The end of the calorie myth: How processed food "tricks" the brain - and harms metabolism

A new study from Virginia Tech, published in Nature Metabolism, reveals that ultra-processed food affects the body and brain differently than unprocessed food, even when the calorie, carbohydrate, and fat composition is identical. Participants who ate processed food showed a dramatic spike in insulin, lower energy expenditure, and changes in brain reward region activity.

A surprising new study from Virginia Tech, published in the journal Nature Metabolism, challenges the basic dietary assumption that meals with identical nutritional profiles affect the body similarly. Researchers, led by Zach Hutelin, tested dozens of healthy volunteers using a 'metabolic chamber' and precise measurements. Each subject consumed two 300-calorie meals, identical in carbohydrates, fats, proteins, salt, and water – the only difference being the level of processing. The ultra-processed meal included a peanut butter and jelly sandwich, turkey sausage, vegetable chip snack, a cookie, and instant mashed potatoes; the minimally processed meal included a banana, dried cranberries, cheese, and a hard-boiled egg. Results showed a dramatic spike in insulin and prolonged high blood sugar levels after the processed meal, along with lower carbohydrate burning. fMRI scans revealed changes in activity in brain reward regions (ventral striatum and nucleus accumbens), providing a biological explanation for why processed food, which makes up over half of calories in the Western diet, is so hard to quit.