The whole egg, yolk and all.
"One egg contains just 70 calories with 6 grams of high-quality protein, and contrary to popular belief, most of the fat in the yolk is unsaturated," says Sass. Plus, eggs are a weight-loss food, she says. Dieters who ate eggs for breakfast lost 65% more weight than those who ate a bagel for breakfast that was equal in calories.
Sass suggests picking up organic eggs (the chickens are fed a healthier, all-vegetarian diet without hormones or antibiotics). Begun is an egg-eater, too: she prepares them several times per week in a veggie omelet or scrambled with sautéed leafy greens.