Ask the Doctors

Dear Doctor: I retired from a demanding desk job last year and, at age 65, have had to face the facts -- I have become sedentary and need to lose at least 20 pounds. My wife is helping me out with a more healthful diet. But my son says that in addition to the swimming and cycling program I'm on, I need to start lifting weights. Why aren't the pool and the bike enough?

Dear Reader: We'd like to congratulate you on your retirement and on your commitment to improving your health. It's all too easy to let the demands of work take precedence over self-care, and getting fit again can be a challenge. You're fortunate to have a supportive wife -- and a savvy son. Recent research shows that he's on the right track with his advice about adding weight training to your exercise regimen.

When it comes to body weight, it's not just what the scale says that matters. The percentage of lean muscle mass to body fat is an equally important metric. But as we age, the metabolic changes that take place mean we also lose muscle mass. So even if someone weighs the same at age 65 as they did at age 35, the composition of their body is not the same. Muscle mass has decreased and body fat has increased, a change that leads to a net drop in metabolic rate.

The challenge for older adults who want to lose weight is that the body burns both fat and muscle when in a calorie-deficit situation. For every pound you lose, up to one-third of it may be muscle. And since muscle is metabolically more active than fat, each pound of weight loss actually makes it a tiny bit harder to lose the next pound. The challenge becomes how to lose fat while preserving muscle.

According to the results of a study published last year, one possible answer is to pair a weight loss program with weight training. Researchers from Wake Forest University in North Carolina studied 249 adults, all in their 60s, all of them either overweight or obese. The participants were divided into three groups that focused on different weight-loss regimens -- diet alone, diet and walking, and diet and weight training.

After 18 months, the group that walked and the group that lifted weights lost 16 and 17 pounds, respectively. The diet-alone group lost 10 pounds. But when it came to loss of muscle mass, the walking group had the highest numbers. The diet-and-walk group lost 4 pounds of muscle mass. The diet-only and the weight training group each lost about 2 pounds of muscle mass.

Preserving muscle mass, which helps with balance and agility, becomes particularly important as we age. And weight lifting has other benefits as well: In addition to the metabolic boost, studies have shown that it can be as effective as yoga in conferring mental health benefits.

We think it's always a good idea to check in with your primary care physician before starting a new exercise program. And if you do take up weight lifting, please consider working with a trainer to be sure your workout is both effective and safe.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

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