Dieting and exercise must accompany drugs.(Obesity Therapy)

DENVER -- Weight-loss medications arguably should never be prescribed without also enrolling patients in some sort of behavioral modification program as well as a dietary intervention, Dr. Samuel Klein said at an international conference of the Academy for Eating Disorders.

This triple-pronged approach is essential. Studies clearly show that the long-term weight loss achieved with orlistat or sibutramine alone--the only two drugs approved for long-term therapy--is rather modest. The cost and side effects of the medication remain the same regardless of whether the regimen also includes behavioral and dietary interventions, but the long-term weight loss is markedly enhanced with multimodal therapy.

In other words, although pharmacotherapy can be useful, the cornerstone of the treatment of obesity remains lifestyle changes, said Dr. Klein, the William H. Danforth Professor of Medicine and Nutritional Science at Washington University, St. Louis.

He provided these insights into the state of the art regarding these interventions:

* Physical activity. This is not a very effective means of reducing weight--the amount needed is just too great for most people--but in selected individuals who have achieved weight loss, exercise is an excellent way to help maintain it long term.

How much is required? Recent studies show that after initial weight loss, an average of about 35 minutes daily of vigorous activity, such as aerobics or fast bicycling, or 80 minutes daily of moderate-intensity activity such as brisk walking is needed for long-term weight maintenance.

But these numbers are based entirely upon retrospective analyses of prospective data. "These are people who chose to be physically active during the follow-up period. That's very different than having a prospective randomized trial telling some people to exercise and others not to," Dr. Klein observed. "In fact, when that's been done you don't see this great benefit of physical activity in maintaining long-term weight loss because people aren't very compliant with long-term physical activity when they're randomized to it."