Nearly three decades ago, when I was an overweight teenager, I sometimes ate six pieces of sliced white toast in a row, each one slathered in butter or jam. I remember the spongy texture of the bread as I took it from its plastic bag. No matter how much of this supermarket toast I ate, I hardly felt sated. It was like eating without really eating.
Other days, I would buy a box of Crunchy Nut Cornflakes or a tube of Pringles, which were an exciting novelty at the time, having only arrived in the UK in 1991.
Although the carton was big enough to feed a crowd, I could demolish most of it by myself in a sitting. Each chip, with its salty and powdery sour cream coating, sent me back for another one.
What characterises ultra-processed foods is that they are so altered that it can be hard to recognise the underlying ingredients (file image)
After one of these binges — because that is what they were — I would speak to myself with self-loathing. ‘What is wrong with you?’ I would say to the tear-stained face in the mirror.
I blamed myself for my lack of self-control. But now, all these years later, having mostly lost my taste for sliced bread, sugary cereals and snack chips, I feel I was asking myself the wrong question.
It shouldn’t have been ‘What is wrong with you?’ but ‘What is wrong with this food?’
Back in the Nineties, there was no one word to cover all the items I used to binge on. Some of the things I over-ate — crisps or chocolate or fast-food burgers –— could be classified as junk food, but others, such as bread and cereal, were more like household staples.
These foods seemed to have nothing in common except for the fact that I found them very easy to eat a lot of, especially when sad.
Ultra-processed foods (or UPFs) now account for more than half of all the calories eaten in the UK
I had no idea that there would one day be a technical explanation for why I found them so hard to resist. The word is ‘ultra-processed’ and it refers to foods that tend to be low in essential nutrients, high in sugar, oil and salt and liable to be overconsumed.
Which foods qualify as ultra-processed? It’s almost easier to say which are not.
I got a cup of coffee the other day at a railway station cafe and the only snacks for sale that were not ultra-processed were a banana and a packet of nuts. The other options were: panini made from ultra-processed bread, flavoured crisps, chocolate bars, long-life muffins and sweet wafer biscuits — all ultra-processed.
What characterises ultra-processed foods is that they are so altered that it can be hard to recognise the underlying ingredients. These are concoctions of concoctions, engineered from ingredients that are already highly refined, such as cheap vegetable oils, flours, whey proteins and sugars, which are then whipped up into something more appetising with the help of industrial additives such as emulsifiers.
Ultra-processed foods (or UPFs) now account for more than half of all the calories eaten in the UK, according to a 2018 study in the journal Public Health Nutrition, and other countries are fast catching up.
These foods are convenient, affordable, highly profitable, strongly flavoured, aggressively marketed — and on sale in supermarkets everywhere.
Some UPFs, such as sliced bread or mass-produced cakes, have been around for many decades, but the percentage of UPFs in the average person’s diet has never been anything like as high as it is today.
It could be your morning bowl of Cheerios or your evening pot of flavoured yoghurt. Savoury snacks and sweet, baked goods. The long-life almond milk in your coffee and the diet drink in the afternoon.
Consumed in isolation and moderation, each of these products may be perfectly wholesome. With their long shelf life, ultra-processed foods are designed to be microbiologically safe. The question is what happens to our bodies when UPFs become as prevalent as they are at the moment.
Evidence now suggests that diets heavy in UPFs can cause overeating and obesity. Consumers may blame themselves for overindulging in these foods, but what if it is in the nature of these products to be overeaten?
The Brazilian government certainly fears this, and in 2014 took the radical step of advising its citizens to avoid UPFs outright. The country was acting out of a sense of urgency, because the number of young Brazilian adults with obesity had risen so far and so fast, more than doubling between 2002 and 2013 (from 7.5 per cent of the population to 17.5 per cent).
These radical new guidelines urged Brazilians to avoid snacking, to make time for wholesome food in their lives, to eat regular meals in company when possible, to learn how to cook and to teach children to be ‘wary of all forms of food advertising’. The biggest departure in the Brazilian guidelines was to treat food processing as the single most important issue in public health.
They condemned at a stroke not just fast foods or sugary snacks, but also many foods which have been reformulated to seem health-giving, from ‘lite’ margarines to vitamin-fortified breakfast cereals.
From a British perspective — where the official NHS Eatwell guide still classifies low-fat margarines and packaged cereals as ‘healthier’ options — it seems extreme. But there is evidence to back up the Brazilian position.
Over the past decade, large-scale studies from France, the U.S., Spain and Brazil itself have suggested that high consumption of UPFs is associated with higher rates of obesity.
When eaten in large amounts (and it’s hard to eat them any other way), they have also been linked to a whole host of conditions, from depression to asthma to heart disease to gastrointestinal disorders. In 2018, a study from France — following 100,000 adults — found that a 10 per cent increase in the proportion of UPFs in someone’s diet led to a higher overall cancer risk.
The concept of UPFs was born in the early years of this millennium when a Brazilian scientist called Carlos Monteiro noticed a paradox. People appeared to be buying less sugar, yet obesity and type 2 diabetes were going up.
