Ultra-processed foods (or UPFs) make up a shocking 60 per cent of the average diet in the UK – and increasing evidence links their high consumption with the rise in obesity, type 2 diabetes and other diseases. 

Here, in the second part of our serialisation of his bestselling book Ultra-Processed People, TV doctor Chris van Tulleken warns of the hidden dangers behind food which we find so tasty.

On a freakishly warm autumn day, I headed with my family to a North London park and bought our three-year-old daughter Lyra a treat. 

It was a giant scoop of pistachio ice cream – from which her one-year-old sister, Sasha, managed to scrounge a few licks. But it didn’t distract Lyra for long: spotting two friends, she handed me her tub and ran off to play on the swings.

Her ice cream, I noticed, was a glistening green ball of pistachio. It took a moment to dawn on me that this was most peculiar. How was it still a ball? The sun was blazing and the outside of the tub was warm to the touch. Something had clearly stopped the ice-cream from melting.

Back home, I looked up the ingredients online. Some were what you’d expect: fresh milk and double cream, sugar, salt, a tiny dash of pistachios. 

Others, however, rang alarm bells: soy protein, soy lecithin, coconut oil, sunflower oil, chlorophyll, glucose, dextrose, stabilisers (locust bean gum, guar gum, carrageenan), emulsifier (mono and fatty acids).

These are all hallmarks of ultra-processed food (UPF). Far from buying my little daughter a proper ice cream, I’d given her what one scientist later memorably described to me as ‘an industrially produced edible substance’. 

‘Far from buying my little daughter a proper ice cream, I’d given her what one scientist later memorably described to me as ‘an industrially produced edible substance’ (stock image)

Did it matter? After all, nobody has yet dropped dead immediately after eating an ultra-processed dessert. The answer, I’m afraid, is that it matters a great deal.

There’s now a huge volume of carefully collected and analysed data that exposes the inherent dangers in consuming complex mixtures of substances that humans have never encountered before.

These substances can’t even really be called ‘food’. Increasingly, the calories we consume come from modified starches, from invert sugars, hydrolysed protein isolates and seed oils that have been refined, bleached, deodorised and hydrogenated.

Added to these are synthetic emulsifiers, low-calorie sweeteners, stabilising gums, humectants [moisturising agents], flavour compounds, dyes, colour stabilisers, carbonating agents, firming agents and bulking – and anti-bulking – agents.

What this means is that everything from chicken nuggets to ice cream can be made from the same base liquids and powders. 

And bear in mind that UPF is not the same as junk food (though all junk food is UPF). It’s far more insidious.

Ultra-processed food makes up an incredible 60 per cent of the average diet in the UK

Ultra-processed food makes up an incredible 60 per cent of the average diet in the UK. For one in five Britons, it’s 80 per cent of what they eat. 

Many children, including my own, get most of their calories from these substances. In short, UPF has become our national diet. It’s now the main stuff from which we construct our bodies.

Yet, since 2010, a vast body of data has emerged which indicates that UPF increases rates of cancer, metabolic disease, dementia and mental illness. 

We also know that it damages our gut lining and the all-important microbiome – the bacteria that live in our intestines.

Our rate of consumption is causing a pandemic of malnutrition – caused by the lack of nutrients in UPF – and obesity. Studies suggest it’s stunted the growth of children.

Five-year-olds in the UK don’t just have some of the highest rates of obesity in Europe, they’re also among the shortest by a significant amount – more than 5cm shorter than Danish and Dutch children of the same age, for instance.

‘In the UK, we eat more ready meals than any other European country. And almost 90 per cent of us eat them regularly’

Without volunteering for it, we’ve become participants in a vast food experiment. New substances – the cheaper, the better – are being tested on all of us all the time.

Can a synthetic emulsifier be used instead of an egg? Can an industrially altered seed oil replace a dairy fat? Can a bit of ethyl methylphenylglycidate be chucked in instead of a strawberry? By buying UPF, we’re driving its evolution.

At the same time – without most of us being aware of it – we’re taking huge risks with our health.

The impact on children is a particular concern. Typically, 60 per cent of the food they eat is UPF, and they’re consuming the stuff while their brains are still developing.

Will their IQ be affected? We simply have no way of knowing.

I started studying the impact of UPF at University College London Hospital, where I do medical research. 

Along with other colleagues, I was keen to find out more. That’s why I agreed to become the first patient in a preliminary study. 

