Raleigh, N.C. — About two-thirds of adults in the United States are overweight, a condition that can lead to other health probelms such as high blood pressure and diabetes.

Recently, 1,000 overweight or obese adults participated in a study to try to lose weight — and keep it off. The study, sponsored by Duke University Medical Center, was the largest of its kind. The results were published in the Journal of the American Medical Association.

Participants were coached to reduce daily calories, increase moderate exercise, eat a well-balanced diet and keep track of calories and activity.

"We talked about making changes in your lifestyle that you could sustain for your life, " Duke's Dr. Laura Svetsky said.

After an initial weight-loss period, participants got support. Half received a monthly motivational phone call; half used an interactive Web site.

"After 2½ years ... about 70 percent weighed less than they had at the very beginning of the study, and that percent was higher for the group who got the personal counseling, Svetsky said.

Participants averaged a 20-pound weight loss. When they found their weight creeping back up, many returned to the lifestyle changes recommended in the beginning.

"That's the way to approach weight loss," Svetsky said. "Change your lifestyle, don't go on a diet."