How ultra-processed food tricks you into eating more, and how you can free yourself of its addictive properties

Statistics show that the majority of most adults' diets are made up of ultra-processed food, or UPF. But what is it? And how harmful is it to our health?

We speak to Dr Chris Van Tulleken, author of Ultra Processed People: Why Do We All Eat Stuff That Isn't Food... and Why Can't We Stop to find out more.

What is the difference between processed and ultra-processed food?

Food processing is ancient. We've been doing it as a species for more than a million years. It’s shaped our bodies. It's shaped our guts. There are broadly three types of food: whole food, which is like an oyster or milk. You can process milk into butter, cheese or yoghurt so that’s processed food. We've been doing that for many thousands of years.

But ultra-processed food has a formal scientific definition that’s very widely recognised by the UN. It boils down to this if it's wrapped in plastic and it contains an additive that you don't find in a typical domestic kitchen, then it is ultra-processed food.

How much UPF do we eat?

Our whole diet is now being replaced, to the extent that this makes up on average 60 per cent of our calories. For kids it's much higher. A very typical teenager might get 70 or 80 per cent of their calories from UPF.

How can we tell if we are eating UPF?

If you can afford it, go and buy a loaf of real bread from your local bakery, sourdough or any traditional bread will do. The supermarket bread is a spongy foam.

If you have an eating race of supermarket bread versus an equal amount of sourdough, you'll find it takes you at least twice as long to consume the sourdough. Real food is much less energy dense, much wetter and much chewier.

That's partly because of the emulsifiers and stabilisers and the way the wheat gluten is added later in the process used to mix it. UPF is incredibly soft. Softness, we think, is one of the main properties of ultra-processed food that drives excess consumption.

How does UPF trick our bodies?

One of the most studied effects is that it drives weight gain. It's so soft that we eat it before our gut hormones have time to catch up and tell us that we're full.

We've got really good data going back to the nineties that shows that when your food is soft and energy dense, you eat it at a rate that's much higher than real food. There are lots and lots of studies showing that this is one of the most important things that determines appetite.

You're just eating foods at a rate that your gut can't keep up with and you consume more calories. Some of the research shows they're digested so early in the gut that they never even make it to the bit of the gut that releases the hormones that tell you to stop eating.

It's because they've been reduced to such elemental forms. They're absorbed very quickly so you never really get the fullness signal. I think people will recognise this from their own experience. They don't satisfy you.

What are the harmful effects that we get from consuming UPF?

Weight gain is one, because of the flavour enhancers, the sugar and the calorie density.

The additives do have some direct effects on our brains and also on our microbiomes. So we think the emulsifiers, molecules that bind fats to water, are a bit like detergent.

In a simple way, and this is this is a bit of a simplification, the emulsifiers act a bit like detergent. They scrub out our guts. They remove the layer of healthy mucus and foster the growth of less friendly, more inflammatory bacteria living inside us.

A lot of that work is currently being done in mice. People are not mice, that’s important to say. But I do think when we're thinking about food additives, to say that something is safe, we should have a much higher threshold of evidence.

What can we do to stop our addiction to ultra-processed food?

For the book, I spoke to lots of people within the food industry. They were really decent, interesting, intelligent people. Many of them, behind closed doors, will say we know this stuff is addictive and we would rather not make it, but we can't be the first to act.

Many of them told me about a design process, which I'd also seen doing an investigation of the baby food industry for the BBC. The food is put through focus groups.

One of the things was about a box of cereal. You have a box of cereal A and B, and the scientists are trying to figure out which one goes to market. If the focus groups eat five per cent more of box B, that's the one that goes to market because it's going to sell well.

That’s the commercial reality of the way the companies run. They can't manufacture foods that people eat less of. And that is, in the end, what real food is. It's food that you just eat a bit less of.

The companies can't pivot to just making money from real food because without the intellectual property these foods are just commodities.