Predicting energy intake with an accelerometer-based intake-balance method.

Nutritional interventions often rely on subjective assessments of energy intake (EI), but these are susceptible to measurement error. To introduce an accelerometer-based intake-balance method for assessing EI using data from a time-restricted eating (TRE) trial. 19 participants with overweight/obesity (25-63 years old; 16 females) completed a 12-week intervention (NCT03129581) in a control group (unrestricted feeding; n=8) or TRE group (n=11). At the start and end of the intervention, body composition was assessed by dual-energy X-ray absorptiometry (DXA), and daily energy expenditure (EE) was assessed for two weeks via wrist-worn accelerometer. EI was back-calculated as the sum of net energy storage (from DXA) and EE (from accelerometer). Accelerometer-derived EI estimates were compared against estimates from the body weight planner of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Mean EI for the control group declined by 33 and 104 kcal/day for the accelerometer and NIDDK methods, respectively (both p ≥ 0.38), versus 300 and 351 kcal/day, respectively, for the TRE group (both p < 0.01). At follow-up, the accelerometer and NIDDK methods showed excellent group-level agreement (mean bias of -71 kcal/day across arms; standard error of estimate 252 kcal/day) but high variability at the individual level (limits of agreement from -577 to +436 kcal/day). The accelerometer-based intake-balance method showed plausible sensitivity to change, and EI estimates were biologically and behaviorally plausible. The method may be a viable alternative to self-report EI measures. Future studies should assess criterion validity using doubly labeled water.