Time Restricted Eating During Chemotherapy for Breast Cancer

Current standard of care during chemotherapy for breast cancer suggests enough daily calories and protein to maintain body weight and avoid muscle loss. However, this approach may be antiquated given weight gain is common during treatment and emerging pre-clinical and clinical evidence suggest that fasting during chemotherapy may improve clinical and patient-reported outcomes. For example, preliminary human trials examining the fasting mimicking diet (very low-calorie, low-protein diet 1-week per month) or short term fasting (48-120 hours (h)), known as periodic fasting, surrounding chemotherapy may increase effectiveness of treatment and decrease side effects related to chemotherapy. Yet these diets have low adherence, side effects of their own, and may increase patient burden and decrease quality of life. In contrast, time restricted eating (TRE) is a form of intermittent fasting with high adherence that may have similar positive effects on treatment outcomes without the untoward side-effects. Moreover, TRE may have beneficial effects on glucose regulation and body composition (i.e., decreased weight and body fat gain) suggesting the potential importance of this regimen to breast cancer recurrence. TRE is extremely accessible with no calorie counting or financial burden to the patient, individuals just shorten their eating window daily. However TRE also does no address diet quality. The Mediterranean diet has also been shown to improve patient and treatment outcomes in this population. The additive effect might be even more beneficial. Despite the potential benefits, TRE alone or TRE combined with a mediterranean has not been investigated in breast cancer patients during chemotherapy treatment. We aim to test the safety and feasibility of 8-h TRE compared to TRE combined with a mediterranean style diet among female breast cancer patients initiating chemotherapy for stage I-III breast cancer. We further strive to examine the preliminary efficacy of TRE or TRE with the mediterranean diet on treatment related outcomes, treatment related side effects, patient-reported quality of life and fatigue, blood-based metabolic markers and body/weight adiposity compared to the current standard of care.