What makes this finding striking is that the link held up after accounting for calories eaten and how active people were. This hints that the composition of food and how it is processed may influence muscle quality beyond simple weight gain or exercise levels. For people worried about mobility, knee pain, or keeping physically active as they age, subtle shifts in muscle composition could matter as much as overall fitness.
Follow the full study to learn what types of ultra-processed items were most associated with muscle fat and how these changes were measured. The results touch on diet, aging, and how we care for joint health, and they raise practical questions about food choices that support long-term strength, movement, and inclusive opportunities for everyone to stay active.
Eating more ultra-processed foods was linked to greater fat buildup inside thigh muscles, according to MRI scans of 615 adults at risk for knee osteoarthritis. Surprisingly, the association remained even after researchers accounted for calorie intake, physical activity, and other factors. Fatty changes in these muscles may weaken support around the knee and potentially increase osteoarthritis risk.
