Although we have all known for a long time that an unhealthy lifestyle, including poor diet and lack of physical exercise, can lead to nonalcoholic fatty liver disease (NAFLD). However, new research led by Keck Medicine USC and published in the scientific journal ‘Clinical Gastroenterology and Hepatology’ quantifies the risk and breaks it down into a specific behavior, our habit of eat fast food.
What is nonalcoholic fatty liver disease?
Nonalcoholic fatty liver disease, also known as hepatic steatosis, can lead to cirrhosis, or scarring of the liver, a disorder that affects one in four adults, and cause cancer or liver failure.
The study
For the study, Ani Kardashian, a hepatologist at the University of Southern California and the study’s lead author, and her colleagues analyzed the most recent data from the nation’s largest annual nutrition survey, the National Health and Nutrition Examination Survey conducted in 2017-2018to determine the impact of fast food consumption on hepatic steatosis, characterizing fast food as self-service restaurant meals.
The researchers evaluated the fatty liver measurement of approximately 4,000 adults whose measurements were included in the survey and compared to their consumption of fast food. According to the results obtained by the survey, 52% consumed some fast food. Of these, 29% consumed a fifth or more of their daily calories from fast food. Although only this 29% experienced an increase in the levels of fat in the liver.
On the other hand, the association between hepatic steatosis and a diet with 20% fast food intake remained stable both for the general population and for people with obesity or diabetes, even after the data were adjusted for other factors. such as age, gender, race, ethnicity, alcohol use, and physical activity.
Therefore, the researchers found that people with obesity or diabetes who eat fast food for 20% or more of their daily calories have significantly higher levels of liver fat than those who eat less or nothing at all. But the study also revealed that even the general population has a high amount of liver fat when fast food makes up a fifth or more of their diet. Thus, the study found that eating fast food is associated with nonalcoholic fatty liver disease, a life-threatening condition in which fat accumulates in the liver.
“Healthy livers contain a small amount of fat, typically less than 5%, and even a moderate increase in fat can lead to non-alcoholic fatty liver disease,” Kardashian said, adding: “Severe increase of fat in the liver in people with obesity or diabetes is especially surprising, and is probably due to the fact that these conditions cause a greater susceptibility to fat accumulation in the liver.”
While previous research has shown a link between fast food, obesity and diabetes, this is one of the first studies to show the negative impact of fast food on liver health, says the hepatologist.
The findings also reveal that a relatively modest amount of fast food, high in carbohydrates and fat, can damage the liver. “If people eat one meal a day at a fast food restaurant, they may think they’re not damaging their liver,” Kardashian confessed. “However, if that meal equals at least a fifth of your daily calories, you are putting your liver at risk,” she added.
“Substantial increase in fast foods during the Covid-19 pandemic”
“Our findings are particularly alarming since fast food consumption has increased in the last 50 years, regardless of socioeconomic status,” Kardashian said. “We have also seen a substantial increase in fast food intake during the Covid-19 pandemic, which is likely related to the decline in full-service restaurant meals and increased rates of food insecurity. We are concerned that the number of people with fatty livers has risen even higher since the time of the survey.”
Finally, the hepatologist hopes that the results of this study will encourage health care providers to offer patients more nutrition educationespecially those with obesity or diabetes who are at increased risk of developing fatty liver due to fast food.