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Am J Clin Nutr. 2015 Aug;102(2):353-8. doi: 10.3945/ajcn.115.111070. Epub 2015 Jun 3.

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

Author information

1
National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD; and.
2
Pennington Biomedical Research Center, Baton Rouge, LA.
3
National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD; and kevinh@niddk.nih.gov.

Abstract

BACKGROUND:

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.

OBJECTIVE:

Our objective was to validate a mathematical method to measure long-term changes in free-living energy intake.

DESIGN:

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.

RESULTS:

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.

CONCLUSIONS:

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.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT00427193.

KEYWORDS:

caloric restriction; dietary assessment; energy balance; energy intake; mathematical modeling; weight loss

PMID:
26040640
PMCID:
PMC4515869
DOI:
10.3945/ajcn.115.111070
[Indexed for MEDLINE]
Free PMC Article

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