ObjectiveThe growing prevalence of severe obesity, combined with the failure of conservative treatments, has led to a significant spread of bariatric surgical procedures. The aim of this study was to emphasize the need of adequate presurgery patient selection and close follow-up after malabsorptive procedures for bariatric surgery. MethodsThe study retrospectively evaluated 25 (20 F, 5 M; mean age 43 ± 13 y) obese patients (mean weight before intervention 134 ± 30.7 kg, body mass index 50.7 ± 10.1 kg/m2) attending our outpatient clinical nutrition unit for severe malabsorption and secondary malnutrition after surgical intervention that had been performed outside the regional area. ResultsAll patients received personalized dietetic indications; in 12 of 25 (48%) cases integrated by oral protein supplements and in 5 of 25 (20%) by medium chain triglycerides. According to screening exams, patients were prescribed oral/parenteral iron, vitamins A, B group, D, and folate supplementation. In 14 of 25 (56%) patients, parenteral hydration and in 4 of 25 (16%), long-term parenteral nutrition was required. Five patients required hospitalization for severely complicated protein–energy malnutrition. ConclusionNutritional deficiencies are common after malabsorptive procedures for bariatric surgery; these can be present or latent before surgery, frequently going unrecognized and/or inadequately treated particularly when patients are not strictly followed up by the operating center. Despite the adequate—even intensive—intervention, clinical nutritional status moderately improved in all patients.