Yerba Mate (Illex Paraguariensis) ingestion augments fat oxidation and energy expenditure during exercise at various submaximal intensities

Background: Ingesting Yerba Mate (YM) has become widely popular for health promotion, obesity prevention and body weight reduction, primarily due its thermogenic effectiveness. However, the YM effects on fat metabolism during exercise, when fat metabolism is already increased several fold, are unknown. The present study investigated whether acute YM ingestion augments fat metabolism parameters of fatty acid oxidation (FAO) and energy expenditure derived from FAO (EEFAO) during exercise with several intensities. Methods: Fourteen healthy males and females were randomised in a repeated measures crossover experimental design. All participants ingested either 1000 mg of YM or placebo capsules (PLC) 60 min before performing two incremental exercise ergometry tests. Power output was initiated at and increased by 0.5 W.kg(-1) of body weight every 3 min stage, until reaching peak oxygen uptake ((V) over dotO(2) (Peak)). Expired gases and stoichiometric indirect calorimetry were used to analyse FAO and EEFAO. Capillary blood samples were collected and analysed for blood lactate concentration (BLC) at rest and at each submaximal and maximal power output. Results: YM significantly increased FAO and EEFAO by 24% in all submaximal exercise intensities below 70% of (V) over dotO(2) peak (p < 0.001, ANOVA main effects) with post hoc tests showing a higher FAO and EEFAO (p < 0.05) at the lower exercise intensities (e.g. 0.26 +/- 0.09 vs. 0.35 +/- 0.10 and 0.25 +/- 0.12 vs. 0.33 +/- 0.11 g.min(-1) at 40 and 50% of (V) over dotO(2) peak respectively). These changes were combined with a trend towards a decrease in BLC (P = 0.066), and without a significant difference in (V) over dotO(2) peak, peak power, peak RER, or peak BLC. Conclusions: Acute YM ingestion augments the exercise dependent increase in FAO and EEFAO at submaximal exercise intensities without negatively affecting maximal exercise performance, suggesting a potential role for YM ingestion to increase the exercise effectiveness for weight loss and sports performance.