October 12, 2026, 3:17 pm | Read time: 4 minutes
Highly processed foods are often linked to health risks—especially concerning metabolism. But is this mainly due to their sugar, fat, or calorie content? Or could the industrial processing itself play a role? Researchers have examined how the body reacts to two meals with nearly identical nutritional values but differing in their degree of processing.
Highly Processed Meal Leads to Greater Insulin Release
The Virginia Tech study shows that the body can react differently to meals with nearly identical calorie and nutrient content. After the highly processed meal, participants released significantly more insulin than after the less processed variant. The overall blood sugar response over the study period was comparable. The results suggest that besides nutritional values, the processing or structure of the foods might influence how the body reacts to a meal.1
How the Study Was Conducted
To examine the potential influence of processing more closely, researchers compared two meals, each with around 300 kilocalories. These were nearly identical in terms of calorie content, nutrient composition, fiber content, and other properties. However, they consisted of different foods.
A total of 57 adults aged 18 to 45 participated in the study. Thirty-two of them completed both metabolic tests. They received a highly processed and a less processed meal on different days. The order was randomly assigned.
After eating, researchers recorded blood sugar and insulin levels, energy expenditure, and carbohydrate and fat burning over three hours.
Additionally, they used functional magnetic resonance imaging (fMRI) to study how the brains of 52 participants reacted to images of highly processed and less processed foods. Participants were also asked how much money they would spend on the shown foods. The researchers aimed to determine whether metabolic reactions were related to the processing of food stimuli in the brain.
Differences in Energy Expenditure and Brain Activity
In addition to insulin release, researchers also found differences in energy expenditure. After the highly processed meal, the body used slightly more energy. At the same time, participants burned fewer carbohydrates and more fat than after the less processed meal.
There were also notable differences in brain activity. Certain metabolic values were linked to the activity of several brain regions, including areas involved in reward processing. Additionally, there were partial differences in how brain activity was related to the willingness to pay for highly processed and less processed foods. Overall, however, participants were not willing to pay more for either food group.
Which properties of the foods were responsible for the observed differences remains unclear. Although the meals were largely similar in terms of nutritional values, they contained different foods and protein sources. Therefore, the researchers could not prove that the degree of processing alone caused the different metabolic reactions.
Moreover, the study only examined short-term reactions after individual meals. Whether the observed differences influence body weight or disease risk in the long term cannot be determined from this.
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Strengths and Weaknesses of the Study
A strength of the study is its controlled design and execution. Since each participant received both meals, individual differences could be better accounted for. Additionally, repeated measurements allowed for precise tracking of metabolic changes over several hours.
However, the study’s significance is limited by the small number of participants. Furthermore, only normal-weight adults were examined. Whether the results also apply to children, older adults, or individuals with overweight or metabolic disorders remains open.
It is also unclear whether larger meals would trigger similar reactions. Additionally, fluctuating food prices could have influenced the willingness-to-pay responses.
Also of interest: Highly processed foods leave measurable traces in the blood
What Earlier Studies Show
Two earlier experiments suggest that processing can play a role beyond individual meals. In a 2019 NIH study, 20 adults consumed about 500 more kilocalories per day with ultra-processed foods and gained weight within two weeks. With unprocessed foods, they lost weight.2 In the British UPDATE study (2025), participants lost more weight with minimally processed foods than with ultra-processed foods, even though both followed official dietary recommendations.3 However, both studies are small, and which properties of the foods are responsible remains unclear.