If to gain 1 pound (450 grams) you need to eat 3500 calories over your maintenance, how does it make sense that eating 400 grams of straight oil (which is 3536 calories) leads to a 450g gain which is more than the weight of excess food Where does the roughly 50 extra grams come from?

Question

If to gain 1 pound (450 grams) you need to eat 3500 calories over your maintenance, how does it make sense that eating 400 grams of straight oil (which is 3536 calories) leads to a 450g gain which is more than the weight of excess food Where does the roughly 50 extra grams come from?

In: Biology

Answer 1

Fats and oils are virtually all just carbon and hydrogen atoms with a few oxygens. When they are digested, other atoms, chiefly more oxygen, will be incorporated. The first stage to break down a fat molecule is to split off separate fatty acids from the glycerol molecule that holds them together. The net difference is the addition of three extra molecules of water so the products are heavier than the starting material.

(Very simplified chemistry for ELI5)