Nonalcoholic steatohepatitis (NASH) is liver inflammation and damage caused by a buildup of fat in the liver. It is part of a group of conditions called nonalcoholic fatty liver disease. You may be told you have a "fatty liver."
My brother was diagnosed with NASH and lived with it for 20 years. In 2014 he noticed that my wife and I lost a bit of weight and decided to follow us into our Low Carbohydrate, High Fat way of eating. Within 4 months he too had lost weight and found that he also lost his fatty liver - with his liver function test results all coming back into the 'normal' range.