Fatty liver is quite harmlful. In fact it has been shown to progress to liver scarring, hardening and also liver cancer.
Lifestyle modifications like exercise and a healthy diet are effective in preventing fatty liver in most individuals.
Most patients are asymptomatic and usually discovered the condition incidentally because of abnormal liver function tests or enlarged liver discovered when they saw the doctor for something unrelated.
Elevated liver enzymes are found in 50% of patients with simple steatosis (fatty change). Some patients developed non-alcoholic steatohepatitis (Nash).
It is thought that about 80% of individuals with fatty liver will not develop significant liver disease. The other 20% will develop Nash. From this, between 20% and 30% will go on to develop cirrhosis and end-stage liver disease, where the only real treatment is a liver transplant.