January 4, 2005
Diet and Lose Weight? Scientists Say 'Prove It!'
By GINA KOLATA
With obesity much on Americans' minds, an entire industry has sprung
up selling diets and diet books, meal replacements and exercise
programs, nutritional supplements and Internet-based coaching, all in
an effort to help people lose weight.
But a new study, published today, finds little evidence that
commercial weight-loss programs are effective in helping people drop
excess pounds. Almost no rigorous studies of the programs have been
carried out, the researchers report. And federal officials say that
companies are often unwilling to conduct such studies, arguing that
they are in the business of treatment, not research.
"In general, the industry has always been opposed to making
outcomes disclosures," said Richard Cleland, the assistant
director for advertising practices at the Federal Trade
"They have always given various rationales," Mr. Cleland
said, from "'It's too expensive,' to even arguing that part of
this is selling the dream, and if you know what the truth is, it's
harder to sell the dream." The study, published in today's issue
of Annals of Internal Medicine, found that with the exception of
Weight Watchers, no commercial program had published reliable data
from randomized trials showing that people who participated weighed
less a few months later than people who did not participate. And even
in the Weight Watchers study, the researchers said, the results were
modest, with a 5 percent weight loss after three to six months of
dieting, much of it regained.
Advertisements for weight loss centers often make it seem that success
is guaranteed for anyone who really wants it. They feature smiling,
thin, healthy people - results, the advertisements imply, of simply
following the program.
Scientists, however, want something more. They would like to see
carefully controlled studies that follow program participants over a
couple of years and compare their success with that of
But that sort of study is almost never done, said Dr. Thomas Wadden,
director of the weight and eating disorders program at the University
of Pennsylvania and the lead author of the new study.
It is not as if no one has asked the companies to conduct such
research, he and others said. About a decade ago, Dr. Wadden, Mr.
Cleland and others met with commercial weight loss companies at the
Federal Trade Commission to discuss getting some solid data on the
"We tried to come up with a set of voluntary guidelines with the
idea that these would be disclosures that weight loss centers would
make prior to consumers' signing on the bottom line," said Mr.
"At the end of the day we agreed to disagree on the issue of
outcomes disclosure. I was convinced that it could be done, but it was
not something the industry was going to voluntarily do."
The F.T.C., he said, could not force companies to do the studies.
Lynn McAfee, the director of medical advocacy for the Council on Size
and Weight Discrimination, was aghast at the conclusion.
"I don't understand how you can have a product you never evaluate
for effectiveness," Ms. McAfee said. "It was a slap in the
face to all people of size."
Still, patients and their doctors need information, Dr. Wadden said.
So he and his colleague, Dr. Adam Gilden Tsai, collected what
information they could on the prices, the methods, and the success of
nine commercial weight loss programs, like Jenny Craig, eDiets and
Optifast and self-help programs, like Overeaters Anonymous.
The investigators looked at the data presented on company Web sites,
called the companies and searched medical journals for published
papers. In their review, they included studies published from 1966 to
2003, finding 108 that assessed commercial programs. Of those, only 10
met their criteria. For example, the studies had to have lasted at
least 12 weeks and to have assessed weight-loss outcomes after a
Dr. Wadden said that even in that handful of studies, hardly any of
them reported data for everyone who enrolled in the weight-loss
programs. Most included only people who had completed the programs,
making the outcomes "definitely best-case scenarios," he
The costs of commercial weight-loss programs can vary from $65 for
three months on eDiets to $167 for the same time in Weight Watchers to
more than $2,000 for a medically supervised low-calorie diet.
"Given the lack of good comparative data, it may make sense to
try the cheaper alternatives first," Mr. Cleland said.
Other experts said that patients might want to forgo the programs
"Doctors could do as well as these programs" in helping
people lose weight, said Dr. George Blackburn, an obesity specialist
at Harvard Medical School, simply by counseling people to diet and
He added, "Doctors can, ought to and are qualified to get
The Weight Watchers study, published in 2003 in The Journal of the
American Medical Association, involved 423 people who weighed an
average of 205 pounds. Half the participants were randomly assigned to
attend Weight Watchers meetings and follow the program. The other half
tried to lose weight on their own. After two years, the participants
in Weight Watchers had lost an average of 6.4 pounds. The other group
had lost no weight. Neither group showed a change in blood pressure,
cholesterol, blood glucose or insulin.
"We found no such evaluations of Jenny Craig or L.A. Weight
Loss," Dr. Wadden and Dr. Tsai wrote.
Kent Coykendall, a vice president of strategic planning and business
development for Jenny Craig, said the company had begun a randomized
study of 70 people on the program. But in the meantime, he said, Jenny
Craig has the records of tens of thousands of participants attesting
to the fact that they lost weight - "a plethora of real data on
real people in the real world under real circumstances," Mr.
In their study, Dr. Wadden and Dr. Tsai also looked at programs, like
Optifast, Health Management Resources and Medifast, that provide
participants with medical supervision and a low-calorie diet - 800 to
to 1500 calories per day. Patients who stay with these programs, the
companies say, can lose as much as 15 to 25 percent of their weight in
three to six months.
But the researchers found no randomized controlled trials of their
effectiveness. And the studies that were conducted independently of
the companies showed that people on the low-calorie diets weighed
about the same a year later as people on conventional diets. In
addition, the companies' own reports found high dropout rates, with
nearly half the participants in an Optifast study dropping out in 26
But Dr. Larry Stifler, the founder and president of Health Management
"Their criteria - one of the things they always like to see - is
randomized controlled trials," Dr. Stifler said. But such
studies, he said, are not feasible when a company is offering a
"People can't be told they can either join the program or be in a
control group. That's not what this treatment is about," he
Dr. Stifler said his company had data showing that patients dropped
large amounts of weight if they stuck with the diet. When the company
assessed patients three years later, some had still kept the weight
off. Much of that data has not been published, Dr. Stifler said, but
it has been presented at professional meetings.
Robert Hallock, vice president and general counsel for Medifast, also
said his company had unpublished but promising data. The company keeps
track of thousands of patients, he said, and "everyone knows that
low-calorie diets and structured programs get huge amounts of weight
As for Internet-based weight loss programs, the only study Dr. Wadden
and Dr. Tsai found was one that Dr. Wadden, Dr. Leslie Womble and
their colleagues conducted, using eDiets, which provides clients with
low-calorie recipes and foods. They randomly assigned participants to
use eDiets or a standard behavioral weight-loss manual. They also
provided counseling and weigh-ins to all the participants. After a
year, the eDiet participants had lost 1.1 percent of their weight
while those using the manual had lost 4 percent.
Susan Burke, vice president of nutrition services at eDiets, says the
program has changed since 2001, when that study was done. "It's
more personalized and flexible," she says, and clients who use
the support programs and diet lose weight.
Programs like Take Off Pounds Sensibly (TOPS) and Overeaters Anonymous
are free or charge only nominal fees, but it is not clear how
participants fare. Carol Trinastic, a spokeswoman for TOPS, said the
organization collected data on weight loss. The most recent, from
2003, indicate that members lost 1,271,466 pounds or 5.9 pounds per
But the modest and temporary weight losses with diet programs are not
a surprise, Dr. Wadden said, because no one knows how to elicit
permanent weight loss.
"I don't blame the diet programs. They're fighting biology,"
Dr. Wadden said. "Even in the best of circumstances, people will
regain a third of what they lost in one year and two-thirds in two
years and they may be back to base line in five years."
He added, "Weight loss is not for the fainthearted."
Of course, some people do lose weight and keep it off, often
succeeding after repeated attempts to diet, said Dr. Rena Wing, a
professor of psychiatry at Brown and a co-founder of the National
Weight Control Registry.
To be part of the registry, people must lose 30 pounds or more, by any
means, including surgery, and keep the weight off for at least a year.
If they regain, they remain in the registry, Dr. Wing said. "Once
you're in, you're in," she said.
In 10 years, the registry has enrolled 4,700 people. Most gained back
some weight, but very few gained back all they lost, Dr. Wing
But there also are those who say they have tried and tried to reduce,
only to regain the weight they so painfully lost. For many, weight
loss is never really out of their minds. Often, the fatter the person,
the greater the concern.
"Your whole life is a diet when you're overweight," said
Janet B. Forton, a Pennsylvania woman who finally had weight-loss
surgery last year after struggling her entire life to lose weight.
"You go to bed at night praying you make the right choices the
Why do so many people keep trying to lose weight when they so often
gain it right back again? Dr. Peter Herman and Dr. Janet Polivy,
psychologists at the University of Toronto, say that just the idea of
dieting may give people a positive lift.
"It turns out that simply declaring you are going on a diet makes
you feel better," Dr. Herman said. "It seems to boost
people's spirits. They feel they are empowering themselves and they
are already imagining themselves as the new and better selves, taking
control of their lives."
Ms. McAfee has a different explanation.
"It is so penalized to be fat in this society that it's an
investment in your future not to be fat," she said. "It
you're an ambitious person you'll do anything," and even if the
lost weight is regained, "you'll do it again and