These fruits are loaded with vitamin C, which your body needs to make a compound called carnitine. “Carnitine shuttles fat into the muscles where it can be used for energy,” explains Carol Johnston, PhD, RD, director of the nutrition program at Arizona State University. “And when you use fat for fuel [instead of glucose], you can exercise for longer periods of time without feeling fatigued.” In onestudy, taking a 500-mg vitamin C supplement also increased physical-work efficiency.

On your plate
Squeeze lemon juice over greens and pasta salads, and in your water or tea; top salads with mandarin or clementine sections; and scoop out half a grapefruit for breakfast. Other vitamin C–rich foods: peppers, broccoli, papaya, and mangoes.

Grapefruit, Avocado. and Watercress Salad with Tarrago-Yogurt Dressing
Napa Cabbage, Orange, and Almond Salad
Pomegranate, Fennel, and Blood Orange Salad


After years of getting a bad rap for their high cholesterol content, eggs are making a comeback. “They consistently outrank milk, beef, whey, and soy in terms of protein quality,” says Jonny Bowden, PhD, CNS, author of The 150 Most Effective Ways to Boost Your Energy (Fair Winds, 2008). Nutrient-rich eggs contain all nine essential amino acids (called essential because your body can’t make them). Just don’t ditch the yolk, which contains choline, a nutrient in the B vitamin family shown to be critical for memory and thought.

On your plate
Cut a hard-boiled egg into your lunch salad; scramble eggs with sautéed vegetables; or crack two eggs into an oversized, lightly oiled mug, add some reduced-fat cheese, microwave for 30 seconds (check for doneness and continue cooking in 10-second intervals, if necessary), and then sandwich the “omelet” between whole-grain bread slices.

Morrocan-Style Egg Soup
Sauteed Onion Salad with Egg
Spinach Salad with Eggs and Watercress Dressing