Fatty liver disease is one of the common liver diseases, could be alcoholic (AFLD) when there is significant alcohol intake or non-alcoholic (NAFLD), when other causes of liver steatosis are ruled out in particular significant alcohol intake and viral hepatitis. The course of NAFLD could have one of two extremes, either benign simple steatosis or steatohepatitis known as NASH that could lead to progressive liver inflammation, cirrhosis and even hepatocellular carcinoma HCC, and is believed to be important cause for liver cirrhosis in those labeled before as cryptogenic cirrhosis. NASH represents more than 10% of liver transplant cases in the USA and unfortunately there is risk of recurrence post-transplant. The underlying cause is multifactorial, related to genetic and acquired factors, the acquired factors are mostly modifiable, related to lifestyle particularly increased calorie intake with limited consumption in people leading sedentary life, and this leads to overweight / obesity, insulin resistance and triglycerides accumulation in the liver. And so the management will mainly rely on reversal of these lifestyle negatives, so stress on the triad: Diet, exercise and weight reduction. In this review will focus on non-alcoholic fatty liver disease in adults, giving comprehensive overview including the latest recommendations about the management in clinical practice.