A study from Keck Medicine of USC published in Clinical Gastroenterology and Hepatology gives people extra motivation to reduce fast-food consumption.
Researchers discovered that people with obesity or diabetes who consume 20% or more of their daily calories from fast food have severely elevated levels of fat in their liver compared to those who consume less or no fast food. And the general population has moderate increases of liver fat when one-fifth or more of their diet is fast food.
While previous research has shown a link between fast food and obesity and diabetes, this is one of the first studies to demonstrate the negative impact of fast food on liver health, according to Kardashian.
The findings also reveal that a relatively modest amount of fast food, which is high in carbohydrates and fat, can hurt the liver. “If people eat one meal a day at a fast-food restaurant, they may think they aren’t doing harm,” said Kardashian. “However, if that one meal equals at least one-fifth of their daily calories, they are putting their livers at risk.”
Non-alcoholic fatty liver disease, also known as liver steatosis, can lead to cirrhosis, or scarring of the liver, which can cause liver cancer or failure. Liver steatosis affects over 30% of the U.S. population. Kardashian and colleagues analysed the most recent data from the nation’s largest annual nutritional survey, the 2017-2018 National Health and Nutrition Examination Survey, to determine the impact of fast-food consumption on liver steatosis.
The researchers evaluated the fatty liver measurement of approximately 4,000 adults whose fatty liver measurements were included in the survey and compared these measurements to their fast-food consumption.
Of those surveyed, 52% consumed some fast food. Of these, 29% consumed one-fifth or more daily calories from fast food. Only this 29% of survey subjects experienced a rise in liver fat levels.
The association between liver steatosis and a 20% diet of fast food held steady for both the general population and those with obesity or diabetes even after data was adjusted for multiple other factors such as age, sex, race, ethnicity, alcohol use and physical activity.
“Our findings are particularly alarming as fast-food consumption has gone up in the last 50 years, regardless of socioeconomic status,” said Kardashian. “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. We worry that the number of those with fatty livers has gone up even more since the time of the survey.”
She hopes the study will encourage healthcare providers to offer patients more nutrition education, especially to those with obesity or diabetes who are at higher risk of developing a fatty liver from fast food. Currently, the only way to treat liver steatosis is through an improved diet.
Paper: Kardashian A, Dodge J, Terrault N. (2023). Quantifying the Negative Impact of Fast-Food Consumption on Liver Steatosis Among U.S. Adults with Diabetes and Obesity. Clin Gastroenterol Hepatol.; https://doi.org/10.1016/j.cgh.2022.11.040/