EFFECT OF GENDER ON THE METABOLIC IMPACT OF A COMMERCIALLY AVAILABLE THERMOGENIC DRINK VINCENT J. DALBO, 1 MICHAEL D. ROBERTS, 2 JEFFREY R. STOUT, 2 AND CHAD M. KERKSICK 2 1 School of Medicine and Applied Sciences, Central Queensland University, Rockhampton, Queensland, Australia; and 2 Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma ABSTRACT Dalbo, VJ, Roberts, MD, Stout, JR, and Kerksick, CM. Effect of gender on the metabolic impact of a commercially available thermogenic drink. J Strength Cond Res 24(6): 1633–1642, 2010—The purpose of this study was to examine the gender effect of daily consumption of a thermogenic drink (TD) containing caffeine, epigallocatechin gallate, and taurine. In a single-blind, matched-pairs, placebo-controlled study, 60 par- ticipants (n = 30 men and n = 30 women) were matched in a balanced fashion according to age and body mass. Participants completed determination of body composition, resting energy expenditure (REE), and serum levels of glycerol and free fatty acids before and after ingesting either 336 mL of a TD or a noncaloric, noncaffeinated placebo (PLA). Participants were supplemented daily with 336 mL of either the TD or PLA and repeated identical testing procedures on day 28. Area under the curve (AUC) analysis on days 0 and 28 were calculated for all blood variables (e.g., glycerol and free fatty acids) and analyzed with REE, respiratory exchange ratio, dietary records, and body composition with separate repeated-measure anal- yses of variance. On days 0 and 28, REE AUC (p , 0.001) was greater in all men compared with in women. Women ingesting the TD had significantly greater free fatty acid AUC values (p = 0.002) when compared with those of men. A significant interaction for glycerol AUC (p = 0.02) revealed greater glycerol concentrations in the male PLA group, which decreased in all other groups from days 0 to 28. The male TD group lost significantly more percent body fat (p = 0.02) than did the female PLA group. The popularity of thermogenic drinks to promote weight loss and body composition changes has grown exponentially. Gender differences after drink ingestion may impact the resulting adaptations and how successful their inclusion impacts weight loss and body-composition changes in those following a regular diet and exercise program. KEY WORDS metabolism, thermogenesis, caffeine, EGCG, energy drink INTRODUCTION T he use of nutritionally supplemented drinks with thermogenic ingredients for weight loss and related improvements while following a diet and exercise program has increased significantly. Specifically, the thermogenic ‘‘energy’’ drink (thermogenic drink [TD]) market was estimated to be a $5.7 billion industry in 2006 with over 500 TDs being marketed worldwide (7). As a result, the need to investigate the efficacy of TDs has increased in an attempt to explain associated efficacy and mechanisms of action (10,15,29). Common ingredients in TDs include caffeine, epigalloca- techin gallate (EGCG), and taurine. Caffeine increases lipolysis through stimulation of adenosine and b-adrenergic receptors resulting in increases in circulating epinephrine (13,26) and serum free fatty acids (26). Epigallocatechin gallate enhances fat oxidation (6), alters food digestibility (20,27), and can downregulate stearoyl-CoA desaturase gene expression (20); an effect linked to a reduction of adiposity and lipid synthesis. Consequently, caffeine and EGCG should work synergistically because epinephrine secretion (from caffeine ingestion) enhances metabolism, whereas EGCG reduces net energy intake and offsets further increases in adiposity. Taurine ingestion may facilitate lipolysis by increasing peroxisome proliferator–activated receptor-g coactivator-1a in white adipose tissue (37), an effect that warrants the addition of taurine to the weight-loss products. Recent research has reported that products containing caffeine and EGCG as primary ingredients (or in combination) increases metabolism and promotes lipolysis (6,10–12,29,31). Although less research is available on taurine, studies have suggested it to positively influence mood, lipid metabolism, and weight loss and when combined with caffeine to influence memory, mood, and information processing (1,34,39,42). Our laboratory has recently found a TD containing caffeine, EGCG, and taurine to significantly increase metabolism and promote lipolysis (10,29). Specifically, acute consumption of this TD significantly Address correspondence to Dr. Chad M. Kerksick, chad_kerksick@ou.edu. 24(6)/1633–1642 Journal of Strength and Conditioning Research Ó 2010 National Strength and Conditioning Association VOLUME 24 | NUMBER 6 | JUNE 2010 | 1633