Dual-energy x-ray absorptiometry metabolic maps to resting energy expenditure estimation, and body size dependence in Brazilian young men.

Objectives: The model most suitable for estimating resting energy expenditure (REE) using dual-energy X-ray absorptiometry (DXA) metabolic maps is not known; moreover, the applicability in individuals with different body sizes also is uncertain. The aim of this study was to test the accuracy of REE estimation from models of DXA metabolic maps with four, five, and six tissue-organ components in young men, stratified by body size.

Methods: We studied 52 young men between the ages of 18 and 29 y. Participants were clustered to small (SW; n = 32) and large (LW; n = 20) weight, and small (SWH; n = 25) and large (LWH; n = 27) weight-height. REE was measured by indirect calorimetry (REE), and predicted from DXA metabolic maps with four (REE), five (REE) and six (REE) tissue-organ components.

Results: REE, REE, and REE explained 54% (P < 0.001), 56% (P < 0.001), and 58% (P < 0.001) of REE variance in all participants, respectively. However, REE showed mean difference between REE (P < 0.001), and REE showed trends in estimating the REE (P < 0.05). In contrast, REE showed limits of agreement (95%) of -248.3 to 285.8 kcal/d, 18.7 ± 136.3 kcal/d of bias, and no trends in the Bland-Altman analysis. The relationship between all predicted models and measured REE decreased in LW and LWH.

Conclusions: REE can be considered the best accurate model of REE estimation in Brazilian young men, providing the REE and metabolically active tissue-organ of four components. Caution should be exercised with the use of DXA metabolic maps in populations with greater weight and greater weight-height.