- BMI ((or projected BMI) > 35 kg/m² (projected BMI = weight over the age- and gender-specific BMI z-score defined as severe obesity corresponding at a projected BMI of 35 at the age of 18y) + 1 or more of the following obesity-related comorbid conditions: Obstructive Sleep Apnea Syndrome, Non-alcoholic steatohepatitis, type 2 diabetes, hypertension, benign intracranial hypertension.