They are also followed medically more closely than just about anyone on Earth: they don’t indulge in regular fast food I wonder what they mean by that. Are ast

They are also followed medically more closely than just about anyone on Earth: they don’t indulge in regular fast food I wonder what they mean by that. Are astronauts explicitly banned from eating fast food, and somehow monitored? Or are they just less likely to eat fast food, since they pay close attention to their fitness and health?