Ultra-Processed Foods Linked to Increased Muscle Fat, New Study Warns
A new study published on April 15, 2026, in the journal Radiology reveals that diets high in ultra-processed foods can significantly impair musculoskeletal health by increasing the accumulation of fat within the muscles. This phenomenon can occur even in individuals who show no other signs of disease, suggesting that the quality of a person’s diet may be more critical to muscle integrity than calorie count or physical activity levels alone.
The research highlights two distinct ways muscles store fat: intermuscular fat, which appears as “streaks” between healthy muscle tissues, and intramuscular fat, which consists of small droplets stored directly within the muscle fibers. While everyone possesses some amount of both, the study found that those consuming high levels of ultra-processed foods—such as sugary drinks, fast food, and salty snacks—showed a higher prevalence of these fat deposits.
To illustrate the severity of this impact, researchers shared an MRI of the thigh of a 62-year-old woman whose annual caloric intake was 87% ultra-processed. The image revealed heavy “marbling,” resembling a high-quality cut of meat with fine veins of fat. According to Dr. Zehra Akkaya, a researcher and consultant with the Musculoskeletal Imaging Clinical and Translational Research group at the University of California in San Francisco, the participant’s diet consisted primarily of sugary bottled drinks, chocolate candies, candy bars, and cold cereals.
Dr. Akkaya, the study’s lead author, explained that these hidden veins of fat within and between muscle fibers can be indicators of serious health problems. The study specifically analyzed how these foods increase intramuscular fat in individuals at risk for knee osteoporosis. This discovery underscores a critical public health concern, as musculoskeletal health is often overlooked in discussions about processed diets.
“What is not as well known is that the diet likewise has a significant impact on musculoskeletal health,” stated Dr. Thomas Link, head of the musculoskeletal imaging section at the University of California in San Francisco and a lead author of the study.
The role of muscle fat varies by fitness level. Christopher Fry, co-director of the Center for Muscle Biology at the University of Kentucky, noted that elite athletes typically do not have thick streaks of intermuscular fat. In athletes, the fat stored as droplets within muscle fibers serves as a vital energy reserve during extraordinary physical exertion. Though, the accumulation seen in those consuming ultra-processed diets represents a deterioration of muscle quality rather than a functional energy reserve.
The prevalence of these foods in the American diet is stark. According to the Centers for Disease Control and Prevention (CDC), more than 50% of calories consumed by adults in the United States come from ultra-processed foods, a figure that rises to 62% among children. These dietary patterns are linked to obesity, weight gain, and chronic conditions including type 2 diabetes, cardiovascular diseases, depression, and cancer, and may even shorten overall life expectancy.
Experts suggest that consumers can limit the intake of additives and ultra-processed ingredients by carefully reading food labels, including those on baby snacks, and foods. Because these industrial products are designed for convenience and long shelf lives, they often combine high levels of salt, sugar, fats, and carbohydrates, which directly alter the body’s muscular structure.
