Motivations and Beliefs Among Current and Former Intermittent Fasters: Links to Restrictiveness, Adherence, and Adherence Challenges

Intermittent fasting (IF) is a dietary pattern that consists of alternating between periods of fasting and feeding within a specified timeframe. IF has become increasingly popular among young adults. Prior research has explored IF broadly, with limited attention to how individuals engage with their IF regimens. The present study aimed to explore restrictiveness and IF adherence among former and current intermittent fasters and assess whether differences in engagement styles exist across motivation for IF engagement, beliefs about IF, and current/former IF status. Participants included 400 U.S. young adults (age M = 26.3, SD = 2.87, 51% cisgender man) recruited via Prolific. Participants completed self-report measures assessing demographic information and IF engagement characteristics, including IF adherence, intended adherence, challenges to adherence, and restrictiveness in the types and amount of foods consumed during feeding periods. Descriptive and inferential statistical analyses were conducted. Most participants reported following a 16:8 regimen (68.3%) and engaging in IF for weight-related reasons (68.8%). Individuals who reported engaging in IF for weight-related reasons endorsed greater restriction and greater challenges to adherence than those engaging for other motives. Most participants considered IF to be a “diet” (63.0%), and these individuals reported greater challenges to adherence than individuals who did not consider IF a diet or were unsure. Additionally, former intermittent fasters reported greater IF adherence, intended adherence, and adherence challenges compared to current intermittent fasters. Future studies should consider whether differences in engagement have implications for disordered eating risk.