- A new study compared how adults responded to ultra-processed and less processed meals with similar nutrients.
- The ultra-processed meal led to a higher insulin response and changed how the body used energy.
- The team also examined the participants’ brain activity while they viewed pictures of ultra-processed and less processed foods.
Nutrition labels can help people choose foods that meet their calorie or protein needs, but those numbers may not tell the whole story about how the body will respond after eating.
Researchers at Virginia Tech recently explored whether food processing affects the body’s response independently of nutrient content.
They compared the body’s responses to two meals that were similar in nutrient makeup but differed in processing level. They also examined brain activity to explore whether metabolic differences related to participants’ responses to food pictures.
The study appears in
Can foods with similar nutrients still affect the body differently?
Ultra-processed foods often have ingredients that improve flavor, texture, or shelf life. The NOVA classification system groups foods by their level of processing. For example, plain nuts and eggs belong to group 1, while soda and many packaged chips belong to group 4.
Since ultra-processed foods can provide nutrients such as protein and fiber, processing level alone does not describe a food’s nutritional profile. To better understand whether processing matters beyond those nutrients, the researchers compared nutritionally matched meals.
The study included 57 healthy-weight adults aged 18 to 45. Of these, 32 completed both meal-testing sessions, and the researchers included 52 in their brain imaging analysis.
After participants fasted overnight, the team collected baseline measurements and served a meal of around 300 calories. Each of the 32 participants ate both meal types on separate days, and the researchers randomized the order.
Both meals contained similar amounts of calories, carbohydrates, fat, protein, fiber, and sodium.
Some of the foods the researchers served in the non-ultra-processed session included banana slices and cheese. For the ultra-processed meal, some foods included a portion of a peanut butter and jelly sandwich and veggie chips.
After the participants finished eating, the researchers collected blood samples multiple times over the following three hours.
During another visit, participants bid on pictured foods while researchers monitored their brain activity with functional MRI. The researchers used the bids to estimate how much participants valued each item.
Ultra-processed meals prompted a greater insulin response
The researchers tracked blood sugar, insulin, and energy use after each meal.
Despite similar overall blood sugar responses, the participants had a greater insulin response after the ultra-processed meal. Their insulin levels stayed higher between 40 and 120 minutes after eating.
The higher insulin response made the researchers wonder whether ultra-processed foods place greater demands on how the body regulates blood sugar. However, the study did not establish that this response was harmful or indicated insulin resistance.
Participants also burned fewer carbohydrates and more fat while expending more energy after eating their ultra-processed meals.
The researchers also linked differences in carbohydrate burning after the meals to differences in brain responses to food images during the MRI visit. The participants bid similar amounts for both food categories, but the findings suggested that metabolic responses may relate to how the brain processes food cues.
Overall, the findings suggest that nutrient content alone may not fully explain the body’s response to food. Processing may also matter.
However, the study tested only one pair of small meals in relatively young, healthy-weight adults. The researchers need to conduct larger, longer studies to determine whether these differences persist and affect health over time.
What do these findings mean for food choices?
Mir Ali, MD, a bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center, who was not involved in the study, discussed the findings with Medical News Today.
“This study showed that ultra-processed foods (UPFs) have a significant hormonal and metabolic effect on the body, altering insulin response and carbohydrate metabolism,” Ali said.
However, I have emphasized that the researchers still need to identify which aspects of these foods drive the differences.
“The study did not differentiate between processing methods and extra ingredients in (ultra-processed foods),” Ali noted. “Further research is needed to determine the most harmful aspects of ultra-processed foods.”
For everyday food choices, Ali recommended limiting ultra-processed foods while acknowledging the challenges people face.
“I advise my patients to minimize UPFs, although they remain difficult to avoid because they are inexpensive, accessible, and highly palatable,” shared Ali.
Qianzhi Jiang, PhD, RD, a pediatric and family dietitian with The Nutrition Changer, also discussed the study findings with MNT.
“It adds to growing evidence that what happens to food during processing may matter beyond what we see on a nutrition label,” shared Jiang, who was also not involved in the study.
Jiang explained that insulin release responds to protein and amino acids and that the differences in ingredients and protein sources could have contributed to the findings.
“We should be cautious about interpreting the higher insulin response as evidence of a more severe problem,” she said.
Jiang pointed out that the study did not examine whether hormones, such as GIP and GLP-1, contributed to the higher insulin response.
She also noted that the NOVA system was not originally intended to be “a measure of nutritional quality or overall healthfulness” and that it would be interesting to see how the foods scored on the Healthy Eating Index.
