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.
