by hunger.


genauer 01.22.13 at 11:50 pm

@ John Quiggin

“evident success in reducing weight to a healthy level and sustaining it, I suggest looking at runners/triathletes”

Just to picturize this here, I have seen “very healthy” people in my company, younger than me, dying from a heart attack after the second marathon run in a month.
Plenty of stories of folks with knee operations, ruined joints in general, in those desperate desires to adjust to some socially required body norms.

Where do you know from, that what these guys are doing is “healthy” as in “increased life expectancy”?

As Bruce Wilder mentioned here already, somewhat indirectly,

correlation is not causation

For the general overall public average there is a weak link between weight and life expectancy.

But that does NOT mean that weight reduction, especially not by drastic means, is healthy.


Donald Johnson 01.23.13 at 12:23 am

Not surprisingly, one of the columnists at Runner’s World is skeptical of the claim that being overweight is good for you. But he makes a good case (by pointing to an earlier paper in JAMA which looked at the data for nonsmokers)

why I’m not sold on benefits of being overweight


Donald Johnson 01.23.13 at 12:24 am

Oops–the earlier paper was from the New England Journal of Medicine.


John Quiggin 01.23.13 at 1:33 am

Another big problem with “overweight is good for you” is that the results are very sensitive to historically arbitrary definitions of overweight, most obviously BMI>25. If you shift the normal range up even a small amount, say 21-26, it’s clear that being overweight (above the range) is bad for you (worse on nearly all measures than being 21-26), as is being underweight. At 1.75m, that shift is only 3 kg.


AB 01.23.13 at 3:13 am

Mortality vs. BMI is a U-shaped curve. Different studies will show it bottoming out at a different BMI, but 22.5-25 seems common. This is very different from “overweight is good for you”.
For an example, see


Donald Johnson 01.23.13 at 12:09 pm

Incidentally, why does BMI depend on the height squared rather than cubed? If healthy tall and short people were geometrically similar, it would be height cubed. Okay, so they’re not–a healthy tall person should have a more slender appearance than a healthy short person and the waist should go up with the square root of the height. But why height squared? Why not height to the 2.14 or 1.93 power?

If it wasn’t just an arbitrary choice, I’m guessing it has something to do with the 3/4 power scaling with weight of the metabolic rate link

I just thought of this, but it’s a guess. Geometrically similar animals would be expected to have metabolic rates that go up with the 2/3 power of their weight (because that’s the way surface area would go up with volume and heat loss varies with area), but they don’t. If you modeled humans as skinny rectangular blocks and their volumes went up with the square of their heights (to match the BMI formula for people with the same BMI), then their lateral areas (neglecting the top and bottom) would go up with the 3/4 power of their volumes. So did the people who came up with the BMI get the squared power from studying massive amounts of data on height weight and health (which seems unlikely to me) or did they base it on some theoretical model?


Donald Johnson 01.23.13 at 12:15 pm

By the way, that last paragraph in my link above–“Since the 3/4 law appears to exist throughout biology, Brown says, it should be considered one of a few known fundamental unifying theories of life. He says the law is further evidence of a common ancestor, and additional support for Darwin’s theory of evolution. “–seems like a non-sequitur to me. Why would it support Darwin? It seems more like an engineering constraint, something that would pop up no matter how organisms came to be. Not that I’m a creationist.

And this wikipedia article disputes the reasoning of the previous link on why the 3/4 power law is true–

Kleiber’s law


Hugh Loebner 01.23.13 at 12:16 pm

I went on a low carb lifestyle about a year ago, and my health changed for the better.

I gave up my proton pump inhibitor: My gastric reflux, from which I suffered for 40 years, disappeared. This alone keeps me on the diet. (Post hoc ergo propter hoc? I think not). Before the diet, at 5’6″ I weighed 170 lbs. After giving up carbs I lost 15 lbs, (and 3 inches from my waist) without trying. They just went away.

I gave up my statins: I am somewhat obsessive and monitor my lipids using a Cardiocheck device. My hdl’s are between 45 and 55 (150 is considered dangerous) (my total cholesterol averages 220 which is “borderline” high) but apparently it is the ratio of triglycerides to hdl which is important >3.8 is dangerous.


