A computational model to determine energy intake during weight loss

Background Energy intake (EI) during weight loss is difficult and costly to measure accurately Objective The objective was to develop and validate a computational energy balance differential equation model to determine individual EI during weight loss Design An algorithm was developed to quantify EI during weight loss based on a validated one-dimensional model for weight change By using data from a 24 wk calorie restriction study we tested the validity of the EI model against 2 criterion measures I) EI quantified through food provision from weeks 0-4 and 4-12 and 2) EI quantified through changes in body energy stores [measured with dual energy X ray absorptiometry (DXA)] and energy expenditure [measured with doubly labeled water (DLW)1 from weeks 4-12 and 12-24 Results Compared with food provision the mean (+/- SD) model errors were 41 +/- 118 kcal/d and -22 +/- 230 kcal/d from weeks 0-4 and 4-12 respectively Compared with EI measured with DXA and DLW the model errors were -71 +/- 272 kcal/d and -48 +/- 226 kcal/d from weeks 4-12 and 12-24 respectively In every comparison the mean error was never significantly different from zero (P values > 0 10) Furthermore Bland and Altman analysis indicated that error variance did not differ significantly over amounts of EI (P values > 0 26) Almost all individual participants values were within CI limits Conclusion The validity of the newly developed EI model was supported by experimental observations and can be used to deter mine an individual participant s EI during weight loss Am J Clin Nutr 2010 92 1326-31