Ultra-processed foods account for nearly 60% of calories consumed by adults in the U.S., according to research published in theAmerican Journal of Clinical Nutrition. That percentage rises to almost 70% in American children. Researchers are already warning that these foods could be linked to higher rates of early-onset colorectal adenomas, precursors to colorectal canceras well as increased risks of obesity, type 2 diabetes, cardiovascular disease, and depression. Now, a new study also suggests that ultra-processed foods may influence how young people respond to hunger and fullness cues.

In November, researchers from Virginia Tech published findings from a study examining the effect of ultra-processed food (defined as foods that contain one or ingredients not typically found in a kitchen) on the eating habits of young adults. The team recruited 27 men and women aged 18 to 25 whose weight had been stable for at least six months and asked them to follow one of two diets for two weeks before switching to the other. The diets included breakfast eaten in the lab, with the rest of the meals prepared in their “metabolic kitchen.” One diet, as the researchers explained, derived 81% of its calories from ultra-processed foods (think soda, flavored yogurt, and prepackaged meals and snacks), while the other contained none.

“We very rigorously designed these diets to be matched on 22 characteristics, including macronutrients, fiber, added sugar, energy density, and also many vitamins and minerals,” Brenda Davy, a senior author on the paper and professor in Virginia Tech’s Department of Human Nutrition, Foods, and Exercise, shared in a statement. “Previous studies had not matched diets to this extent.”

After each two-week eating window, participants were asked to freely eat from a breakfast buffet with about 1,800 calories, consuming as little or as much as they wanted. Then, after breakfast, they received a tray of snacks, asked to take a bite of each, and rate their “pleasantness.”

The researchers discovered that while total calories consumed at the buffet remained unchanged across the group, participants aged 18 to 21 ate during the post-meal snacking phase after following the ultra-processed diet, even when they were no longer hungry. The authors noted that this suggests ultra-processed foods could disrupt appetite regulation in younger people.

“Our adolescent participants had just consumed in the buffet meal after the ultra-processed diet. Then, given the opportunity to snack when not hungry, they ate yet again,” Alex DiFeliceantonio, a neuroscientist and co-author of the study, explained. “Snacking when not hungry is an important predictor of later weight gain in young people, and it seems ultra-processed food exposure increases this tendency in adolescents.”

The biggest limitation, the researchers said, was time, as it focused on only one meal experience, which “may not capture the constant food availability that many people experience.” However, as Davy added, “Although this was a short-term trial, if this increase in caloric intake persists over time, this could lead to weight gain in these young people.”