Since SCD seems to be related with obesity and insulin resistance, we aimed to study a) whether the methylation of the SCD gene promoter is associated with obesity and insulin resistance in morbidly obese subjects, b) its evolution after bariatric surgery and c) whether its change after bariatric surgery is associated with the changes found in different metabolic variables. Here, SCD is linked to obesity due to melanocortin 4 receptor deficiency.