Anyone who exercises intensely regularly will know the answer which is, of course, significant cardiovascular exercise. It always amazes me how my appetite, especially for sweets, dramatically decreases after exercise. Now Japanese investigators have performed rat experiments that validate this observation. My guess is the mechanism is related to a dramatic reduction in insulin levels after exercise. Elevated insulin levels are one of the primary reasons for food cravings and if the insulin level is reduced many of these cravings disappear. So if you haven't already picked up the exercise habit, here is a powerful motivation to do so if you struggle with sweet cravings.
Experimental Biology 2004 Conference Washington D.C. April 20, 2004