Eating lots ultra-processed foods could leave you with more fat in your body regardless of how calorific they are, concerning research has suggested.
Additive-laden foods like crisps and sweets have been vilified for decades over their supposed risks, with dozens of studies linking them to type 2 diabetes, heart disease and cancer.
Experts have even called for ultra-processed foods (UPF) — typically anything edible that has more artificial ingredients than natural ones — to be slashed from diets.
Now, US scientists who tracked over 600 overweight Americans discovered those who ate more junk food had higher amounts of fat stored inside their thigh muscles.The amount of calories in the foods made no difference to the effect.
Diets high in UPFs even impacted muscle quality regardless of how much exercise participants did.
While the risk was only small, the team argued their findings echoed calls to limit certain types of UPFs and warned that higher amounts of fat in the thigh muscle could increase the risk for knee osteoarthritis.
Dr Zehra Akkaya, a radiology and biomedical imaging researcher at the University of California and study co-author, said: ‘The novelty of this study is that it investigates the impact of diet quality, specifically the role of UPFs in relation to intramuscular fat in the thigh muscles assessed by MRI.’
Diets high in UPFs even impacted muscle quality regardless of how much exercise participants did.
In the study, 666 adults with an average age of 60 and BMI of 27 were quizzed on their daily diet and undertook MRI scans.
Approximately 40 per cent of the foods that they ate in the past year were ultra-processed.
They found that the more UPFs people consumed, the more intramuscular fat they had in their thigh muscles, regardless of energy intake — how many calories they ate.
The research will be presented in full at the Radiological Society of North America’s annual conference in Chicago today.
Dr Akkaya said: ‘In an adult population at risk for knee or hip osteoarthritis, consuming UPFs is linked to increased fat within the thigh muscles.
‘These findings held true regardless of dietary energy content, BMI, sociodemographic factors or physical activity levels.’
‘Targeting modifiable lifestyle factors, mainly prevention of obesity via a healthy, balanced diet and adequate exercise, has been the mainstay of initial management for knee osteoarthritis.’
She added: ‘Osteoarthritis is an increasingly prevalent and costly global health issue.
The Nova system, developed by scientists in Brazil more than a decade ago, splits food into four groups based on the amount of processing it has gone through. Unprocessed foods include fruit, vegetables, nuts, eggs and meat. Processed culinary ingredients — which are usually not eaten alone — include oils, butter, sugar and salt
‘It is the largest contributor to non-cancer related health care costs in the US and around the world.
‘Since this condition is highly linked to obesity and unhealthy lifestyle choices, there are potential avenues for lifestyle modification and disease management.’
The umbrella term, UPFs, is used to cover anything edible made with colourings, sweeteners and preservatives that extend shelf life.
Ready meals, ice cream and tomato ketchup are some of the best-loved examples of products that fall under the umbrella UPF term.
This is now synonymous with foods offering little nutritional value.
They are different to processed foods, which are tinkered to make them last longer or enhance their taste, such as cured meat, cheese and fresh bread.
The UK is the worst in Europe for eating UPFs, which make up an estimated 57 per cent of the national diet.
They are thought to be a key driver of obesity, which costs the NHS around £6.5billion a year treating weight-related disease like diabetes, heart disease and some cancers.