[Kirby64]

> Also, calories in calories out is bunk. It's true to some degree in that they are related, but ignores the fact that (1) how much your body is spending is highly variable, even somewhat independent of movement -- imagine how much energy your body has to spend to fight an infection for example

The human body is not that variant. Sure, during illness you may burn more calories from the illness and potential fever… but you’re also usually extremely low on movement since your body physically makes you exhausted. The rest of the time though? No way. Humans generally are not that variant in expenditure.

> (2) why would anyone imagine every calorie consumed will actually be absorbed? the gut is highly complex and depending on many factors calories could be absorbed or go right out the other end unused, and the gut flora interacts complexly with all this. Focus on eating healthy things first above healthy amounts. It's easier, and will have a positive impact all its own, creating another stepping stone towards other goals.

What evidence do you have to the contrary? The human body is extremely efficient at absorbing calories, and outside of extremes (eating 10kcal a day, or having some sort of deficiency such as celiacs that doesn’t let you digest certain things), I see no reason why you don’t absorb the vast, vast majority of all calories consumed.

[galdosdi]

Even something as commonplace as chewing more carelessly will result in finding seeds in your faeces.

But what's the point of giving you more specific examples? You seem to be eager to "no true scotsman" your way out of this by labelling every example of varying calorie consumption as an exception.

Even the top article referenced in this wikipedia article admits it's based on a study of bushmen who -- surprise surprise -- were in very healthy average weight and also did tremendous physical activity. What a coincidence. But sure, keep telling yourself exercise doesn't matter and it's all about Calories In Calories Out and that the body is as trivial and simple a machine as an internal combustion engine.

[Kirby64]

> Even something as commonplace as chewing more carelessly will result in finding seeds in your faeces.

Most people’s diets do not consist of fully intact seeds, or at very least it is not a large proportion of their calories. And any processing of said seeds would give you all the calories in them. This is a trivial example to discard, since most people do not have undigested food bits consistently in their stool (unless you constantly eat corn, then maybe).

To be clear, I never said exercise is not capable of burning calories. It clearly does, however the impact is pretty muted compared to the relatively easy task of adjusting one’s intake. For people that have to do enormous physical activity or just walk a ton, they are going to burn quite a bit more calories. But your natural expenditure individually doesn’t vary that much unless you wildly change your behavior around exercise.

[galdosdi]

And my point that I've repeated over and over, is that the benefit of exercise is far broader than just merely numerically burning calories. It is in all these other beneficial effects that it can indirectly help. Focusing solely on calories in calories out is a big mistake when improving health and/or tackling obesity.

[Kirby64]

> Focusing solely on calories in calories out is a big mistake when improving health and/or tackling obesity.

For improving health? Certainly I’d agree. You have to be quite overweight before the risk factors really catch up.

For tackling obesity? Absolutely disagree. You’re asking someone who is likely making poor choices with food and exercise to make multiple lifestyle changes. We want something that’s going to be able to adherent to the broader populous. Saying you need both exercise and dieting to lose weight is a setup for failure. The predominantly most important factor in losing weight is diet. Exercise helps you be more healthy, but doesn’t meaningfully help you lose weight.