Introduction:
Ecological momentary assessment (EMA) assesses individuals' experiences, behaviors, and moods as they occur in real time and in their own environment, making it useful to understand the processes of behavior change. We report the use of EMA to study the triggers of lapses after intentional weight loss in a 12-mo. study that includes a standard behavioral weight loss intervention.
Purpose: We examined daily self-reports of self-efficacy and how they were related to unplanned eating episodes (‘lapses’) and weight change over the first 6 mos. of the study.
Hypothesis:
Higher self-efficacy is related to fewer “lapses” and better weight loss over time.
Methods:
Participants were provided a smartphone app programmed to administer EMA assessments up to 5 randomly-selected times/day. Each assessment included the self-efficacy query, How confident are you that if you have an urge to go off your healthy lifestyle plan, you can resist the urge? measured on a scale of 1-10. Participants were weighed at weekly, and after 3 months bi-weekly, group sessions. To account for replicate observations among subjects, generalized estimating equations were used to fit logistic regression models predicting lapses as a function of self-efficacy, adjusting for location (e.g., home, work, restaurant) and social setting (e.g., with others, alone).
Results:
The sample (N = 151) was 90.7% female and 79.5% White, and on average, 51.18 (10.22) years of age with a mean BMI of 34.0 (4.6) kg/m2. Of the 59,913 random assessments conducted over 6 mos., eating episodes were recorded in 7,991 (13.34%) of those assessments, of which 881 (11.03%) were not planned. Most of the 7,991 planned and unplanned eating episodes were captured when individuals were with others who were eating (49%), or when completely alone (24%). After adjusting for location and social setting, self-efficacy remained a significant predictor of a lapse (p < 0.001). The odds of a lapse decreased by 70% (95% CI, 64%, 76%) for every unit increase in self efficacy. After controlling for social setting, participants were estimated to lose 0.35 more lbs/mo. (SE = 0.14; p = 0.02) for each unit increase in self efficacy. Self-efficacy maintained a stable level between 7.3 and 7.4 for the first 4 mos., before decreasing at a rate of 0.11 points/month (SE = 0.04; p = 0.002) in the last 2 mos. This temporal trend in self-efficacy was paralleled by a similar trend in participants’ weights; they lost an average of 3.26 lbs/mo. (SE = 0.18) in the first 4 mos. compared to only 0.59 lbs/mo. (SE = 0.29) in the last 2 mos.
Conclusions:
The data suggest that as self-efficacy decreased to near 7.0, individuals were at greater risk to experience a lapse in their diet, an integral part of the healthy lifestyle plan. Targeting enhanced and sustained levels of self-efficacy above 7 may enable a person to resist lapses and prevent weight regain.
An Ecological Momentary Intervention for weight loss and healthy eating via smartphone and Internet: study protocol for a randomised controlled trial
