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This fact sheet provides information on weight-loss dietary supplements, including summaries of research on the safety and efficacy of several of the most commonly used ingredients in these products.
More than two-third of adults and almost one-third of children and adolescents in the United States are overweight or obese. Forty-five percent of overweight Americans and 67% of those who are obese are trying to lose weight.
Health experts agree that making lifestyle changes—including following a healthy eating pattern, reducing caloric intake, and engaging in physical activity—is the basis for achieving long-term weight loss. But because making diet and lifestyle changes can be difficult, many people turn to dietary supplements promoted for weight loss in the hope that these products will help them more easily achieve their weight-loss goals.
Approximately 15% of U.S. adults have used a weight-loss dietary supplement at some point in their lives; more women report use (21%) than men (10%). Americans spend about $2.1 billion a year on weight-loss dietary supplements in pill form, tablets, capsules, and softgels, and one of the top 20 reasons why people take dietary supplements is to lose weight.
Dietary supplements promoted for weight loss encompass a wide variety of products and come in a variety of forms, including capsules, tablets, liquids, powders, and bars. Manufacturers market these products with various claims, including that these products reduce macronutrient absorption, appetite, body fat, and weight and increase metabolism and thermogenesis. Weight-loss products can contain dozens of ingredients, and some contain more than 90. Common ingredients in these supplements include botanicals (herbs and other plant components), dietary fiber, caffeine, and minerals.
In its report on dietary supplements for weight loss, the U.S. Government Accountability Office concluded that “little is known about whether weight loss supplements are effective, but some supplements have been associated with the potential for physical harm”. Many weight-loss supplements are costly, and some of these products’ ingredients can interact or interfere with certain medications. So it is important to consider what is known—and not known—about each ingredient in any dietary supplement before using it.
People who are considering using weight-loss supplements should talk with their health care provider to discuss these products’ potential benefits and risks. This is especially important for those who have medical conditions, including high blood pressure, diabetes, and liver or heart disease. Yet, according to a large national survey, less than one-third of U.S. adults who use weight-loss dietary supplements discuss this use with a health care professional.
*Dietary supplements are labeled with a Supplement Facts panel and do not include meal replacement shakes or prescription or over-the-counter medications.
Regulation of Weight-Loss Dietary SupplementsThe U.S. Food and Drug Administration (FDA) regulates dietary supplements, including those promoted for weight loss. Like other dietary supplements, weight-loss supplements differ from over-the-counter or prescription medications in that the FDA does not classify them as drugs. Unlike drugs, dietary supplements do not require premarket review or approval by the FDA. Supplement manufacturers are responsible for determining that their products are safe and their label claims are truthful and not misleading. If the FDA finds a supplement to be unsafe, it may take enforcement action to remove the product from the market or ask the manufacturer to recall the product. The FDA and the Federal Trade Commission can also take regulatory actions against manufacturers that make unsubstantiated weight-loss claims about their products. The FDA does not permit dietary supplements to contain pharmaceutical ingredients, and manufacturers may not promote dietary supplements to diagnose, treat, cure, or prevent any disease.
For more information about dietary supplement regulation, see the Office of Dietary Supplements (ODS) publication, Dietary Supplements: What You Need to Know.
Common Ingredients in Weight-Loss Dietary SupplementsWeight-loss dietary supplements contain a wide variety of ingredients. Not surprisingly, the amount of scientific information available on these ingredients varies considerably. In some cases, evidence of their purported benefits consists of limited data from animal and laboratory studies, rather than data from human clinical trials. In other cases, studies supporting a given ingredient’s use are small, of short duration, and/or of poor quality, limiting the strength of the findings. In almost all cases, additional research is needed to fully understand the safety and/or efficacy of a particular ingredient.
Complicating the interpretation of many study results is the fact that most weight-loss dietary supplements contain multiple ingredients, making it difficult to isolate the effects of each ingredient and predict the effects of the combination. Evidence may exist for just one of the ingredients in a finished product, and no evidence may be available for an ingredient when it is combined with other ingredients. Furthermore, dosages and amounts of active components vary widely among weight-loss supplements, and a product’s composition is not always fully described in published studies. Studies might also use different and sometimes inappropriate assessment techniques to measure the effectiveness of a given treatment. All of these factors can make it difficult to compare the results of one study with those of another.
Table 1 briefly summarizes the findings discussed in more detail in this fact sheet on the safety and efficacy of the most common ingredients of weight-loss dietary supplements. These ingredients are listed and discussed in the table and text in alphabetical order. Dosage information is provided when it is available. However, because ingredients might not be standardized and many products contain proprietary blends of ingredients, the active compounds and their amounts might not be comparable among products
|Hoodia (Hoodia gordonii)||Suppresses appetite, reduces food intake||Very little published research in humans
Research findings: No effect on energy intake or body weight based on one study
|Some safety concerns reported, increases heart rate and blood pressure|
Reported adverse effects: Headache, dizziness, nausea, and vomiting