Heart failure risk with liver disease may be explained by obesity

The excess weight that causes fatty liver disease also raises a person’s risk for heart failure, a recent study suggests.

While non-alcoholic fatty liver disease (NAFLD) has long been linked to heart failure, the current study followed fatty liver patients over five years and found obesity may be the real culprit.

“It’s critical to both your liver health and your heart health to maintain a healthy weight,” said study coauthor Dr. Lisa VanWagner of Northwestern University Feinberg School of Medicine in Chicago.

Most people have a little bit of fat in their liver, but fatty liver disease can be diagnosed when more than 5% of the liver is made up of fat. If the condition isn’t linked to liver damage from heavy drinking, it’s known as NAFLD and is most often associated with obesity and certain eating habits.

The study followed 159 people with NAFLD and 1,668 people without the condition over five years.

People with NAFLD had an average body mass index (BMI) of 36, meaning they were obese. Those without NAFLD had an average BMI of 29.6, which is overweight but at least a few pounds shy of being considered obese.

Participants with fatty liver were more likely to have risk factors for heart failure like high blood pressure and diabetes than those without NAFLD. In heart failure, the heart is too weak to properly pump blood through the body.

Once researchers accounted for other heart failure risk factors, they still found that people with fatty liver were roughly twice as likely as those without it to develop structural problems with the heart that lead to heart failure.

And once researchers also factored in weight, there was no longer a meaningful difference in the risk of heart problems between the two groups, suggesting that weight explains the difference.

“We already knew that fatty liver disease is connected with the presence of damage in the heart structure and function,” said Dimitrios Koutoukidis, a researcher at the University of Oxford in the UK who wasn’t involved in the study.

“This study tells us that fatty liver disease is linked to the development and worsening of such damage in the heart over 5 years, and that this link was mostly due to the higher levels of obesity in people with fatty liver disease,” Koutoukidis said by email.

The study wasn’t designed to prove whether fatty liver disease actually causes heart failure. Another limitation of the study is that too many people were obese for researchers to determine how much the risk might differ between overweight versus obese individuals.

It’s possible that inflammation and high blood sugar, which can be more common in people with obesity, also contribute to fatty liver and heart failure, the study team notes in the Journal of the American Heart Association.

A low-calorie healthy diet and higher levels of physical activity that lead to weight loss can help overweight or obese people prevent fatty liver disease, Koutoukidis added.

“Even a small amount of weight loss can also help people with fatty liver disease and overweight improve their liver and reduce their risk for heart disease,” Koutoukidis said.