Thermogenic effect of an acute ingestion of a weight loss supplement

The purpose of this study was to examine the acute effects of a weight loss supplement on resting oxygen uptake (VO₂), respiratory quotient (RQ), caloric expenditure (kcal), heart rate (HR), and blood pressure (BP) in healthy and physically active individuals.

Ten subjects (5 male, 5 female; 20.2 ± 1.2 y; 172.2 ± 8.9 cm; 71.5 ± 17.2 kg; 17.3 ± 2.6% body fat) underwent two testing sessions administered in a randomized and double-blind fashion. During each session, subjects reported to the Human Performance Laboratory after at least 3-h post-absorptive state and were provided either 3 capsules of the weight loss supplement (SUP), commercially marketed as Meltdown^® or 3 capsules of a placebo (P). Subjects then rested in a semi-recumbent position for three hours. VO₂ and HR were determined every 5 min during the first 30 min and every 10 min during the next 150 min. BP was determined every 15 min during the first 30 min and every 30 min thereafter. The profile of mood states was assessed every 30 min.

Area under the curve analysis revealed a significant 28.9% difference in VO₂ between SUP and P for the three hour study period. In addition, a significant difference in energy expenditure was also seen between SUP (1.28 ± 0.33 kcal·min^-1) and P (1.00 ± 0.32 kcal·min^-1). A trend (p = 0.06) towards a greater utilization of stored fat as an energy source was also demonstrated (0.78 ± 0.23 kcal·min^-1 and 0.50 ± 0.38 kcal·min^-1 in P and SUP, respectively). Significant elevations in HR were seen during hours two and three of the study, and significantly higher average systolic BP was observed between SUP (118.0 ± 7.3 mmHg) and P (111.4 ± 8.2 mmHg). No significant differences were seen in diastolic blood pressure at any time point. Significant increases in tension and confusion were seen in SUP.

Results indicate a significant increase in energy expenditure in young, healthy individuals following an acute ingestion of a weight loss supplement. In addition, ingestion of this supplement appears modify mood and elevate HR and systolic BP following ingestion.