Acute Effects of Creatine and Branch Chain Amino Acids on Resting Energy Expenditure: Considerations for Testing

Introduction: The purpose of this study to was to elucidate the potential effects of acute creatine monohydrate (CM) and branched chain amino acid (BCAA) ingestion on resting energy expenditure (REE). Methods: Young physically active individuals (n=60) were randomly allocated to a single treatment: 1) Placebo (PL), 2) CM, or 3) BCAA. Participants completed a REE test via indirect calorimetry to establish baseline REE prior to ingesting their corresponding treatment. A post-REE was then conducted 60-mins after treatment consumption. Estimate daily caloric expenditure at rest was compared between treatments. Results: PL consumption did not result in changes of REE from pre- (1691 ± 360) to post-ingestion (1671 ± 319; p= 0.395; d= 0.06). However, acute ingestion of BCAA (p= 0.008; d= 0.12) resulted in significantly higher REE pre- (1678 ± 401) versus post- (1761 ± 357) . A non-significant trend towards decreases in REE were noted pre- (1663 ± 421) to post- (1590 ± 346) for CM (p=0.056; d=0.17). The magnitude of the effects for all conditions were small or trivial. These findings suggest that while the popular supplements CM and BCAAs alter REE acutely, the small changes may not be practically important to consider for REE testing. Conclusions: While the effects were small, individualized considerations for REE testing may still be necessary, but further testing using larger and more diverse sample sizes are needed.