Healthy for Life: What to Eat in Your 20s, 30s, 40s, and Beyond

Nutrition in Your 40s

"This is when women start to find some time for themselves again," says Hill. "They're really anxious to improve their health and fitness." To conquer your biggest diet dilemmas:

Beat your belly bulge. If your belly seems a little rounder, blame it on estrogen withdrawal. "In her childbearing years, a woman puts on weight in her butt, hips, and thighs to fuel breastfeeding," says FITNESS advisory board member Pamela Peeke, MD, author of Fit to Live. "The fat cells in those areas have estrogen receptors. As you go through estrogen withdrawal, those receptors aren't being activated anymore." That signals your body to sock away the fat in your tummy. Dr. Peeke's solution: cardio five days a week and resistance training on the other two.

Cut just 100 calories a day. "For every decade after 40, there's roughly a 1 percent decrease in calorie requirements," says Bonci. "That's the equivalent of one extra cookie." Eating every three to four hours to keep your metabolism revved can also help keep off the weight.

Calcium: As you approach menopause, bone-building estrogen starts to decline and calcium becomes more important. Ironically, you absorb less calcium from the food you eat because your stomach doesn't make as much of the acid necessary for absorption. Aim for 1,000 milligrams a day from low-fat dairy, supplements, or a combination.

Vitamin D: This nutrient helps your body absorb calcium, keeps your immune system strong, protects against breast and colon cancers, and even prevents hearing loss. But by the time you reach your 40s, levels of D quickly start to plummet. "There's no way to get enough vitamin D from your diet because very few foods contain it," says Bonci. Your best bet: a daily supplement of 600 to 1,000 international units.

Fiber: It reduces bloat and makes you feel fuller longer. Plus, "fiber helps decrease cholesterol and your risk for colon cancer," says Dr. Peeke. Aim for a mix of soluble (from fruits, vegetables, barley, and oats), and insoluble (from whole wheat bread and bran).