Energy expenditure by doubly labeled water: validation in humans and proposed calculation

Abstract

To further validate the doubly labeled water method for measurement of CO2 production and energy expenditure in humans, we compared it with near-continuous respiratory gas exchange in nine healthy young adult males. Subjects were housed in a respiratory chamber for 4 days. Each received 2H2(18)O at either a low (n = 6) or a moderate (n = 3) isotope dose. Low and moderate doses produced initial 2H enrichments of 5 and 10 X 10(-3) atom percent excess, respectively, and initial 18O enrichments of 2 and 2.5 X 10(-2) atom percent excess, respectively. Total body water was calculated from isotope dilution in saliva collected at 4 and 5 h after the dose. CO2 production was calculated by the two-point method using the isotopic enrichments of urines collected just before each subject entered and left the chamber. Isotope enrichments relative to predose samples were measured by isotope ratio mass spectrometry. At low isotope dose, doubly labeled water overestimated average daily energy expenditure by 8 +/- 9% (SD) (range -7 to 22%). At moderate dose the difference was reduced to +4 +/- 5% (range 0-9%). The isotope elimination curves for 2H and 18O from serial urines collected from one of the subjects showed expected diurnal variations but were otherwise quite smooth. The overestimate may be due to approximations in the corrections for isotope fractionation and isotope dilution. An alternative approach to the corrections is presented that reduces the overestimate to 1%.

Comparison of physical activity energy expenditure in Japanese adolescents assessed by EW4800P triaxial accelerometry and the doubly labelled water method

“…where TBW is the total body water, and we assumed that isotope fractionation applied to both breath and transdermal water using equation (A6) from Schoeller et al (11) with the revised dilution space constant of Racette et al (12) . Calculation of TEE DLW (kJ/d) was performed using a modification of Weir's formula based on the r CO2 and mean food quotient of the subjects in the study (13,14) .…”

Validation of the doubly labeled water method in Japanese Quail Coturnix c. japonica chicks: is there an effect of growth rate?

“…The results on humans also showed that one general model (Eq. A6 derived by Schoeller et al 1986) is applicable at all stages. In contrast to the model employed by us on the Japanese Quail, Schoeller et al's (1986) Eq.…”

Body composition changes in female bodybuilders during preparation for competition

“…A Europa Scienti®c Geo 20 ± 20 (Europa, Crewe, Cheshire, UK) isotope ratio mass spectrometer, which was calibrated against Vienna Standard Mean Ocean Water (V-SMOW) and International Atomic Energy Agency (IAEA) enriched standards 302A and 302B, was used to measure the 2 H 2 O concentrations in the batch doses and saliva samples (Dighton et al, 1997). The isotope dilution space was calculated in accordance with the recommendations of Schoeller et al (1986), who advocate a 4% correction factor for the exchange of deuterium with nonaqueous hydrogen. Our latest reliability and precision data for two TBW trials on alternate days (n 10) yielded an ICC of 0.998 and a TEM of 0.28 kg.…”