Change in Physical Activity During a Weight Management Intervention for Breast Cancer Survivors: Association with Weight Outcomes

Abstract

Objective: This study examined the effects of a group phone-based weight management intervention on change in physical activity as measured via accelerometer and self-report in rural breast cancer survivors. The study also evaluated the role of physical activity on clinically meaningful cut points for weight loss (baseline to 6 months) and weight loss maintenance (6 to 18 months). Methods: Participants were breast cancer survivors in a weight management intervention who provided valid weight and accelerometer data (N = 142). Participants were categorized into four groups based on weight loss ≥10% and weight regain ≥5% at 18 months. Results: Accelerometer-measured moderate-to-vigorous physical activity (MVPA) significantly increased from baseline to 6 months (+46.9 minutes). MVPA declined during maintenance but remained significantly greater than baseline. Self-reported MVPA followed a similar pattern as accelerometer MVPA, but estimates were significantly higher. Participants in the high loss, low regain group had significantly higher MVPA at all points. Conclusions: A distance-based weight management intervention for survivors improved physical activity outcomes over 18 months. Self-reported physical activity was substantially higher than accelerometer measured. Findings highlight the importance of device-based measurement for characterizing the magnitude of physical activity change as well as the role of physical activity in weight management outcomes.