Budget your food as you do your money. A rough guideline for daily caloric intake: Multiply your ideal body weight by 10 (i.e., 1,200 calories if you want to weigh 120 pounds) and then add another 600 calories if you're moderately active, a few hundred more if you're very active. Divide those calories out across the day to keep yourself well fed.

-Nancy Clark, a registered dietician, author and sports nutritionist with a practice at Healthworks Fitness Center in Chestnut Hill