Ultra‑processed foods and muscle fat

A new imaging study found that people who ate more ultra-processed foods had more fat marbled into their thigh muscles, even after researchers accounted for calories and exercise. (pubs.rsna.org) The study, published April 14 in *Radiology*, analyzed 615 adults in the Osteoarthritis Initiative, a National Institutes of Health-backed project on knee osteoarthritis. Participants were about 60 years old on average, 340 were women, and ultra-processed foods made up about 41.4% of their diets. (pubs.rsna.org) Researchers used magnetic resonance imaging, or MRI, to look for fatty streaks inside thigh muscles, a sign of lower muscle quality rather than just higher body weight. They adjusted for age, sex, smoking, depression, physical activity, daily calories, body mass index and abdominal circumference, and the association still held. (rsna.org, pubs.rsna.org) That distinction matters because muscle can look normal on a scale while losing strength and function as fat replaces muscle fibers. A 2019 review of knee osteoarthritis research linked thigh muscle fat infiltration with poorer physical function, muscle impairment and metabolic problems. (rsna.org, pubmed.ncbi.nlm.nih.gov) The paper does not prove that ultra-processed foods caused the muscle changes. It was a cross-sectional analysis, meaning diet and MRI were measured at the same point in time in people already considered at risk for knee osteoarthritis. (pubs.rsna.org) The food category in question is broad. The Radiological Society of North America press release said it included items such as packaged snacks, soft drinks, hot dogs, frozen pizzas, ready-to-eat meals, mass-produced breads, candies and desserts. (rsna.org) Illinois lawmakers are trying to turn that research trend into school policy. House Bill 5507, filed February 13, 2026, would require school districts to begin eliminating “ultraprocessed foods of concern” and “restricted school foods” by July 1, 2029, with vendors barred from offering them to schools starting July 1, 2032. (my.ilga.gov, ilga.gov) The bill leaves key definitions to rulemaking by the Illinois Department of Public Health, working with the State Board of Education, and it would require vendor reporting and staff training. On March 26, the House Public Health Committee voted 6-2 to advance it; on April 17, it was re-referred to the Rules Committee. (ilga.gov, ilga.gov, my.ilga.gov) For now, the science is narrower than the politics: one April 2026 study tied higher ultra-processed food intake to fattier thigh muscles in adults at risk for knee osteoarthritis, and Illinois is debating whether that kind of evidence belongs in cafeteria rules. (pubs.rsna.org, my.ilga.gov)