Time-Restricted Eating Intervention Reduces Cardiovascular Risk in Older Breast Cancer Survivors

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In a Canadian single-institution feasibility study reported in JACC: CardioOncology, Amy A. Kirkham, PhD, of the University of Toronto, and colleagues found that a time-restricted eating intervention reduced cardiovascular risk among older breast cancer survivors with risk factors for cardiovascular disease mortality.1

Study Details

In the study, breast cancer survivors from a single center aged ≥ 60 years with overweight or obesity (body mass index [BMI] ≥ 25 kg/m2) who had completed anthracycline treatment within the past 1 to 6 years were invited by mail to participate in a time-restricted eating intervention. Recruitment occurred from August 2020 to January 2021, during the COVID-19 pandemic and prior to vaccine availability.

“We found that weekday 16:8 [time-restricted eating] was a highly feasible and low-symptom intervention that reduces calorie intake without fat-free mass loss or the need to count calories among [breast cancer survivors].”
— Amy A. Kirkham, PhD

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Time-restricted eating interventions commonly consist of limiting energy intake within a specified time window, usually 8 hours, followed by fasting for 16 hours (16:8 time-restricted eating). In the current study, breast cancer survivors were asked to eat ad libitum (as much or as often as desired) between 12 noon and 8 PM on weekdays and any time of day on weekends and to consume only water, black coffee, or black tea outside of those hours for 8 weeks. Intervention support consisted of the following:

  • A preintervention phone call from a registered dietitian
  • Check-in phone calls from study staff members at 1, 3, and 6 weeks
  • Weekday twice-daily automated text messages asking participants to provide the times of day they started and stopped eating.

Phone calls involved discussion of adherence, symptoms, barriers, and facilitators.

Key Findings

Of 228 invited patients, 22 (10%) enrolled and completed the intervention. Among the 22 patients, the mean age was 66 years, mean BMI was 31 kg/m2, and the mean time from completion of anthracycline treatment was 3 years. No patients had received trastuzumab, 50% had received left-sided radiation therapy, and 91% were currently receiving tamoxifen and/or aromatase inhibitor treatment.

Patients responded to 99% of text messages and adhered to ≥ 16 hours of fasting for a median of 98% (range = 85%–100%) of days. Reported adverse events, including headache and irritability, were minor and persisted for 5 minutes to 3 hours.

Compared with baseline, after 8 weeks, there was no significant change in fat-free mass (−0.1 ± 1.6 kg, P = 0.76). Calorie intake was reduced by a median of 450 kcal (interquartile range [IQR] = 28–765 kcal), representing a 22% relative reduction (P < .001). Median Framingham 10-year cardiovascular disease risk decreased from 10.9% (IQR = 8.6%–13.7%) to 8.6% (IQR = 7.6%–10.0%), representing a 15% relative reduction (P = .037).

Significant reductions in mean magnetic resonance imaging–derived visceral adipose tissue (−5% ± 7%, P = .009), median bioelectric impedance-derived whole-body fat mass (−0.9 kg, IQR = −1.5 to 0.1 kg, P = .046), and median body mass (−1.0 kg, IQR = −2.3 to 0.2 kg, P = .025) were observed, with no significant change in mean BMI (−0.2 ± 0.7 kg/m2, P = .10).

At baseline, 15 patients were classified as cardiometabolically unhealthy, defined as meeting criteria for metabolic syndrome or for pharmacologic preventive treatment of cardiovascular disease risk (statins), according to Canadian Cardiovascular Society guidelines. After 8 weeks, 8 of the 15 patients (53%) no longer met criteria for metabolic syndrome or pharmacologic treatment, having been reclassified as being at “low” (< 10%) 10-year Framingham cardiovascular disease risk.

The investigators concluded: “We found that weekday 16:8 [time-restricted eating] was a highly feasible and low-symptom intervention that reduces calorie intake without fat-free mass loss or the need to count calories among [breast cancer survivors]. Our preliminary efficacy findings include a 2% absolute or 15% relative [cardiovascular disease] risk reduction within just 8 weeks among [breast cancer survivors] at risk for [cardiovascular disease] mortality because of overweight or obese status, older age, and receipt of anthracyclines. [Time-restricted eating] also significantly decreased [visceral adipose tissue], which our team has previously found to accumulate rapidly with cardiotoxic treatment and predict later cardiac events among [breast cancer survivors].” 

DISCLOSURE: Dr. Kirkham reported no conflicts of interest.


1. Kirkham AA, Ford KL, Topolnyski J, et al: Time-restricted eating to reduce cardiovascular risk among older breast cancer survivors: A single-arm feasibility study. JACC: CardioOncol 4:276-278, 2022.