It's weird, I'm a recovering binge eater, and I've never once gotten 'the munchies'. If anything I tend to eat less when I'm stoned, even just a bit.
When I was first starting to go to the gym, years and years ago, I was told that a couple of puffs before lifting was the way to go, then save the rest of the joint for when you get home. I did it once, and was so bloody paranoid that I've not tried it since. Granted, back then I had virtually no tolerance. And now I have no more sources, so I can't repeat the experiment. Besides, my lungs are in rough shape, so if I had some herb I'd probably rather not smoke it anyway.