Validation of an inexpensive and accurate mathematical method to measure long-term changes in free-living energy intake

• Published in: The American journal of clinical nutrition Vol. 102; no. 2; pp. 353 - 358
• Main Authors: Sanghvi, Arjun, Redman, Leanne M, Martin, Corby K, Ravussin, Eric, Hall, Kevin D
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Nutrition, Inc 01.08.2015; American Society for Nutrition
• Subjects: Accuracy; Adult; Algorithms; Bioenergetics; Body Mass Index; Body Weight; Caloric Restriction; Demographics; Diet, Reducing; Dietary restrictions; Energy and Protein Metabolism; Energy Intake; Energy Metabolism; Female; Humans; Male; Mathematical models; Metabolism; Middle Aged; Models, Biological; National Institute of Diabetes and Digestive and Kidney Diseases (U.S.); Nutrition Assessment; Obesity; Overweight - diet therapy; Overweight - metabolism; Reproducibility of Results; United States; Weight; Weight Loss; Young Adult; United States; energy intake; mathematical modeling; weight loss; dietary assessment; energy balance; caloric restriction
• ISSN: 0002-9165; 1938-3207; 1938-3207
• DOI: 10.3945/ajcn.115.111070

Accurate measurement of free-living energy intake (EI) over long periods is imperative for understanding obesity and its treatment. Unfortunately, traditional methods rely on self-report and are notoriously inaccurate. Although EI can be indirectly estimated by the intake-balance method, this technique is prohibitively labor-intensive and expensive, requiring repeated measures of energy expenditure via doubly labeled water (DLW) along with multiple dual-energy X-ray absorptiometry (DXA) scans to measure changes in body energy stores. Our objective was to validate a mathematical method to measure long-term changes in free-living energy intake. We measured body weight and EI changes (ΔEI) over 4 time intervals by using the intake-balance method in 140 individuals who underwent 2 y of caloric restriction as part of the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy study. We compared the ΔEI values calculated by using DLW/DXA with those obtained by using a mathematical model of human metabolism whose only inputs were the initial demographic information and repeated body weight data. The mean ΔEI values calculated by the model were within 40 kcal/d of the DLW/DXA method throughout the 2-y study. For individual subjects, the overall root mean square deviation between the model and DLW/DXA method was 215 kcal/d, and most of the model-calculated ΔEI values were within 132 kcal/d of the DLW/DXA method. Accurate and inexpensive estimates of ΔEI that are comparable to the DLW/DXA method can be obtained by using a mathematical model and repeated body weight measurements.