When Bryce Martinez was growing up in Warrington, a small suburb in Pennsylvania, his days were filled with all sorts of delicious snacks: Jell-O, Oreos and Pop-Tarts, among others.

But in 2022 his doctor delivered some devastating news: Martinez, then 16, had developed type 2 diabetes and non-alcoholic fatty liver disease.

Aggrieved, the teenager decided to take the matter to court. Two years later, he sued Kraft Heinz, Coca-Cola, Nestlé and eight other ‘Big Food’ companies, accusing them of deliberately engineering and marketing ‘addictive’ products to children, causing chronic disease.

The first-of-its-kind case cited alarming statistics: ultra-processed foods – those high in sugary, salty, savoury, creamy or crunchy qualities – now make up 55 per cent of the US diet, climbing to 67 per cent among teenagers.

Similar figures are reported in the UK, at 57 and 66 per cent, respectively. And all around the globe, consumption of ultra-processed foods is on the rise.

On average, more than 1 in 2 calories consumed in the US comes from an ultra-processed source.

It’s an alarming trend, given that scientists have linked such diets to obesity, cancer, mental disorders, cardiovascular disease, dementia and early death.

Martinez lost his case, though, with the judge ruling there wasn’t sufficient evidence to prove that his consumption of the companies’ products directly caused his illnesses.

But the case “creates more questions than it answers,” says Prof Emily Broad Leib, who heads Harvard University’s Center for Health Law and Policy Innovation.

In particular: can ultra-processed foods be truly addictive, in the same way as alcohol and cigarettes? It’s a complex question – one that researchers have grown increasingly interested in over the past 15 years.

“Back then, the idea was very controversial,” says Dr Ashley Gearhardt, a clinical psychologist who studies addiction at the University of Michigan. She recalls being heckled at a conference in 2017 for suggesting that some foods may act as addictive substances.

“Today, there’s much broader recognition that ultra-processed foods can be addictive,” she says, “though debate continues about the mechanisms and policy implications.”

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Engineering ingenuity

In fact, Gearhardt and others believe that it’s precisely the multitude of ingredients present in ultra-processed foods that makes them so hard to resist. Flavour and texture additives, for instance, boost sweet and savoury tastes, as well as mouthfeel.

They’re even on some packaging, says Gearhardt, especially those of frozen foods. Some manufacturers, for example, lace ice-cream wrappers with a caramel scent. “So you get one big burst of aroma before you’ve even eaten it,” she says.

Food companies are able to engineer nearly every aspect of our taste experience, adds Gearhardt.

“They can manipulate things down to the molecular level,” controlling factors like how rapidly substances get into your system and how “different sensory properties burst at different times as you chew.”

Another ploy: they’re able to make foods soft and easy on the palate. As van Tulleken writes: “This means you eat [them] fast, which means you eat far more calories per minute, and don’t feel full until long after you’ve finished.”

This was demonstrated in a small-scale experiment conducted in the US.

Researchers found that when 20 adults were offered an unlimited amount of ultra-processed foods for two weeks, they consumed 500 more calories daily – and put on significantly more weight – as compared to when they were on a diet comprising only unprocessed foods for the same amount of time.

But what really packs an addictive punch, says Gearhardt, is the way in which ‘Big Food’ firms combine ingredients in specific ratios of fat, salt and sugar – combinations that don’t occur in nature – creating a ‘bliss point’ that makes it hard to stop eating.

“If you look at foods that exist in nature, they very rarely, if ever, deliver high levels of both carbohydrates and fats,” she says.

Read the complete article at BBC Science Focus