WEDNESDAY, March 28 (HealthDay News) -- Weight loss and regular exercise help prevent disability in obese people with type 2 diabetes, according to new research.

After four years, 21 percent of people enrolled in a lifestyle-intervention program focusing on diet and physical activity had severe disability compared with 26 percent of those enrolled in a diabetes support group. What's more, the lifestyle-intervention group had about half the risk of losing their mobility compared to the support group.

"The lifestyle intervention combined caloric restriction and increased activity," said study author, W. Jack Rejeski, a professor of health and exercise science at the Wake Forest University School of Medicine, in Winston-Salem, N.C. "More of the lifestyle intervention group remained in the good-mobility category. And, that was with modest changes. Just a 6 percent change in body weight helped to ward off an important outcome."

Results of the study are published in the March 29 issue of the New England Journal of Medicine.

The study included slightly more than 5,000 overweight or obese adults who had type 2 diabetes. All were between the ages of 45 and 74, with an average age of 59. The researchers excluded anyone with a hemoglobin A1C (HbA1C) above 11 percent. HbA1C is a long-term measure of blood-sugar control, and the American Diabetes Association generally recommends that people with diabetes should aim for an HbA1C of less than 7 percent. They also excluded people with very high blood pressure or high triglycerides (a type of blood fat).

At the start of the study, just one-third of the study volunteers reported good mobility. That means around two-thirds had at least some type of mobility disability, according to the study.

The volunteers were randomly assigned to one of two treatment groups. The first included lifestyle interventions to lose weight and get more physical activity. The goal in this group was to lose more than 7 percent of body weight and exercise more than 175 minutes a week, according to the study. The second group was a diabetes support and education program.

To evaluate mobility, the researchers asked the study volunteers how well they could perform certain activities, such as running, lifting heavy objects, pushing a vacuum cleaner, playing golf, climbing a flight of stairs, bending, kneeling, stooping, walking more than a mile or walking one block.

At the end of four years, those in the lifestyle intervention group had a 48 percent reduction in mobility-related disability compared to the support group.

Almost 39 percent of the lifestyle intervention group reported good mobility at the end of the study compared to 32 percent of those in the support group, according to the study.

For every reduction of 1 percent of body weight, there was a 7.3 percent reduction in the risk of mobility disability. For every 1 percent improvement in fitness, there was a 1.4 percent drop in the risk of mobility disability. But, Rejeski pointed out that doing both interventions is best for your overall health.

"If all you do is lose weight, the danger of losing muscle mass is greater. The message is that you need to lose weight and be active to enhance your function and not lose muscle mass," he said.

Dr. Joel Zonszein, director of the clinical diabetes center at Montefiore Medical Center, in New York City, said lifestyle changes are as important as medications. "Papers like this continue to show how important lifestyle changes are," Zonszein said. "But, the issue always is in the implementation. We can tell patients to exercise and lose weight, but we don't have the resources to follow up as they do in clinical trials."

For people who want to make changes on their own, Rejeski recommended trying to cut calorie consumption to about 1,800 calories a day. Then, he said, find a place to walk -- the mall, a walking path, a school track -- and get a walking buddy so that you can each keep the other one accountable. If you haven't exercised in a while, start by walking just a little bit, and then the next day add a few more steps. "Eventually, you'll make progress. And, the lower your function was to start with, the more you'll notice the change," he said.

Current U.S. government recommendations are to exercise at a moderate pace for at least 30 minutes most days of the week.

More information

Learn more about how exercise can benefit you from the U.S. National Institute on Aging.