If you had to replace our diet with the diet of a different animal

[Mirage]

They don't need a small amount of food because of what they eat, but because of their own size. You're getting their diet, not their daily energy requirements. You'd have to eat like a bucket of trash a day.

Flies don't have to eat a bucket of trash a day - they can eat pretty much everything humans eat, can't they? I imagine that, when compared to other animals, ants/flies/cockroaches probably can get by with a fairly "human" diet.

Yes, they could, but almost every group of animals could eat tons of the same food humans eat, if they just avoid a few ingredients. A dog could eat steak, a cat could eat fried eggs, a bear could eat sliced bread with honey on. So it's really just breaking the point of the thread.