If you've recently resolved to lose weight, you may increase your odds of success by joining a structured weight loss program, according to a recent study by researchers at the New York Obesity Research Center, Columbia University.

The two-year study, published in the Journal of the American Medical Association, followed more than 420 women and men who were randomly assigned to one of two groups: a non-structured, self-help group or a commercial weight loss program. The self-help group had two 20-minute counseling sessions with a nutritionist and received information on exercise and healthy eating. The other group participated in the Weight Watchers program, which involved weekly group meetings, a food and activity plan, and strategies for changing eating behaviors. At the end of two years, this group achieved better weight loss overall, averaging about six pounds, versus just one pound in the self-help group. (The study was supported by a grant from Weight Watchers International, and its chief scientist was a member of the research team.)

This may not sound like a great deal of weight, but it is significant, stresses Tom Wadden, Ph.D., director of the Weight and Eating Disorders Program at the University of Pennsylvania.

"The people in the commercial weight loss program lost about 5 and a half percent of their body weight at the end of one year, versus 1 and a half percent in the self-help group," Dr. Wadden says. "That's important because other studies have shown that losing this amount of weight is associated with a reduction in risk for certain diseases, such as diabetes."