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

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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?

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24 Answers

Anonymous 0 Comments

This is quite complex and depends on a lot of things. Firstly a lot of the food is just water and will be absorbed into the blood stream and end up in the urine. Similarly a lot of vitamins and minerals will take the same way unless it is actually used in the body. And then there is protein which can be converted to carbohydrates but only through a process that uses energy. So you might start with two amino acids and get one glucose molecule from it, the remainder will turn into carbon dioxide which you breathe out or other molecules that goes out with the urine. There is also some loss when breaking down longer carbohydrates like starch and fibers as well as when converting carbohydrates into fat.

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