Author Description

Components of energy balance and metabolic hormones were compared in amenorrheic exercising (AEx; n=14), menstruating exercising (MEx; n=20), and menstruating sedentary (MSed; n=7) women. AEx had a lower (P<0.001) resting metabolic rate (RMR) when adjusted for lean body mass. The index of a metabolically-adjusted energy balance, defined as the ratio of measured RMR to predicted RMR, was lower (P=0.016) in AEx compared to MEx. Total 3,3',5-triiodothyronine (TT3) was decreased ( P=0.016) in AEx compared to all other groups. Leptin was 65% lower (P=0.004) in AEx versus MSed, and ghrelin was 45% higher (P=0.013) in the AEx compared to all other groups. The index of a metabolically-adjusted energy balance appears to be a reliable marker of energy deficiency in exercising women. In addition, lower serum TT 3 and leptin, elevated ghrelin concentrations, and a lower RMR after adjusting for lean body mass in AEx are consistent markers indicative of a hypometabolic state.