Effects of a Single Dose of BURN-XT™ on Resting Metabolic Rate, Substrate Oxidation, and Various Indices of Affect

Main Article Content

Michael La Monica
Tim Ziegenfuss
Hector Lopez


thermogenic, metabolism, resting energy expenditure


Introduction: Many consumers use dietary supplements in the hopes of increasing energy and burning more calories, which if sustained over time may help accelerate weight loss. The purpose of this clinical trial was to investigate the effects of an over-the-counter thermogenic supplement called Burn-XT™ (BXT) on metabolic rate, substrate oxidation, and various psychometric indices of affect that impact weight management. 

Methods: Using a double-blind, placebo-controlled, cross-over design, 16 women and 10 men (29.3 ± 7.3 yr, 169.4 ± 8.6 cm, 75.5 ± 14.3 kg) underwent two testing sessions: placebo (PL) and BXT.  Seated metabolic rate and substrate oxidation, vital signs, and anchored visual analogue scale (VAS) assessments of energy, mood, motivation, focus, fatigue, concentration, and appetite were made before supplementation and hourly for three hours post-ingestion. Two-factor (2x4) factorial ANOVAs and paired sample t-tests (corrected for multiple comparisons) were used for analyses.

Results: Significant increases in metabolic rate (oxygen consumption) were noted at 60 minutes in BXT (+11.9 mL O2/min) vs. PL (-2.5 mL O2/min), p = 0.004, d = -0.74.  Only BXT increased metabolic rate compared to baseline at 60 minutes (+11.9 mL O2/min, p = 0.021, d = -0.53) and 120 minutes (+12.1 mL O2/min, p = 0.019, d = -0.54).  The AUC for resting energy expenditure increased more in BXT vs. PL (p = 0.007, d = -0.57).  VAS detected significant improvements in energy, mood, focus, and concentration for BXT vs. PL at 120 and 180 minutes (all p < 0.05, d = -0.58 to -0.68).  In all cases, within-group changes from baseline for these VAS parameters were significant (all p < 0.05, d = -0.76 to -1.38) in BXT but not in PL.  No within or between group differences in appetite, substrate oxidation, or heart rate were noted.  Small (~3-4 mm Hg), but statistically significant (p < 0.05, d = -0.51 to -0.69) increases in diastolic blood pressure were noted in BXT at 60, 120, and 180 min vs. PL; and in systolic blood pressure at 60 min vs. PL. In all cases, values remained within normal clinical hemodynamic ranges.

Conclusions: A single dose of BXT safely increased metabolic rate, energy, mood, focus, and concentration. Given that these factors are known to favorably impact weight management, future studies should determine whether daily supplementation with BXT reduces body weight and improves body composition.

