Comparing Appetite and Dietary Intake Responses to Resistance Exercise in Breast Cancer Survivors Undergoing Adjuvant Endocrine Therapy Versus Individuals Without Cancer: A Secondary Analysis

Breast cancer survivors (BCS) undergoing adjuvant endocrine therapy have increased risk of obesity. Estrogen and exercise suppress appetite in non-BCS populations, but their combined effects in BCS are unknown. This secondary analysis compared the impact of acute resistance exercise (REx) on appetite and energy intake in estrogen-suppressed BCS versus females without cancer ('non-BCS'). Premenopausal inactive BCS (stage 0-III estrogen receptor-positive breast cancer, <5 years post-diagnosis, undergoing estrogen-targeted therapy) and non-BCS completed REx or sedentary (SED) conditions 35 min after a standardized breakfast. Appetite visual analog scales and hormones (ghrelin and peptide-YY [PYY]) were measured before and after breakfast and REx/SED; energy intake was assessed 3 h post-breakfast (1.5 h post-REx or SED). Fifteen BCS (age: 46 ± 7; BMI: 25.0 ± 3.8 kg/m²) and 12 non-BCS (age: 37 ± 8; BMI: 29.0 ± 5.1 kg/m²) were included. BCS showed greater PYY 90 and 120 min post-breakfast compared to non-BCS, particularly after REx (group x time x condition: <i>p</i> = 0.009, <i>p</i> = 0.005, respectively). No group effects were observed for ghrelin. BCS had lower body mass-adjusted energy intake compared to non-BCS (<i>p</i> = 0.036), despite similar appetite ratings. Estrogen-suppressed BCS exhibit heightened PYY and lower energy intake after REx, revealing novel effects of exercise on appetite in a state of low estrogen.