Cutting back on ultra-processed foods helped older adults lose weight, improve cholesterol and insulin sensitivity, and reduce inflammation—regardless of whether their diet emphasized animal or plant protein.
Researchers wanted to know whether lowering ultra-processed food intake, while still following U.S. Dietary Guidelines, could improve cardiometabolic health in aging adults.
Both low–ultra-processed omnivorous and vegetarian diets produced similar health benefits, suggesting flexibility in how older adults can eat for better health.
As the U.S. population grows older, rates of obesity, diabetes, and cardiovascular disease continue to rise, placing pressure on both individuals and the health care system.
A new study published in Clinical Nutrition suggests that one practical change — reducing ultra-processed foods — could significantly improve cardiometabolic health in older adults, without requiring strict calorie counting or adherence to a single dietary ideology.
The research builds on concerns that ultra-processed foods (UPFs) — industrially manufactured products often high in refined starches, sugars, and additives — may worsen age-related metabolic vulnerability. While previous studies have linked UPFs to poor health outcomes, few controlled trials have tested whether cutting them back can deliver measurable benefits in older adults while still aligning with the Dietary Guidelines for Americans (DGA).
About the study
To address that gap, researchers analyzed secondary outcomes from the Protein-Distinct Macronutrient-Equivalent Diet 2 (PRODMED2) trial. The study enrolled 36 community-dwelling older adults and compared their habitual diets — about half of daily calories coming from ultra-processed foods — with two structured, low-UPF eating patterns. One diet featured minimally processed pork as the main protein source, representing an omnivorous approach, while the other used lentils to reflect a lacto-ovo vegetarian pattern.
Each participant followed both low-UPF diets for eight weeks, separated by a two-week washout period. Importantly, the diets were not calorie-restricted; participants were encouraged to eat until satisfied. Researchers measured dietary intake, body composition, blood lipids, insulin-related markers, inflammation, and hormones involved in appetite and energy regulation before and after each diet. Some measures were repeated about a year later to see whether changes lasted.
The results
The results were striking. Simply moving away from a high-UPF baseline diet—without intentional calorie cutting—led participants to consume 300 to 400 fewer calories per day on average.
That spontaneous reduction translated into meaningful weight loss of about eight to 10 pounds over each eight-week period, along with significant losses in fat mass.
Both dietary patterns delivered comparable metabolic improvements. Measures of insulin resistance, including HOMA-IR, insulin, and C-peptide, improved significantly, as did total cholesterol, LDL cholesterol, apolipoprotein B, and markers of inflammation such as C-reactive protein.
The researchers found no significant differences between the animal-based and plant-based diets, suggesting that food processing level mattered more than protein source.
Participants ate less without trying
Hormonal changes provided clues about how these benefits might occur. Levels of leptin, a hormone associated with fat mass and appetite regulation, declined, while fibroblast growth factor 21 (FGF21) — a hormone involved in nutrient sensing and energy balance — increased during both low-UPF diet phases. These shifts may help explain why participants naturally ate less and lost weight without being told to restrict calories.
However, the study also highlighted how difficult it can be to sustain dietary changes. At the roughly one-year follow-up, ultra-processed foods once again made up nearly 44% of daily energy intake. As UPF exposure rose, body weight, fat mass, and cardiometabolic markers drifted back toward baseline levels.
Taken together, the findings suggest that low–ultra-processed eating patterns are both feasible and effective for older adults, whether they include animal products or rely on plant-based proteins. By aligning with existing dietary guidelines and focusing on minimally processed foods, such diets may offer a realistic strategy to support healthy aging.
For policymakers and clinicians alike, the message is clear: reducing ultra-processed foods could be a powerful, flexible tool to improve metabolic health and extend health span in an aging population.