Eli5: why are humming birds and flys metabolisms so fast when your motabolism speeds up the more mass you have?

Question

Edit: spelling errors

In: 2

Answer 1

I don’t know where you’ve heard that second part, but it’s backwards. I don’t know how fast is a fly’s metabolism, but most small animals (warm blooded anyway) have faster metabolism, because they shed heat faster (square-cube law) and therefore need to generate it faster. Plus, for something like a hummingbird, they also need to generate A LOT of energy to power those wings.