Why is it the calorie count of food, and not the mass, that determines weight gain?

Question

Why is it the calorie count of food, and not the mass, that determines weight gain?

In: 2

Answer 1

Your body will expel anything it can’t process and usefully store/use. Generally it can only use the calories to convert to bodymass.

The easiest way to visualise it is water. If you drink a litre of water then yeah immediately you will be 1kg heavier. But give it a few hours and your body gets rid of it anyway so there’s no net gain. It can’t turn water to fat, it uses it internally then gets rid of it.

Normal food has water in it that adds to weight without adding to calories. There’s also other things in there that your body can’t process usefully (fibre is one of them) to convert to fat so they just get rid of.