Players obviously get smashed in preseasons but in season it's not like you have time to do huge amounts of pure fitness. Players drinking and/or eating stuff they shouldn't is largely down to them. Ultimately I think they have to fix that themselves through discipline.
So, I know first hand from the Sports Nutritionist who was brought in by Brad Thorn for the Reds, that the Reds did little to help with this aspect prior to Brad coming in.
Players had no idea how to properly fuel themselves before, during and after training. They had no idea how much protein/carb they needed and how to make good, smart food choices. Simply telling a 18/22 year old "make sure you eat and drink" is useless when they have had no education on what is actually required of them.
Hell, the Reds didn't have Gels and other in-game supplements until Brad brought them in.
The Reds did not have food on hand before/after training sessions and if they did it was never enough resulting in players having to leave to go to Subway/Nandos.