The plan was to get data from my experience that would help us win funding for a much larger study (which we’re now undertaking).

The idea was simple: I’d quit all ultra-processed food for a month. Then, the following month, I’d eat a diet where 80 per cent of my calories came from UPF – just like a fifth of UK residents.

But, initially, I kept a food diary of a typical week. That was the first surprise: it turned out that I was generally getting about 30 per cent of my calories from UPF.

After years of writing and broadcasting about food, I’d imagined I had a pretty reasonable diet. It looked something like this: black coffee for breakfast, a sandwich and crisps for lunch and a fairly healthy home-cooked dinner (chicken, rice and broccoli is a staple), followed by a supermarket dessert.

Every few nights, rather than cooking the main course, we’d have a UPF microwave lasagne or a UPF pizza. 

I’d have a takeaway about once a week, usually UPF thanks to liberal use of modified starches and flavour enhancers.

Anyway, when I started on my first month without any UPF, I found it surprisingly hard. Suddenly I had a craving for those microwave meals, supermarket desserts and takeaways.

It was also difficult to find anything non-UPF to buy for lunch.

Most food from the hospital canteen and nearby shops were ruled out. I couldn’t buy a sandwich because of the emulsifiers in the bread and the maltodextrin and preservatives in the spreads.

So I had to make my own sandwiches – mainly cheese, butter and proper sourdough bread from a local bakery. 

I couldn’t even add my favourite Hellmann’s mayonnaise (rapeseed oil, water, pasteurised egg & egg yolk, spirit vinegar, salt, sugar, flavourings, lemon juice concentrate, calcium disodium EDTA, paprika extract). 

My belt got looser, sure, but I started looking forward to my UPF diet.

I even began obsessing over stuff I didn’t typically think about, such as takeaways from the McDonald’s and KFC across the road from the hospital.

Finally the great day arrived when I embarked on the kind of ultra-processed diet that’s totally normal for one in five people in the UK.

I didn’t try to force-feed myself – this wasn’t Super Size Me. I just ate UPF whenever I felt like it. At the same time, I was continuing my research by speaking to the world’s leading experts on food, nutrition, eating and ultra-processing.

Remember my daughter’s pistachio ice cream? Still wondering why it had so many ingredients, and was so reluctant to melt, I contacted a food-industry insider.

Paul Hart worked for 20 years at Unilever, as a biochemist and then as a designer of food production systems. There’s almost nothing he doesn’t know about UPF or the industry that makes it.

By the time I met him – appropriately enough, at a KFC outlet – I’d had a look at the ice creams on sale at my local Tesco.

Almost all, I noted, contained xanthan gum, guar gum, emulsifiers and glycerine. 

Could he explain why? ‘We can use ice cream as an example to explain nearly everything about UPF,’ he told me. ‘It’s all about price and costs – those ingredients save money.’

This is important to British consumers. In 2017, before the current cost-of-living crisis, we were spending just 8 per cent of our household budget on food, less than almost anywhere else in the world. 

Germany, Norway, France and Italy, for instance, spend 11 to 14 per cent of their budget on food.

You don’t get much whole food, such as meat and broccoli, for eight per cent of your budget. UPF, however, is quite a bit cheaper.

That’s one of the reasons why, apart from the US, we eat more of the stuff than any other country.

Imagine you’re in the poorest half of all UK households. If you wanted to adhere to our national healthy-eating guidelines, you’d need to spend almost 30 per cent of your disposable income.

But back to ice cream. How, I asked Paul, do UPF ingredients stop it quickly melting into a puddle? First, he explained, they make the ice cream tolerant of warmth. The gums, glycerine and emulsifiers stop ice crystals forming, which means it can be easily transported without the need for very low temperatures at all times.

Contrast that with what I’d call real ice cream. Cream o’ Galloway vanilla ice cream appears to be made from the same ingredients that you might use at home: milk, cream, sugar, skimmed milk powder, egg yolk, vanilla essence. 

That’s great, but the result is that the product can’t be sold nationwide. Real ice cream is less tolerant of all that transporting around.

The ingredients used in Cream o’ Galloway vanilla ice cream are also reflected in the price: £3.60 for 500ml. That’s about 14 times more expensive than, for example, Ms Molly’s Vanilla, exclusive to Tesco, which is £1 for two litres. 

