Obesity is a serious health problem throughout the world. More than half of U.S. adults are overweight (61%) and more than a quarter (26%) of U.S. adults are obese. The inability of many individuals to keep their weight in check by diet and exercise has created a need for additional therapeutic means to combat obesity. Despite great effort, the pharmaceutical industry has not come up with the solution; because most weight-loss drugs to date have serious adverse effects to health and well-being. The theory that beta agonists, especially beta 3 agonists, can affect body weight and fat mass is well accepted. Ephedrine has proven time and time again that it is an effective weight loss agent through its ability to increase thermogenesis and quench appetite. However, the publicity concerning adverse reactions has led to its gradual withdrawal from use by many despite the perceived consequences of obesity. Many companies are now substituting Citrus aurantium for ephedra in their formulations. Citrus aurantium, an agent containing beta agonists, has been reported to aid in weight loss in two studies and increase thermogenesis, at least to some extent, in three studies. Colker et al. (1999) reported that in a double-blind, placebo-controlled, randomized study the subjects receiving a combination of Citrus aurantium, caffeine and St John's Wort, lost significant amounts of total body weight while on a strict diet and exercise. Those in the placebo and control groups who also were on the same restricted diet did not. However, intergroup analysis showed no statistical significance among the weight changes in the three groups. In contrast, the loss of fat mass in the test group was significantly greater compared to the placebo and control groups. Jones describes an open labeled study performed on 9 women. The subjects showed a mean of 0.94 kg lost during the first week when no product was given and 2.40 kg during the second week when a Citrus aurantium product was taken. Body weight losses were statistically greater during the second week compared to the first week. Since most clinicians would agree that the most weight loss should occur initially coinciding with a greater fluid loss during the first week, these differences are even more remarkable. Three studies reported increased metabolic rates when ingesting Citrus aurantium products, however, at least two of these studies were acute. At present, Citrus aurantium may be the best thermogenic substitute for ephedra. However, more studies are needed to establish this definitively.