Dietary Composition, Meal Timing, and Cancer-Related Fatigue: Insights From the Women's Healthy Eating and Living Study.

Background: Cancer-related fatigue is difficult to treat, and dietary interventions are promising yet underused.

Objective: We explored associations between dietary patterns and fatigue, and the effect of a dietary intervention versus control on fatigue using Women's Healthy Eating and Living study data, plus mediators and moderators of the intervention effect.

Methods: The Women's Healthy Eating and Living study was a randomized controlled trial among early-stage breast cancer survivors. The 4-year intervention encouraged fruits, vegetables, fiber, and 15% to 20% calories from fat. Fatigue outcomes included a 9-item energy scale and a single-item tiredness question. Dietary quality was estimated using a modified Healthy Eating Index (24-hour dietary recall) and serum carotenoid concentrations. Nutrient timing was obtained from 4-day food logs.

Results: Among 2914 total participants, lower body mass index was associated with less tiredness and more energy at baseline ( P < .001 for both). Earlier start and end times for daily eating windows were associated with less tiredness ( P = .014 and P = .027, respectively) and greater energy ( P = .006 and P = .102, respectively). The intervention did not lead to improvements in fatigue on average ( P > .125). However, the intervention was more effective for participants who were younger, had fewer comorbidities, and did not have radiation treatment. Mediators included increases in serum carotenoids, increases in the modified Healthy Eating Index, and weight loss/maintenance.

Conclusion: Diet quality and earlier eating windows were associated with less fatigue.

Implications for practice: Programs that encourage high diet quality and a morning meal and discourage nighttime eating should be tested for efficacy in reducing cancer-related fatigue in survivorship.