Nonalcoholic steatohepatitis is part of the broader spectrum of nonalcoholic fatty liver disease, strongly associated with insulin resistance, obesity and the metabolic syndrome. Its increasing prevalence appears to be closely related to the increased frequency of overweight or obesity; which is associated with changes in dietary habits, including an increased consumption of hypercaloric food and saturated fat, often concurrent with decreased activity and energy expenditure. Weight loss through dieting and increasing energy expenditure through the practice of regular exercise has been shown to be effective in improving nonalcoholic fatty liver disease/nonalcoholic steatohepatitis, and is considered the mainstay of treatment. The effectiveness of these lifestyle interventions seems to rely chiefly on an improvement in insulin sensitivity. At present, disease management using a multidisciplinary team is probably pivotal for patient-centered quality of care.