Researchers gave study participants two meals with almost identical macronutrient composition. However, one meal spiked their blood sugar, and the other did not.
“The two meals are matched within one percent of carbs, fat, proteins, calories, water and salt,” said Virginia Tech biomedical researcher Zach Hutelin, the study’s first author. “If these meals had a nutritional label, they would be practically identical.”
Both meals were 300 calories. And their macronutrients were identical. One meal was a hard-boiled egg, banana, cranberries, cheese and sea salt. The other meal was a small PB&J on white bread, veggie chips, frosted wheat cereal, a chocolate chip cookie, instant mashed potatoes and deli turkey.
“We know that the majority of ultra-processed foods are high in fat, they’re high in sugar, they’re low in fiber, and they’re low in protein,” said Alex DiFeliceantonio, a Virginia Tech associate professor. “But if we artificially hold all of those things constant, is there something about the processing that leads to a different outcome?”
Blood tests taken during the three hours after each meal showed that the ultra-processed meal led blood glucose to remain elevated for longer. The people’s insulin rose significantly higher after the ultra-processed meal and stayed higher for approximately two hours. The ultra-processed meal also raised metabolic rate and burned more fat during the three hours after a person ate. But they burned fewer carbs.
“We were shocked when every single metabolic metric differed,” said Dr. Hutelin. “What we noticed with the ultra-processed food (UPF) is that insulin response was much higher and blood sugar stays a little bit higher for a little bit longer.”
The researchers believe that processing may alter the nutritional availability of foods. They also think commercial additives in UPFs impact how our bodies digest them. The researchers want to study that next.
The researchers also had the participants look at pictures of UPFs and minimally processed foods that had the same nutritional value while being scanned by MRI. They measured blood flow in different areas of the brain related to learning, motivation and reward. The brain scans showed differences that reflected the disparity in how carbohydrates were burned when people ate the different meals.
The study had limitations, as all studies do. All the participants were young, healthy-weight adults and less than a third were men. The two meals’ protein sources were different, and that could impact insulin response.
The takeaway from this study is that food labels don’t tell the full story of how a food may impact the body. Earlier research has linked a diet high in UPFs to poorer health. Eating more whole foods and avoiding UPFs can be a route to healthier blood sugar.
