The simple truth is that men are larger and have more muscle than women due to the hormone testosterone. They are genetically designed to have a higher percentage of muscle and less fat -- which works in favor of keeping them fit and allowing them to eat more calories.

But with a little work, women can even up the odds a bit. To build more muscle and get your engine revving, pick up some weights and start pumping. You'll increase your muscle mass and decrease your fat stores by doing strength training at least twice a week.

Not only will strength training build muscle mass and help you burn more calories, but it will also strengthens your bones, preventing osteoporosis -- a disease primarily of women. (And, of course, it gives you a more shapely physique.)

There is at least one area where women have the edge, weight-wise. When men deposit fat, it most often goes to their middles, while women's excess weight tends to settle below the belt and in the middle. And it turns out that the "pear-shaped" body has a health advantage over the "apple": Those who carry extra fat mostly around their middles are at higher risk of developing heart disease than those who are bottom-heavy.