Background: Patient-reported lower satisfaction with the abdomen preoperatively is a strong predictor of undergoing DIEP flap surgery. The authors evaluated physical well-being of the abdomen before and after flap-based breast reconstruction to determine potential predictors for decreased postoperative abdominal well-being. Methods: The authors retrospectively analyzed an institutional breast reconstruction registry, selecting patients who underwent abdominally based autologous flap breast reconstruction from 2010 to 2015. The authors' primary outcome was the Physical Well-being of the Abdomen domain from the BREAST-Q, measured preoperatively and at 6- and 12-month follow-up visits after final reconstruction. The authors classified two patient groups: those who experienced a clinically important worsening of Physical Well-being of the Abdomen score and those who did not. The authors used the chi-square test, t test, and Wilcoxon rank sum test, and multivariable logistic regression to identify potential predictors. Results: Of 142 women identified, 74 (52 percent) experienced clinically important worsening of physical well-being of the abdomen, whereas 68 (48 percent) did not. The first group experienced a 25-point (95 percent CI, 22 to 28) decrease and the latter an 8-point (95 percent CI, 5 to 10) decrease in score compared to baseline. Multivariable analysis showed an association between higher baseline score and race, with higher odds of decreased score at the 12-month follow-up. A higher baseline RAND-36 general health score, bilateral reconstruction, and a lower body mass index demonstrated a trend for clinically important worsening of physical well-being of the abdomen. Conclusions: More than half of flap-based breast reconstruction patients experienced clinically important worsening of abdominal well-being after final breast reconstruction. Clinicians may use these findings to identify patients at higher risk of worsened postoperative abdominal well-being. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.