(31) A CAFFEINATED DIETARY FAT LOSS SUPPLEMENT SIGNIFICANTLY INCREASES ACUTE RESTING ENERGY EXPENDITURE COMPARED TO NON-CAFFEINATED DIETARY SUPPLEMENT

Purpose: Throughout an athlete’s macrocycle it may be necessary to employ methods to reduce body fat for either performance or health reasons. Some athletes may choose to utilize fat loss supplements either in lieu of or in addition to nutritional interventions. Many fat loss supplements induce a thermogenic effect through a combination of ingredients, with caffeine typically being one of the main active ingredients. Caffeine is well understood to have an effect on the central nervous system, although that effect is not always desired. There has been a subsequent rise in popularity of “non-stimulant” or caffeine-free fat loss supplements, however it is not well understood if those fat loss supplements are still effective at enhancing thermogenesis without caffeine’s influence. Therefore, the purpose of this study was to compare changes in resting energy expenditure (REE) and respiratory exchange ratio (RER) in metabolically healthy participants after acute consumption of a caffeinated and non-caffeinated fat loss dietary supplement.

Methods: Twenty-five metabolically healthy male and female participants (age: 23±4 yrs; height: 163±9.9 cm; weight: 68.9±15.9 kgs) participated in this randomized, double-blind, placebo-controlled cross-over study. Each participant underwent 3 different trials. For visit #1 participants came to the laboratory after an overnight fast for a baseline REE. Following this, each participant ingested a caffeine-containing [200 mg] dietary fat loss supplement (Phoenix® [CAF]), a non-caffeinated dietary fat loss supplement (Phoenix Stim-Free® [NON-CAF]), or a placebo (PLAC) of inert ingredients and repeated the REE assessments at 60, 120, & 180-minutes post-ingestion. On 2 subsequent laboratory visits the alternative supplements were ingested using the same protocol. Data were analyzed via a 2-factor [3x4] within-subjects repeated measures analysis of variance (RMANOVA). Paired samples t-tests were used for post-hoc analyses, and alpha was set at p≤0.05.

Results: CAF significantly elevated REE greater than NCAF and PL at all time points (p< 0.05). There was a significant interaction for RER (p=0.009), but no post-hoc analyses were statistically significant at any time point.

Conclusions: The caffeinated dietary fat loss supplement significantly increased REE over a 3-hour period as compared to a non-caffeinated and placebo treatment. In addition, there were no significant changes in RER at any time point regardless of treatment.  

PRACTICAL APPLICATIONS: For athletes desiring to lose body fat, a caffeine-containing dietary fat loss supplement is able to significantly increase REE as compared to a non-caffeinated or placebo treatment. In accordance with the energy balance model of body composition, in conditions where energy intake is held constant, a loss of body fat could be realized over time.

Acknowledgements: This study was funded by a grant from Legion Athletics, Inc. and the Florida High Tech Corridor.