Hugh Loebner 01.23.13 at 12:23 pm

There is an error in my previous post. It should have read:
“My hdl’s are between 45 and 55 (<40 is considered dangerous) my triglycerides average 60 (150 is considered dangerous) …”


Hugh Loebner 01.23.13 at 12:34 pm

Can I recommend a preview or edit function for this blog? The italics should have preceded “(<40" not "dangerous"

I'm typing on an android tablet, and the final editing change in the entry window seems not to be applied to the text. I moved the italic tag before hitting submit.


JW Mason 01.23.13 at 4:37 pm

I think Donald Johnson @72-73 is the most interesting contribution to this thread so far. Allometries are cool!


Yarrow 01.23.13 at 5:37 pm

John Quiggan @ 70 : If you shift the normal range up even a small amount, say 21-26

The standard normal range is 18.5 – 25, so shifting to 21-26 is a fairly large jump for the low end. It makes sense that cutting off the lower end would make a big difference. Eyeballing the graphs in the Runner’s World article Donald Johnson linked to, it looks like the all-population sweet spot is 21-27.5 for women and 22.5-30 for men, going up sharply at lower weights and more slowly at higher weights (for women, 18.5 is about as bad as 37.5; for men, about as bad as 41).

For people who’ve never smoked and don’t have any signs of cancer or heart disease, risk increases less rapidly at the low end and more rapidly at the high end. They don’t give a separate graph for smokers and ex-smokers; presumably that would show higher BMIs as being even better than for the whole population, and lower BMIs even worse.

I do wish that at least people would stop considering BMIs under 20 to be healthy — 19 seems to be OK for healthy males who’ve never smoked, but no one else. The recent Flegal, et al. meta analysis is at least muddied by the fact that they’re throwing the 18.5-20 range into “normal”. (Because that’s what the studies they rely on did.)


John Quiggin 01.23.13 at 6:35 pm

@Yarrow – AFAICT the extension down to 18.5 was recent, US-specific and not evidence-based. I think we may see a reversion to the old 20-25 range.

On allometry, this guy has recently argued that the correct power is 2.5, which obviously allows a bit more weight for tall people and a bit less for short. I’m just above his estimated crossover at 1.75m.


Dr. Hilarius 01.23.13 at 6:50 pm

Longevity is one measure of health but not the only one and not necessarily the best. Consider two individuals: Fred Beckey is a well-known climber and alpinist with more first ascents by far than anyone else in history. I just saw photos of him climbing at Joshua Tree at age 90. Not as hard, not as fast as when he was a child in his 70’s but still. Then consider another 90 year old who has been living in a nursing home for the past decade, either bed-ridden or in a wheelchair suffering from numerous chronic health problems. It’s not just how long you live, it’s how you live.


genauer 01.23.13 at 7:08 pm

@ Hugh Loebner

thank you for bringing up the cardio check toy! Looks like something I would buy on occasion : – ) Disadvantage is that each measurement point costs 3 x 3 dollar, or ?

I am a physicist/ engineer, and I love measurement tools. I have of course a weight scale, heart pressure monitor, blood sugar, even an oximetry 24 h tool (comes at less than 100 Euro nowadays, with some ), a heart beat string to be used with a smart phone, just to mention the health related stuff : -)

All little nice toys you play with for a few weeks, before they go to a box, to collect some dust. And for less than 100 they provide more fun than an opera ticket.

The link to the runners world is interesting, but it is a meta analysis of existing data sets, not new data. That the BMI optimum is <= 25 for perfectly healthy folks, I believe.

What is unfortunately missing, is an analysis for the interaction between physical activity and BMI, which is somewhat surprising, because they go into significant detail with multi levels for smoking. And as "better a little heavier but active" seems to be mostly agreed upon now, certainly not some absurd side question.

From my present knowledge, also mentioned by others above, more physical activity should shift this optimum to higher BMI levels (I have recently seen a study, where my BROAD maximum 15 minutes daily activity sentence above came from, I have to find it). What is further worth to mention, if you look in the appendix (page 18) of the study, that as a former smoker, my optimum would be around BMI 30 : – )

And again, if higher weight is a healthy reaction of the body to whatever reasons, attempts to lower it not by living healthier, like more moderate activity & healthy food, but by other or more agressive means, it is likely counterproductive.

