Ultra-processed food intake potentially boosts the likelihood of developing knee osteoarthritis.
Ultra-processed food intake potentially boosts the likelihood of developing knee osteoarthritis.
People who frequently consume highly-processed foods were found to have an increased buildup of fat in their thighs in a recent study, potentially increasing their risk of developing knee osteoarthritis.
The study revealed that this fat accumulation occurred regardless of the participants' calorie intake or physical activity level.
The findings of the imaging study were presented at the Annual Meeting of the Radiological Society (RSNA) of North America in December 2024, although it has not yet been published in a peer-reviewed journal.
Previous research has linked the replacement of muscle in the thigh with fat to reduced knee function. This is the first study to directly connect this phenomenon to the consumption of highly-processed foods.
What are highly-processed foods?
Highly-processed foods are mass-produced items that are a mainstay of many diets. They are primarily engineered for taste, convenience, and affordability, with nutritional value taking a back seat.
These foods often contain five or more ingredients and are high in sugar and fats. Highly-processed foods usually contain additives such as flavor enhancers, food colorings, sweeteners, and preservatives, as well as modified starches and hydrogenated fats.
In the study, researchers analyzed MRI scans from 666 individuals who participated in a nationwide study, the . The average age of the participants was 60, with 455 men and 211 women. Their average body mass index (BMI) was 27, and none of them had developed osteoarthritis yet.
Study co-author Zehra Akkaya, MD, a radiologist at Ankara University in Turkey, noted in a press release that, “on MRI images, this decline can be seen as fatty degeneration of the muscle, where streaks of fat replace muscle fibers.”
Highly-processed foods lead to fat accumulation in the thighs
“We expected that highly-processed foods would increase insulin resistance and adipose tissue — visceral fat — which is harmful fat and linked to inflammation and diabetes,” Gowri Reddy Rocco, MD, MS, founder and president of Optimum Wellness And Longevity, who was not involved in the study, told Medical News Today.
Rocco said of its findings that “this is something that’s tangible,” and “to show that [highly-processed foods] replace the muscle with fat, that’s pretty novel.”
Paul Arciero, MS, DPE, professor in the Health and Human Physiological Sciences Department at Skidmore College in Saratoga Springs, NY, who was not involved in the study, hypothesized that:
“The most likely trigger of a highly-processed food diet that leads to increased total body, and specifically thigh, fat is the high sugar intake from grains, high fructose corn syrup, soda, candy, cookies, juices, and other packaged foods.”
“Other contributing sources are sodium from processed animal products and excess refined fats and oils — hydrogenated, fried foods, margarine, trans fats, and chips — in these foods. All of these processed foods trigger the release of pro-inflammatory substances such as glucose, insulin, cytokines, and other damaging molecules such as free radicals. These substances also increase pain,” Arciero explained to MNT.
Fat accumulation in the thighs may increase the risk of knee osteoarthritis
“Osteoarthritis is the most common form of arthritis,” said Rocco. “It’s chronic inflammation in one or more of the joints. Inflammation starts deteriorating the cartilage there, which is a spongy material, if you will, that helps keep the joint healthy.”
“When you exercise, your muscles strengthen your joints. Muscle weakness is actually a risk factor for osteoarthritis,” she noted.
However, Rocco pointed out, when “muscle fiber in the thigh is getting replaced with fat fibers, your muscles are much weaker and regardless of your exercise, regardless of your calorie intake,” they can no longer effectively protect the joints, allowing osteoarthritis to develop and progress.
Fortunately, when a person's diet is corrected, muscle can regenerate, become stronger, and regain the ability to strengthen cartilage and protect joints. Joint damage cannot be repaired, but it may be slowed or halted.
Preventing knee osteoarthritis
“A poor diet of highly-processed foods, inactivity, sitting, overweight, and obesity are the primary risk factors” for knee osteoarthritis, said Arciero. “There may be a small genetic component, however, lifestyle is by far the greatest risk factor.”
“Obesity,” Rocco opined, “is probably the most common now because, sadly, we’re seeing osteoarthritis starting in younger age groups, 30s, and 40s, as opposed to before, when it used to be more at 45 and older.”
“Obesity increases stress and strain on the knees, on the hips, on the body. So number one is to lose weight to reduce overuse of joints,” she added.
“Excessive wear and tear through repetitive movement patterns,” noted Arciero, “improper footwear and biomechanics may also play a role.”
"Menopause is a potential issue as well, in the context of women," Rocco mentioned.
Identifying Submuscular Thigh Fat in Women
If you're worried about the possibility of knee osteoarthritis, there are ways to identify the presence of submuscular thigh fat in women.
"An experienced medical professional, fitness trainer, exercise physiologist, or healthcare expert might use indirect methods to assess fat accumulation in the thigh," Arciero explained.
"This can be achieved through techniques such as measuring circumferences, taking skinfold readings, and utilizing bioelectrical impedance analysis (BIA), which are all relatively straightforward procedures that can be performed in various outpatient, fitness, or healthcare facilities," he elaborated.
"Moreover, iDXA (dual X-ray absorptiometry) scans can also pinpoint the amount of fat in the thigh. However, these are more specialized and pricey, and they're primarily accessible in healthcare or research settings," Arciero continued.
"Prevention is the key strategy," he suggested.
"A balanced diet is the primary way to combat excessive fat buildup anywhere in the body, particularly in areas like the abdomen (visceral fat), hips, and thighs," Arciero advised.
"Our research has consistently shown the effectiveness of this nutritional approach in significantly decreasing thigh, hip, and abdominal fat for several years," he concluded.
The study suggests that a diet high in highly-processed foods can lead to fat accumulation in the thighs, which could potentially increase the risk of developing knee osteoarthritis due to muscle weakness and reduced knee function. Zohra Akkaya, a radiologist at Ankara University, noted that high consumption of these foods can result in fatty degeneration of the muscle in the thighs.
Gowri Reddy Rocco, an expert not involved in the study, highlighted that the findings show that highly-processed foods can replace muscle with fat in the thighs, which is novel in this context. Paul Arciero, another expert, hypothesized that high sugar intake and excess refined fats in highly-processed foods could be the main triggers for this fat accumulation.