For runners without eating disorders, under-eating may simply be a failure to increase calories with higher training loads.

To increase calories, use more fruit juices or dried fruits rather than whole fruits.

"Strength training builds muscles, which increases metabolism and burns more calories."

Ephedra, an adrenalinelike stimulant promoted as a weight-loss aid and energy booster, excites the central nervous system and speeds metabolism, increasing the rate at which a person burns calories.

Turns out, just 300 liquid calories a day increase the risk of weight gain and diabetes - and many summer sippers have so much more!

Nutritional deficiencies can be minimized by modifying the texture and consistency of the diet and by adding more frequent meals and snacks to increase calories and protein.

"On average, most people lose 6-8 pounds in the first phase, then it slows down to a few pounds a week in the other phases as you increase calories," he says.