Middle-age weight gain: inevitable or not?

The inevitability question

Is weight gain with age a fact of life, as inevitable as aching knees or graying hair?

The question is intriguing not only to middle-aged people, but also to researchers who have focused their attention on the question in recent years. And for good reason. More members of the U.S. population are becoming overweight, and many are in their middle years. About 97 million adult Americans (more than 50%) are now either overweight or obese, according to the National Heart, Lung and Blood Institute.

But gaining weight with each birthday is NOT a given, most researchers insist. Lifelong weight control is possible, they say, although it's far from easy for most. The key word here is control keeping your weight within a healthy range so you can minimize your risk of high blood pressure, type II diabetes, heart disease, stroke and other problems that can accompany excess weight.

Where does the weight come from?

Keeping your weight the same as it was at age 18 may be an admirable goal (assuming you were a healthy weight then), but it's not always achievable.

By and large, "the reason there is middle-age weight gain is that we continue to eat the American diet usually high in fat and on average, we become less physically active with age," says Douglas Seals, Ph.D., a professor of kinesiology and applied physiology and medicine at the University of Colorado.

Yes, it's the familiar calories-in, calories-out equation. But what you might not realize is how much you have to exercise and how much you should cut down on calories as you get older.

Exercise is a must

The minimum daily exercise prescription of 30 minutes of physical activity on most days, recommended in the 1996 Surgeon General's Report on Physical Activity and Health, may not be enough to ward off the middle-age spread.

"We think those government guidelines are good recommendations for the comatose," says Paul T. Williams, Ph.D., a researcher at the Lawrence Berkeley National Laboratory in Berkeley, California, which conducts unclassified research for the federal government.

If you are middle-aged and serious about weight maintenance, Williams says, you must do something more demanding than the light gardening or housecleaning that count as physical activity under the Surgeon General's guidelines.

He bases that conclusion on a study he conducted of nearly 7,000 male runners, published in 1997 in the American Journal of Clinical Nutrition. He wanted to find out if vigorous exercise could prevent weight gain, or just compensate for some of the age-related physiological changes (so far not entirely understood even by the researchers) that may lead to weight gain.

What does the research tell us?

After evaluating male runners under age 50 and over age 50 and taking into account weekly miles and weight at one point in time, Williams found that even devoted exercisers find it more difficult to stay slender with age. If the average six-foot man in his study continued to exercise and eat the same amount, he would gain about 3.3 pounds each decade.

The solution? Either increase exercise (for the runners, about 1.4 miles per week every year, Williams estimates), decrease calories, or both. Williams is recruiting now for a women's study, to see if the same findings will apply. (See Resources below.)

In another study, Seals of the University of Colorado found that women who engage in vigorous endurance exercise and keep it up as they age may gain no body weight and have only half the increase in overall body fat as their sedentary counterparts. He compared 59 active women with 36 sedentary women in two age ranges: 18 to 37 and 49 to 73, publishing his findings last year in The American Journal of Physiology, Endocrinology and Metabolism.

The younger runners logged 38 miles a week and the older ones 28, but they all had high caloric intakes. The take-home point, Seals suggests, is not that everyone should run the equivalent of a marathon each week but to realize that exercise does help keep off the weight. And if calorie intake is reduced, you don't have to walk or run as far.

Eating less as you age

How much you must reduce calories to maintain your weight as you age is highly variable, researchers say, and depends on your personal metabolic rate and how much it declines as you age.

It might sound odd, but staying faithful to your exercise might help you reduce calories as well. How so? If you exercise for 45 minutes a day, you tend to experience an increase in psychological well-being, finds John Foreyt, Ph.D., director of the Nutrition Research Clinic at Baylor College of Medicine, Houston. "People who feel better about themselves have an easier time making [sensible] food choices."

Changing your habits

Besides looking at calories-in and calories-out, researchers are examining other strategies to help people maintain healthy weights. In a three-year study reported in this month's American Journal of Public Health, epidemiologists Robert W. Jeffery, Ph.D., and Simon A. French, Ph.D., of the University of Minnesota assigned 1226 participants (ages 20 to 45) to three groups. The first group received no intervention about weight control, another group received monthly newsletters with tips on eating and exercise, and a third got the newsletter plus incentives such as free health club membership.

Those in the intervention group made some positive behavior changes, but not enough to make a difference. Subjects in each group gained an average of four pounds during the study.

Still, French says, she's not discouraged. Pointing to the positive behavior changes, she adds, "We concluded that the program may not have been intense enough. Our study did show that those who practice weight control behaviors (exercising more, eating lower fat diets) gain less weight over time."

True, agrees Susan Speer, R.D., clinical instructor of nutrition at Santa Monica-UCLA Medical Center's family practice program in Santa Monica, California, who counsels many middle-aged, overweight clients. She boils down the findings from dozens of research studies for her middle-aged patients concerned about putting on weight and tells them to avoid three specific behaviors:

• Eating too quickly (which can lead to eating too much)
• Eating a high-fat diet
• Watching too much television