A diet high in ultra-processed foods is linked to higher amounts of fat stored in the inner thigh muscles, regardless of the amount of calories consumed or level of physical activity, according to a study presented at the annual meeting of the Radiological Society of North America .

Highly processed foods include breakfast cereals, margarines and spreads, packaged snacks, hot dogs, soft drinks, energy drinks, candy and desserts, frozen pizzas, ready-to-eat meals, packaged breads and other foods with synthetic ingredients, which contain a combination of sugar, fat , salt and carbohydrates.

MRI images of the lateral folds of the quadriceps femoris muscles of two female study participants, aged 58 (A) and 62 years (B). In woman A, whose diet consisted of 68% highly processed foods, the thigh muscles show many fatty streaks. In woman B, whose diet contained only 36% ultra-processed foods, the thigh muscles showed fewer fatty streaks. CREDIT: Radiological Society of North Aurora (RSNA) and Zehra Akkaya, MD

The researchers set out to assess the effect of diet quality on intramuscular fat using magnetic resonance imaging in 666 subjects (455 men and 211 women). On average, the participants were 60 years old, overweight with a body mass index of 27, and about 40% of the food they consumed in the last year was highly processed.

It found that the more highly processed foods participants consumed, the more intramuscular fat they had in their thigh muscles, regardless of caloric intake, physical activity level, body mass index and sociodemographic factors.

Researchers warn that higher amounts of intramuscular fat in the thigh could increase the risk of knee osteoarthritis.

“Understanding this relationship could have important clinical implications as it offers a new perspective on how diet quality affects musculoskeletal health,” notes study leader Zehra Akaya, a researcher in the Department of Radiology and Biomedical Imaging at the University of California in San Francisco.