It used to be that people with liver disease were mostly heavy drinkers. But as waistlines began to expand in the ’80s and ’90s, doctors noticed an increasing number of overweight and obese patients who seemed to have liver disease but who didn’t drink. Further research found that it was their weight, not their alcohol consumption that was causing problems for their liver function. Past guidelines had suggested that exercise might help stave off liver disease, but new research has shown that exercise is better than most realized.
How does being overweight cause liver disease?
While doctors and scientists are still trying to figure out exactly why fat damages the liver, it seems that fat deposits in the liver as part of a group of illnesses called metabolic syndrome. Metabolic syndrome includes being overweight, having trouble keeping your blood sugar under control, having high cholesterol, and having high blood pressure. These changes indicate that the body is less able to properly handle the large amounts of carbohydrates and fat circulating in the blood.
What seems to happen when a person is obese and has metabolic syndrome is the liver is flooded with fat and doesn’t seem to get rid of it fast enough. It also seems to struggle to properly package and deal with cholesterol. On top of that, the liver seems to become less able to protect itself from the harmful effects of the chemical reactions it uses to detoxify the blood and regulate energy use in the body.
There are probably several other players, including the hormone insulin and several of the body’s other regulators of fat and energy use in the body.
What happens to the liver?
Over time, fat accumulates both around and within the liver. As this fat fills the cells of the liver, the liver has more and more trouble performing the functions it needs to. Blood becomes less able to pass through the liver for detoxification and backs up. Hormones and harmful chemicals that would otherwise be removed continue to circulate in the blood and start to cause problems. This leads to a disease called non-alcoholic fatty liver disease (NAFLD). If this process is allowed to go on for too long, a person can go into liver failure and may even need a liver transplant.
What did these researchers hope to find?
Past research had indicated that exercise might be helpful in slowing or reversing NAFLD. These researchers wanted to get a better sense of what types of exercise might be most helpful in stopping or reversing liver damage related to obesity and metabolic syndrome. They recruited 48 overweight or obese individuals and had them follow one of four regimens: a placebo regimen that involved stretching and massage, one to two hours per week of moderate intensity exercise, three to four hours per week of moderate intensity exercise, and one to two hours per week of high intensity exercise. They measured abdominal fat, the amount of fat in the liver, physical fitness, blood pressure and a variety of blood chemicals indicative both of liver damage and of diabetes or high cholesterol.
What did the researchers find?
All of the exercise regimens lowered the amount of fat in the liver by about the same amount. The placebo group actually saw an increase in the amount of fat in their liver over the course of the study. Importantly, these positive changes in liver fat happened regardless of whether a person lost weight during the study or not.
How does this affect me?
This study adds one more reason to exercise if you’re overweight or obese. It shows that regardless of what kind of exercise you choose, you’ll be doing your body some good. Finally, don’t worry so much about whether or not you lose weight as a result. This study shows that you’re probably still boosting your health even if you don’t see a change on the scale.