This key dietary component becomes even more critical starting in the 40s, when muscle mass begins to decline by up to 1 percent a year. That drop slows metabolism, which makes the pounds pile on more easily. The double whammy consequence: Added weight puts your health at risk, and down the road, diminished muscle mass can throw off your balance (upping chances of a fall), sap your strength, and even threaten your ability to recover from an illness or accident.

To hang on to your metabolism-boosting muscle — and keep you feeling full after meals (another protein plus) — experts recommend eating plenty of skinless chicken and turkey breast, lean beef and pork, eggs, beans, and seafood. And don't forget protein-rich dairy: Minerals (primarily calcium, phosphorus, and potassium) in fat-free milk and yogurt as well as low-fat cheeses help to keep blood pressure healthy, pudge in check, and bones strong. News flash: Calcium can't build bone if you're not getting enough protein, and current recommendations — about five ounces a day for a 145-pound woman — are too low, says Robert P. Heaney, M.D., professor of medicine at Creighton University in Omaha. Our Anti-Aging Meal Plan provides about 11 ounces of protein daily.

Another reason to spoon up some yogurt: Eating at least 1/4 cup every day led to a 60 percent lower risk of gum disease and a 50 percent lower risk of tooth loss in a Japanese study published in the Journal of Periodontology. The effect is thought to be linked to the probiotics in yogurt, but not in most other dairy.