Abstract 12484: Weekday 16:8 Time-Restricted Eating in Breast Cancer Survivors: Feasibility, Safety, and Effects on Cardiometabolic Health

Abstract

Introduction: Time-restricted eating (TRE) is a form of intermittent fasting involving ad libitum energy intake within a set time window, commonly 8 hours, followed by a water-only fast for 16 hours (i.e., 16:8 TRE). TRE is a practical approach to improve cardiometabolic health but has not been tested in cancer populations. Hypothesis: TRE is feasible (>85% adherence), safe (no major adverse events), and will improve cardiometabolic health in breast cancer survivors. Methods: Women who completed chemotherapy for early-stage breast cancer 1-6 years earlier, are ≥60 years, have a BMI >25 kg/m 2 , and not taking lipid or glucose-lowering medications were enrolled in a single-arm study of 16:8 TRE on weekdays for 8 weeks. Participants could eat ad libitum between 12-8 pm on weekdays and all weekend. No other dietary or physical activity instructions were given. Adherence was collected by twice daily text messages that asked participants to respond with the times that they started/stopped eating. The Framingham 10-year cardiovascular disease (CVD) risk score and heart age, and ectopic adipose tissue (3T magnetic resonance imaging) were assessed before and after 8 weeks of TRE. Results: Fifteen participants (66±4 years, 31±4 kg/m 2 ) have completed the study. Participants responded to 99% of text messages and adhered to the 16-hour fast a median of 98% of days (range 93-100%). Reported symptoms were minor and transient. At baseline, 73% of participants were at ‘intermediate’ (10-19%) CVD risk, and pharmacological treatment was indicated. Among those at intermediate risk, 8 weeks of TRE decreased the absolute CVD risk by a median of 2% and heart age by 6 years, and reversed the need for pharmacological treatment (i.e., reclassification to ‘low’ risk) or metabolic syndrome in 45%. In all participants, visceral adipose tissue decreased by a median of 6% (p=0.018) and triglycerides by 17% (p=0.008). There were no significant changes in hemoglobin A1c, or ectopic adipose tissue in the liver or thigh. Conclusions: Eight weeks of weekday 16:8 TRE is highly feasible, safe, and reduces CVD risk among older breast cancer survivors with overweight/obesity at moderate CVD risk. Improvements in glucose control and liver/thigh ectopic adipose tissue may require a longer intervention.