Eli5: When you go to sleep weighing a certain amount and wake up weighing less. Where did that weight go?

Question

Eli5: When you go to sleep weighing a certain amount and wake up weighing less. Where did that weight go?

In: Biology

Answer 1

There’s two main sources of weight loss.

Any fat/carbohydrate burning done (by your metabolism to keep you alive if nothing else) will create CO2 and H2O vapor, and breathing it out will be fat/carbs that are no longer weighing you down.

Your body is constantly using water for a number of other things as well, and as that water evaporates/is wicked off by your bedding, it is (water) weight lost.