Skip the Ultra-Processed Foods, Keep the Weight Off: What New Research Shows

A new study shows that older adults can significantly reduce ultra-processed foods while maintaining a balanced, familiar diet, leading to natural weight loss and improvements in how their bodies regulate appetite and metabolism. Researchers found that when people ages 65 and older cut ultra-processed foods from over 50% of their daily calories down to less than 15%, they experienced meaningful health gains—including weight loss, better insulin sensitivity, healthier cholesterol levels, and reduced inflammation—without being told to restrict calories or exercise more.

What Exactly Happened in This Study?

A team of nutrition researchers led by Moul Dey at South Dakota State University enrolled 43 older Americans, many of whom were overweight or had metabolic risk factors like insulin resistance or high cholesterol. Of those, 36 completed the full study, which lasted eight weeks with a two-week break in the middle.

The researchers took a realistic approach: they prepared all meals and snacks for participants, who followed two different diets low in ultra-processed foods. One diet included lean red meat (pork), while the other was vegetarian with milk and eggs. Both diets emphasized minimally processed ingredients and aligned with the 2020-2025 Dietary Guidelines for Americans. Importantly, participants were not instructed to restrict calories, lose weight, or change their physical activity levels.

What Are Ultra-Processed Foods, and Why Do They Matter?

Ultra-processed foods are made using industrial techniques and ingredients you wouldn't typically use in home cooking. These products often contain additives such as emulsifiers, flavorings, colors, and preservatives. Common examples include packaged snacks, ready-to-eat meals, and some processed meats.

The problem is significant: in a typical American diet, more than 50% of total daily calories come from ultra-processed foods. Studies have linked diets high in these foods to poorer health outcomes, including obesity and age-related chronic diseases such as type 2 diabetes and heart disease.

What Were the Key Health Improvements?

When participants ate fewer ultra-processed foods, several positive changes occurred naturally:

• Weight Loss: Participants lost weight, including reductions in total body fat and abdominal fat, without being told to diet or count calories.
• Insulin Sensitivity: The body's ability to regulate blood sugar improved, reducing the risk of type 2 diabetes.
• Cholesterol Levels: Participants showed healthier cholesterol profiles, a key marker of heart health.
• Inflammation: Signs of inflammation in the body decreased, which is linked to aging and chronic disease.
• Appetite Hormones: Favorable changes occurred in hormones that help regulate appetite and metabolism, making it easier to maintain healthy eating patterns.

Notably, these improvements were similar whether participants followed the meat-based or vegetarian diet, suggesting that the type of protein source matters less than simply reducing ultra-processed foods.

Why Does This Matter for Older Adults?

For older adults especially, maintaining metabolic health—the efficiency with which your body processes food and energy—helps preserve mobility, independence, and quality of life. As the global population ages, strategies that protect metabolic health become increasingly important.

The study's findings are particularly relevant because they reflect real-world eating patterns more closely than previous research. Most earlier feeding studies compared diets made up almost entirely of ultra-processed foods with diets containing little to none at all. This new research shows that a realistic reduction in ultra-processed foods—not an extreme elimination—produces measurable health benefits beyond just losing weight.

What's the Catch? What We Still Don't Know

While the results are encouraging, the study was small and had limitations. It was not designed to show whether the metabolic improvements observed can prevent or delay diseases such as diabetes or heart disease over time. Larger, longer studies will be needed to answer that question.

Additionally, researchers note that it remains unclear whether people can cut back on ultra-processed foods in their daily lives without structured support, and what strategies would make it easier to do so. It's also not fully understood which specific aspects of processing—such as additives, emulsifiers, or extrusion—matter most for health.

Despite these unknowns, the research points toward a practical path forward. Answering these remaining questions could help food manufacturers produce foods that are healthier but still convenient, making it easier for people to choose better options without feeling deprived.