All these studies do NOT show that certain specific diets are healthy in any way.


Zeb By Proxy 01.23.13 at 8:31 pm

Just a quick piece of input: I lost 35 kg over the course of 9 months, or 1 kg per week (from 115 kg to 80 kg) by doing nothing other than decreasing the size of my portions and shifting my snacks from crackers, cheese and pastries to fruit. I maintained a very carbolicious diet (beer and pasta for everyone!). No real change in exercise. It’s been 16 months now and I haven’t gained any of it back. Weight Watchers! Whoulda thunk it? I’m no body builder, but my experience falls heavily into the: Input – Output = Change in Storage side of things.


Donald Johnson 01.23.13 at 8:34 pm

My post 72 wasn’t clearly written, I see now–never post when I first wake up. But I’m glad people enjoyed the links. From John’s 2.5 link it turns out that the BMI isn’t really based on any detailed analysis of health, height and weight, but is only a computationally convenient (in the days before calculators) way of taking into account that tall healthy people tend to be skinnier-looking than short healthy people. I should have known.


Manuel 01.23.13 at 9:44 pm

JQ, as you say, no amount of argument by vigorous anecdote can undo the laws of physics. Here’s how I explain the notion of set-points and feedbacks in humans with respect to calories in, calories out, and weight change to my students in first year biology:
1. we tend to have a set-point of glycogen that our body attempts to maintain.
2. we do NOT have set point (per se) of body fat percentage, though we cannot, without extreme pathology, drop below about 6-8% because of metabolic processes that kick in around that level.
3. in most cases of normal (under 90minutes or so of vigorous exercise, we burn our calories from our glycogen stores.
4. our body attempts to restore glycogen levels to their ‘set-point’.
5. if we eat the amount we burned, that restoration comes from ‘new’ calories, and little fat loss (or long-term weight loss) occurs.
6. if we eat less than we burned, then the restoration comes from fat stores and we do see a reduction in body and long-term weight loss.
7. the feeling we call ‘hunger’ is a complex outcome of gastric physical & chemical processes and of neurobiological tricks we have evolved to help recover our depleted glycogen.


Yarrow 01.24.13 at 3:03 am

John Quiggan @ 79: AFAICT the extension down to 18.5 was recent, US-specific and not evidence-based.

That seems not to be the case. According to
this table from a history of U.S. criteria for overweight and obesity in the American Journal of Clinical Nutrition, the U.S. had a hodgepodge of various standards (which mostly ignored underweight) until 1998 when it started adopting the World Health Organizations’s 1997 Consultation on Obesity standards, including its 18.5 cutoff for underweight.

(A BMI below 17.5 is apparently one criterion in diagnosing anorexia, which underscores the weirdness of treating 18.5 as normal. That’s kind of like saying 25 is normal and 26 is morbid obesity.)

No argument on “not evidence-based”. I mean really — aren’t all those numbers suspiciously round? 25, 30, 25, even 18.5? According to the AJCN article, when the U.S. was transitioning away from life insurance tables to a BMI-based scheme, 27.8 was too heavy for men and 27.3 for women (with no gradations between overweight, obesity type 1, type 2, and so forth). That was the 85th percentile of people aged 20-29 in the NHANES II study. “The rationale for selecting this age group as the reference population was that young adults are relatively lean and the increase in body weight that usually occurs with age is due almost entirely to fat accumulation.”

Now you can see those BMI numbers as sort of evidence-based, if you look at them sideways and squint hard. If we take on faith the idea that having more fat than the average young adult is always bad (which now seems to be false), but that being within one standard deviation from the mean is safe, then it makes sense to say “if you’re a woman with BMI over 27.3 or a man with BMI over 27.8, you might want to look into that.”

On the other hand, using 20, 25, 30, 35, 40 seems reasonable for a research program, when you’re just trying to see what makes sense. But clearly those numbers were pulled out of someone’s butt and cry out for calibration. Moreover it seems unlikely that the best weight/height ratio for, say, women between 180-190 cm and 25-30 years would be the same as the best weight/height ratio for men between 160-170 cm and 65-70 years.


