Resting metabolic rate in Italians: relation with body composition and anthropometric parameters

The objectives of this study were to obtain values for resting metabolic ra te in Italians in relation to parameters of body composition, and to compar e them to predicted values using the FAO/WHO/UNU equation. We performed a c ross-sectional observational study of 131 healthy subjects (46 males and 85 females) at the Human Nutrition Unit, University Tor Vergata, Rome. Body c omposition was determined by dual energy X-ray absorptiometry (DXA) and res ting metabolic rate was calculated using the Weir formula. Resting metaboli c rate was 1865 +/- 234 kcal/day in males and 1354 +/- 154 kcal/day in fema les. These values decreased slightly with age. The relationships with weigh t and age were stronger than that with lean mass from DXA as independent va riables in multiple regression analysis. Mean resting metabolic rates predi cted with FAO/WHO/UNU and Harris-Benedict formula were not significantly di fferent from measured values except for the Harris-Benedict value for femal es (p < 0.01). Individual differences between measured and predicted values were notably high. The measured values were higher than those reported in the literature. The prediction of resting metabolic rate is more accurate w ith simple anthropometric parameters than with fat-free mass obtained by DX A. The individual error in the predicted Values can be so high that for ind ividual use a measured value is preferred over an estimated value.