The following article comes from the U.S. News ebook, How to Live to 100, which is now available for purchase.
If your mental image of an older person is someone frail and thin, it may be time for an update. For the generation currently moving through middle age and beyond, a new concern is, well, growing: obesity. Government figures show that Americans in their 60s today are about 10 pounds heavier than their counterparts of just a decade ago. And an even more worrisome bulge is coming: A typical woman in her 40s now weighs 168 pounds, versus 143 pounds in the 1960s. "People used to start midlife [at a lower weight] and then lose weight when they got into their 50s, but that doesn't happen as much anymore," says David Kessler, former commissioner of the Food and Drug Administration and author of The End of Overeating.
If you're entering that danger zone now, be aware that it's not going to get any easier to lose weight, because people need fewer calories as they age. Blame slowing metabolism and the body's tendency starting in midlife to lose muscle mass—a process known as sarcopenia—and gain fat, especially around the abdomen. (Fat burns fewer calories than does muscle.) "All that conspires to make it harder for people to maintain the same body weight when they eat their usual diets," says Alice Lichtenstein, director of the cardiovascular nutrition laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. "People have fewer discretionary calories to play with, so they need to make better food choices."
But paying attention to what you eat isn't only about controlling weight; the need for certain vitamins and minerals increases with age. One is calcium, necessary to protect bones. Another is B12, since some older adults make less of the stomach acid required to absorb the vitamin. More vitamin D also is required. "The skin gets less efficient at converting sunlight into this vitamin, so more is needed from other sources," Lichtenstein says. Fewer than 7 percent of Americans between ages 50 and 70 get enough vitamin D from the foods they eat, and fewer than 26 percent get enough calcium.
Eating right and staying lean are both crucial for maintaining health throughout the years. Carrying an extra 20 or 30 pounds with you into old age doesn't bode well for attempts to head off the myriad diseases that strike in midlife and later and are linked to weight—including diabetes, arthritis, heart disease, and some forms of cancer. If weight is a problem, it is especially important to limit processed foods that combine sugar and fat. Studies with rats indicate that when the two are added to chow, animals can't easily stop eating, says Kessler. This happens in humans, too, he says, and food manufacturers have taken note and added sugar and fat to many products.
So what should people eat? A healthful diet at midlife is the same as for younger adults—it's just that the stakes may be higher. The focus should be on fruit, vegetables, whole grains, low- and nonfat dairy, legumes, lean meats, and fish. (While there is no single "longevity diet," a Mediterranean diet—similar to a conventional healthful diet but with more emphasis on fish and olive oil—has been tied to a decreased risk of heart disease and reductions in blood pressure and "bad" LDL cholesterol. Mediterranean dieters may also outlive non-followers by two to three years, research suggests.) For someone whose current diet is far from this ideal, Lichtenstein advises starting small: load more veggies on the dinner plate; eat more skinless chicken or beans in place of hamburger. (A singly daily serving of processed or unprocessed red meat may boost the risk of premature death, according to a recent study by Harvard School of Public Health researchers.) And exercise. Walking briskly for at least 30 minutes every day makes it easier to get away with the occasional cookie. With further fine-tuning of that basic healthful eating plan, you can greatly improve your odds of staving off the major barriers to a vital old age: