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Low Calories, Empty Promises Study Sees Little Proof of Weight-Loss Programs' Effectiveness

Posted on: Thursday, 6 January 2005, 12:00 CST

With obesity much on peoples' 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 this week 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 U.S. Federal Trade Commission.

"They have always given various rationales," 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 Tuesday'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 nonparticipants.

But that sort of study is almost never done, said 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, Wadden, Cleland and others met with commercial weight loss companies at the Federal Trade Commission to discuss getting some solid data on the programs' effectiveness.

"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," Cleland said.

"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 trade commission, 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," she said. "It was a slap in the face to all people of size."

Still, patients and their doctors need information, Wadden said. So he and his colleague, Adam Gilman 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 year.

Wadden said that even in that handful of studies, hardly any of them reported data for everyone who enrolled in the weight-loss program. Most included only people who had completed the programs, making the outcomes "definitely best-case scenarios," he said.

Some experts concluded that patients might want to forgo the programs altogether. "Doctors could do as well as these programs" in helping people lose weight, said George Blackburn, an obesity specialist at Harvard Medical School, simply by counseling people to diet and exercise.

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, or 93 kilograms. 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," Wadden and 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 that they lost weight.

In their study, Wadden and Tsai also looked at programs, like Optifast, Health Management Resources and Medifast, that provide participants with medical supervision and a very low-calorie diet 800 to 1,500 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 very 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.

Lawrence Stifler, president of Health Management Resources, objected: "Their criteria one of the things they always like to see is randomized controlled trials." Such studies, he said, are not feasible when a company is offering a treatment. Stifler said his company had data showing that patients dropped large amounts of weight if they stuck with the diet.

As for Internet-based weight loss programs, the only study Wadden and Tsai found was one that Wadden, 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.

The modest and temporary weight losses with diet programs are not a surprise, Wadden said, because no one knows how to elicit permanent weight loss. "I don't blame the diet program. They're fighting biology," he 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."

Source: International Herald Tribune

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