This is an interesting discussion about body fat.
I don’t think it hits the answer since I have dogs that get fat if not kept on limited intake, however a I have a young dog who just is muscle–no fat anywhere a pit bull. Another pit bull–same way–muscled. .
Cats, horses, cows, pigs don’t fit the theory proposed. Do birds get fat–not likely.
Comparison of chimp fat percentage is impressive though.
I am not willing to tell what my fat level is–but you can go to those spa places and they put you in a tub and give you a percentage fat so you can compare to your fatter friends.
Fat is like a gas tank, energy available–so I could easily survive a period of starvation if I had enough water.