no 

Animals under natural conditions? I think even humans who spend most of their time and strength keeping themselves and their family alive will not suffer from these illnesses.

Pets do a lot of things humans do and wild animals don't, like being grown-up and still playing. But I think a pet that feels unloved (which I think might happen) will not feel it's because it LOOKS bad.

Though some cats and dogs who live with humans all their lives definitely can be proud or ashamed of something new in their looks, like a shave.

But to worry about being FAT... and to get the connection between being fat and eating... I should say NO. They aren't smart enough to be so stupid.

I agree with the foregoing answers. In particular, if the idea is of a mental condition related to self-image or social position, I cannot think of any animal that has a clear mental connection between its diet and its attractiveness. Most animals anyway do not encounter such supplies of food that they can overeat to any great extent, and most others stop when they have had enough. Sometimes baby animals being raised by soft-hearted humans die of overfeeding, but that is hardly a close analogy.

When there is a disease or injury, things may become more complicated. A parasitised animal for example, might stop eating or may overeat when the parasite damages its brain, but again, that animal is not what you might call a "going concern", a functional creature in its own right; it is more like a puppet.

And that still doesn't look much like bulimia or anorexia, or even gluttony  to me!

Urrp!

'Scuse me!

Jon