(P15-002-23) Time Restricted Eating (TRE) Within a 10 Hour Window Is a Popular Practical Intervention in a Study of 148,374 People: The ZOE BIG IF Study

Objectives: Intermittent fasting (IF) in the form of TRE has grown in popularity as a flexible dietary method that focuses on the timing of eating rather than the quantity and content of caloric intake. Despite increased popularity of IF, evidence of its feasibility in everyday human life is lacking. This research explored factors contributing to user retention and fasting patterns in participants of the ZOE BIG IF Study.

Methods: UK participants completed a baseline habitual eating phase (1 wk) followed by an intervention TRE phase (2 wks) (eating window of ≤10 hours) as part of the BIG IF study (NCT05558423). Participants could opt in for additional IF weeks beyond 2 wks. Participants self-reported daily eating windows, as well as hunger, mood, energy and symptoms, using the ZOE Health smartphone App. Baseline characteristics (sex, age, physical activity (PA) levels, sleep quality, smoking status, socio-economic status (SES), body mass index (BMI)) and diet data (food frequency questionnaire (FFQ)) were collected. Retention for up to 16 weeks was quantified based on self-reported fasts. Retention was modelled using a Cox proportional hazards regression.

Results: 148,374 of active ZOE Health Study users signed up to the BIG IF study; n=65,583 (44.2%) of participants started daily logging, n=37,545 completed the core intervention period (baseline wk and 2 IF wks) and n=36,231 opted-in for additional weeks. Participants were aged (mean, SD) 60 years (12), predominantly female (74%), and had a baseline eating window of 11.3h (95% CI 11.3-11.4). On average, participants increased their fasting windows by 1.68h (95% CI 1.66-1.70). IF retention was positively associated with (lower hazard ratio (HR [95% CI])) higher age (60-70y: 0.94 [0.92-0.97] vs 18-30y: 1.86 [1.70-2.04]), higher PA levels (0.89 [0.87-0.90]), good sleep quality (0.97 [0.94-0.99]) and non-smoking status (0.86 [0.84-0.87]). Adherence was higher in individuals with 1) greater baseline mood and energy status; 2) positive changes in mood, energy and hunger during the intervention.

Conclusions: In this study of mobile app users in real-world conditions, IF in the form of TRE appears to be a sustainable dietary approach for many people who self-reported benefits. Understanding who benefits most from this simple sustainable intervention will be a valuable public health tool.

Funding Sources: ZOE Ltd