Hektor Bim 01.24.13 at 2:27 pm

Any time anyone says something is “simple physics”, and it isn’t obvious to you it is simple physics, be very wary. This is true of everyone, including physicists, by the way. (As a physicist, this is one of the things my field has to struggle with.) If an economist says something is simple physics, you can almost always directly discount it, since economists have no training in science and usually just dabble in math or statistics.

Weight regulation is not “simple physics”, it is a very complicated feedback system that is actually “biology”, and as we all know, biology is a lot more complicated than physics. As many people have reiterated upthread, people are not isometric to wood stoves.

I want to reiterate what shah8 said above. To lose weight and keep it off, you have to change your life. You don’t go on a diet that is temporary, you start doing things differently and then you keep doing them differently for the rest of your life. What worked for me was changing my diet to more salads and vegetables, much less carbs and I lost 25 pounds in four months. But you have to change for good to keep it off. Increase or decrease in exercise had no impact, though getting more sleep definitely does help you lose weight.


genauer 01.24.13 at 7:32 pm

Having a PhD in physics myself,

I fully support the statement of Hektor Bim.


Mao Cheng Ji 01.26.13 at 7:11 am

Hektor Bim,
if you have a dog, try to give it a little less food, and see what happens. Then give it more, and see what happens now.

I am sure your and genauer’s bodies really are temples of the holy spirit and/or biological mysteries, but at least some of the rest of us are still mere mammals.

Similarly, for some of us switching to more salads/fewer hamburgers may not necessarily constitute such a profound and dramatic change in lifestyle as it obviously did for you.


genauer 01.26.13 at 11:15 pm

@ Mao,

I think you misunderstand something here.

I am an infidel in many things, and I did try to run things down this conventional “physical” model. With calculations, spreadsheet, a box full of gizmos, and spending for a time something like 3 hours a day with physical activity.

And after some time, you look at the data, what it is and what it should be.
And believe me, if I am scolding at least 2 times a month somebody for looking at data the way they want them, I took significant effort to not fall myself into the same trap.

Those animal bodies like ours are damned clever little robust beasts, much more complicated than my usual physics/ engineering stuff.


Hektor Bim 01.27.13 at 2:02 am


You are right that calorie restriction will reduce weight, all other things being equal. But all other things are rarely equal, particularly for human beings. The feedback mechanisms are quite complex, and pure calorie restriction is difficult to pull off, which is why additional mechanisms to reduce appetite are useful.


Hektor Bim 01.27.13 at 2:04 am


Just for the record, I eat just about the same number of hamburgers now as I did before my diet change, that is less than 2 a year. So I once again reiterate that it is substantially more complicated for most people then you seem to think.


spyder 01.27.13 at 7:13 am

Late to this discussion:

About twenty-five years ago, a small group of us in California, began a study of converting the economy into payment in kilojoules, based on the service one provided to the nation. It was exhausting, but also interesting as well.

If one were to eat at the fat end of the food spectrum, one would have to pay more in kilojoules than one who ate at the lean end. If one served in a role such as roadwork or construction, the pay would be higher in kjs than those who sat on their hands all day. Teachers would be highly rewarded, and able to purchase more kjs than say, bankers. And so forth. In all, it served, however awkward, as a proposal for a more equitable economic system.

Your interest in kjs vs Cals stokes my heart!


Mao Cheng Ji 01.27.13 at 9:11 am

“Those animal bodies like ours are damned clever little robust beasts”

But all that complexity is irrelevant to the energy in/energy out approach.

In general, the internal complexity doesn’t rule out the possibility of simple control. The car you drive is an extremely complicated machine, full of sophisticated electronics, valves, loop-back mechanisms. These days it might even have two engines, one electric and one internal combustion. And yet you control its speed with just one pedal. You don’t need to be aware of any internal intricacies.


Hektor Bim 01.27.13 at 1:55 pm

Your body unlike your car can spontaneously change its efficiency in response to the wide variety of nutrients available. It can also induce the driver to buy certain varieties of food that have a much higher caloric intake. It is much more difficult for people to change their dietary preferences than for you to put less gasoline in your car and drive less.


genauer 01.27.13 at 5:59 pm


I am very aware of our nice physics conservation laws, I dont need to know the intracies of a machine, to know, that perpetuum mobiles dont work.

