Regular fast food consumption linked to liver disease, USC study says

A new study from the University of Southern California’s Keck School of Medicine has linked the regular consumption of fast food with a potentially life-threatening liver disease.

The study published this week posits that eating fast food can increase the likelihood of developing nonalcoholic fatty liver disease, which causes fat to build up in the liver.

While regular fast food consumption has been linked to obesity and diabetes, researchers say this is one of the first studies to demonstrate a negative impact on the liver as well.

As part of the study, researchers found that people who suffer from obesity or diabetes and also consume 20% of their daily calories from fast food have highly elevated levels of fat in their livers compared to the same subset of people who eat less fast food or avoid it entirely.

Among the general population, those who get 20% of their daily calories from fast food also experience a moderate increase of liver fat versus those that don’t consume as much fast food.

Ani Kardashian, lead author of the study and an assistant professor of medicine in gastroenterology and liver diseases, said healthy livers usually contain a small amount of fat, but even the slightest increase in fat can lead to nonalcoholic fatty liver disease.

“The severe rise in liver fat in those with obesity or diabetes is especially striking, and probably due to the fact that these conditions cause a greater susceptibility for fat to build up in the liver,” Kardashian wrote.

Perhaps the biggest takeaway from the study is that even just a modest amount of regular fast food consumption can lead to disease.

“If people eat one meal a day at a fast-food restaurant, they may think they aren’t doing harm,” Kardashian said. “However, if that one meal equals at least one-fifth of their daily calories, they are putting their livers at risk.”

Nonalcoholic fatty liver disease can lead to cirrhosis, or scarring of the liver. Cirrhosis can lead to liver cancer or even liver failure. It’s estimated that nonalcoholic fatty liver disease affects more than 30% of the U.S. population.

Kardashian said the findings are particularly alarming because fast food consumption has risen significantly over the last 50 years among all walks of life.

“We’ve also seen a substantial surge in fast-food dining during the COVID-19 pandemic, which is probably related to the decline in full-service restaurant dining and rising rates of food insecurity,” Kardashian said. “We worry that the number of those with fatty livers has gone up even more since the time of the survey.”

For more on the study, including the methodology used, click here.

Researchers hope that the findings of the study will encourage health care providers to offer more nutrition education, especially for those who have obesity or diabetes and are at increased risk of developing fatty liver disease — the only treatment of which is an improved diet.