Ultraprocessed foods, the packaged snacks, sugary drinks and quick meals that make up more than half of American diets, are convenient and affordable, but new research suggests they may raise the risk for diabetes earlier than expected.
In a four-year study of 85 young adults, researchers at the Keck School of Medicine of USC found that higher ultraprocessed food intake was linked to prediabetes and early signs of insulin resistance, when the body becomes less effective at managing blood sugar. The findings, published in Nutrition & Metabolism, add to evidence that diet quality can influence metabolic health long before symptoms appear.
“Our findings show that even modest increases in ultraprocessed food intake can disrupt glucose regulation in young adults at risk for obesity,” said senior author Vaia Lida Chatzi, MD, PhD, professor of population and public health sciences and pediatrics at USC. “These results point to diet as a modifiable driver of early metabolic disease and an urgent target for prevention strategies among young people.”
Participants, ages 17 to 22, shared detailed food records at two points four years apart. Those who reported a 10% increase in calories from ultraprocessed foods had a 64% higher risk for prediabetes and were more likely to show early disruptions in glucose metabolism, the same biological changes that can lead to type 2 diabetes.
Ultraprocessed foods include many products that are industrially formulated with ingredients not typically used in home cooking, such as refined starches, flavor enhancers and stabilizers, to extend shelf life or modify taste and texture. They range from sodas and sweets to flavored yogurts, cereals and restaurant meals.
Still, not all processed foods are harmful. Some processing helps make foods safer, more accessible, or fortified with nutrients. The concern, researchers say, is when these products crowd out whole foods like fruits, vegetables, beans and whole grains that support stable blood sugar and overall metabolic health.
“Young adulthood is a critical window for shaping long-term health,” Chatzi said. “By focusing on young adults, we have an opportunity to intervene early, before prediabetes and other risk factors become lifelong conditions.”
The study reinforces a growing body of research showing that dietary habits formed early can echo for decades. While grabbing quick meals is often unavoidable, cutting back on ultraprocessed snacks and beverages, and replacing them with more whole, minimally processed foods, may help keep blood sugar steady and reduce long-term disease risk.
This study was funded by the National Institute of Environmental Health Sciences (NIEHS) of the National Institutes of Health, with additional support from the U.S. Environmental Protection Agency, the European Union and the Hastings Foundation.