One example (carbon mass conservation), which is surprisingly difficult to accept for many people:
if the thickness of the humus (mud) underneath the rain forest doesnt increase, it will in the long run not be a net CO2 absorber, no if, else, or but : – )
No matter what Greenpeace says.

Of course, some of our physical laws are hard, absolute laws. But, just as Hektor says, in the very most cases, people invoke them, in different, not so hard cases.

But you will not be able to draw down your body weight along those lines.
It will revolt.

Compared to that, the likelyhood that if somebody promises you very consistent very high returns on some investment, that there is something wrong, is a soft law.
Very likely, but not totally impossible.

And since I am at it. If you measure long enough enough parameters of your body, you will find something, and some specialist will recommend some stuff. Be very careful to get real information, about what is “normal”, and for your age, weight, etc.

Beyond that, on a lighter side, I have 3 pedals, gas, brake, clutch, and the gear, to control my speed : – )


Mao Cheng Ji 01.27.13 at 7:05 pm

“It is much more difficult for people to change their dietary preferences than for you to put less gasoline in your car and drive less.”

Difficult for some, not so hard for others, and it also depends on your priorities: you may, after all, prefer to indulge in gluttony at the expense of vanity, and other good things.

Nevertheless, the bottom line is the same: if you want to lose weight, you just have to eat less. What else is there to talk about?


Salient 01.27.13 at 10:25 pm

if you want to lose weight, you just have to eat less. What else is there to talk about?

I guess naked aggression is par for the course on a health thread, but wow. I can just see you spitting this while standing half an inch from Hektor’s face, giving ’em a methhead stare. What else is there to talk about, bitch? Huh? What else is there to talk about?

Well, there’s this: Even at fairly healthy weight, while consuming below 1000 kCals / day long-term you’re risking severe heart complications, and at below 500 kCals / day you’re risking brain damage even in the short term. (These are fairly conservative estimates; 1200 kCal is the usually-cited threshold for DO NOT DO THIS WITHOUT MEDICAL SUPERVISION.) Worse still, these numbers are not constant with respect to weight.

Not that I expect you to care about other peoples’ risk of health degradation or organ damage, given that you basically advocated mistreating one’s pets for the sake of casual experiment. (I can already see you getting all excited, ready to (1) protest that nobody could have possibly taken you literally, and (2) tell me about how all those stupid people are already risking even more horrible fates by not doing what you propose.) And at this point there’s no hope that you’ll come around to understanding anything even as simple as “substantial changes in eating habits prompt changes in metabolism that are not reliably predictable and that vary considerably from person to person,” given that that would get in the way of your opportunity to be self-righteous about How Simple It Is.

You must get exasperated with other people a lot. Those silly people. It’s all so simple. How can they not understand. And you’ve tried so hard to explain and they won’t listen. You even shove cold obvious logic in their face, and they still don’t concede your point!


Salient 01.27.13 at 10:38 pm

…yeah, sometimes the automod gets it exactly right, it’s better if that one never sees the light of day.

So, let me retry: Mao, there are interesting and nontrivial answers to What else is there to talk about?, but you’re not really receptive to those answers, and that makes your question sound like an aggressive attempt to shut down or shout down. Please don’t do that, let people share their understanding and experiences. The last thing people working on their health improvement need is the “but it’s all so simple” lecture; we get enough of a hard time as it is, and trust me, we’ve heard “but if you just eat less everything will work out for you” a thousand times. (It’s really just a version of the reality that many anorexics assert for themselves.)

If health-improving weight loss were really as simple as you envision — using starvation would be the obvious limiting case, for people — you would think there would be some solid medical evidence in the medical literature. And nobody wants health-destroying weight loss (not even the anorexics who might be resigned to it). You’re considering weight loss in a vacuum, but in a vacuum, the really obvious weight loss solution has nothing to do with eating: just saw off some of your body parts. Boom, you lose 40% of your body mass in like twenty minutes. It’s a trade-off, right? Some people will prefer the ‘vanity’ of having limbs?


