A new study has uncovered a concerning link between ultra-processed foods (UPFs) and changes in muscle structure. Researchers found that a diet high in UPFs leads to fat buildup in the thighs, resembling the marbling seen in steak, potentially increasing the risk of knee osteoarthritis. The findings were published in Radiology, a journal of the Radiological Society of North America (RSNA).
UPFs Linked to Worse Muscle Health
While marbling in steak may be desirable, having it in your body is not. The study revealed that individuals consuming more ultra-processed foods tend to have higher levels of intramuscular fat in their thigh muscles, regardless of calorie intake, physical activity, or sociodemographic factors. This association was particularly strong among those at risk of knee osteoarthritis. Higher intramuscular fat in the thigh could increase the likelihood of developing knee osteoarthritis, a debilitating condition affecting millions worldwide.
What Are Ultra-Processed Foods?
Ultra-processed foods include cookies, chips, soft drinks, and other items with long shelf lives. They are often highly appealing due to their combination of sugar, fat, salt, and carbohydrates, which affect the brain's reward system, making them hard to resist. However, not all UPFs are obvious; some seemingly healthy options like breakfast cereals, margarines, packaged snacks, hot dogs, energy drinks, candies, frozen pizzas, ready-to-eat meals, and mass-produced packaged breads also fall into this category, as they contain synthetic ingredients.
Obesity and Knee Osteoarthritis on the Rise
The study highlights a close connection between UPF consumption and obesity. Lead author Zehra Akkaya, M.D., a researcher at the University of California, San Francisco, noted: "Over the past decades, in parallel with the rising prevalence of obesity and knee osteoarthritis, the use of natural ingredients in our diets has steadily diminished and been replaced by industrially processed, artificially flavored, colored, and chemically altered food and beverages." The research team analyzed data from 615 participants in the Osteoarthritis Initiative, a nationwide study sponsored by the National Institutes of Health. These participants, with an average age of 60 and a BMI of 27, were not yet affected by osteoarthritis. On average, 41% of their food intake over the prior year consisted of UPFs.
The More UPFs, the More Fat
The findings were striking: higher UPF consumption correlated with greater intramuscular fat in the thigh, visible on MRI as fatty degeneration where fat streaks replace muscle fibers. Dr. Akkaya emphasized the accessibility of this approach: "In addition to investigating the quality of our modern diet, we used widely available, non-enhanced MRI, making our approach practical for routine clinical use. These MRIs do not require advanced technology, allowing easy incorporation into standard diagnostics." She added: "This research underscores the vital role of nutrition in muscle quality for knee osteoarthritis. Addressing obesity is a primary objective, but dietary quality warrants greater attention. Weight-loss regimens should consider diet quality beyond caloric restriction and exercise."
The Takeaway
Preventing obesity involves targeting modifiable lifestyle factors such as a healthy, balanced diet and adequate exercise. These strategies are also key for managing knee osteoarthritis initially. Reducing UPF intake helps preserve muscle quality, potentially alleviating the burden of knee osteoarthritis. Dr. Akkaya concluded: "Recent studies have shown the detrimental impacts of UPFs on health, but data on their relationship with body composition in knee osteoarthritis are limited. This is the first study assessing UPF impact on thigh muscle composition using MRI, providing valuable insights into dietary influences on muscle health."
This research serves as a reminder that what we eat affects not just our weight but the very structure of our muscles, with long-term implications for joint health.
