Food Quotients From Assessments Of Dietary Intake Reduce Bias In Measurement Of Total Energy Expenditure

The doubly labeled water (DLW) technique is the gold standard for determining total daily energy expenditure (TEE) in a free-living setting. Using an assumed Respiratory Quotient (RQ) in the Weir equation may introduce error in TEE at the individual level particularly with extremes in macronutrient intake. Purpose: We sought to determine the effect of macronutrient composition on bias between TEE calculated using an assumed RQ of 0.85 vs a Food Quotient (FQ) derived from 24-hour Food Recalls (24 h Recs), Food Intake Records(FIRs), or both. Methods: The findings that follow represent 46 (26 male) healthy participants across a spectrum of habitual PA (sedentary to ultra-endurance athletes) (age 20-55). CO2 production (rCO2) was measured by urinary isotope elimination using laser spectroscopy. Dietary macronutrient intake was obtained using 24 h Recs (3 days) and FIRs (4 days). Using the Weir equation, TEE (TEE.RQ) was calculated from rCO2 and an assumed RQ of 0.85 vs estimates of FQs from 24 h Recs (TEE.Rec), FIRs (TEE.FIR) and a weighted mean of both (TEE.FQ). Pairwise comparisons of TEE were performed using repeated measures ANOVA and Tukey post-hoc analysis. Bland-Altman plots were used to determine bias among all pairs. We regressed the biases from Bland-Altman plots on %CHO. %CHO was categorized into low, moderate, and high carbohydrate diets. Results: %CHO was accounted for sizeable differences in bias (R2 = .87 to.89, P < .0001). Bias was largest at the extremes of %CHO particularly at the low levels of carbohydrate intake. Conclusions: Variability in %CHO is a source of bias in calculating TEE using the DLW method particularly at the individual level. Estimating FQ from rigorous assessment of dietary assessment using 24-hour recalls and/or FIR may be a means for reducing bias in the assessment of TEE. VT Translational Obesity Research Interdisciplinary Graduate Education Program Predoctoral Fellowship; OPN: VT Presidential Postdoctoral Fellowship; GZR: NextGeneration EU funds Margarita Salas Postdoctoral Fellowship.