Maximal fat oxidation capacity is associated with cardiometabolic risk factors in healthy young adults

It is unknown whether resting fat oxidation (RFO), maximal fat oxidation (MFO) and FatMax (intensity at which MFO is reached) are related to cardiometabolic risk (CMR). Thus the aim of this study was to examine the association of RFO, MFO and FatMax with CMR. 81 healthy adults (n = 31 women; 22.72 ± 4.40 years) participated in this cross-sectional study. Glucose and triglycerides were analysed in plasma. Body composition, anthropometry, physical activity, blood pressure (BP) and heart rate measurements were taken. RFO and MFO were determined through indirect calorimetry. Maximal oxygen uptake (VO 2 max) test was performed until exhaustion after MFO test. The CMR cluster was created from individual CMR factors: waist circumference, body fat percentage, systolic BP, diastolic BP, blood glucose and plasma triglycerides. Groups of high and low MFO and VO 2 max were created. RFO was not associated with CMR (p < 0.05). FatMax, MFO and VO 2 max were associated with individual CMR factors as waist circumference (R 2 = 0.144; R 2 = 0.241; R 2 = 0.285; p = 0.001; respectively) and plasma triglycerides (R 2 = 0.111; p = 0.004 and R 2 = 0.130; p = 0.002 and R 2 = 0.093; p = 0.008; respectively) and clustered CMR factors (R 2 = 0.105; p = 0.008 and R 2 = 0.162; p = 0.001 and R 2 = 0.239; p = 0.001; respectively). VO 2 max was also associated with body fat percentage (R 2 = 0.105; p = 0.003) and diastolic BP (R 2 = 0.083; p = 0.01), even adjusting for sex or age (p < 0.05). Groups with high level of MFO or VO 2 max obtained lower CMR (p = 0.001), even adjusting for sex or age (p < 0.01). FatMax, MFO and, especially, VO 2 max are associated with CMR, regardless of age and sex. However, RFO is not associated with CMR.