Ultra-Processed Foods May Raise Prediabetes Risk in Young Adults, New Study Shows
A new long-term study has added fresh insight into how ultra-processed foods—the packaged snacks, sugary drinks, fast-food meals, sweetened cereals, candy, flavored yogurts, and other heavily altered products—may influence blood sugar regulation in young adults. While the connection between these foods and type 2 diabetes is already well established in older populations, research focusing specifically on adolescents and early-twenties adults has been limited. This new work aims to fill that gap by tracking changes in diet and metabolic health over several years.
The study, conducted by researchers at the Keck School of Medicine of USC, followed 85 young adults for a period of about four years. All participants were part of the broader Southern California Children’s Health Study and had a history of overweight or obesity—a demographic already known to have an elevated risk of metabolic diseases. Participants were between 17 and 22 years old at the start of the study, a life stage when physical growth is complete but long-term lifestyle habits are still being shaped.
To understand how ultra-processed foods might be linked to early metabolic dysfunction, the researchers collected two main types of data: diet records and glucose-insulin test results. At both the baseline and follow-up visits (spanning roughly 2014–2018 for the first visit and four years later for the second), each participant reported everything they had eaten over one weekday and one weekend day. Foods were categorized as either ultra-processed or not ultra-processed, and researchers calculated the percentage of total daily calories that came from UPFs.
In addition to dietary reporting, participants also provided blood samples. These were taken both before and after drinking a sugary beverage so scientists could observe how effectively the body handled a controlled glucose load—essentially a test of how well insulin was functioning. These measurements allowed researchers to detect early signs of insulin resistance, disrupted glucose regulation, and prediabetes.
The results were striking. A 10% increase in the amount of daily calories consumed from ultra-processed foods was linked to a 64% higher risk of prediabetes by the follow-up visit. The same increase was also connected to a 56% higher risk of impaired glucose regulation, a metabolic warning sign that may precede prediabetes. Participants who already consumed more UPFs at the beginning of the study tended to show elevated insulin levels four years later—an early indication that the body is working harder than it should to maintain normal blood sugar levels.
These findings reinforce what many nutrition scientists have been cautioning about: that ultra-processed foods are not just empty calories—they appear to influence biological pathways tied to long-term disease risk. The study’s authors highlight young adulthood as an especially important window. People at this age often develop eating habits that can persist for decades. If those habits include frequent UPF consumption, they may unknowingly increase their risk of type 2 diabetes later in life.
The senior researchers behind the study emphasized that even modest increases in UPF intake seemed to have measurable effects on insulin function and blood sugar regulation. That makes these foods a modifiable factor in preventing early metabolic disease. Instead of highly processed meals, adopting more whole foods—such as fruits, vegetables, nuts, whole grains, and minimally processed proteins—could help lower the likelihood of future glucose-related disorders.
While the study provides important insights, it also comes with certain limitations. The sample size of 85 individuals is relatively small, and the participants shared the common characteristic of having experienced overweight or obesity earlier in life. This means the findings might not apply equally to young adults who have never been overweight. Moreover, food intake was recorded only across two days at each visit, which may not capture every nuance of a person’s usual diet. Nevertheless, the longitudinal design strengthens the overall conclusions by observing changes over time rather than at a single snapshot.
The researchers behind the project have expressed interest in expanding their work in several directions. Future studies with larger populations could help clarify which specific types of ultra-processed foods are most closely linked to metabolic disruption. They also hope to investigate the biological mechanisms involved—for example, how particular additives, sweeteners, or fats used in UPFs may influence insulin and blood sugar pathways. Understanding these mechanisms may eventually help public health experts develop clearer dietary guidelines tailored to younger populations.
To give readers broader context, it’s helpful to know what exactly defines an ultra-processed food. UPFs fall under the NOVA classification system, which groups foods based on their level of industrial processing. Ultra-processed foods generally contain ingredients not commonly found in home kitchens—such as artificial flavors, colorings, emulsifiers, stabilizers, modified starches, hydrogenated oils, and various forms of added sugars. These foods typically undergo multiple processing steps designed to extend shelf life, improve taste, or enhance convenience, often at the cost of nutritional quality.
Globally, UPFs have become a major part of modern diets. In the United States, they account for more than half of all calories consumed, especially among teenagers and young adults. Their popularity stems from their affordability, easy availability, and aggressive marketing, particularly to younger age groups. Unfortunately, repeated studies have shown strong associations between ultra-processed food consumption and multiple health issues, including obesity, hypertension, cardiovascular disease, and type 2 diabetes. This new study adds evidence that these risks may begin accumulating much earlier than previously assumed.
Prediabetes itself is a condition defined by blood sugar levels that are higher than normal but not high enough to be classified as diabetes. It often develops silently because many people experience no symptoms. However, it signals that the body is struggling to regulate glucose efficiently. Without intervention through diet, exercise, or medical care, prediabetes can progress to type 2 diabetes, often within several years. Detecting early signs of disrupted glucose homeostasis can therefore be a valuable opportunity to intervene long before major health complications develop.
From a practical perspective, reducing UPF consumption doesn’t necessarily require drastic changes. Even substituting a few meals per week with less processed alternatives may offer benefits. Examples include swapping sugary breakfast cereals for oatmeal, replacing packaged snacks with nuts or fruit, or choosing simple home-cooked meals over fast food. Young adults especially may benefit from forming these habits early, before chronic disease risks become deeply entrenched.
As the scientific community continues exploring how ultra-processed foods affect human health, studies like this highlight the increasing need for awareness. While UPFs are convenient and often inexpensive, their long-term impact on metabolic health—especially starting from adolescence—may be far more significant than previously recognized. Understanding these risks can empower individuals to make more informed food choices.
Research Reference
https://link.springer.com/article/10.1186/s12986-025-01036-6
