Impact of Body Mass Index on Outcomes Following Autologous Breast Reconstruction: A Focus on Low-BMI Patients

Background: Although outcomes following autologous breast reconstruction (ABR) have been evaluated across body mass index (BMI) cohorts, patient-reported outcomes remain understudied. This study aimed to compare 1-year BREAST-Q scores and complication rates across BMI cohorts following ABR. Methods: All female patients ≥ 18 years who underwent ABR from January 2010 to December 2024 were included. Patients were stratified into three BMI cohorts: <21, 21–25, and >25–30. The primary outcome was 1-year BREAST-Q scores, and secondary outcomes included postoperative complications. Results: A total of 2366 patients were included: 263 with BMI < 21, 936 with BMI 21–25, and 1167 with BMI > 25–30. DIEP flap was the predominant flap (72%), followed by TRAM flaps (13%). At 1-year, patients with BMI < 21 demonstrated higher Physical Well-being: Chest scores (85 vs. 76 vs. 76; p = 0.007) and Physical Well-being: Abdomen scores (76 vs. 70 vs. 69; p < 0.001). Satisfaction with Breasts, Psychosocial Well-being, and Sexual Well-being did not differ significantly across cohorts (p > 0.05). Mastectomy skin flap necrosis rates were lowest in the BMI < 21 cohort (5.7%; p = 0.029), and 30-day readmission rates were lowest in the BMI 21–25 cohort (5.0%; p = 0.033). All other complications were comparable across groups. Conclusions: Physical well-being scores at 1 year favored lower-BMI patients, while breast satisfaction, psychosocial well-being, and sexual well-being were equivalent across cohorts. These findings may inform preoperative counseling regarding physical recovery expectations in higher-BMI patients, while suggesting BMI in this range is not a primary driver of patient-reported satisfaction.