[panarky]

The idea that the only way to lose weight is to reduce calorie intake to below calorie burn is not true in any practical sense.

And it's not just a matter of willpower.

If you add up the calories in the food you eat, then subtract the calories you burn through exercise, respiration, beating heart, etc., you cannot compute weight gain or loss.

That's because the body doesn't use 100% of calories in food. Some calories are never absorbed and are excreted as waste. And if you eat a big meal and then you don't exercise immediately to offset it, the excess calories are not automatically converted to fat.

And different bodies have different metabolisms, which is nearly impossible to quantify in any practical way. In fact, cutting back on calorie intake can actually cause some bodies to add fat.

So the whole idea of applying a simplistic equation to a complex and dynamic process like this probably does more harm than good.