In the United States, ultra-processed foods (UPFs) now account for more than half of the calories people eat each day. These products include fast food and packaged snacks that are typically high in salt, added sugars and unhealthy fats. Previous research has firmly connected heavy consumption of these foods to type 2 diabetes and other chronic illnesses in adults, but their impact on younger people has received far less attention.

To help fill that gap, scientists at the Keck School of Medicine of USC conducted one of the first long-term studies focused on how UPFs affect glucose processing, a key indicator of diabetes risk. By following participants over several years, the researchers were able to observe how changes in diet were linked to changes inside the body.

Four-Year Study Tracks Early Metabolic Changes
The research team followed 85 young adults for a four-year period. Their analysis showed that participants who increased their intake of ultra-processed foods were more likely to develop prediabetes, a condition marked by elevated blood sugar levels that often precedes type 2 diabetes. Higher UPF consumption was also associated with insulin resistance, meaning the body struggled to use insulin effectively to regulate blood sugar.

The study, which received partial funding from the National Institutes of Health, was recently published in the journal Nutrition and Metabolism.

“Our findings show that even modest increases in ultra-processed food intake can disrupt glucose regulation in young adults at risk for obesity. These results point to diet as a modifiable driver of early metabolic disease, and an urgent target for prevention strategies among young people,” said Vaia Lida Chatzi, MD, PhD, a professor of population and public health sciences and pediatrics and director of the Southern California Superfund Research and Training Program for PFAS Assessment, Remediation and Prevention (ShARP) Center at the Keck School of Medicine, who is the study’s senior author.