Resting energy expenditure from DXA: A Cross-Sectional Study

Abstract Background: The traditional methods used to estimate Resting Energy Expenditure (REE) is bases of the indirect calorimetry (IC) is a global approach, and does not consider the different metabolic activities of organs (heart, kidney and liver), bone tissue (BT), adipose tissue (AT) and skeletal muscle tissue (SMT). Then, our objective is to validate a 3C approach model of REE measured by dual-energy x-ray absorptiometry (DXA) based on IC. Methods: Participated in this cross-sectional study 155 college students, both sexes (18 to 30 years old). Anthropometric measures, REEs estimated via IC and whole-body DXA-scan (3C approach) were determined. The REE of each component was determined after transforming the DXA components at the molecular level to the organ tissue level. Bland-Altman and proportional bias analysis were used to verify agreement between methods (IC and DXA). Results: The results show significant ( p<0.05 ) higher fat-free mass index (FFMI), cranial area and residual tissue (RT) in men. And they have smaller amounts of fat mass (FM) and AT in comparison to women. Also higher REEs ( p <0.001) were found among men for all components in comparison to women, except for AT expenditure ( p <0.001). Conclusions: This approach has important implications for the interpretation of multicomponent energy metabolism, considering interpersonal differences in terms of heat production. It is a strategy applicable in the health and sports contexts to prescribe exercises and diets because it shows the REE magnitude of each body component.