Calories in, calories out is completely accurate and ironclad as an observation or description of obesity. No doubt some cases of obesity can be solved with red

Calories in, calories out is completely accurate and ironclad as an observation or description of obesity. No doubt some cases of obesity can be solved with reducing calories in (eating less) or increasing calories out (more activity). Indeed, we have existence proofs, because there are people who beat obesity in this way. Unfortunately, it seems like many cases of obesity - perhaps the vast majority, though we don’t know for sure - are not as amenable to these solutions. If you reduce calories in by eating less, the body often compensates by reducing energy out (lethargy), quite happily reducing energy levels below what’s needed in the modern era e.g. to continue to go to work. If you try to increase calories out by exercising, the body often compensates by taking that energy from your base metabolic rate, reducing energy expenditure on other things like body maintenance (getting sick, being in pain) or brain expenditure (causing brain fog). And perhaps most pernicious of all, the mechanism for both (decreasing calories in, increasing calories out) is exertion of willpower, which is a biological process that happens in the brain and as such the body can influence that process (often with hormones), decreasing your willpower and robbing you of the ability to will yourself to eat less or exercise more. We shouldn’t be surprised at this, either. Obesity is not a pleasant condition and almost every obese person would be thin if it was an easy choice to make. Yet we have an epidemic of obesity that has proven very difficult to fix, so we should suspect that something more than simple choice is going on here.