Intra-Assessment Resting Metabolic Rate Variability Is Associated with Cardiometabolic Risk Factors in Middle-Aged Adults.

The intra-assessment resting metabolic rate variability is related to cardiometabolic health, as suggested by previous literature. We studied whether that variability (expressed as coefficient of variation [CV; %]) for oxygen consumption (VO 2 ), carbon dioxide production (VCO 2 ), respiratory exchange ratio (RER), and resting energy expenditure (REE) is similar between men and women, and if is similarly associated with cardiometabolic risk factors. Gas exchange in 72 middle-aged adults was measured by indirect calorimetry. Anthropometrics and body composition, cardiorespiratory fitness, circulating cardiometabolic risk factors, and heart rhythm parameters were also determined. Men and women presented similar intra-assessment resting metabolic rate variability (all p > 0.05). Notably, in men, CV for RER was positively associated with BMI and adiposity (both standardized β = 0.35, Ps ≤ 0.048), while CVs for VO 2 , VCO 2 , and REE were negatively associated (standardized β ranged from -0.37 to -0.46, all p ≤ 0.036) with cardiometabolic risk factors. In women, CVs for VCO 2 and REE were negatively associated with adiposity (both standardized β = -0.36, Ps ≤ 0.041) and cardiometabolic risk Z-score (standardized β = -0.40 and -0.38, respectively, Ps ≤ 0.05). In conclusion, intra-assessment resting metabolic rate variability could be considered an indicator of cardiometabolic health in middle-aged adults.