Inclusion Criteria:  age from 18 to 65 years old body mass index ≥ 35 kg/m2 with comorbidities disease or body mass index ≥ 40 kg/m2, with failure of non operative attempts to lose weight a minimum 2-year follow-up at our outpatient clinic.  Exclusion Criteria:  secondary causes of obesity (e.g. endocrine diseases) patients unable to participate in medical follow-up; associated comorbidities or diseases impacting on weight loss.