Evaluation of the effects of a new standard equation for doubly labeled water studies

Accurate measurement of energy expenditure is critical for metabolic research and public health. Doubly labeled water (DLW) is the gold standard for assessing free-living energy expenditure, yet inconsistencies in equations impede comparability across studies. This analysis evaluates a newly proposed standardized equation of energy expenditure from the DLW method against commonly employed historical equations. Using validation data from whole-room indirect calorimetry, we demonstrate that the new equation offers improved accuracy. Further, analysis of a large historical dataset and mathematical modeling revealed a systematic bias of ∼1.6%, indicative of an underestimation of energy expenditure estimates with the new equation compared to previous equations. Application of a newly developed correction factor mitigated this bias, allowing for closer alignment between equations. These findings support adoption of the new standard equation and offer a corrective approach for harmonizing data, thereby facilitating methodological consistency in DLW studies and allowing for the preservation of the utility of historical datasets.