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Consumers of large amounts of highly processed foods increased thigh muscle fattiness regardless of how much they ate, scientists have found, in another sign the products’ health risks could stretch beyond excessive calories.
The study, to be presented on Wednesday at the annual meeting of the Radiological Society of North America in Chicago, will intensify debate over the risks of so-called ultra-processed foods.
While attention has focused on how the industrial addition of appealing ingredients such as flavourings, sugars, fats and salt can lead to overconsumption and obesity, new research on other possible health problems caused by UPFs is still emerging.
“Muscle fattiness seemed to happen regardless of calorie intake,” said Zehra Akkaya, part of the team of Turkey- and US-based researchers. “We hypothesise that muscle fatty infiltration is related to the type of food — ultra-processed foods in the diet.”
UPFs refer to mass produced goods, made mostly from substances extracted from whole foods, such as fats, starches and added sugars, and formulated to be more palatable to consumers. There is no generally agreed definition of the term, which was coined by Brazilian nutritional scientist Carlos Monteiro as part of the Nova food classification system he developed to assess the diets’ impact on health.
Early studies have linked UPFs to diseases including cancer, obesity and heart diseases. Research since has suggested they may contribute to many other health problems, from tooth decay to dementia to accelerated ageing.
The scientists examined muscle fattiness grades from magnetic resonance images of 666 participants at risk of osteoarthritis, a chronic joint condition that causes pain, swelling and restricted movement and estimated to affect more than half a billion people worldwide. Osteoarthritis may be linked to deterioration in the health of the thighs, as streaks of fat replace muscle fibres.
The study’s subjects — more than two-thirds of whom were men — were on average 60-years-old and overweight with a body mass index of 27. About 40 per cent of the foods they ate in the previous year were ultra-processed, the researchers said.
The scientists used a questionnaire that asked how often and in what quantities participants had consumed particular foods and drinks over the previous 12 months. They used the classification system developed by Monteiro and others to assess processing levels.
The possible impact of highly processed foods on the thighs could have “important clinical implications” and offer “new perspective on how diet quality affects musculoskeletal health”, Akkaya said.
Since osteoarthritis is “highly linked to obesity and unhealthy lifestyle choices, there are potential avenues for lifestyle modification and disease management”, Akkaya said.
While the study demonstrated thigh muscle fattiness was associated with the consumption of highly processed foods, it did not demonstrate a causal link, she added. The researchers also saw the same effect on the upper legs even when they accounted for other factors such as physical activity, age, gender and race.
The food industry has dismissed much of the research on UPFs, saying that there is no official definition or sufficient evidence to prove causal links. Few national regulators have addressed UPFs in their dietary guidelines, with the exception of a handful of countries such as Brazil, Israel and Belgium.
However, the risk of greater regulation looms since the nomination of Robert F Kennedy for secretary of health and human services by US president-elect Donald Trump.
Kennedy has promised to transform the US’s food system, and has blamed the food industry for the surge in obesity rates.
