- A new study compared how adults responded to ultra-processed and less-processed meals containing similar nutrients.
- The ultra-processed meal led to a higher insulin response and changed the way the body used energy.
- The team also looked at participants’ brain activity while they viewed images 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 of how the body responds after eating.
Virginia Tech researchers recently studied whether food processing affects the body’s response independent of nutrient content.
They compared the body’s responses to two meals that were similar in nutritional composition but differed in the level of processing. They also examined brain activity to determine whether metabolic differences were related to participants’ responses to food images.
Ultra-processed foods often contain ingredients that improve flavor, texture or shelf life. The NOVA classification system groups foods according to their level of processing. For example, nuts and plain eggs are in group 1, while soda and many packaged chips are in group 4.
Because ultra-processed foods can provide nutrients such as protein and fiber, the level of processing alone does not describe a food’s nutritional profile. To better understand whether processing is important beyond these nutrients, the researchers compared nutritionally tailored 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 approximately 300 calories. Each of the 32 participants ate the two types of meals on different days, and the researchers randomized the order.
Some of the foods served by the researchers during the non-ultra-processed session included banana slices and cheese. For the ultra-processed meal, some foods included a serving of a peanut butter and jelly sandwich and vegetable chips.
After the participants finished eating, the researchers collected blood samples several times over the next three hours.
During another visit, participants bid on illustrated foods while researchers monitored their brain activity using functional MRI. The researchers used the bids to estimate the value participants placed on each item.
The researchers tracked blood sugar, insulin and energy consumption after each meal.
Despite similar overall glycemic responses, participants had a greater insulin response after the ultra-processed meal. Their insulin levels remained higher between 40 and 120 minutes after eating.
The higher insulin response has led researchers to wonder whether ultra-processed foods place higher demands on how the body regulates blood sugar. However, the study did not establish that this response was harmful or indicative of insulin resistance.
Participants also burned fewer carbs and more fat while expending more energy after eating their ultra-processed meals.
Researchers also linked differences in carbohydrate burning after meals to differences in brain responses to food images during the MRI visit. Participants offered similar amounts for the two food categories, but the results suggested that metabolic responses might be linked to how the brain processes food signals.
Overall, the results suggest that nutrient content alone cannot fully explain the body’s response to food. Treatment may also matter.
However, the study only tested a pair of small meals in relatively young, healthy-weight adults. Researchers need to conduct larger, longer studies to determine whether these differences persist and affect health over time.
Mir Ali, MD, a bariatric surgeon and medical director of Orange Coast Medical Center’s MemorialCare Surgical Weight Loss Center, who was not involved in the study, discussed the findings with Medical news today.
“This study showed that ultra-processed foods (UPF) have a significant hormonal and metabolic effect on the body, altering the insulin response and carbohydrate metabolism,” Ali said.
However, he stressed that researchers have yet to identify which aspects of these foods are causing the differences.
“The study did not differentiate between processing methods and additional ingredients in (ultra-processed foods),” Ali noted. “More research is needed to determine the most harmful aspects of ultra-processed foods.”
For everyday food choices, Ali recommended limiting ultra-processed foods while recognizing the challenges people face.
“I advise my patients to minimize UPFs, although they remain difficult to avoid because they are inexpensive, accessible and very tasty,” Ali explained.
Qianzhi Jiang, PhD, RD, pediatric and family dietitian at The Nutrition Changer, also discussed the study results with MNT.
“This 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 proteins and amino acids and that differences in ingredients and protein sources could have contributed to the results.
“We need to be careful about interpreting the higher insulin response as evidence of a more serious problem,” she said.
Jiang pointed out that the study did not examine whether hormones, such as GIP and GLP-1, contributed to a higher insulin response.
She also noted that the NOVA system was not initially intended to be “a measure of nutritional quality or overall health” and that it would be interesting to see how foods ranked on the Healthy Eating Index.
Gn Health
