Study Links Ultra-Processed Foods to Increased Insulin Response

Alexandra DiFeliceantonio, PhD, an associate professor at Virginia Tech’s Fralin Biomedical Research Institute, highlighted that over half of the calories consumed by individuals in the US come from UPFs. She noted established correlations between high UPF consumption and increased rates of obesity, cardiac events, type 2 diabetes, and certain mental health issues.

A recent study published in Nature Metabolism aimed to cleanly compare processed and unprocessed diets by controlling various nutritional factors. The researchers ensured that two meals matched closely on calories, carbohydrates, fats, proteins, fiber, sodium, water, and weight, with a margin of less than 1.6% on all measures, including glycemic index and glycemic load.

Zach Hutelin, the study's first author, emphasized that although the meals appeared similar nutritionally, their metabolic impacts were distinct. In trials involving 57 healthy-weight adults, participants showed significantly higher insulin levels after consuming the ultra-processed meal compared to the non-UPF meal. Participants also burned more fat and expended more energy after eating the UPF.

"We were shocked when every single metabolic metric differed," Hutelin stated. He observed that while total glucose exposure was similar for both meals, insulin levels remained elevated for a longer period after consumption of the ultra-processed meal.

Each meal consisted of 300 calories, with the ultra-processed meal including deli turkey, instant mashed potatoes, and a chocolate chip cookie, while the non-UPF meal contained a hard-boiled egg, sliced banana, cheese, and dried cranberries. To balance weight and water content, the ultra-processed meal was supplemented with water.

The study also examined brain activity by employing functional magnetic resonance imaging (fMRI) while participants viewed food images. The data indicated a correlation between increased insulin levels from the ultra-processed meal and activity in brain regions linked to motivation and reward. However, participants did not express a preference for UPFs in an auction task related to food choices.

Despite the compelling results, the authors caution that their findings do not establish long-term health effects, as the study involved healthy adults and evaluated only a single meal's impact. Additional variables, such as differing protein sources and the presence of additives in the ultra-processed meal, could also influence insulin responses. DiFeliceantonio stated that future research will focus on identifying specific processing factors that contribute to these varied health outcomes.