Abstract 423 | PDF Downloads 189


1. Watanabe, M., Risi, R., Masi, D., Caputi, A., Balena, A., Rossini, G., ... & Lubrano, C. Current evidence to propose different food supplements for weight loss: A comprehensive review. Nutrients. 2020;12(9);2873.
2. Kovacs, E. M. R., & Mela, D. J. Metabolically active functional food ingredients for weight control. Obesity Reviews. 2006;7(1);59-78.
3. Clark, J. E., & Welch, S. Comparing effectiveness of fat burners and thermogenic supplements to diet and exercise for weight loss and cardiometabolic health: Systematic review and meta-analysis. Nutrition and Health. 2021;1-15. doi: 10.1177/0260106020982362
4. Acheson, K. J., Zahorska-Markiewicz, B., Pittet, P., Anantharaman, K., & Jéquier, E. Caffeine and coffee: their influence on metabolic rate and substrate utilization in normal weight and obese individuals. The American Journal of Clinical Nutrition. 1980;33(5);989-997.
5. Montoya, G. A., Bakuradze, T., Eirich, M., Erk, T., Baum, M., Habermeyer, M., ... & Richling, E. Modulation of 3′, 5′-cyclic AMP homeostasis in human platelets by coffee and individual coffee constituents. British Journal of Nutrition. 2014;112(9);1427-1437.
6. Stohs, S. J., & Badmaev, V. A review of natural stimulant and non‐stimulant thermogenic agents. Phytotherapy Research. 2016;30(5);732-740.
7. Dulloo, A. G., Duret, C., Rohrer, D., Girardier, L., Mensi, N., Fathi, M., Chantre, P., and Vandermander, J. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. The American Journal of Clinical Nutrition. 1999;70(6);1040-1045.
8. Belza, A., Frandsen, E., & Kondrup, J. Body fat loss achieved by stimulation of thermogenesis by a combination of bioactive food ingredients: a placebo-controlled, double-blind 8-week intervention in obese subjects. International Journal of Obesity. 2007;31(1);121-130.
9. Rondanelli, M., Riva, A., Petrangolini, G., Allegrini, P., Perna, S., Faliva, M. A., ... & Gasparri, C. Effect of Acute and Chronic Dietary Supplementation with Green Tea Catechins on Resting Metabolic Rate, Energy Expenditure and Respiratory Quotient: A Systematic Review. Nutrients. 2021;13(2);644.
10. Karlic, H., & Lohninger, A. (2004). Supplementation of L-carnitine in athletes: does it make sense?. Nutrition. 2004;20(7-8);709-715.
11. Lee, M. S., Lee, H. J., Lee, H. S., & Kim, Y. L-carnitine stimulates lipolysis via induction of the lipolytic gene expression and suppression of the adipogenic gene expression in 3T3-L1 adipocytes. Journal of Medicinal Food. 2006;9(4);468-473.
12. Obici, S., Feng, Z., Arduini, A., Conti, R., & Rossetti, L. Inhibition of hypothalamic carnitine palmitoyltransferase-1 decreases food intake and glucose production. Nature Medicine. 2003;9(6);56-761.
13. Rogers, J., Urbina, S. L., Taylor, L. W., Wilborn, C. D., Purpura, M., Jäger, R., & Juturu, V. Capsaicinoids supplementation decreases percent body fat and fat mass: Adjustment using covariates in a post hoc analysis. BMC Obesity. 2018;5(1);1-10.
14. Lopez, H.L., Ziegenfuss, T.N., Hofheins, J.E., Habowski, S.M., Arent, S.M., Weir, J.P. & Ferrando, A.A. Eight weeks of supplementation with a multi-ingredient weight loss product enhances body composition, reduces hip and waist girth, and increases energy levels in overweight men and women. Journal of the International Society of Sports Nutrition. 2013;10;22.
15. Ziegenfuss, T. N., Lopez, H. L., Sandrock, J. E., Kedia, A. W., Habowski, S., & Kerksick, C. Effect of a multi-nutrient over-the-counter supplement on changes in metabolic rate and markers of lipolysis. Journal of Dietary Supplements. 2017;14(3);288-302.
16. Dalbo, V. J., Roberts, M. D., Stout, J. R., & Kerksick, C. M. Acute effects of ingesting a commercial thermogenic drink on changes in energy expenditure and markers of lipolysis. Journal of the International Society of Sports Nutrition. 2008;5(1);1-7.
