On this topic, I think they have to be professional about what they eat, drink, shag and so forth. The thing is that some might say they are not supposed to smoke or drink, but there are plenty of them who does, even in their haydays. Gazza is one, Teddy Shringham is another, Didi Hamman is another that I can remember. Apart from that, most of them would drink champagne rather than beer or hard liquor, reason being champagne is easier to be broken down by their body, and of course, made them look 100 times more classy than say a bottle of scotch.

Like giotto said, the days of them downing a pint or 10 after a match / training session and whatever is gone, most of them don't even drink.

On your question on protein pewder, i am sure that they do take some sort of supplement to help as most of these are quick fixes, but of course, it doesn't beat the real thing, milk and meat.