Low Energy Availability Alters Metabolome With And Without Daily Exercise

PURPOSE: To characterize the changes to the metabolome induced by low energy availability (LEA) with and without daily exercise. METHODS: Blood samples from two short-term, repeated measures, crossover design studies, of which one involved daily aerobic exercise expending 15 kcal · kg fat-free mass (FFM)-1 · day-1 and one which did not exercise, were analyzed for 250 metabolites using nuclear magnetic resonance. Differences in changes to selected metabolite concentrations (mmol · L-1) between LEA (15 kcal · kg FFM-1 · day-1) and control (CON; 40 kcal · kg FFM-1 · day-1) were assessed using paired Wilcoxon signed rank tests with the significance level set at p < .05 after correction for multiple tests. RESULTS: LEA reduced carbohydrate availability compared to CON in both the non-exercising (-3.45 ± 0.31 g · kg body mass (BM)-1) and exercising (-3.95 ± 0.89 g · kg BM-1) studies. Following LEA, greater reductions in concentrations of triglycerides (-0.30 ± 0.39 vs 0.03 ± 0.22, p < .05) and fatty acids (-1.29 ± 1.53 vs 0.05 ± 1.02, p < .05) were observed while concentrations of ketone bodies (0.42 ± 0.36 vs -0.03 ± 0.04, p < .05) and branched-chain amino acids (0.01 ± 0.14 vs -0.11 ± 0.18, p < .05) were elevated compared to CON. Changes in glucose between LEA and CON (-0.23 ± 0.43 vs 0.12 ± 0.60, p = .10) did not achieve statistical significance. CONCLUSION: Short-term LEA with or without daily exercise reduced carbohydrate availability which altered the metabolome consistent with an increase in fat utilization. Figure 1: Heat map displaying mean changes of metabolite concentrations in LEA normalized to the mean changes observed in CON displayed as standard deviations.This project was funded by an internal award from Technical University of Munich.