Study Design and Results: Researchers from the Obesity Research Center, St Luke's-Roosevelt Hospital Center and Department of Medicine, Columbia University College of Physicians and Surgeons in New York, examined the short-term safety and efficacy for weight loss of an herbal supplement containing Ma huang (ephedra), guarana (containing caffeine), and other ingredients in overweight humans (Metabolife-356®) (1). This study, reported by Boozer et al., was designed as a double-blind, placebo controlled study of a combination of ephedrine from ephedra (72mg daily) and caffeine from guarana (240mg daily) in 67 overweight men and women (body mass indices (29 kg/m2 and (35kg/m2). Subjects were randomized to receive either the combination of ephedrine and caffeine, or placebo over an eight-week period. The authors reported that subjects in the ephedrine/caffeine group experienced a significant mean weight loss vs. placebo (-4.0kg and -2.1%, respectively), as well as a significant mean reduction in fat composition vs. placebo (-0.8kg and 0.2%, respectively). Notably, independent laboratory testing (San Rafael Chemical Services, Salt Lake City, UT) on the product reported that the amounts of constituents listed on the package were less than what was actually contained in the tablet. The trial demonstrated a significant mean decrease in body weight in the active therapy group. However, this effect cannot be attributed to Ma huang or guarana specifically because of the use of a combination product. Notably, the product contained at least 21 other ingredients including chromium picolinate, which has also been studied for weight loss.

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