It's not easy. I go out, run six miles and burn 600 calories. I come home and I'm really hungry. I eat some soup, a bowl of ice cream, some fruit, some raisin toast, a couple handfuls of candy, a glass of milk... I'm still hungry and I'm WAY over 600 calories.
OTOH, my waist size went from 31 to 35 in a few years just before I started running. After I started running my weight dropped from 162 to 154 and my waist down to 33. 11 years later my weight is back up to 160, but my waist is still 33.
I'm not seeing too many of my peers with 33 inch waists nowadays, and most of them seem to be constantly trying to watch what they eat. So SOMEthing is working. Maybe it's true that your metabolism stays high long after you've finished exercising?
Enough blogging, I'm hungry!