Most Commercial Dieting Programs Don't Work

By Sondra Forsyth

Only a few commercial weight-loss programs have shown that their users lose more weight than those not using them, researchers say.

A team of Johns Hopkins investigators reviewed 4,200 studies for evidence of the programs’ effectiveness.

The findings were published in the Annals of Internal Medicine.

“Primary care doctors need to know what programs have rigorous trials showing that they work, but they haven’t had much evidence to rely on,” said Kimberly Gudzune, M.D., M.P.H., an assistant professor of medicine and a weight-loss specialist at the Johns Hopkins University School of Medicine. “Our review should give clinicians a better idea of what programs they might consider for their patients.”

According to a release from Johns Hopkins Medicine, the investigators found that of 32 major commercial weight-loss programs marketed nationwide, only 11 have been rigorously studied in randomized controlled trials.

Of these studies, the researchers said, they found only two programs are supported by gold-standard data showing that participants, on average, lost more weight after one year in these programs than people who were either dieting on their own, got printed health information, or received other forms of education and counseling sessions.

However, the researchers said, results were generally “modest” in those programs, with participants losing on average between 3 and 5 percent more than nonprogram participants.

“Clinicians could consider referring patients who are overweight or obese to Weight Watchers or Jenny Craig. Other popular programs, such as NutriSystem, show promising weight-loss results, but additional studies evaluating long-term outcomes are needed,” according to the published report.

The researchers cautioned that not all the the 42 studies they analyzed were equally well designed. And since they found few studies that ran 12 months or longer, it was often unclear how many participants sustained their weight loss over the long term.

“We want people to experience the health benefits of weight loss — lower blood pressure, cholesterol and blood sugar, and lower risk of developing diseases like diabetes,” says Jeanne Clark, M.D., M.P.H., the Frederick Brancati, M.D., M.H.S., Endowed Professor of Medicine, director of the Division of Internal Medicine and a study co-author. “Those benefits are long-term goals; losing weight for three months, then regaining it, has limited health benefits. That’s why it’s important to have studies that look at weight loss at 12 months and beyond.”

According to the Hopkins Medicine news release, the NutriSystem program also produced more weight loss at three months than counseling or education alone, but the authors couldn’t find any long-term trials of that program. Programs based on the Atkins diet — high in fat, low in carbohydrates — also helped people lose more weight at six months and 12 months than counseling alone. The approach “appears promising,” the researchers wrote.