Two meals can contain almost identical amounts of calories, protein, carbohydrates and fibre, yet the body may respond to them differently. New research suggests that the degree of food processing could influence what happens after eating, even when nutritional values appear closely matched.

Scientists from Virginia Tech investigated whether ultra-processed foods affect metabolism independently of their nutrient composition.

Their findings, published in Nature Metabolism, revealed differences in insulin release and energy use, offering fresh insight into how food preparation and manufacturing may influence human physiology.

<h3>Looking Beyond Nutrition Labels</h3>

Ultra-processed foods frequently contain ingredients added to improve flavour, texture, appearance or shelf life. They include many packaged snacks, ready-made meals and commercially produced bakery products. However, processing does not automatically determine nutritional quality. Some packaged foods contain substantial amounts of protein, fibre and essential nutrients.

To explore this distinction, researchers recruited 57 healthy-weight adults aged between 18 and 45.

Of these participants, 32 completed two meal-testing sessions, while 52 were included in a separate brain-imaging analysis.

The meals provided approximately 300 calories each and contained comparable amounts of major nutrients and sodium.

One meal included relatively unprocessed ingredients such as banana slices and cheese. The alternative featured more heavily processed products, including a peanut butter and jam sandwich and vegetable crisps.

<h3>A Surprising Insulin Response</h3>

Following an overnight fast, participants consumed the test meals on separate days. Researchers then collected blood samples over three hours to monitor metabolic changes. Blood glucose responses were broadly similar after both meals. Insulin levels, however, told a different story.

The ultra-processed meal produced a stronger insulin response, with concentrations remaining higher between 40 and 120 minutes after eating. Insulin helps regulate blood glucose by supporting the movement of sugar from the bloodstream into cells. A higher response does not necessarily indicate poor health, and the researchers did not establish that participants developed insulin resistance.

Nevertheless, the difference suggests that nutritional information alone may not fully predict the body's reaction to a meal.

<h3>Changes In Energy Metabolism</h3>

The scientists also examined how participants used carbohydrates and lipids for energy. After consuming the ultra-processed meal, participants burned fewer carbohydrates and more lipids. Their energy expenditure was also higher.

During a separate experiment, researchers used functional magnetic resonance imaging to observe brain activity while participants viewed photographs of different foods.

Participants assigned similar monetary values to both food categories. However, differences in carbohydrate metabolism were associated with variations in brain responses to food images.

These findings raise questions about possible connections between metabolism and the brain's processing of food-related information.

<h3>How Experts Interpret The Results</h3>

Bariatric surgeon Mir Ali, who was not involved in the study, explained that the findings suggest food processing may influence hormonal and metabolic responses. However, he stressed that further investigation is necessary to identify which ingredients or manufacturing methods contribute to these differences.

Dietitian Qianzhi Jiang also urged caution. She pointed out that insulin release depends on several factors, including protein composition and amino acids, which may help explain the results.

Both experts emphasised that the study cannot determine whether the observed changes cause long-term health problems.

<h3>What This Means For Your Diet</h3>

The research involved a relatively small number of healthy adults and examined immediate responses to just two meals. It therefore cannot establish how different eating patterns affect health over months or years. For everyday food choices, a balanced approach remains sensible. Vegetables, fruit, wholegrains, legumes and minimally processed protein sources provide valuable nutrients.

Packaged foods can also contribute to a nutritious diet, particularly when they offer convenience and affordability. The findings highlight an important scientific question: understanding a food's effects may require looking beyond the numbers printed on its packaging.