Preoperative malnutrition and weight loss negatively impact postoperative outcomes in various surgical fields. However, for gynecologic surgery, evidence is still scarce, especially if surgery is performed within enhanced recovery after surgery (ERAS) pathways. This study aimed to assess the prevalence and impact of preoperative weight loss in patients undergoing major gynecologic procedures within a standardized ERAS pathway between October 2013 and January 2017. Out of 339 consecutive patients, 33 (10%) presented significant unintentional preoperative weight loss of more than 5% during the 6 months preceding surgery. These patients were less compliant to the ERAS protocol (>70% of all items: 70% vs. 94%, p < 0.001) presented more postoperative overall complications (15/33 (45%) vs. 69/306 (22.5%), p = 0.009), and had an increased length of hospital stay (5 ± 4 days vs. 3 ± 2 days, p = 0.011). While patients experiencing weight loss underwent more extensive surgical procedures, after multivariate analysis, weight loss ≥5% was retained as an independent risk factor for postoperative complications (OR 2.44; 95% CI 1.00–5.95), and after considering several surrogates for extensive surgery including significant blood loss (OR 2.23; 95% CI 1.15–4.31) as confounders. The results of this study suggest that systematic nutritional screening in ERAS pathways should be implemented.