Time-restricted Eating Versus Daily Continuous Calorie Restriction on Body Weight and Colorectal Cancer Risk Markers

Approximately 42% of the U.S. adult population is obese and data suggests that persons with obesity are at a 30% greater risk of developing colorectal cancer (CRC). Therefore, efficacious approaches to preventing and treating obesity will have significant effects on CRC incidence in the U.S. Although calorie restriction through lifestyle intervention is the most common approach to treat obesity, clinically meaningful weight loss is difficult to achieve via this method due to low adherence with calorie monitoring, indicating a need for innovation. Time-restricted eating, a type of intermittent fasting, has been shown in animals to impart cancer protective effects including lower body weight, decreased systemic inflammation, and improved glucose metabolism. Time-restricted eating is where individuals are asked to consume all their food for the day within a specified time frame, and water fast for the remaining hours of the day. We recently performed two short-term (≤12-weeks) pilot studies of time-restricted eating to evaluate its safety and preliminary efficacy on body weight and chronic disease risk markers in adults with obesity. Our results show the intervention is a safe and acceptable approach to weight loss among obese adults. Moreover, time-restricted eating produced approximately 3% weight loss from baseline and reductions in systolic blood pressure, oxidative stress and insulin resistance. Although these pilot findings show promise for time-restricted eating as an effective tool for CRC risk reduction among obese individuals, these data still require confirmation by a well powered longer-term clinical trial. The present proposal aims to implement a 12-month (6-month intervention, 6-month maintenance) controlled, parallel arm trial among 255 obese adults (45-70 years old) who have had a colonoscopy. Subjects will be randomized to 1 of 3 groups: 1) 8-hour time-restricted eating (daily ad libitum food intake from 12pm - 8pm), 2) Calorie restriction (daily 25% calorie restriction), or 3) Control (daily ad libitum food intake, no meal timing restrictions) to compare the effects on: (1) Body weight, body composition, and intervention adherence; (2) Circulating metabolic, inflammation, and oxidative stress-related biomarkers; (3) Colonic mucosal gene expression profiles and mucosal inflammation, DNA damage and cellular growth; and (4) maintenance of benefits on body weight/composition and CRC markers.