A scientist who used to advise ultra-processed food companies shares 2 surprising ways they make food irresistible

• Ultra-processed foods have been linked to health problems including type 2 diabetes.
• Professor Barry Smith used to work with UPF companies to enhance their products.
• Companies appeal to all the senses, including hearing, to make their food appealing.

It's no secret that ultra-processed foods like potato chips, cookies, and chocolate, are easy to overeat. In fact, they're often specifically designed to be irresistible, a scientist who used to work with UPF companies told Business Insider. He shared two surprising ways UPFs are manufactured to make us crave them.

Professor Barry Smith, an expert in the multisensory experience of eating based at the Centre for the Study of the Senses at the University of London, has worked with companies such as Kellogg's, Coca-Cola, and Ferrero. Initially, companies would come to him asking how to reduce the salt and sugar in their products without compromising flavor, he said.

But over time, Smith said companies became more interested in enhancing food to make it irresistible to the point where people feel they can't stop eating it. "And I thought, well wait, that's not the same message as we want to make healthier food," he said.

Smith decided to stop consulting on UPFs for ethical reasons and cut them out of his own diet entirely because of the associated health risks. They have been linked to many health problems including type 2 diabetes, cardiovascular disease, certain cancers, and depression.

UPFs are foods that contain ingredients you wouldn't find in a regular kitchen and are made using industrial processes. They tend to be hyperpalatable, shelf-stable, and highly marketed.

Before you've even taken a bite of a UPF, you've already got a hit of dopamine, the pleasure hormone, Smith said.

"If you are walking down the supermarket aisle and you're seeing all of these exciting packets, that's when your dopamine spikes, not when you're actually eating the thing," he said.

And it's not just how it looks that matters. UPF companies take advantage of all the senses to draw people to their products.

"There's the look, the smell, and sometimes the sound of it," he said.

Companies use what's called sonic branding

You might be surprised to hear that the satisfying click a can of soda makes when opened, the brisk snap you hear when a bar of chocolate is broken in half, or the rustle of a bag of chips, are usually intentional.

That's because sonic branding, or associating a sound with a product, can make us want to consume it, Smith said. "That's all preparing you for what's about to follow, and it's encouraging you to expect and to desire," he said.

He referenced the suction sound a bottle of Snapple makes when you open it, or the click and tear of a can of Coca-Cola.

"If you're listening to somebody else opening a can of Coke, you might think, 'Ooh, yes, I want a can of Coke,'" he said.

Most of what we taste comes from our sense of smell

A lot of what we think of as taste actually comes from our sense of smell. Scientists have estimated that smell might be responsible for as much as 75 to 95% of what we taste.

So, similar to sound, companies use our sense of smell to grab our attention and make us crave their products. A grocery store, for example, might pump out the smell of baking to encourage customers to buy baked goods, even if they just came to buy vegetables, Smith said.

He shared a "particularly innovative" marketing move that Mars used for its ice cream bar. The company decided to infuse the ribbing at the end of the packaging with a chocolate and caramel scent as frozen things have no smell, he said.

"You tear it to open it and you have a little sense of caramel and chocolate odor so that it smells just like having a Mars bar," he said. "I think that's so clever and so cool."

Smith draws a distinction between leading a consumer to a product, which he thinks is acceptable, and misleading them, which he doesn't agree with.

"If you lead someone to a product by reminding them of what's in it and those ingredients really are in the product, then you're leading them by giving them a sensory cue or expectation for what follows," he said. But if you're giving them a cue for something that isn't in there, then you're misleading them, he said.