17. Outlaw, J., Wilborn, C., Smith, A., Urbina, S., Hayward, S., Foster, C., ... & Taylor, L. Effects of ingestion of a commercially available thermogenic dietary supplement on resting energy expenditure, mood state and cardiovascular measures. Journal of the International Society of Sports Nutrition. 2013;10(1);1-8.
18. Wilborn, C., Taylor, L., Poole, C., Bushey, B., Williams, L., Foster, C., & Campbell, B. Effects of ingesting a commercial thermogenic product on hemodynamic function and energy expenditure at rest in males and females. Applied Physiology, Nutrition, and Metabolism. 2009;34(6);1073-1078.
19. Rigamonti, A. E., Casnici, C., Marelli, O., De Col, A., Tamini, S., Lucchetti, E., ... & Sartorio, A. Acute administration of capsaicin increases resting energy expenditure in young obese subjects without affecting energy intake, appetite, and circulating levels of orexigenic/anorexigenic peptides. Nutrition Research. 2018;52;71-79.
20. Josse, A.R., Sherriffs, S.S., Holwerda, A.M., Andrews, R., Staples, A.W., & Phillips, S.M. Effects of capsinoid ingestion on energy expenditure and lipid oxidation at rest and during exercise. Nutrition and Metabolism. 2010;7(1);1-10.
21. Pooyandjoo, M., Nouhi, M., Shab‐Bidar, S., Djafarian, K., & Olyaeemanesh, A. The effect of (L‐) carnitine on weight loss in adults: a systematic review and meta‐analysis of randomized controlled trials. Obesity Reviews. 2016;17(10);970-976.
22. Harpaz, E., Tamir, S., Weinstein, A., & Weinstein, Y. The effect of caffeine on energy balance. Journal of Basic and Clinical Physiology and Pharmacology. 2017;28(1);1-10.
23. Shabir, A., Hooton, A., Tallis, J., & F Higgins, M. The influence of caffeine expectancies on sport, exercise, and cognitive performance. Nutrients. 2018;10(10);1528.
24. Zabelina, D. L., & Silvia, P. J. Percolating ideas: The effects of caffeine on creative thinking and problem solving. Consciousness and Cognition. 2020;79;102899.
25. Schubert, M. M., Irwin, C., Seay, R. F., Clarke, H. E., Allegro, D., & Desbrow, B. Caffeine, coffee, and appetite control: a review. International Journal of Food Sciences and Nutrition. 2017;68(8);901-912.
26. Whiting, S., Derbyshire, E., & Tiwari, B.K. Capsaicinoids and capsinoids. A potential role for weight management? A systematic review of the evidence. Appetite. 2012;59;341-348.
27. Bakuradze, T., Parra, G. A. M., Riedel, A., Somoza, V., Lang, R., Dieminger, N., ... & Richling, E. Four-week coffee consumption affects energy intake, satiety regulation, body fat, and protects DNA integrity. Food Research International. 2014;63;420-427.
28. Duarte, C., Stubbs, J., Pinto-Gouveia, J., Matos, M., Gale, C., Morris, L., & Gilbert, P. The impact of self-criticism and self-reassurance on weight-related affect and well-being in participants of a commercial weight management programme. Obesity Facts. 2017;10(2);65-75.
29. Ryan, R. M., & Frederick, C. On energy, personality, and health: Subjective vitality as a dynamic reflection of well‐being. Journal of Personality. 1997;65(3);529-565.
30. Brown, A. L., Lane, J., Coverly, J., Stocks, J., Jackson, S., Stephen, A., ... & Hendrickx, H. Effects of dietary supplementation with the green tea polyphenol epigallocatechin-3-gallate on insulin resistance and associated metabolic risk factors: randomized controlled trial. British Journal of Nutrition. 2008;101(6);886-894.
31. Smith, A. P., Brockman, P., Flynn, R., Maben, A., & Thomas, M. Investigation of the effects of coffee on alertness and performance during the day and night. Neuropsychobiology. 1993;27(4);217-223.
32. Hoffman, J. R., Kang, J., Ratamess, N. A., Rashti, S. L., Tranchina, C. P., & Faigenbaum, A. D. Thermogenic effect of an acute ingestion of a weight loss supplement. Journal of the International Society of Sports Nutrition. 2009;6(1);1-9.
33. James, J. E. Critical review of dietary caffeine and blood pressure: a relationship that should be taken more seriously. Psychosomatic Medicine. 2004;66(1);63-71.
34. Higdon, J. V., & Frei, B. Coffee and health: a review of recent human research. Critical Reviews in Food Science and Nutrition. 2006;46(2);101-123.