That doesn't make sense. If calories are all that matter, then simple math shows that being off by 2% over the course of the years easily leads to weight loss or gains. You've seen this math numerous times in the context of "if you just didn't eat one donut hole a day you'd weight X pounds less a year". If the labels are off by 10% or 30%, then it can't be just "calories are all that matter"; you'd be losing or gaining a dozen pounds a year, unexpectedly vs. what your projections expected.

If, of course, the body is a dynamic process that reacts to what it encounters in the world, then of course the dynamic reaction is what dominates the situation, not percentages of error in calorie counting.

(The way the nutritionists managed to turn "The body reacts dynamically to incoming input" into unthinkable heresy in favor of a model in which the body is essentially modeled as a hapless passive recipient of "calories" with no feedback loop will someday be seen right up there with pholostigon theory, except less excusable. Any time you speak of a bodily process and aren't thinking about the feedback loops, you've bounded your best-case outcome to "utter failure" before taking the first step.)

I think the point is that if you reduce your possibly inaccurately calculated calorie intake until you start losing weight and then keep your intake steady it doesn't matter if that value is 1000 or 100,000. Over time the method will definitely work.

To calculate weight loss or weight gain (by counting calories) you need to know how many calories you eat and how many calories you burn. Since the latter is nearly impossible to guess, it's usually estimated with the first one and weight loss during the first month.

This automatically adjusts to any error in the calorie estimation.

Lets say someone eats 2000 kcal a day, but the "real" number is actually 1900 kcal. Lets also assume that in fact his weight maintenance level is 1900 kcal. After a month the person has neither lost nor gained any weight. This person will then incorrectly assume that his true maintenance level is actually 2000 kcal, and reduce his estimated calories to 1900 kcal, thus starting the weight loss process.

Yes, it would be nice to get perfect estimates, but it doesn't matter much in the weight loss or weight gain process. In addition, most people don't have a deficit or surplus of a mere 100 kcal, it can be 500 to 1000 kcal, which makes the error in "true" calories even less important.

This x10. I lost 43 lbs in 6 months upping my calorie intake by 500-1000 calories a day. But I drastically changed what types of calories I ate. I also halved my triglycerides, and brought my HDL and LDL levels far into the healthy ranges.

All by cutting out grains and sugar and replacing them with lots and lots of vegetables and meat (I'm lying, it was mostly bacon).

To a person who vehemently believes in the thermodynamic weight loss hypothesis (calories in minus calories out!), it would be more convenient if your anecdote, and others like it, did not exist.

For weight, it's always calories in vs calories out.

Scientifically sound food recommendations [1] accept that different types of calories make you feel more or less full.

If you supplied your entire day's calories in sugar, you'd be insanely hungry.

While short-term weight loss studies from the 90s focus on calorie counts, modern studies take a longer term view and examine how well weight is maintained based on diet.

This is where the type of calorie becomes important for most people in weight regulation. (vitamins etc are another topic)

[1] http://www.hsph.harvard.edu/nutritionsource/healthy-eating-p...

"At the end of the day, it's always calories in vs calories out.

Scientifically sound food recommendations [1] accept that different types of calories make you feel more or less full."

That's a contradiction. The entire idea of "calories in, calories out" is precisely that there is no difference and all calories are exactly the same. If some make you feel less full than others, then you're invoking the existence of the feedback loop that "calories in, calories out" explicitly denies.

If you, as this article does, point out that many things affect whether a calorie can be absorbed, that is, again, another difference between calories.

If modern science is moving on... and it is, at an inexcusably sluggish pace... it's moving on from "calories in, calories out". There's really no way to salvage it... even if you want to go with "calories digested vs. expended" you've still got a complicated feedback loop even there between the pancreas, insulin, blood stream, various bits of the brain, the metabolic consumers of blood sugar (significant differences here too between muscles vs. organs), etc, and even two people who hypothetically start with the exact same blood sugar levels and digestive system state will rapidly diverge as this feedback loop does different things between them. "Calories in, calories out" is only true as a limit on the system of the bodies, it isn't even remotely suitable for use as "the only parameter in a model, which gets set to a constant value". (What other bodily function works so simply? What makes digestion so bizzarely unique that it can be modeled so simply? None and nothing.)

(And a rather pointless limit in some ways, too... nobody is running around claiming that the human digestive system is an over-unity perpetual motion machine, so making such a big deal about thermodynamic limits is rather silly.)

> That's a contradiction.

No, its not.

> The entire idea of "calories in, calories out" is precisely that there is no difference and all calories are exactly the same.

The idea is that they are the same to the extent that net calorie consumption, irrespective of source, determines weight loss. Effects on satiety and other effects which influence the ability of the dieter to adhere that come with different calorie sources are not ruled out by "calories in vs. calories out" approach, which doesn't hold that all calories are equal in there influence on your ability to maintain a diet regime, but only that they are equivalent in their effect on your weight when you consume them.

This is not to say that "calories in vs. calories out" is right or useful, just that this particular effect isn't inconsistent with it (though it is one of the less important reasons its of limited utility.)

That's not true. If some calories are not absorbed, then they're not really "in", are they?

This partially expresses what I wanted to reply.

The other part is that food calories are the amount of energy needed to raise the temperature of one kilogram of water by one degree celsius. By that definition, calories in vs calories out seems pretty darn close to reality, and if it's not perfect, it's likely so close you're not going to notice a significant difference.

It works exactly the same for me. I approximately know how much calories I should eat during the day and if I keep below it I slowly but steadily lose weight. It does not even matter what I eat, as long as I stay below the threshold I will lose weight.

At the moment though I am gaining weight. My life is stressful at the moment and one way of dealing with this is eating tons of food. Because of this I gained about 10 kg during the last year.