The prevalence of obesity has continued to increase over the last several years in the United States. Per the National Health and Nutrition Examination Survey (NHANES) for the 2007-2008 year, the prevalence of obesity, defined as a body mass index (BMI) ≥ 30
, among adults was greater than 30% and those who were overweight or obese (BMI ≥ 25
) was almost 70% for both men and women. The trend over the past 20 years has shown an increase in the prevalence of obesity of six to seven percent every 10 years [1
]. In addition, health care costs are approximately 42% higher for obese patients when compared to normal-weight patients [2
Dietary supplements for weight loss are marketed to offer patients improved success that is faster and easier than calorie reduction and increased exercise. Despite concerns with efficacy and safety, these products continue to be an appealing alternative or adjunct to weight management [3
]. A national survey published in 2008 found that 33.9% of adults who have made a weight loss attempt had used a dietary supplement to do so. It was also found that the use was more common among women, younger adults, minorities, and those with less education and lower incomes [5
]. Reasons why patients may opt for dietary supplements include the perception that they are “natural” and perhaps safer than prescription medications. In addition, patients often do not perceive a need to seek the assistance of a healthcare professional with these alternative therapies, and they also may be an alternative to previously failed attempts with conventional approaches [6
Despite widespread use, there is still limited data on the safety and efficacy of the products currently on the market. Because dietary supplements are viewed as food and not drugs, they are not regulated by the Food and Drug Administration (FDA). Instead, under the Dietary Supplement Health and Education Act (DSHEA), dietary supplements can be marketed without evidence to support efficacy and safety. If a dietary supplement appears to be unsafe after being marketed, the FDA can then decide whether or not to have the product removed from the market. This was the case for the weight loss supplement ephedra which was removed from the market in 2004 after reports of serious health risks [5
]. The literature published in the arena of weight loss continues to be plagued by concerns such as: small studies, inconsistency with participant body weight (BMI), variation in length of studies, use of exercise, and a variety of products at differing dosages.
Several mechanisms are proposed to differentiate how these products work. These include products that claim to be: fat blockers, lipotropics or fat busters, thermogenic or energy modifiers, and products that can change carbohydrate metabolism, water elimination, or the feeling of satiety or fullness. The purpose of this paper is to review the literature on dietary supplements currently being marketed and promoted for weight loss via the mechanisms of altered fat absorption, fat metabolism and/or the storage of fat.