JMIR Publications

ABSTRACT

Background:

Intermittent fasting (IF) emerges as a promising dietary approach against obesity, which can be implemented as a feasible and cost-effective web-based strategy. We have developed a Brief Online IF Program (OIF), which features self-administered fasting regimen supported with meals delivery, online guidance, and app messages.

Objective:

This pilot study aimed to assess the effectiveness, feasibility, and safety of the OIF among overweight Japanese adults.

Methods:

Study design was 1:1 randomized controlled trial for 12 weeks. Overweight adults with a body mass index from 23 to <35 were recruited in 1 university, 1 hospital and 2 company offices. For the intervention group, meal replacements for their weekly intermittent fasting were provided and an online guidance was given via Zoom. They were instructed to fast weekly by consuming provided fasting meals and to read the app messages encouraging fasting practices and healthy lifestyles. The control group received only app messages encouraging healthy lifestyles. A non-blinded researcher administered the interventions for both groups. Primary outcome was change in body weight assessed under intention-to-treat, with primary analysis to estimate between-group mean difference, adjusted for sex, age, and baseline weight. Secondary outcomes encompassed laboratory-based measures (body compositions, blood pressures, and biomarkers such as hemoglobin A1c, triglycerides, cholesterols), and questionnaire-based measures (quality of life, total physical activity, adherence to the intervention, adverse events, and freely written feedback on the interventions).

Results:

A total of 57 individuals were enrolled, with 28 allocated to the intervention group and 29 to the control group. At 12 weeks, 25 participants in the intervention group and 27 participants in the control group were followed-up. Baseline median weight was 75.8 kg for the intervention group and 74.8 kg for the control group. The mean weight change was −0.9 (SD 1.9) kg in the intervention group and 0.6 (SD 1.4) kg in the control group. The primary analysis revealed a significant between-group difference of −1.6 (95% CI −2.5 to −0.8; P<.001) kg. However, no significant difference was observed in fat mass change (mean difference −0.1 kg, 95% CI −1.3 to 1.4), but a reduction in muscle mass was implied (mean difference −1.3 kg, 95% CI −2.5 to −0.2). Adherence to the intervention was 79% (22/28) in the intervention group and 59% (17/29) in the control group. No serious adverse events were reported.

Conclusions:

The 12-week OIF can promote weight loss in overweight adults, but may not result in improvements in body composition. The low dropout rate and modest adherence, with no serious adverse events, indicates the feasibility and safety of the program. The future trial should be conducted with the integration of other components such as consistent mentoring and exercise recommendations to improve body composition and overall health outcomes. Clinical Trial: UMIN-CTR UMIN000050437