For a long time, the prevailing view in nutritional science was that foods with the same nutritional value would have identical effects on blood glucose levels and metabolism. However, a new study from Virginia Tech, published in Nature Metabolism, challenges this paradigm. The findings show that the degree of industrial food processing has an independent effect on both metabolic processes and the brain’s neurobiological response.
The researchers enrolled healthy adults aged 18 to 45 in the experiment. The aim was to determine whether the body’s response would change when macronutrient composition remained unchanged and the only difference was the degree of food processing. To this end, participants were given two types of food — minimally processed and ultra-processed, according to the NOVA classification.
Both portions contained exactly 300 calories and matched each other within 1% in terms of carbohydrates, fats, proteins, water and salt, as well as weight.
The ultra-processed meal consisted of a peanut butter and jelly sandwich, processed turkey meat, vegetable chips, cookies and instant mashed potatoes.
The minimally processed meal consisted of sliced banana, dried cranberries, cheese and eggs.
According to study co-author Zach Hutelainen, if these meals had nutritional labels, they would be virtually identical.
Metabolic changes
To study the metabolic effects, participants were placed after an overnight fast in a specialized airtight metabolic chamber that measures energy expenditure and metabolism. After they ate the meal, blood samples were collected six times over a three-hour period.
The data showed that after consuming the ultra-processed food, the insulin response was substantially higher, while blood glucose levels reached higher levels and remained elevated for longer. At the same time, the body burned less carbohydrate for energy (carbohydrate oxidation), but total energy expenditure increased. Chronically elevated blood glucose levels are known to be directly associated with the risk of developing type 2 diabetes and other metabolic disorders.
Neurobiological response and the brain’s reward system
In addition to metabolic changes, the study also examined neurobiological responses. Using functional magnetic resonance imaging (fMRI), neuroscientist Alex DiFeliceantonio and his team analyzed the brain’s response to visual food cues.
They found marked differences in the activity of brain regions involved in motivation and the reward system, particularly the ventral striatum and the nucleus accumbens. The researchers found that the altered rate of carbohydrate oxidation was directly correlated with the brain’s altered response when participants viewed food. Although participants rated the two meals similarly based on their subjective perceptions, at the neural level, the industrially processed food activated distinctly different and potentially less healthy mechanisms in the brain.
According to Carlos Monteiro, an epidemiologist at the University of São Paulo and the creator of the NOVA classification, the study represents an important step toward resolving the debate over what drives adverse health effects — the composition of food itself or the industrial processing it undergoes. The data suggest that the negative effects associated with ultra-processed foods, including obesity, diabetes and cardiovascular disease, cannot be explained solely by an imbalance in macronutrients. In future research, scientists plan to examine in greater detail the role of specific commercial additives and chemical structures.