John Quiggin 01.28.13 at 4:35 am

A large proportion of the comments on this thread appear to be restatements of footnote 1, but with the implication that it’s too important for a footnote. At least that’s how I read them. Is anyone actually claiming that

(a) the law of conservation of energy doesn’t apply to humans; or
(b) that losing weight is not merely difficult, but impossible, because of feedback mechanisms etc.

If not, then we seem to be in excessively furious agreement. If anyone does want to claim (a) or (b), I’ll be happy to set them straight.


Mao Cheng Ji 01.28.13 at 6:55 am

97,98. What in god’s name would compel a person to type this?


genauer 01.28.13 at 12:29 pm

@ all,

Since some folks here are familiar with scientific papers with respect to weight / health:

What is your favourite / convincing study, that (substantial) weight loss in which way is good for your health, as in “lower mortality”?

Because when I look stuff up, like
you find that they have stopped it, that the benefits of weight loss werent there,

and that a certain type of ideological demgagogues then nearly always try to reinterpret the findings. e.g. ” this study and others ”
“modest weight loss has been shown to prevent or delay developing type 2 diabetes”

No, this study did not show this, the folks had already diabetes 2 going into this study.

And this systematically dishonest behavior of the hunger fanatics is extremely typical.
In fact they have to carefully sort out the many cases of “reverse causation”

“Weight loss is associated with particularly high mortality risk even when the typical BMI change is from obesity to overweight.”

But I am interested to hear from the other side.


you came across as pretty arrogant. Not that this would ever happen to me … LOL.
And sometimes this triggers reactions, like from Salient.

And since we are at the 7 deadly sins, you might not indulge in gluttony, but beyond your self admitted vanity I also definitely detect superbia : – )

Your loose talk, and the similar from many others, drives millions every days to unhealthy weight reduction efforts. You dont see most of that in a university mensa with 20 somethings. But go into a company cafeteria with folks in the 30ties – 50ties, and also look at energy levels in meetings before and after lunch. So many people, who try to conform to some supposed social norm, stirred by comments like

Your “Difficult for some, not so hard for others, and it also depends on your priorities”.

You deserve the ear wash, you got from “salient” : – )


Hektor Bim 01.28.13 at 12:32 pm

John Quiggin,

If I were to restate your post, I’d say that footnote 1 should be in the main body of the text and that the whole calories in versus calories out should be in the footnote. Mainly because that paradigm is not very helpful to many people.


Salient 01.28.13 at 12:35 pm

100. Well, Mao, it’s not pleasant to go back and explain a statement I regretted sending as soon as I clicked, so, I apologize for #97 as unnecessary/inappropriate reaction to perceived aggression, but I’m standing by #98 completely.

You’ve been encouraging (by providing arguments for) starvation diets as panacea, you’ve responded dismissively to people who pointed out how/why that’s bad logic supporting a bad idea by suggesting they can see your logic in action by intentionally under-feeding their pets, and you’re telling people who repeatedly try and explain why starve-until-you-lose is a terrible idea that “all that complexity is irrelevant.” I don’t believe you literally want people to intentionally under-feed their pets, but it’s still an awful thing to say, and does nothing to further your point. (If you don’t see how it’s awful, consider if you had replaced pets with children. Telling people “if you don’t believe me, go commit this atrocity and see what happens” is plainly aggressive.)

You’re repeating the shaming motto “if you want to lose weight, you just have to eat less,” and making the shaming explicit by stating those who don’t follow your dictum must “prefer to indulge in gluttony at the expense of vanity.” (Contrast with what JQ has said, which takes pains to avoid shaming.) The contextualization you’re pushing is a pretty low blow to people who are struggling with health, and it’s an especially low blow to people who are struggling with an unhealthy predisposition to psychologically compelling vanity. (The folks on the ‘vanity’ side of your spectrum being, obviously, anorexics and bulimics.) To make the shaming more explicit, in case you’re honestly unmindful of it, here’s what you’re saying: If you really want to lose weight, just eat less and put up with the suffering this causes you, you delicate little flower. If you don’t do that, you must not really want to lose the weight, so just admit you’d rather be an overfed fat fuck already, geez.

