Two meals. Similar calories and nutrients. Different effects on the body.
A new study finds that ultra-processed foods can affect the body differently, even when calories and nutrients are closely matched.
We often judge foods by how many calories they contain or how much sugar, fat, or sodium they provide. Researchers wanted to understand whether the degree of processing also matters, even when foods have similar nutritional content.
The study involved healthy-weight adults ages 18–45. Fifty-two participants underwent functional MRI (fMRI) brain scans to examine responses to food pictures, and 32 completed meal tests. During the meal tests, participants ate an ultra-processed meal on one day and a non-ultra-processed meal on another. The meals were closely matched for calories, carbohydrates, fat, protein, fiber, sodium, and other nutritional characteristics.
Researchers monitored participants’ blood sugar, insulin, and how their bodies used energy for three hours after each meal. Having each person eat both meals allowed researchers to compare responses within the same individual.
Despite the nutritional similarities, the ultra-processed meal produced a greater insulin response. Insulin is the hormone that helps regulate blood sugar. Overall blood sugar responses were similar, but participants had higher insulin levels in their blood after eating the ultra-processed meal. Their bodies also burned fewer carbohydrates for energy during the monitoring period.
Why might processing make a difference?
Processing can change a food’s physical structure, potentially affecting how nutrients become available during digestion. The researchers suggest this could help explain the different responses, although the study could not identify exactly which aspects of processing were responsible.
These differences could help explain why higher consumption of ultra-processed foods has been linked to metabolic health problems. However, the study examined short-term responses to two specific meals. It did not establish whether those differences lead to diabetes, weight gain, or other long-term health problems.
The takeaway: Calories and nutrients may not tell the whole story. This study found that nutritionally similar meals produced different responses in the body, adding evidence that how food is processed may matter alongside what it contains.
Read the full article published by Nature Metabolism.
