Associations Among Self-monitoring, Leisure Physical Activity, And Weight Loss: 6-month Results From The Smart Trial

Abstract

Weight loss has been associated with higher leisure physical activity (LPA) levels and frequent dietary self-monitoring. Less is known about how self-monitoring (SM) affects adherence to LPA goals, LPA levels and weight. PURPOSE: To examine associations among SM methods and adherence, LPA levels and adherence, and weight loss. METHODS: The SMART Trial is a clinical weight loss trial in which 210 overweight adults were randomized equally to one of three SM methods: 1) paper diary (PD); 2) personal data assistant with a dietary and PA software (PDA); and 3) PDA with daily tailored feedback message (PDA+FB). Participants were asked to record daily minutes of LPA in a weekly diary. SM adherence was based on submission of diaries and LPA adherence as recorded minutes divided by LPA goals at both baseline and 6 months (50 and 150 minutes, respectively). LPA levels were measured via self-report by the Modifiable Activity Questionnaire at baseline and 6 months. RESULTS: Data are presented on 189 participants with complete 6-month LPA data [84% female, 77% White, mean (± SD) age: 47.3 ± 8.8 years, mean (± SD) BMI: 34.1 ± 4.5 kg/m2]. Median LPA level (MET-hr/wk) was 7.4 at baseline (IQR: 2.1, 16.3) and 13.4 at 6 months (IQR: 5.4, 24.8), with no differences by SM method at baseline (p =.99) or 6 months (p =.75). However, participants in the PDA and PDA+FB groups were more likely to maintain high (i.e., 100%) LPA adherence over time, which in turn was related to higher LPA levels at 6 months. Median 6-month LPA (MET-hr/wk) was 22.4 (12.2, 37.5) for those with 100% LPA adherence, compared with 11.7 (4.4, 16.4) for those with < 50% LPA adherence and 9.1 (3.7, 24.5) for those who did not SM (p <.05). The group with high adherence to LPA goals (i.e., ≥ 100%) experienced more weight loss at 6 months than those with < 50% LPA adherence (p <.01). An increase in LPA levels was related to weight loss from baseline to 6 months (r = -.27, p <.01). CONCLUSIONS: Greater adherence to LPA was more likely in participants in the two PDA groups and was related to higher 6-month LPA levels; a greater increase in LPA levels was in turn associated with greater weight loss. These results suggest that compared to PD use, use of a PDA might improve adherence to LPA goals, which in turn can improve weight loss. It remains unknown if these improvements can be sustained. Supported by NIH Grant R01 DK071817.