Older adults can dramatically reduce the amount of ultraprocessed foods they eat while keeping a familiar, balanced diet—and this shift leads to improvements across several key markers related to how the body regulates appetite and metabolism. That’s the main finding of a new study my colleagues and I published in the journal Clinical Nutrition.
Ultraprocessed foods are made using industrial techniques and ingredients that aren’t typically used in home cooking. They often contain additives such as emulsifiers, flavorings, colors and preservatives. Common examples include packaged snacks, ready-to-eat meals and some processed meats. Studies have linked diets high in ultraprocessed foods to poorer health outcomes.
My team and I enrolled Americans ages 65 and older in our study, many of whom were overweight or had metabolic risk factors such as insulin resistance or high cholesterol. Participants followed two diets low in ultraprocessed foods for eight weeks each. One included lean red meat (pork); the other was vegetarian with milk and eggs. For two weeks in between, participants returned to their usual diets.
A total of 43 people began the dietary intervention, and 36 completed the full study.
In both diets, ultraprocessed foods made up less than 15 percent of the total calories—a significant reduction from the typical American diet, where more than 50% of total calories comes from ultraprocessed foods. The diets were designed to be realistic for everyday eating, and participants were not instructed to restrict calories, lose weight or change their physical activity.
We prepared, portioned and provided all meals and snacks for the study. Both diets emphasized minimally processed ingredients and aligned with the 2020-2025 Dietary Guidelines for Americans, the U.S. government’s nutrient-based recommendations for healthy eating, while providing similar calories and amounts of key nutrients.
The 2025-2030 Dietary Guidelines for Americans, released on Jan. 7, 2026, explicitly recommend eating less ultraprocessed food, but the previous versions of the guidelines did not specifically address food processing. Our feeding study design allowed us, for the first time, to examine the health effects of reducing ultraprocessed foods while keeping nutrient levels consistent with recommended targets.