Pilot study to assess prolonged overnight fasting in breast cancer survivors (longfast)

Abstract

Retrospective analysis of nightly fasting among women with breast cancer suggests that fasting < 13h may be associated with a higher risk of breast cancer recurrence. We sought to evaluate prolonged overnight fasting (POF), an accessible nonpharmacological intervention, in a prospective feasibility study. We designed a single-arm, pilot study to evaluate the feasibility of fasting for 13h overnight for 12weeks among women with a history of early-stage breast cancer survivors. Baseline and end of study assessments included measurements of body mass index (BMI), blood biomarkers, quality of life (QOL), mood, fatigue, and physical activity. Patient-reported outcome questionnaires were also administered at 6weeks. Feasibility was defined as ≥ 60% of participants documenting fasting for 13h on at least 70% of nights during the study period. Forty women with a history of breast cancer were enrolled with a median age of 60 (range 35-76) and median time since diagnosis of 4.5years (range 0.8-20.7). At baseline, BMI was ≥ 25 in 37.5%. Ninety-five percent of participants fasted ≥ 13h for at least 70% of study days (95% CI 83-99%). There was a statistically significant improvement in anxiety (p = 0.0007) at 6weeks and BMI (p = 0.0072), anxiety (p = 0.0141), depression (p = 0.0048), and fatigue (p = 0.0105) at 12weeks. There was no significant change in overall QOL, physical activity levels, or blood biomarkers at 12weeks. POF is feasible among patients with a history of breast cancer and may potentially improve BMI, mood, and fatigue without detrimental effects on overall QOL.