Unsurprisingly, Ms Molly uses very different ingredients: reconstituted skimmed milk concentrate, partially reconstituted whey powder (milk), glucose syrup, sugar, dextrose, palm stearin, palm oil, palm kernel oil, emulsifier (mono- and diglycerides of fatty acids), stabilisers (guar gum, sodium alginate), flavouring, colours (carotenes).

According to Paul, many of these – palm stearin, palm kernel oil, the reconstituted milks, the emulsifiers – are simply mimicking real and expensive ingredients such as milk, cream and eggs. This molecular replacement is key to all UPF.

Traditional food (or, as we might more properly call it, food) is made from three broad categories of molecules that give it its taste, texture and calories: fats, proteins and carbohydrates.

The secret to ultra-processed ice creams is that they’re constructed from the cheapest possible versions of those three essential molecules.

And not just ice creams. Pies, fried chicken, pizza, butter, pancake mix, pastries, gravies, mayonnaise – all began as real food. 

But the non-UPF versions are expensive, so their traditional ingredients are often replaced with cheap and sometimes entirely synthetic alternatives. 

Usually, these are extracted from crops grown for animal food. The molecules are then refined and modified.

‘We can replace almost any ingredient with a cheap modified alternative,’ said Paul.

Take starch, which is extracted from cheap crops. Once modified, there’s little you can’t do with a starch. 

It can give a ‘milkshake’ a surface sheen and creamy texture. It can replace expensive dairy fats. Thin starch with acid and it’s useful for textiles and laundry. 

Treat it with propylene oxide and you get that gloopy feel for salad dressings. Mix it with phosphoric acid and you can improve stability through multiple cycles of freezing and thawing – perfect for pie fillings.

What about the gums in my daughter’s ice cream? If you look at food labels, you’ll see lots of these, including guar gum, locust-bean gum, alginate, carrageenan and the near-ubiquitous xanthan gum.

The last of these is quite revolting. It’s the slime that bacteria produce to allow them to cling to surfaces. Think of xanthan gum next time you scrape the gunk from your dishwasher filter.

Like the modified starches, gums are used to replace more expensive molecules and give food a longer shelf-life. This reminded Paul of a tortilla conference he’d attended.

‘One company was boasting, in jest, that their products were essentially embalmed, with a shelf-life extending for years,’ he said.

I must have looked horrified, because he quickly clarified that ‘everyone was delighted!’

Even that session with Paul didn’t manage to put me off my UPF diet.

At the end of Week Two, I was still looking forward to Morrisons All Day Breakfast, a frozen meal that comes in a three-compartment plastic tray with a film lid – 768 calories of baked beans, hash browns, pork sausages, omelette and bacon.

Oven-ready in minutes.

In the UK, we eat more ready meals than any other European country. And almost 90 per cent of us eat them regularly.

One day, while my All Day Breakfast sat in the oven, my wife Dinah and I cooked some salmon, rice and broccoli for her and the kids. 

This involved 20 minutes of preparation, using knives, three pans and a chopping board, resulting in a pile of washing-up and fishy hands.

Forget exercise to lose weight – cut the UPFs

Lack of exercise has long been assumed to be a main reason for obesity. ‘Eat less, move more,’ is the mantra we’re encouraged to adopt.

Makes perfect sense, doesn’t it? If you move more, you’ll burn more calories and lose weight. Unfortunately, we now know this isn’t true.

Exercise won’t burn any extra calories from your daily total, not even if you walk ten miles after breakfast.

Herman Pontzer, from Duke University in the US, is one of the scientists who’s transformed how we think about diet and metabolism.

For his seminal study, he spent time with the Hadza, a tribe of hunter-gatherers in northern Tanzania, measuring the total number of calories they burned daily. 

The results were contrary to expectations.

Even though the Hadza were walking miles each day, the 2,500 calories they burned were almost exactly the

same as those burned by the average UK office-worker.

The same thing has been reported in monkeys and apes: whether they’re in the wild or captive in zoos, they burn the same number of daily calories.

The significance of this is immense: it means we cannot lose weight just by increasing activity. 

So how do we square this with previous studies showing that coal-mining burned eight times as many calories as office work? 

Well, it turns out that no one actually took measurements from coal miners. The data was all based on surveys and assumptions.

When a team from the US and Turkey finally did proper measurements, they found that miners burned between 2,100 and 2,800 calories per day. 

The same as the rest of us. It seems impossible, I know, but there’s a simple explanation: when we take exercise, our bodies compensate by using less energy on other things, so our overall calorie-burning stays the same. 

