Non-alcoholic steatohepatitis (NASH) in obese and severely obese populations is associated with the metabolic syndrome, with features of the syndrome predicting those who will have NASH rather than simple steatosis, a more benign form of non-alcoholic fatty liver disease. Substantial weight loss is proving the most effective therapy for obesity-related conditions. Improvements have seen the development of less invasive procedures. There is growing evidence that laparoscopic adjustable gastric banding and roux-en-Y gastric bypass provide effective therapy.