Doubly Labeled Water (DLW)
Stable-isotope reference method for measuring total energy expenditure in free-living conditions, exploiting differential disappearance of orally administered 2H218O.
Also: DLW
After a loading dose of water enriched in deuterium (2H) and oxygen-18 (18O), 2H is lost as water while 18O is lost as both water and CO2; the difference yields CO2 production over 7-14 days. DLW is the gold standard against which all other energy expenditure and self-reported intake methods are validated. It has been the foundation of EER (Estimated Energy Requirement) equations in the DRIs.
How one textbook covers it
Modern Nutrition in Health and Disease, 12th ed. — Ch 1: Energy
After a loading dose of water enriched in deuterium (2H) and oxygen-18 (18O), 2H is lost as water while 18O is lost as both water and CO2; the difference yields CO2 production over 7-14 days. DLW is the gold standard against which all other energy expenditure and self-reported intake methods are validated. It has been the foundation of EER (Estimated Energy Requirement) equations in the DRIs.
Related terms
24-hour recall, EER, Total energy expenditure