Johns Hopkins: In a bid to help physicians guide obese and overweight patients who want to try a commercial weight-loss program, a team of Johns Hopkins researchers reviewed 4,200 studies for solid evidence of their effectiveness but concluded only a few dozen of the studies met the scientific gold standard of reliability.
In a review of the best research available through late 2014, the
results suggest that only a few programs have shown that their users
lose more weight than those not using them. The findings are published
in the April 6 Annals of Internal Medicine, along with a call for more rigorous tests of the programs for longer periods of time so effectiveness can be better judged.
“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,”
says 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
Among the findings, the investigators found that of 32 major commercial
weight-loss programs marketed nationwide, only 11 have been rigorously
studied in randomized controlled trials. And from these studies, they
say 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
Moreover, they wrote that results in those programs were generally
“modest,” with participants losing on average between 3 and 5 percent
more than the studies’ control groups of nonprogram participants.
Because of the way weight loss is generally tracked in research, the
team did not gauge the average number of pounds lost in each program,
“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
For the study, the researchers collected peer-reviewed research
articles from two major research literature databases and the
weight-loss programs themselves. To aid their search for reliable
evidence, they focused their review on studies that ran for 12 weeks or
longer, and on randomized controlled trials, which assigned participants
either to a commercial program or a less intensive option offering
educational handouts, counseling sessions or no assistance, depending on
the study design.
Because the majority of weight-loss programs have never been studied in
randomized clinical trials, the researchers say, they ended up with 39
trials covering 11 programs. Included were three high-intensity programs
— Weight Watchers, Jenny Craig and NutriSystem — which incorporate goal
setting, self-monitoring, nutritional information and counseling. Three
very-low-calorie meal replacement programs — HMR, Medifast and OPTIFAST
— were also included, along with five self-directed programs — Atkins,
SlimFast, and the Internet-based Biggest Loser Club, eDiets and Lose It!
The researchers cautioned that not all the studies in any category 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
Based on their analysis of the studies, the researchers found Jenny
Craig and Weight Watchers were backed by clinical trials that lasted 12
months or longer and showed program participants had a greater weight
loss than nonparticipants. “Given these findings,” the authors write,
“it may be reasonable for clinicians to refer patients to Weight
Watchers or Jenny Craig.” NutriSystem also produced more weight loss at
three months than counseling or education alone, but the authors were
unable to find any long-term trials of that program. Participants in the
very-low-calorie meal replacement programs lost more weight than
nonparticipants in trials lasting from four to six months. But the
authors found only one long-term study, which showed no benefit from
such a program at 12 months. The authors noted that very-low-calorie
programs also carry higher risks of complications, such as gallstones.
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 authors write.
No definite conclusions could be made about Slim-Fast and the
The researchers also tallied the costs of the commercial programs,
which ranged from zero for Web-based weight-loss apps to between $570
and $682 per month for programs that require clients to buy replacement
Two-thirds of U.S. adults are overweight or obese, and nearly
two-thirds of adults say they have tried to lose weight. Weight-loss
programs were a $2.5 billion-per-year business in 2014, and the industry
is expected to grow. Federal matching funds provided by the Affordable
Care Act make obesity screening and counseling available to people
covered by federal health insurance exchanges and some Medicaid
recipients. Some private insurers may phase in similar coverage. As a
result, physicians across the country will be referring more patients to
weight-loss services in coming years, the Johns Hopkins experts say.
Other authors include Ruchi S. Doshi, Ambereen K. Mehta, Zoobia W.
Chaudhry and Clare J. Lee at the Johns Hopkins University School of
Medicine; David K. Jacobs at the University of Maryland School of
Medicine; Sara N. Bleich at the Johns Hopkins Bloomberg School of Public
Health; and Rachit M. Vakil at the Rutgers Robert Wood Johnson Medical
This research was funded by grants from the National Heart, Lung and
Blood Institute; the National Institute of Diabetes and Digestive and
Kidney Diseases; the JHU-UMD Diabetes Research Center; and the Dean’s
Office Summer Research Funding.