eli5: Why are herbivorous animals usually fatter/bigger than carnivorous animals?

Question

eli5: Why are herbivorous animals usually fatter/bigger than carnivorous animals?

In: 119

Answer 1

Herbivorous animals look “fat” because they need a large digestive system. Cows eat grass, it gets cut in small pieces and disolved so the bacteria can break down the celluloce in the feed. The reason why they don’t need protein in their food is that they get it from digesting the bacteria in the gut.