What is fatty liver disease?


My doctor says I have fatty liver disease, but I rarely drink. So how is this possible?


I can understand your surprise, since it used to be that fatty liver disease was usually caused by abusing alcohol. However, it has also been true that obesity and diabetes could cause fatty liver. Perhaps you have one of these conditions. In the past 30 years, as obesity and diabetes have become more common, so has fatty liver disease.

Scientists aren’t sure how the disease begins. They suspect the condition gets started because of insulin resistance (itself a consequence of obesity). When people are insulin-resistant, their muscle, fat and liver cells don’t respond normally to insulin. So levels of the hormone — and the blood sugar it ushers into cells — build up in the blood. This increases the risk of developing diabetes and heart disease.

In people with insulin resistance, there is an increase in the amount of fat molecules circulating in the blood. In addition, liver cells are more likely to take fat molecules out of the blood and store the fat inside them. When these liver cells start to store fat, they can begin to cause inflammation in the liver. Immune system cells enter the liver, and sometimes scars start to form. This condition is called NASH. Between 5 percent to 10 percent of people with fatty liver disease develop NASH.

NASH is often a relatively stable, low-grade condition that people live with for years, with few if any symptoms. But it can also start a cascade of serious damage to the liver. And fatty liver disease may add to the already high risk of heart disease if you are obese or have diabetes.

Now that you’ve been diagnosed, what can you do? The best treatment is weight loss, ideally from changes in diet and an increase in physical activity. Weight loss has a very direct effect: As people lose weight, the fatty liver becomes less fatty.

There’s been some research into using diabetes drugs, vitamin E and fish oil to treat fatty liver disease and NASH. But there’s not enough evidence yet to recommend them.

Research on fatty liver disease is intense. Many different hormones that the body naturally makes are being linked to it. All of us carry trillions of bacteria in our intestines, but there is some evidence that the type of bacteria in our gut may influence whether we get fatty liver disease. I regard all of this as interesting but speculative; we still don’t really understand what causes the condition.

However, we do know this: (1) if you are overweight or obese, losing weight will help reduce the fatty liver; (2) if you have diabetes, treatments for it (particularly those that act to reduce insulin resistance) also often help.