[ELI5] Which part of macronutrients turn into feces?

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Lately, I’ve been delving deeply into macronutrients, and from what I’ve gathered, food primarily consists of carbohydrates (starches, sugars, fiber), fats ([un]/saturated, trans fat), and proteins.

However, I’m still struggling to grasp which calories listed in the food labels are converted into faeces. Could someone please help me break it down?

In: Biology

3 Answers

Anonymous 0 Comments

What is your source saying trans fat? Trans fat was quickly banned and should not be in any substantial amounts in most food.

Anonymous 0 Comments

Nutrients are, by definition, absorbed into the body. Maybe not completely, but mostly. Feces are mostly things that can’t be absorbed, such as fibers, plus digestive juices and gut bacteria, with most of the water absorbed.
Once absorbed, nutrients are broken down and used by the body, and the waste products are mostly either exhaled or expelled in the urine.

Anonymous 0 Comments

Solid waste is mostly dietary fiber. If you are going to insist on categorizing everything as a macronutrient, this is a carbohydrate, but it is in a form that our bodies find essentially impossible to digest. Green vegetables are mostly fiber and water, which is why they have essentially no calories despite their considerable mass. Lots of herbivores can properly digest these materials, which is how cows and horses live on a diet of just grass. Other plant products contain fiber too, just mixed in with digestible carbs (fruits and grains), protein (beans),and/or fats (nuts).