How much food is absorbed, and how much comes out again?

Question

I always thought that most of the food comes out again after nutrients are absorbed.

For example, here is a can of noodles. It says the 800gr in the can have a total of something like 600kcal. If the entire can would be converted into fat, this would have to be about 5500 kcal. That would mean that about 90% of it comes out again.

But sometimes I eat and eat and eat and a lot less is coming out then went in.

So, how much food is actually coming out again after being processed in the body?

In: 128

Answer 1

Everything that goes in must come out (eventually) one way or another.

Some will come out as air as you chew, some will be waste, some will be used in the body to make energy or build muscle/skin/hair/fat.