Can the government have a food mandate, which decides what we can or cannot eat to “keep us healthy”?

Considering that 2/3 of Americans are either obese or overweight, a food mandate sounds like a great idea to keep people healthy. I can foresee people saying “how are they going to do that?”, let's just assume there was a way to do it. Would the government be allowed to do it? And where does their mandate power stop?

I don't know if there's going to be different answers for state and federal governments, but if there was, both answers would be appreciated.