https://www.bbc.co.uk/food/articles/van_tulleken

https://www.theguardian.com/books/2023/may/15/the-big-idea-why-we-need-a-new-definition-of-junk-food

But just over a decade ago a team of scientists in Brazil noticed a paradox in the data from their national nutrition surveys. Obesity had gone from being rare, to being the country’s dominant public health problem – even though people were buying less oil and sugar. What they wereeating more of was industrially processed food: biscuits, emulsified breads, confectionary and so on. The team developed a definition that distinguished between traditional food, whole or processed, and these items, which they termed ultra processed foods, or UPFs for short.

The full definition is pages long because it needs to encompass so many different products. But if you’re trying to work out if something is a UPF, a good rule of thumb is that it’ll be wrapped in plastic and contain an ingredient you don’t find in a domestic kitchen.

The Brazilian team’s work meant that the hypothesis – that UPFs were themselves the cause of health problems – could be tested. There are now hundreds of robust scientific studies which show that higher UPF intake is associated with weight gain, stroke, heart attack, cancer, type 2 diabetes, high blood pressure, fatty liver disease, inflammatory bowel disease, depression, dementia and early death.

In the UK we get around 60% of our calories from UPFs, and that figure is even higher for young people. At this point, it is our national food culture, and the material we build our children’s bodies from. Much of it is familiar as “junk food”, but our traditional idea of what constitutes that – chips, crisps, fizzy drinks – needs adjusting. It should include all supermarket bread; likewise breakfast cereal; packaged snacks, reconstituted meat products and frozen meals. And beware: lots of UPFs are being marketed as healthy, nutritious or useful for weight loss.

The evidence now shows that UPFs are harmful not simply because they are salty, fatty, sugary and low in fibre; the processing itself is at fault. Read the ingredients list and you’ll see that most UPFs are made from commodity crops such as corn or soy deconstructed into their most basic molecules (protein isolates, refined oils and modified carbohydrates). These are then reassembled with additives to produce food in any shape or texture desired.

This manipulation of texture is a big part of the problem. UPFs are often very soft and very dry. The illusions of moisture is created with gums and oils, but the water content is low in order to improve shelf life. As a result these foods are extremely energy dense. High energy density combined with softness means you eat quickly, and bodily systems evolved over millions of years to tell you when you’re full can’t keep up.

There is a very long list of other possible explanations for the damage UPFs cause. For example, fruits and vegetables are complex, containing tens of thousands of phytochemicals – molecules which are essential for dietary health. UPFs have dramatically reduced levels of these. And many of the additives used (such as emulsifiers, flavour enhancers and sweeteners) have direct undesirable effects on our metabolic health and our microbiomes.