**3. Epidemiology**

NAFLD is becoming the leading cause of liver disease. One of the causes is the increasing of obesity[2].

The incidence of NAFLD has been evaluated in a few number of studies, it ranges from 31-86 cases/1000 person-year in Japan to 29 cases per 100000 person-year in England [3, 4].

The prevalence of NAFLD is increasing. Recent studies presented in the Digestive Diseases Week 2012 summarizes this increased prevalence over the last 20 years [5, 6]. Investigators report an increasing in obesity. This increase is followed by a rising in steatosis and NASH, the presence of steatosis among obese people has increased from 23% in the 80s, 43% in the 90s and finally to 60% nowadays [4]. Even in non-obese patients, the prevalence of steatosis increased from 12%, to 27% and 36%, respectively [5].

In children/adolescents, over the last 20 years, obesity has increased from 11% to 21%, sus‐ pected NAFLD from 4% to 10, and the prevalence of altered aminotransferases among obese adolescents has increased from 17% to 37% [6].
