A recent study reveals that consuming ultra-processed foods (UPFs) can lead to an unexpected buildup of fat in thigh muscle tissue, even in individuals who exercise regularly or maintain a balanced calorie intake. This fat accumulation may also contribute to a heightened risk of knee pain and osteoarthritis. The findings could have important implications for those seeking to improve their overall muscle health and joint function.
Ultra-processed foods and fat in muscle tissue
In an investigation involving nearly 700 adults, researchers found a significant connection between ultra-processed food consumption and an increase in fat deposits within the thigh muscles. This study, which used magnetic resonance imaging (MRI) to assess muscle tissue quality, demonstrated that the more ultra-processed foods a person consumed, the greater the fat buildup within their muscles. Participants were an average of 60 years old and had a body mass index (BMI) suggesting they were typically overweight.
Dr. Zehra Akkaya, MD, the lead researcher and former Fulbright Scholar, emphasized the robustness of these findings: “These findings held true regardless of dietary energy content [calorie intake], BMI [body mass index], sociodemographic factors, or physical activity levels.” The persistence of this relationship, even after controlling for a range of factors, underscores the potential health risks posed by ultra-processed foods, regardless of one’s exercise regimen or caloric intake.
The role of ultra-processed foods in modern diets
Ultra-processed foods are mass-produced products that contain minimal whole plant or animal ingredients. These items are typically chemically altered and often include artificial additives like flavoring and coloring agents. Examples range from breakfast cereals, packaged snacks, hot dogs, and sodas to frozen meals and ready-to-eat products.
The research highlights that about 40 percent of participants’ diets consisted of ultra-processed foods. Those who consumed the highest proportion of these foods showed a considerable increase in thigh muscle fat. To illustrate this, researchers provided a case study of two obese women, both consuming ultra-processed foods at different rates. One woman’s diet was composed of 68% ultra-processed foods, resulting in noticeably higher muscle fat compared to the other woman, whose diet consisted of only 36% such foods.
Implications for joint health and knee osteoarthritis
One of the most concerning findings of the study is the potential link between excess thigh muscle fat and the increased risk of knee osteoarthritis, a degenerative joint disease more commonly found in individuals who are overweight or obese. While the study was not designed to prove a direct causal relationship between ultra-processed food consumption and muscle degeneration, the MRI results revealed muscle damage in participants who were neither elderly nor diagnosed with osteoarthritis.
Ali Guermazi, MD, PhD, a professor of radiology at Boston University, remarked on the unexpected nature of these findings: “No impairment of muscle quality would be expected in those individuals.” This suggests that even in relatively healthy individuals, ultra-processed food consumption could contribute to muscle degradation, which may, in turn, influence joint health.
David Gimarc, MD, an assistant professor of radiology at the University of Colorado Anschutz Medical Campus, further elaborated on potential interventions: “It is reasonable to assume that dietary modifications—which can have downstream effects such as reduced weight, improved obesity, and improved muscle quality, affecting things such as balance and core muscle support across joints—could indeed improve their pain.” Reducing ultra-processed food intake, according to Dr. Gimarc, could help alleviate inflammation and improve muscle quality, which is essential for supporting the joints.
The importance of whole foods for muscle health
Nutrition experts agree that a diet rich in whole foods is vital for maintaining healthy muscles. Connie Diekman, RD, LD, a food and nutrition consultant, explained that “Muscle mass requires adequate calories and protein.” By choosing lower-nutrient foods, individuals may struggle to maintain muscle mass, which can lead to fat deposition in muscles and, subsequently, weaker muscles. This weakness can contribute to poor joint health and increased pain.
For optimal muscle and joint health, Diekman recommends focusing on a balanced diet with an emphasis on whole grains, fruits, vegetables, and lean protein sources. Including plant-based protein such as beans, nuts, and seeds can further enhance the quality of muscle tissue. She added, “The quality of muscle in the body, along with bone health, does align with how we fuel the body.”
A call for dietary reevaluation
The new findings raise significant concerns about the widespread consumption of ultra-processed foods and their impact on muscle health and joint function. While further research is needed to establish a direct cause-and-effect relationship, it is clear that a diet high in ultra-processed foods could have serious consequences, not just for fat accumulation, but for the quality of muscle tissue and long-term joint health.
As experts suggest, focusing on whole foods and nutrient-dense options may be one of the most effective ways to protect both muscles and joints. A shift toward more natural, minimally processed foods could be key in preventing muscle degeneration and mitigating the risks of knee osteoarthritis, ultimately improving overall quality of life for those seeking better health.
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