Compared with our ancestors, Western societies today lead a lifestyle that is much more sedentary, probably as a result of cultural changes stemming from modern socio-economic morays. Taking into account differences in body size, our energy expenditure per kilogram of body weight has been estimated to be <40% of that of our prehistoric ancestors.1 Current estimates suggest that 7 out of 10 adults are inactive or lack adequate conditioning,2 and this lack of adequate exercise, combined with dietary indiscretion, has contributed to the worldwide epidemic of obesity and non-alcoholic fatty liver disease (NAFLD). Within the USA, data suggest that 64.5% of the adult population is now overweight or obese, with a worldwide prevalence of 40–60%.3^–5 Obesity, combined with host factors such as diet, sedentary lifestyle and genetic predisposition, has been directly associated with increases in the prevalence of insulin resistance, diabetes mellitus and the metabolic syndrome. The hepatic manifestation of the metabolic syndrome, NAFLD, has also increased in prevalence, now considered to be around 20–30% in Western countries. Among morbidly obese patients undergoing bariatric surgery, approximately 90% have NAFLD and 36–37% have the more aggressive form of fatty liver, non-alcoholic steatohepatitis (NASH).6 7 In patients with NAFLD, advancing age, increasing weight, the number of features of the metabolic syndrome and the degree of insulin resistance have all been independently associated with NASH severity.8 Evidence-based treatment options for NAFLD are currently lacking. Recent data suggest that the thiazolidinedione class of insulin sensitisers may be efficacious, but widespread utilisation of these agents awaits further investigation.9 Evidence also supports a role for weight loss, achieved through diet and exercise.

The purpose of this review is to describe the currently accepted pathophysiology of NAFLD, to highlight the known dietary and exercise habits of patients with NAFLD, …