A functioning liver is vital to human life. Your liver filters harmful substances out of your blood and converts the food you eat into nutrients your body uses. A liver with too much fat - over 5 to 10 percent of the liver's weight - is considered a fatty liver.

While fatty livers are often linked to use of alcohol, some people have fatty livers without consuming excessive alcohol. This condition is called non-alcoholic fatty liver disease (NAFLD). This condition can develop in people who are overweight or have diabetes. It may also be caused by rapid weight loss and unhealthy eating habits. However, some people with none of these risk factors also develop NAFLD.

Some people with the condition have livers that become swollen and scarred. This is called non-alcoholic steatohepatitis (NASH). Scarring, or cirrhosis, is a very serious condition that involves permanent liver damage. It can lead to liver cancer and even liver failure.

Many people with NAFLD (without scarring) have no symptoms. However, symptoms can include:

Severe tiredness
Generally feeling bad (malaise)
Full, uncomfortable feeling in the upper abdomen
Unexplained weight loss
Nausea with or without vomiting
Abdominal pain and swelling (ascites)
Swelling in the legs (edema)
Blood in stools or bowel movements
Jaundice (yellowed skin and white of the eyes) or discolored skin
Bleeding from the gums or nosebleeds
Red, spidery blood vessels just under the skin surface.

Symptoms of NASH (with scarring) indicate a more serious condition, and should be checked immediately. The symptoms are:

Severe abdominal pain
Abdominal bloating or swelling
Mental status or behavior change (for example, confusion, delirium, hallucinations, delusions, and reduced awareness or alertness)
Change in consciousness or alertness (for example, passing out or being unresponsive)
Severe tiredness
Vomiting blood or black material (resembles coffee grounds)
Sudden behavioral changes

There are no treatments specifically for NAFLD or NASH. However, there is evidence that diet plays an important role in controlling or reversing the symptoms of NAFLD. Doctors recommend a healthy diet low in saturated fat, transfat, sugar (including sugary drinks) and meat. They recommend switching to polyunsaturated fat from plant oils, and consuming more omega-3 fatty acids from fish. It's also important to lose weight, if needed, and exercise regularly.

Other recommendations include avoiding alcohol consumption and not taking unnecessary medicines. Experimental treatments include antioxidants such as vitamin E, betaine, and selenium. These agents reduce the oxidative stress that seems to build up inside the livers of people with NASH. But their ability to effectively treat the disease has not yet been proven.

Clinical studies are currently examining whether diabetes medicines can help treat NASH. Most people with NASH are insulin sensitive, which means that their insulin is unable to effectively control their blood sugar and fatty acid levels in their bloodstream. Some diabetes drugs, including metformin, rosiglitazone and pioglitazone, may help the body become more sensitive to insulin and also prevent liver damage in people with NASH.