A team of Brazilian nutrition researchers led by Monteiro, based at the University of Sao Paulo, had been tracking the nation’s diet since the Eighties, asking households to record the foods they bought. One of the biggest trends to jump out of the data was that, while the amount of sugar and oil — as products on their own — people were buying was going down, their sugar consumption was vastly increasing, because of all of the ready-to-eat sugary products that were now available.
And when Monteiro looked at the foods that had increased the most in the Brazilian diet, what they had in common was that they were all highly processed.
Yet he noticed that many of these commonly eaten foods did not even feature in the standard food pyramids of U.S. nutrition guidelines, which show rows of different whole foods according to how much people should consume, with rice and wheat at the bottom, then fruits and vegetables, then fish and dairy and so on. This was a whole new type of food. And a dangerous one at that.
Monteiro’s suspicions were put to the test in 2018 when nutrition researcher Kevin Hall, of the National Institute of Diabetes and Digestive and Kidney Diseases at Bethesda, Maryland, and his team became the first scientists to test — in randomised controlled conditions — whether diets high in ultra-processed foods could actually cause overeating and weight gain.
For four weeks, ten men and ten women agreed to be confined to a clinic under Hall’s care and agreed to eat only what they were given, wearing loose clothes so that they would not notice so much if their weight changed. For two weeks, Hall’s participants ate mostly ultra-processed meals such as turkey sandwiches with crisps, and for another two weeks they ate mostly unprocessed food such as spinach omelettes with sweet potato hash.
Day one on the ultra-processed diet included a breakfast of Cheerios with whole milk and a blueberry muffin, a lunch of canned beef ravioli followed by cookies and a pre-cooked TV dinner of steak and mashed potatoes with canned corn and low-fat chocolate milk.
Day one on the unprocessed diet started with a breakfast of Greek yoghurt with walnuts, strawberries and bananas, a lunch of spinach, chicken and bulgur salad with grapes to follow, and dinner of roast beef, rice pilaf and vegetables, with peeled oranges to finish. The results were definitive. During the weeks of the ultra-processed diet, the volunteers ate an extra 500 calories a day, equivalent to a quarter pounder with cheese.
Blood tests showed that the hormones in the body responsible for hunger remained elevated on the ultra-processed diet compared to the unprocessed diet, which confirms the feeling I used to have that however much I ate, these foods didn’t sate my hunger.
Over just two weeks, the subjects gained an average of 1kg. This is a far more dramatic result than you would expect to see over such a short space of time (especially since the volunteers rated both types of food as equally pleasant).
It’s a damning conclusion, not least because it could already be too late to wean us off UPFs.
To be told to avoid ultra-processed food — as the Brazilian guidelines do — would mean rejecting half or more of what is for sale as food, including many basic staples that people depend on, such as bread. (The majority of supermarket loaves count as ultra-processed, regardless of how much they boast of being multiseed, malted or glowing with ancient grains.)
Earlier this year, Monteiro and his colleagues published a paper titled ‘Ultra-processed foods: What they are and how to identify them’, offering some rules of thumb.
The paper explains that ‘the practical way to identify if a product is ultra-processed is to check to see if its list of ingredients contains at least one food substance never, or rarely, used in kitchens, or classes of additives whose function is to make the final product palatable or more appealing (‘cosmetic additives’)’.
Tell-tale ingredients include ‘invert sugar, maltodextrin, dextrose, lactose, soluble or insoluble fibre, hydrogenated or interesterified oil’. Or additives such as ‘flavour enhancers, colours, emulsifiers, emulsifying salts, sweeteners, thickeners and anti-foaming, bulking, carbonating, foaming, gelling and glazing agents’.
But for most modern eaters, avoiding all ultra-processed foods is unsettling and unrealistic, particularly if you are on a low income or vegan or frail or disabled.
Even more concerning is the fact that we still don’t know what it is about ultra-processed food that generates weight gain. The rate of chewing may be a factor.
In Hall’s study, on the ultra-processed diet people ate their meals faster, maybe because the foods tended to be softer and easier to chew.
On the unprocessed diet, a hormone called PYY, which reduces appetite, was elevated, suggesting that home-made food keeps us fuller for longer.
Even if scientists do succeed in pinning down the reason why ultra-processed foods make us gain weight, it’s not clear what policy-makers should do about UPFs, except for giving people the support and resources they need to cook more fresh meals at home. To follow the Brazilian advice entails a total rethink of the food system.
When fat was seen as the devil, the food industry gave us a panoply of low-fat products. And the result of the sugar taxes around the world has been a raft of new artificially sweetened drinks. But if you accept the argument that processing is itself part of the problem, all of this tweaking and reformulation has simply been meaningless window-dressing.
Nutritionists remain hopeful that there may turn out to be some way to adjust the manufacture of ultra-processed foods to make them less harmful to health.
But Hall is keenly aware that the problems of nutrition cannot be cured by ever more sophisticated processing.
‘How do you take an Oreo and make it non-ultra-processed?’ he asks. ‘You can’t!’