I've always understood "fat chance" to be ironic, so I'm sticking to my preferred chance being morbidly obese

"fat chance (of that happening)" is always sarcasm

Chances are Fatboy Slim

thicc

Well since BMI is a horrible metric for anything it really doesn't matter.

I can only ever succeed if the odds are stacked, that says something about me but I'm not sure what

Oh no problem, buff baddie that’s gonna work out.

"The chances are in-shape and visit the gym at least 3 times a week"

“There’s a dad-bod chance of that happening”