For the most part, I've learned to control my munchies. Doesn't mean that I don't love eating when vaked though! When I feel like letting my munchies run free, I prepare healthy food ahead of time. Large amounts of fruits & veggies or lots of salad. Sometimes I find something low calorie to dip the fruits or veggies in, and I try to use a vinaigrette with the salads. Sometimes I add some roasted chicken to the salad. When you're vaked, all that shit taste AMAZING
When I'm having a difficult time stopping myself from munching, I'll try to drink a lot of liquids to fill my stomach. Personally, I like yerba mate tea. Just make sure whatever you drink is low in sugar/fat so you can just keep enjoying it without worrying.
EDIT: jeffp & Stu got it right, at least in my opinion. There may be biochemical reasons for the munchies, but it really can be controlled. I just realized that this is what I do. Do more productive/entertaining things while high, and food isn't so important anymore. Just like bad trips, munchies are all in the mind.