Objective estimates of activity patterns and energy expenditure (EE) are important for the measurement of energy balance. The Intelligent Device for Energy Expenditure and Activity (IDEEA) can estimate EE from the thirty-five postures and activities it can identify and record. The present study evaluated the IDEEA system's estimation of EE using whole-body indirect calorimetry over 24 h, and in free-living subjects using doubly-labelled water (DLW) over 14 d. EE was calculated from the IDEEA data using calibration values for RMR and EE while sitting and standing, both as estimated by the IDEEA system (IDEEAest) and measured by indirect calorimetry (IDEEAmeas). Subjects were seven females and seven males, mean age 38·1 and 39·7 years, mean BMI 25·2 and 26·2 kg/m2, respectively. The IDEEAest method produced a similar estimate of EE to the calorimeter (10·8 and 10·8 MJ, NS), while the IDEEAmeas method underestimated EE (9·9 MJ, P < 0·001). After removing data from static cycling, which the IDEEA was unable to identify as an activity, both the IDEEAest and IDEEAmeas methods overestimated EE compared to the calorimeter (9·9 MJ, P < 0·001; 9·1 MJ, P < 0·05 and 8·6 MJ, respectively). Similarly, the IDEEA system overestimated EE compared to DLW over 14 d; 12·7 MJ/d (P < 0·01), 11·5 MJ/d (P < 0·01) and 9·5 MJ/d for the IDEEAest, IDEEAmeas and DLW, respectively. The IDEEA system overestimated EE both in the controlled laboratory and free-living environments. Using measured EE values for RMR, sitting and standing reduced, but did not eliminate, the error in estimated EE.

The aim of the present study was to investigate whether the impairments in cognitive function observed in unsupported dieting are related to compromised Fe status. During a non-clinical intervention, overweight participants (age: 18–45 years, BMI: 25–30 kg/m2) either participated in a commercially available weight-loss regimen (n 14), dieted without support (n 17) or acted as a non-dieting control group (n 14) for a period of 8 weeks. Measurements of cognitive function and blood chemistry were taken at a pre-diet baseline, after 1 week and 8 weeks of dieting. After 1 week, unsupported dieters displayed impaired verbal memory, executive function and slower reaction speeds than the other two groups, this difference disappearing by the end of the study. There were no significant group-related changes in blood chemistry over the course of the study, although there were group-related changes in a number of self-reported food-related cognitions. In conclusion, impaired cognition among unsupported dieters is not due to compromised Fe status and is most likely to result from psychological variables.