What is Double Labelled Water (DLW)?

Technique DLW is currently considered the most accurate technique for measuring TEE in free- living individuals. It is the method used to measure the average total energy expenditure of free-living individuals over several days (usually 10 to 14), based on the disappearance of a dose of water enriched with the stable isotopes ²H and ¹⁸O. The use of the doubly labelled water (DLW) (²H,¹⁸O) technique to calculate total production of carbon dioxide (CO₂) over several day's and, from this, total energy expenditure was originally developed for use in small animals and its application was later validated in humans. TEE measured by this method includes basal metabolism, the metabolic response to food, thermoregulatory needs, physical activity costs, and the energy cost to synthesize growing tissues. Consequently, energy requirements are calculated as the sum of TEE plus the energy deposited as protein and fat in growing tissues and organs.