Monitoring Energy Intake: A Hand-Held Personal Digital Assistant Provides Accuracy Comparable to Written Records

New approaches to assess energy intake (EI) may have advantages over traditional written methods, but validity of these emerging methodologies must be demonstrated. This exploratory study compared EI obtained using a hand-held personal digital assistant (PDA) and traditional written records with total energy expenditure measured by doubly labeled water (TEEDLW). Twenty-six volunteers (aged 23±4 years, body mass index [calculated as kg/m2] 24±2) participated in a randomized (either PDA or written record group) and matched (for sex, age, and body mass index) study for 7 consecutive days between June 2005 and April 2006 to record EI. Group comparisons were made with t and Mann-Whitney U tests. Bland-Altman plots were used to compare limits of agreement between methods. Volunteers remained weight stable during the study period (0.2±0.8 kg; P>0.05). Reported EI by written record and PDA were similar to TEEDLW; 105% vs 92% of TEEDLW, respectively (P>0.05). There was a significant relationship between reported EI by PDA and TEEDLW (r=0.60, P<0.05), but not for written record (r=0.45, P>0.05). Limits of agreement indicated both written record and PDA had large variability (range 1,394 to −1,472 kcal/day). Findings suggest the bias in using a PDA is similar to that observed when using a written record for estimation of EI in weight-stable volunteers.