Feasibility and outcomes from using a commitment device and text message reminders to increase adherence to time-restricted eating: A randomized trial

Background: Obesity is strongly associated with cardiovascular disease, particularly through its effects on blood pressure. Though maintaining a negative caloric balance leads to weight loss, many patients struggle to adhere to low calorie diets over the long term. Time-restricted eating, a subtype of intermittent fasting (IF), may be an easier dietary pattern for patients to initiate and maintain. We tested the feasibility of a bidirectional texting strategy to help patients with obesity and hypertension initiate and maintain time-restricted eating, and whether a commitment device, a pledge to behave in a certain way in the future while making nonadherence costlier, would increase adherence beyond bidirectional texting.

Methods: Patients with obesity and hypertension seen in cardiology clinics were provided education on time-restricted eating and randomized to a commitment device versus attention control. Attention control consisted of daily bidirectional text messages asking whether patients adhered to IF and weekly text messages asking participants to send their weight and blood pressure. The commitment device involved the same text messages as attention control, plus a commitment contract, setting of implementation intentions with respect to details of time-restricted eating, and involvement of a support partner who received weekly updates on the participant's adherence to time-restricted eating. The intervention lasted 12 weeks, followed by a 6-week follow-up period. The primary outcome was days per week adherent to time-restricted eating over the 18-week study period, measured by daily self-report. We also compared change from baseline weight and blood pressure between randomized groups.

Results: A total of 37 patients were randomized and started the study-20 to attention control and 17 to the commitment device. Mean age was 60 years old, and mean BMI was 38.4 kg/m². Over the 18-week study period, the mean ± standard deviation (SD) number of days per week adherent to time-restricted eating was 4.7 ± 1.9 in the control arm and 5.4 ± 1.7 in the intervention arm (P = .23). Mean systolic blood pressure declined from 135 to 128 mm Hg among all participants (P = .006) with no difference between groups in change from baseline blood pressure (P = .74). Weight decreased from 229 to 223 pounds among all participants (P = .25) with no significant difference between groups in change from baseline weight (P = .84).

Conclusions: A bidirectional texting strategy was feasible for helping patients with obesity and hypertension initiate and adhere to time-restricted eating. Adding a commitment device to bidirectional texting did not increase adherence to time-restricted eating compared with attention control, nor were there significant between group changes in blood pressure or weight, but these comparisons were underpowered. A larger randomized trial of the effect of this scalable intervention, compared with usual care, on blood pressure and weight among patients with obesity and hypertension is warranted.

Clinical trials registration: clinicaltrials.gov; unique identifier: NCT04836312.