Evaluation of the Major Commercial Weight Loss Programs

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The summary below is from the full report titled "Systematic Review: An Evaluation of Major Commercial Weight Loss Programs in the United States." It is in the 4 January 2005 issue of Annals of Internal Medicine (volume 142, pages 56-66). The authors are A.G. Tsai and T.A. Wadden.

What is the problem and what is known about it so far?

In 2000, 64% of adult Americans were overweight. Overweight people are more likely than normal-weight people to have chronic health problems such as diabetes, high blood pressure, and knee arthritis. Overweight people also die at younger ages than persons of normal weight. Many overweight people want to lose weight to improve their health and their appearance. Since losing weight can be difficult, and because most health care facilities do not offer weight loss programs, several commercial weight loss programs have been developed. Unfortunately, many patients and their doctors know little about the effectiveness and safety of these programs.

Why did the authors do this review?

To summarize what is known about major commercial weight loss programs in the United States.

How did the authors do this review?

The authors looked for studies of the following types of commercial weight loss programs: nonmedical programs (Weight Watchers, Jenny Craig, and L A Weight Loss), very-low-calorie diet, medically based programs (Health Management Resources and OPTIFAST), and commercial Internet-based programs (eDiets.com). They also included 2 nonprofit self-help programs (Overeaters Anonymous and Take Off Pounds Sensibly). The authors chose these programs because information about them has been published. The authors looked for studies that included adults in the United States, had more than 10 participants, lasted more than 12 weeks, and examined the program under the same conditions as it is offered to the public. The authors collected information about each program, the studies that had been done, and weight loss achieved in the studies.

What did the authors find?

Few high-quality studies have assessed weight loss programs. Many of the existing studies present the best-case scenario because they do not account for people who drop out of the program. Of the programs the authors evaluated, Weight Watchers had the strongest studies to support it. The best study found that participants lost 5% of their initial body weight (about 10 pounds) in 6 months and kept off 3% (about 5 pounds) at 2 years. The authors found no published high-quality studies of Jenny Craig or L A Weight Loss. The studies of the very-low-calorie diet, medically-based programs were of limited quality. They found that patients who stayed on the program lost about 15% to 20% of initial body weight in 6 months. However, many patients dropped out of these programs. Even those who completed the program regained about half of their lost weight in 1 to 2 years after treatment. The few studies of Internet-based and self-help programs were of limited quality and found that these approaches produced minimal weight loss.

What are the implications of the review?

With the exception of Weight Watchers, the evidence to support the effectiveness of major commercial weight loss programs is limited. Patients considering the use of commercial weight loss programs should realize that these programs have not been carefully studied and that they vary greatly in cost.