PREDICTORS OF RESTING ENERGY EXPENDITURE AND RESPIRATORY QUOTIENT IN OBESE PREMENOPAUSAL FEMALES 260

Abstract

Resting energy expenditure (REE) and fat oxidation assessed by respiratory quotient (RQ) may play an important role in the etiology of obesity. The purpose of this study was to determine the best predictors of REE and RQ in a group of 19 sedentary and obese premenopausal females, mean age = 42.0± 8.1 years. All females underwent measurements of REE and RQ using the SensorMedics 2900 Metabolic Cart following an overnight fast. The volume and area of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were directly assessed from a single magnetic resonance image at the L4/5 level which yielded 10mm slices. Nutrient intake (NI) was assessed from a 3-day food log and body composition was determined using bioimpedance. Results showed that REE could best be predicted by a 3 component model which included area of VAT, area of SAT, and percent total fat Kcals (r2 =.66; p<0.001). Furthermore, substitution of volume for area of VAT and SAT did not change the predictive value of the model. For RQ, the volume of VAT was the single best predictor of RQ (r=.33; p <0.05) with the volume of VAT, the percent of fat Kcals and lean body mass serving as the best 3-component model (r2=.41; p <0.05). Our findings indicate that measures of VAT, SAT, and NI can significantly predict REE in this population. This is in contrast to previous work showing that lean body mass and/or age are significant indicators of REE. Additionally, volume of VAT rather than any single measure of NI can be used to best predict RQ.