It’s not just poor nutrition that links ultra-processed food to health harms, a new study finds.
The body’s response is also determined by the amount of processing the food has gone through, which changes the way we get energy from food.
Researchers at Virginia Tech gave 32 study participants two different meals three days apart. The meals had the same amount of calories and nutrients, but one was ultra-processed and the other wasn’t.
Participants had a greater insulin response after eating the ultra-processed meal, meaning their bodies were working harder to regulate their blood sugar. Their brain activity also changed when they looked at pictures of ultra-processed foods, or UPF.
How the study measured UPF metabolism
In the study, published recently in Nature Metabolism, the researchers wanted to find out whether a meal of ultra-processed food would be metabolized, or used for energy, differently than a meal of minimally processed food.
The researchers designed two 300-calorie meals whose nutrition matched: They were nearly identical in calories, carbs, fat, fiber, protein, sodium and water content.
The ultra-processed meal included portions of a peanut butter and jelly sandwich, deli turkey, veggie chips, instant mashed potatoes, cereal and a cookie. These foods are not always ultra-processed, but the brands used in this study were.
The minimally processed meal was made from banana, dried cranberries, cheese and egg.
Participants ate the meals three days apart. Before and after each meal, they entered a metabolic chamber – an airtight room that measures calories burned based on the amount of oxygen and carbon dioxide in the chamber.
Researchers found that the ultra-processed meals led to higher insulin, the hormone that regulates blood sugar, and lower use of carbohydrates for energy.
How the study measured brain activity
The study also assessed whether the two meals would activate the brain in different ways.
Researchers later showed participants pictures of ultra-processed and minimally processed foods while they received a specialized brain scan called a functional MRI. Some of the food pictured was the same food used in the study’s meals.
One key finding: Ultra-processed food caused different responses in the area of the brain related to motivation and reward.
That might mean that, in addition to variations in how our bodies use food for energy, the ways the brain thinks about and values food fluctuates depending on how processed it is.
Science is showing that food processing can affect health
Some researchers say nutrition, not processing, makes ultra-processed food harmful to health. It’s true that ultra-processed foods are often high in added sugar and saturated fat, and low in beneficial nutrients like fiber and protein.
But this isn’t the first study to show that processing plays a role. In 2019, the first randomized controlled trial showed that an ultra-processed diet led to greater calorie intake and weight gain than a minimally processed diet – even when they had the same nutritional profile.
What’s more, many researchers who have critiqued the main classification system for ultra-processed food have received food industry funding.
What you can do
It’s not practical for most people to avoid all ultra-processed food – they’re widely available, affordable and appealing for consumers. Research has even shown that food companies took tips from the tobacco industry to create products with maximum pleasure and appeal.
The federal government has failed to regulate ultra-processed food. States like California are taking the lead, recently enacting a law establishing a “non-ultra-processed” label for foods sold in California stores.
Until change comes to your state, you can use EWG’s Food Scores, which rates more than 150,000 products on nutrition, ingredients and processing and flags UPF for you.
Shoppers on the go can also use EWG’s Healthy Living app to find non-UPF options at the grocery store.
