The effect of an herbal dietary supplement containing ephedrine and caffeine on oxygen consumption in humans

Objective: To determine if an herbal dietary supplement for weight loss inc reases metabolism. Design: Measurement of peak oxygen consumption in response to the supplemen t followed by a double-blind placebo-controlled crossover measurement of ox ygen consumption in response to the supplement. Setting: The study was conducted in an academic research clinic. Subjects: Ten obese females (aged 41 +/- 4 years [body mass index (BMI) 33. 3 +/- 2.6 kg/m(2)) participated in the peak oxygen consumption test; six of these females participated in the crossover trial. Interventions and Outcome Measures: Peak oxygen consumption was measured fo r 45 minutes after taking two herbal dietary supplement capsules orally, ea ch containing the equivalent of 10 mg of caffeine and 5 mg of ephedrine. Th e crossover trial measured oxygen consumption for 45 minutes after taking t wo herbal dietary supplement capsules or two placebo capsules orally. Results: The herbal dietary supplement increased peak oxygen consumption 0. 178 +/- 0.03 (SEM) kcal/min (8.01 +/- 1.35 kcal/min expressed over 45 minut es) above baseline (p < 0.0001), and 2.0 <plus/minus> 0.56 kcal/min over 45 minutes compared to placebo (p < 0.006). Conclusions: The herbal dietary supplement increased oxygen consumption whe n taken according to the package directions. The significance of this rise for weight loss requires further research.