Think about it. If you could fly and had super strength from the sun, wouldn't you just be a vat of fat? And how the heck is he going to work out, anyway?
I don't think he'd necessarily be fat but I've thought about it before. Shouldn't he be scrawny? I mean, how is he working out to get those muscles?
Yes, but they really don't hint at it the way they do with The Flash. In the movie and the tv series they've referenced how much he consumes in terms of food or how he can't really get sh** faced due to his high metabolism. So essentially Supes could be fat as hell if he wanted to be.
All of you are assuming he’s human. He’s a Kryptonian. These measly human characteristics do not apply to the superior anatomy of one from Krypton. In a nutshell, Kal-El is just a Kryptonian in average kryptonian shape. That’s why he usually gets his ass beat when the odds are even.