In the United States, ultra-processed foods (UPFs) constitute over half of the caloric intake among the population, forming a pervasive element in American diets. These foods, typified by fast food, sugary snacks, sodas, and packaged meals, are laden with excessive sodium, refined sugars, and unhealthy fats. While extensive research has established the deleterious effects of UPFs on adult metabolism—most notably their association with the onset of type 2 diabetes and cardiovascular disease—their impact on younger demographics remains significantly underexplored. Addressing this knowledge gap, a pioneering longitudinal study from the Keck School of Medicine at the University of Southern California (USC) has illuminated the metabolic consequences of UPF consumption in young adults, with a particular focus on their body’s glucose regulation mechanisms.
This novel research aimed to unravel the intricate link between ultra-processed food intake and glucose homeostasis, a critical physiological process underpinning diabetes risk. By assessing changes in dietary patterns alongside metabolic markers over a substantial four-year span, the investigators provided compelling evidence that even moderate increases in UPF consumption compromise the body’s ability to regulate blood sugar effectively. Such dysregulation is an early harbinger of prediabetes, a condition characterized by elevated blood glucose levels that precedes type 2 diabetes.
The study cohort comprised 85 young adults aged between 17 and 22 years, all with a history of overweight or obesity—a population segment uniquely vulnerable to metabolic disturbances. Baseline dietary assessments were conducted between 2014 and 2018, with follow-up evaluations approximately four years later. Food consumption was meticulously recorded for representative weekday and weekend days, with participants self-reporting all intake during these periods. Foods were then systematically categorized into ultra-processed and non-ultra-processed groups based on established definitions, with UPFs encompassing items such as sweets, sodas, breakfast cereals with additives, flavoured yogurts, and various meals sourced from restaurants.
Crucially, metabolic assessments involved oral glucose tolerance testing (OGTT), wherein participants ingested a standardized sugary beverage, and subsequent blood samples were collected to evaluate the body’s insulin response. The researchers analyzed changes in insulin secretion and glucose levels, allowing for a granular understanding of how dietary changes impacted glucose homeostasis. Statistical adjustment accounted for confounders such as age, sex, ethnicity, and physical activity levels to isolate the effect of UPF consumption.
Results revealed a stark association: a mere 10% increment in the proportion of calories derived from ultra-processed foods correlated with a 64% increase in the risk of developing prediabetes and a 56% heightened prevalence of impaired glucose regulation. Participants exhibiting higher UPF consumption at the study’s inception exhibited increased fasting insulin levels during follow-up, indicating the development of insulin resistance. Insulin resistance denotes a pathological state wherein target tissues become refractory to insulin, prompting compensatory hyperinsulinemia and progressively deteriorating glycemic control.
These findings bear profound implications, particularly given that young adulthood represents a critical window for establishing enduring health trajectories. Whereas much prior research has concentrated on middle-aged or older adults, this study spotlights the metabolic vulnerabilities intrinsic to late adolescence and early adulthood. Dr. Vaia Lida Chatzi, senior author and professor of population and public health sciences and pediatrics at USC’s Keck School of Medicine, emphasized the modifiability of diet during this life stage, highlighting the potential for early intervention to forestall the progression of metabolic diseases.
The research underscores the necessity of dietary shifts away from ultra-processed consumption towards whole, minimally processed foods rich in fruits, vegetables, and whole grains. Such nutritional realignments are anticipated to enhance insulin sensitivity and stabilize glucose levels, mitigating long-term diabetes risk. This transition is particularly salient in populations predisposed to obesity, where metabolic dysregulation is already underway. The study’s longitudinal design strengthens causal inferences, shedding light on temporal dynamics between dietary choices and physiological outcomes.
Beyond epidemiological associations, the study team advocates for mechanistic investigations to unravel how specific components of ultra-processed foods influence metabolic pathways. Additives, emulsifiers, flavor enhancers, and macronutrient imbalances characteristic of UPFs may disrupt gut microbiota, promote systemic inflammation, or alter insulin signaling cascades. Such insights could pave the way for targeted nutritional recommendations and regulatory policies to curb the pervasive consumption of metabolically harmful foods.
Lead author Yiping Li, a doctoral candidate in quantitative biomedical sciences at Dartmouth College, reflected on the importance of expanding research cohorts and refining dietary measurement methodologies. Deploying objective biomarkers and high-resolution diet tracking would allow disaggregation of UPFs by subtype, illuminating which food categories pose the greatest hazards to young adults’ metabolic health.
This investigation was conducted in the context of the broader Metabolic and Asthma Incidence Research (Meta-AIR) study, nested within the Southern California Children’s Health Study, which tracks environmental and biological factors influencing pediatric and adolescent health. The research was supported by multiple grants from the National Institute of Environmental Health Sciences (NIEHS), the U.S. Environmental Protection Agency, the European Union, and other funding bodies, reflecting its multidisciplinary and international relevance.
Collectively, this study crystallizes the escalating public health challenge posed by ultra-processed foods, spotlighting critical vulnerabilities during the transition to adulthood. In the face of a global rise in type 2 diabetes incidence among youth, these findings amplify calls for comprehensive dietary interventions, public education campaigns, and policy measures designed to reduce UPF availability and consumption. Addressing the metabolic consequences of food processing transcends simple nutritional debates, intersecting with broader socioeconomic, cultural, and regulatory dimensions of health promotion.
By focusing on the young adult demographic, researchers and healthcare professionals gain a strategic vantage point to implement early preventive strategies, potentially averting lifelong metabolic dysfunction. This emerging evidence base supports a paradigm wherein nutritional quality, food processing degree, and metabolic health are inseparably linked—an insight that may redefine counseling, clinical practice, and public health initiatives in the coming decades.
Subject of Research: Ultra-processed food consumption and its longitudinal effects on glucose regulation and prediabetes risk in young adults with a history of overweight or obesity.
Article Title: Ultra-processed food intake is associated with altered glucose homeostasis in young adults with a history of overweight or obesity: a longitudinal study.
News Publication Date: November 10, 2025.
Web References: Nutrition and Metabolism Journal Article, DOI: 10.1186/s12986-025-01036-6.
Keywords: Metabolic disorders, diabetes, obesity, dietetics, diets, age groups, adolescents, young people, insulin resistance, insulin.
Tags: connection between diet and glucose homeostasisdietary patterns and blood sugarglucose regulation mechanismsimpact of fast food on metabolismlong-term effects of processed foodsmetabolic consequences of unhealthy dietsnutritional research on UPFsprediabetes and dietary habitsprediabetes risk in young adultsultra-processed food consumptionUSC study on diet and healthyoung adults and diabetes risk
