Fast food can lead to fatty liver disease, study finds

Researchers at the university found that people who obtain only a fifth or more of their daily intake of calories from high-carb, high-fat fast food have moderate increases of fat in their liver. That fat can build up in time to become dangerous.

Diabetics and obese people suffer from much higher levels of fat in their liver than those who eat less or no fast food. For them, therefore, the consumption of fast food can be even more damaging.

The study defined fast food as that served either through a drive-through restaurant window or without wait staff. The definition includes pizza.

Can lead to liver failure

Nonalcoholic fatty liver disease, which is also called liver steatosis, can lead to scarring, or cirrhosis, of the liver. That, in turn, can cause liver failure or liver cancer.

The disease impacts almost a third of the U.S. population.

Healthy livers include a small degree of fat, usually less than 5%, explains Dr. Ani Kardashian, a hematologist at Keck Medicine who is lead author of the study. Even a modest increase in the fat content can lead to nonalcoholic fatty liver disease, she says.

Especially striking is the build up that takes place when the person is obese or diabetic, Kardashian says. This build-up probably takes place because both those people who have obesity and diabetes are more susceptible to a build up of fat in the liver in the first place.

First to show a link

Previous studies have demonstrated a link between fast food and diabetes as well as obesity, but this study is the first to show the negative effect of fast food on the health of a person’s liver, Kardashian adds.

In addition, the findings show that even a relatively moderate amount of fast food, which is high in fat and carbohydrates, can harm a person’s liver, she notes.

Putting your liver at risk

If you eat one meal a day at a fast-food restaurant, you might think you are not doing yourself any harm, Kardashian says. If that one meal is equal to at least a fifth of your daily calorie intake, however, you are putting your liver at risk, she warns.

She adds that the findings are especially alarming as the consumption of fast food has risen in the last five decades, regardless of people’s socioeconomic status.

Increase during pandemic

A significant increase in fast-food dining has been noted during the COVID-19 pandemic, Kardashian says, making the research study’s findings particularly alarming. That surge is likely linked with the drop in full-service dining at restaurants as well as increasing rates of food insecurity.

The researchers are concerned, therefore, that the rise in the number of those suffering from fatty livers has risen even more since the time in which the information for the survey was gathered. It was based on information from the 2017-2018 National Health and Nutrition Examination Survey.

Health providers can help

Kardashian says she hopes that the study’s findings will encourage providers of health care to educate their patients more fully on nutrition, particularly those who suffer from diabetes or obesity who are at a higher risk of developing a fatty liver as a result of eating fast food.

The only way to treat liver steatosis is through a better diet, she adds.

The researchers measured the fatty liver of about 4,000 adults and compared them with measures of their consumption of fast food.

Of those surveyed, more than half ate some fast food. Of those, almost a third ate a fifth or more of their daily calorie intake from fast food. Only that third suffered a rise in the levels of fat in their livers.

That link between a 20%, or one-fifth, diet consisting of fast food held for those with obesity or diabetes as well as for the general population. The data were adjusted for multiple other factors, such as sex, age, race, alcohol use, ethnicity, and physical activity.

The study appears in Clinical Gastroenterology and Hepatology.