It is best to eat smaller meals more frequently.  This technique prevents binge eating of unhealthy foods.  On multiple occassions, when I get too busy to stop and eat a little snack, I ended up either indulging in a vending machine candy bar or eating too much pizza.  Both of which contain more fat and calories than a small, healthier, snack would have.  If I had eaten a piece of fruit or even a peanut butter and jelly sandwich, I would have consumed more healthy nutrients.