20 Fittest Foods

10) Beef
163 calories per 3-oz serving
Eat 3-4 servings per week
It's not only high in muscle-building amino acids, it's also a powerhouse of iron and zinc, which aid circulatory health. In fact, beef is so nutrient-dense that a three-ounce serving supplies more than 10% of your recommended daily intake of a number of nutrients, including protein, B6 and B12, selenium, phosphorus, niacin, and riboflavin. Worried about the fat? Don't. According to USDA data, today's beef is up to 20% leaner than it was a decade ago. In fact, 19 cuts of beef meet government guidelines as being a lean meat. To keep the meat you're buying lean as well as tender and flavorful, opt for cuts with the words round or top in the name-things like eye round roast, top round, or top sirloin steak.

9) Whole-Wheat Bread
140 calories per 2 slices
Eat 6 slices per week
White flour doesn't just rob you of fiber and protein, it also digests incredibly quickly in the body, giving you a rapid spike of energy-but one that comes crashing down just as fast. Over time, those spikes in insulin production wear on the body, damaging cells and promoting excess storage of fat. So why would you ever eat white bread?

"Even if you're cutting carbs, there's still a place for complex whole grains in your diet," says Mohr. "They leave you feeling fuller longer, and they provide the longest possible supply of sustained energy." Just watch out when you're buying something that claims to be whole grain. It may only look brown because it's colored with molasses. Rather than buying based on color, check the ingredient list. The only true whole-grain products are those that contain 100% whole wheat or whole grain listed as the first ingredient on the packaging.