New Research Links Ultraprocessed Foods to Muscle Health Issues

Recent findings published in the journal Radiology indicate that consuming an excess of ultraprocessed foods may negatively impact muscle health.

Ultraprocessed foods—think salty snacks, sugary drinks, and fast food—make up a significant portion of Americans’ caloric intake. While the detrimental effects on heart health and diabetes risk are well-known, the implications for muscle health are less discussed.

Dr. Thomas Link, a prominent figure in musculoskeletal imaging at the University of California, San Francisco, noted that diet plays a crucial role in musculoskeletal health, though it’s often overlooked.

Muscles can accumulate fat in two primary ways: through streaks of fat found between them (intermuscular fat) and droplets stored within muscle fibers (intramuscular fat). It’s worth mentioning that everyone possesses some level of both types, but extreme athletes typically have minimal intermuscular fat, according to Christopher Fry, co-director of the Center for Muscle Biology at the University of Kentucky.

This distinction relates to how the body utilizes fat for energy. For athletes, fat within muscle fibers is a vital energy reserve for intense physical exertion. When energy reserves are not utilized, particularly in cases like Type 2 diabetes, fat starts to accumulate, especially between muscles.

Fry remarked, “Everyone has a bit of fat between their muscles, but an increase isn’t ideal.” He amusingly compared muscle fat to cuts of beef, saying, “We want a sirloin steak, not a ribeye.”

Link and his colleagues examined data from 615 participants, averaging around 60 years old, who were part of the National Institute of Arthritis and Musculoskeletal and Skin Diseases’ Osteoarthritis Initiative. They found that increased levels of intermuscular fat are associated with knee osteoarthritis, given that all subjects were at risk due to obesity, being overweight, or having prior knee injuries.

The buildup of fat in muscles not only alters muscle structure but also affects force exertion, impacting how the knees absorb forces from leg movements. This dynamic can damage cartilage and contribute to arthritis, Fry pointed out.

The research team analyzed participants’ BMI, diets, and MRI scans of their thighs, which revealed varying fat levels within the muscles. Interestingly, despite about 65% of participants being overweight, those who consumed a lot of ultraprocessed foods showed higher amounts of fat in their muscles, independent of their BMI or calorie intake.

Further studies are necessary to clarify causation—specifically, whether a diet rich in ultraprocessed foods leads to increased intramuscular fat.

Link originally hypothesized that obesity or excess belly fat was the primary concern tied to high caloric intake. However, the findings have broadened his perspective.

While protein is essential for muscle building and maintenance, omega-3 fatty acids and iron also play critical roles. Sadly, ultraprocessed foods are often calorie-dense yet lacking vital nutrients for muscle health, according to Link.

Dr. Tamiko Katsumoto from Stanford University noted that if it becomes clear that ultraprocessed foods contribute to muscle fat accumulation, it could extend beyond just the thighs, impacting overall health. She emphasized the importance of strong leg muscles for knee function and stability, warning of potential broader issues caused by fat accumulation in other muscles.

A previous study found that each 1% increase in muscular fat heightens a person’s risk of cardiovascular disease by 7%, while other research has linked high levels of intramuscular fat to increased Type 2 diabetes risk. The mechanisms behind these connections aren’t fully understood, but Link mentioned that fat-storing muscles can release inflammatory molecules like cytokines, possibly leading to health complications.

Fortunately, reversing muscle fat buildup is achievable through a diet rich in whole foods and reduced ultraprocessed food intake. Regular exercise and muscle mass maintenance during fat loss are equally important, according to Link.

Fry added that weight loss is beneficial across the body; however, since fat accumulation in muscles doesn’t happen overnight, significant lifestyle changes will be necessary for long-term results.

“What we choose to eat habitually can influence the health and longevity of our muscles,” Fry concluded.