Regular exercise improves liver function and cuts type 2 diabetes risk in obese individuals

Obese individuals with nonalcoholic fatty liver disease (NAFLD) who are also at risk of developing type 2 diabetes may be able to improve the condition of their livers and boost their metabolic health through moderate amounts of aerobic activity, according to a new study from researchers at the Cleveland Clinic.

As the obesity epidemic continues, NAFLD is becoming increasingly common. It can cause scarring in the liver, which eventually may lead to cirrhosis or organ failure. Many of the risk factors for type 2 diabetes, including a large waistline and a fatty diet, also predispose individuals to NAFLD.

However, reducing the threat to the liver may be as simple as walking on a treadmill every day. For the new study, which will be presented at the Experimental Biology 2011 meeting this week, researchers asked a group of obese individuals with NAFLD and risk factors for type 2 diabetes to walk on a treadmill for one hour each day for one week.

Before and after the study, the researchers measured participants' blood sugar, insulin and adiponectin levels. The latter is a hormone that improves the body's response to insulin and has anti-inflammatory properties. Obese individuals often have low levels of the hormone. Much of the liver damage caused by NAFLD is thought to result from inflammation.

By the conclusion of the one-week study, researchers found that participants made significant improvements in all of these measures, particularly in the level of adiponectin in their arteries. The researchers said their findings underscore the importance of regular physical activity.

"Exercise appears to affect the cumulative metabolic risk factors for the progression of nonalcoholic fatty liver disease," said Dr. Jacob Haus, who led the study. "We like to think of exercise as medicine."