Introduction
fat loss
HEAT, SYMPATHOMIMETIC
Thermogenic supplements are widely used in the general population to support attempted fat loss; however, the efficacy and safety of the variety of ingredient blends in such supplements are questioned. Thermogenic products can stimulate metabolic rate and the production of heat, which is why supplements that claim to acutely increase energy expenditure or fat metabolism are commonly referred to as fat burners.Caffeine is often the main ingredient in commercially available thermogenic supplements due to its ability to increase resting energy expenditure (REE) as well as augment fat oxidation and fatty acid turnover both at rest [Compounds that mimic the activity of the sympathetic nervous system (SNS) are known as sympathomimetic because they stimulate thermogenesis and fat oxidation similarly to true SNS activity [Several other sympathomimetic compounds found in thermogenic supplements are believed to augment the accumulation of cAMP by stimulating β-2 and β-3 adrenergic receptors. When caffeine is combined with these other ingredients, the accumulation of cAMP, and subsequently increases in circulating epinephrine and free fatty acids [Stimulant-based supplements often raise concerns for the potential negative impact on hemodynamic variables such as heart rate (HR) and blood pressure (BP). Elevations in HR and BP have been reported in some studies involving thermogenic supplements containing caffeine [Of the available literature on thermogenic supplements and their impact on metabolic rate and hemodynamic responses, the outcomes seem to be contradictory in the magnitude at which the effect is observed. Furthermore, the safety and efficacy of specific, commercially available multi-ingredient supplements must be evaluated. Therefore, the purpose of this study was to determine whether a thermogenic supplement affects metabolic rate, hemodynamic responses, and mood states, and to what extent these responses were seen.