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

You breath it out.

You breath in air that is about 20% Oxygen. That oxygen is used up by your body and when exhaled, has an extra Carbon atom attached (CO2).