We can be very active for a period of time but we claw back that energy debt later. 

Partly we do this through rest and partly our bodies are doing it for us subconsciously.

After you’ve burned a lot of calories by being active, your body scales back on routine non-essential processes, reducing the amount of energy spent on your immune, endocrine, reproductive and stress systems.

But what about office workers – how do they manage to burn up 2,500 calories without moving much?

Scientists believe we expend those spare calories on other things – such as getting stressed, leading to increased levels of adrenaline, cortisol and white blood cells.

A sedentary lifestyle will also lead to higher levels of testosterone and oestrogen, which can lead to increased risk of cancer. In short, don’t stop exercising!

If you really want to lose weight (without medical intervention), there’s one sure-fire solution – cut down as much as you can on ultra-processed food.

When we finally sat down to eat, Dinah read out the ingredients of my ready meal: ‘Dextrose, stabiliser (diphosphates), beef collagen casing, capsicum extract, sodium ascorbate, sodium nitrite, stabilisers (xanthan gum and diphosphates), flavourings.’ She looked up. ‘Why are you eating diphosphates?’

The diphosphate stabilisers hold everything together through the freezing process so the water doesn’t form crystals on the surface.

They’re just one aspect of what makes the All Day Breakfast such an enjoyable product, with the hash browns a little crispy and just the right level of salt and pepper.

Above all, it’s an easy meal. Easy to prepare and easy to eat fast. While Dinah was still chewing her second mouthful, I was licking the container. 

Things started to change during the third week of my ultra-processed diet, by which time I was speaking to dozens of experts. 

I’d come off a phone call to an academic in France or Brazil, then sit down to a banquet of UPF.

Often, I’d even be eating UPF during the call. But it felt increasingly like reading about lung cancer while smoking a cigarette. 

By that third week, I was struggling to eat the UPF without thinking about what the experts had told me. 

One of these was Nicole Avena, a visiting professor at Princeton whose research focuses on food addiction and obesity. 

Without additives, she told me, the base industrial ingredients of UPF would probably not be recognisable as food by our tongues and brains.

‘It would be almost like eating dirt,’ she said.

After that, I started to notice that much of what I was eating had little more than a veneer of food. 

This was especially true of the snacks and cereals manufactured from pastes of raw materials, which had been fried, baked or puffed.

For example, I’d come to enjoy a Grenade Carb Killa Chocolate Chip Salted Caramel Bar as a mid-morning snack. It seemed a little healthier than a simple chocolate bar.

After speaking with Avena, I inspected the ingredients. Like many other bars, it’s constructed from very modified carbohydrates, protein isolates from milk and beef (calcium caseinate, whey protein isolate, hydrolysed beef gelatine) and industrially processed palm fat, all bound together with emulsifiers. 

Without salt, sweetener and flavouring, I realised, my mid-morning snack would probably be unpleasant to eat.

So would Maryland Minis Chocolate Chip Cookies, a favourite in the tea-room at work.

Again, they contain modified carbs (refined flour and invert sugar syrup), plus industrial fats (palm, sal, shea), plus added protein (whey), glued together with soy lecithin emulsifier.

All made palatable with salt, sugar and flavouring.

As if this wasn’t off-putting, a Brazilian academic, Fernanda Rauber, talked to me at length about the plastics in UPF packaging. 

Especially when heated, she said, they significantly decrease fertility – and according to some experts, may even cause shrinkage of the penis.

It was Rauber who told me that ‘most UPF is not food – it’s an industrially produced edible substance’.

These words began to haunt my every meal. They echoed and underlined Avena’s idea that without the colouring and flavouring, UPF would most likely be inedible.

As I ate, there was a tussle in my brain. I still wanted this food that, according to Rauber, wasn’t really food, but at the same time I was no longer enjoying it.

Meals took on a uniformity: every­thing seemed similar, regardless of whether it was sweet or savoury. I was never hungry, but I was also never satisfied.

Suddenly there was nothing I wanted more than fresh vegetables, a few slices of free-range chicken and a tart-tasting apple.

Adapted from Ultra-Processed People: Why Do We All Eat Stuff That Isn’t Food … and Why Can’t We Stop? by Chris van Tulleken (Cornerstone, £22). © Chris van Tulleken 2023. To order a copy for £19.80, visit www.mailshop.co.uk/books or call 020 3176 2937. 

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