We all know how athletic and physically taxing drumming can be. Approach it as if you're going on a double-century bike ride or you're about to participate in a full-court basketball game.

I make certain that I take vitamins regularly, especially before a show. Also, I use Smartwater (not the flavored one). It has potassium and other goodies.  Remain hydrated. I'll eat a few hours before the gig and then take along some type of Power Bar or Met-Rx bar for extra energy.

I also take along a little container of all-natural bee pollen (consult your physician before using). That stuff has real kick.

That helps provide the energy when I need it. Eating after the gig may feel good, but it's energy provided too late and is more likely to turn into fat.

I was on a schedule that had me eating at about 10:00 and going to bed around 10:45. I didn't gain any weight and wasn't effected badly by it. My only thought was that I would get acid reflux. I didn't have that problem.
You are burning lots of calories playing and you should probably replace them. The challenge is eating healthy food and not stopping at the Krystal.
Have somthing planned to eat when you get home. It shouldn't be too much food. And stay hydrated, as has already been mentioned, during the gig.

It's the raw pollen and not the processed tablets. I should have said it this way.