Processed Foods Alter Metabolism, Brain Activity

A new study suggests that meals with identical calories, fat, and carbs can affect metabolism and brain activity differently based on their level of processing. Researchers at Virginia Tech’s Freylin Biomedical Research Institute found that even when two meals have nearly the same nutritional content, the body and brain respond differently to minimally processed and ultraprocessed foods.

Study Design and Findings

The study involved 57 healthy adults aged 18 to 45, who consumed two 300-calorie meals on separate visits. The meals were carefully matched for calories, carbohydrates, fat, protein, water, and salt. One meal was ultraprocessed, including items like a peanut butter and jelly sandwich, deli turkey, and instant mashed potatoes. The other was minimally processed, featuring foods like banana, dried cranberries, cheese, and egg.

Participants’ energy expenditure and metabolism were measured in a sealed metabolic chamber after consuming each meal. Researchers found that when participants ate the ultraprocessed meal, their bodies expended more energy and burned fewer carbohydrates for fuel compared to the minimally processed meal.

Metabolic and Brain Responses

The study’s first author, Zach Hutelin, expressed surprise at the results, stating that “every single metabolic metric differed” between the two meals. This finding raises questions about how food processing influences metabolic responses, even when nutritional content appears identical.

To explore the connection between metabolism and brain activity, 32 participants underwent functional MRI scans while viewing images of minimally processed and ultraprocessed foods. Although participants did not report valuing one type of food over the other, differences in carbohydrate oxidation were linked to variations in brain activity, particularly in regions associated with reward, motivation, and learning.

Implications and Limitations

The study does not establish a direct link between ultraprocessed foods and diseases like diabetes or obesity. It also does not identify which specific aspects of food processing drive these metabolic changes. The participants were young and healthy, and the study examined only one pair of meals, with differences in protein sources and additives. Additionally, researchers did not fully analyze the physical and chemical structure of the foods.

Published in Nature Metabolism, the findings contribute to a growing understanding of how food processing impacts health. They suggest that the body can distinguish between processed and unprocessed foods, even when nutritional labels appear identical, opening up new avenues for nutritional research and dietary recommendations.

Of the 57 participants, 32 provided both metabolic and brain-imaging data, allowing researchers to link bodily responses to neural activity in the same individuals.