The conceit is this: there’s nobody on your proposed spectrum that’s trying to develop a more able body or healthier lifestyle. (Contrast with JQ’s plainly stated interest in how to improve health/athleticism.) If you acknowledged that the vast majority of individuals contemplating weight loss are seeking to maintain or even improve their body’s health, the entirety of your proposal immediately falls apart completely in every meaningful way. It’s very very easy to devise a plan to lose weight, but for people already struggling with health conditions — including obesity — it’s damned difficult to do so in a way that will improve their short-term health without compromising their long-term health, and it’s extra damned difficult to do so if they’ve been using food as a form of medication for pain or stress.

The logic you are arguing for has led a lot of people to compromise their health by failing to understand the consequences of undernourishment. It’s a pernicious line of argument. And that’s the whole point, that’s what people have been trying to get you to understand, with remarkable patience and kindness (except me).

All that as it is, what pushed me to respond: You responded to the very patient “Your body unlike your car can spontaneously change its efficiency in response to the wide variety of nutrients available” with So what? “What else is there to talk about?” Obviously, how the body changes its efficiency in response to the wide variety of nutrients available is the already-given answer to your question. When you respond to information by demanding that information, that’s only coherent as an act of aggression — you’re not honestly asking, you’re using the question rhetorically as a replacement for SHUT UP SHUT UP SHUT UP.

And the last time I recall that rhetorical tactic being used, it was druggies literally getting in the face of other Occupy Assembly folks, literally standing half an inch from people’s faces spitting ‘The Assembly has been following all the agreed-upon rules for financial disclosure. What else is there to talk about, b–? Huh? What else is there to talk about?’ If you honestly asked that question hoping to learn what else is there to talk about, instead of to aggressively assert that there is nothing else to talk about shut up shut up shut up, then I’ll retract my entire reaction with apologies (and with a lot of genuine puzzlement; you’re not in terribly good rhetorical company, and people have been trying to provide answers to that question before you asked it.) On the other hand, if you weren’t asking with genuine curiosity and interest–which still seems like the more plausible interpretation, to me–then I don’t feel terribly bad about my latter comment (#98), and hopefully this comment helps answer your question about what compels a person to say the kind of thing I said in the kind of context in which I said it.


Katherine 01.28.13 at 1:12 pm

Salient, your comments continue to be sensible and interesting, and I don’t blame you for being impatient. I’ve stayed well, well away from this thread simply because I’ve found there’s nothing but pain involved in debating weight on the internet. Unless you’re doing so in some very specific places, someone will always come along and say fat people are obviously just lazy because losing weight is just about consuming fewer calories, complexity be damned.


Mao Cheng Ji 01.29.13 at 12:41 pm

103. Ah. Yes, I am, in fact, a puppy-eating zombie Nazi, but that doesn’t negate the laws of physics.
…except maybe for the zombie part.

And your hatred for me, for what the society made me, is … despicable.


Tinky 01.30.13 at 6:37 am

For those interested in one of, if not the most informative site relating to this topic, I strongly recommend Stephan Guyenet’s blog. He is a esearcher investigating the causes of obesity and the regulation of body fat by the brain, and his blog is a treasure trove of interesting and useful information. Here’s the link:


Salient 01.30.13 at 5:40 pm

Argleblarg. But eating the puppy would increase your body mass!

It’s a relief that we’re at the making fun of ourselves / mistaking exasperation for hatred stage of disagreement, where we get to use adjectives and then give it a rest. So. Under the almighty laws of immutable physics, the quickest way to lose weight is to lose body mass, so, I dunno, just take a chainsaw to your midsection, or, if you prefer for the lost energy to be used for something, self-immolate. That is a completely consistent application of the physical laws you are citing, and both options are considerably faster at reducing your body mass than the slow drain of starvation (or the far slower drain of nonzero-but-lowered calorie intake).

If we’re going to take biology/physiology/medicine into account, and discuss only health-improving forms of weight loss, then nonzero-but-lowered calorie intake is definitely in the suite of reasonable options, buuuuut, you really don’t want to rest your case for it on a line of supporting argument that works even better for advocating a chainsaw or immolation mass-loss plan. Argleblarrrg!


Trader Joe 01.30.13 at 9:09 pm

I find that reading a few of these posts right before lunch really helps reduce my appetite.

It remains to be seen whether this will result in my losing any weight : )

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