Ultra-processed foods have long been tied to obesity, heart disease, and type 2 diabetes. Now researchers are documenting a broader set of physical consequences, including damage to muscles, bones, and reproductive health.
A study published in Radiology, a journal of the Radiological Society of North America, found that people who ate more ultra-processed foods showed increased fat storage inside thigh muscles, regardless of how many total calories they consumed. That buildup of intramuscular fat is linked to a higher risk of knee osteoarthritis.
"Over the past decades, in parallel to the rising prevalences of obesity and knee osteoarthritis, the use of natural ingredients in our diets has steadily diminished and been replaced by industrially-processed, artificially flavored, colored and chemically altered food and beverages," said lead study author Zehra Akkaya, MD, a researcher at the University of California, San Francisco. The finding matters because intramuscular fat is not always visible or tied to a person's overall weight, meaning even people who appear lean could be affected if their diets are heavy in processed products.
A separate study published in March drew on data from 160,000 participants in the UK Biobank and followed them for more than 12 years. Researchers found that high consumption of ultra-processed foods was associated with lower bone mineral density at several key locations, including the upper femur and the lumbar spine, as well as a higher risk of hip fractures. The effects showed up across age groups, including adults under 65 and those who were underweight.
"High intakes of ultra-processed foods were linked to a reduction in bone mineral density at several sites including key areas of the upper femur and the lumbar spine region," said Lu Qi, MD, PhD, co-author of the study and a professor at Tulane University's Celia Scott Weatherhead School of Public Health and Tropical Medicine. Participants in that study were eating around eight servings of ultra-processed foods per day on average. For every 3.7 additional servings consumed daily, fracture risk and bone density loss increased measurably.
Beyond bone and muscle, recent research has also identified links between high ultra-processed food intake and reduced fertility in females, according to findings reported by Healthline. That dimension of the research is newer and still being examined, but it adds to a growing body of evidence that the effects of these foods extend well beyond cardiovascular and metabolic health.
What connects these findings is that the harms appear to be independent of caloric intake alone. The muscle fat study specifically controlled for overall calorie consumption, suggesting that something about the composition or processing of these foods, rather than simply how much someone eats, is driving the damage. Researchers have pointed to factors such as artificial additives, disrupted nutrient profiles, and the absence of fiber and micronutrients typically found in whole foods.
Ultra-processed foods are broadly defined as industrial formulations that contain ingredients not typically used in home cooking, including emulsifiers, artificial flavors, colorings, and preservatives. They include packaged snacks, mass-produced breads, flavored drinks, instant noodles, and many ready-to-eat meals. Their dominance in modern diets, particularly in the United States and United Kingdom, has made them a central focus of nutrition research over the past decade.
