Standing in her kitchen in downtown Toronto chopping vegetables for dinner, Pat Guillet is aware she has entered the battleground.

"Whenever you go grocery shopping, or into your kitchen, you're in a war zone. You have to really be prepared before you go in," she said. She decides, in advance, exactly what she's going to eat, and she forces herself to stick to the plan. Because she knows she is just one sweet mouthful away from a descent back into hell. Pat Guillet is a food addict.

"I ate to the point it hurt to move. And I would just lie in my bed and wish I was dead," she said. She has finally wrestled her addiction under control and now she counsels other food addicts to avoid processed food. "Yeah, just the sight of the packages will trigger cravings," she said.

Craving. It doesn't just happen to food addicts. Most people have experienced the impulse to seek out and consume a favourite packaged snack food. On one billboard, recently put up in Toronto, the intention to make you reach for another one is prominently declared, in large letters that tower over the city street. It's a picture of a box of crackers, and the promise "You'll be back for more."

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They know you will be back, because they've done the research necessary to make it happen.

"These companies rely on deep science and pure science to understand how we're attracted to food and how they can make their foods attractive to us," Michael Moss said.

The New York Times investigative reporter spent four years prying open the secrets of the food industry's scientists.

"This was like a detective story for me, getting inside the companies with thousands of pages of inside documents and getting their scientists and executives to reveal to me the secrets of how they go at this," he said. What he found became the title of his new book, Salt, Sugar Fat: How the food giants hooked us.

"I was totally surprised," he said. "I spent time with the top scientists at the largest companies in this country and it's amazing how much math and science and regression analysis and energy they put into finding the very perfect amount of salt, sugar and fat in their products that will send us over the moon, and will send their products flying off the shelves and have us buy more, eat more and …make more money for them."

It's not surprising to Bruce Bradley. He's a former food industry executive who spent 15 years working at General Mills, Pillsbury and Nabisco, and ran some common food brands including Honey Nut Cheerios and Hamburger Helper. But one day he discovered he couldn't do it anymore.

"There were certainly times that I felt uncomfortable or troubled by what I was doing," he said. "I think that's ultimately one of the reasons why I left the industry. As you start to get glimpses of products and you understand better how consumers are using them, and then you see trends like obesity and health issues that are increasing, mainly driven by the food we eat, it was hard for me not to just take a more thorough assessment of what I was doing."

Now he writes a blog, critical of the food industry.

"I decided to step out and ultimately speak out in hopes of bringing more awareness to the issue," he said. "What we eat and drink from a lot of these big food and beverages companies isn't that good for us and we should reconsider it," he said. "These products are designed to keep you coming back to eat more and more and more. They're trying to increase their share of your stomach."

Pat Guillet said it's hard to overcome the addictive appeal of processed foods like ice cream. (CBC)

A Google search of the patents held by the food industry provides a glimpse of the complex technical engineering that goes into building a simple cracker. Scan the scientific journals, or read the food industry publications and a picture emerges of an army of chemists, physicists and even neuroscientists, all working to make sure you want a second cookie.

And to understand the research, you need to speak the language. There's 'mouth feel,' 'maximum bite force,' and the important concept of 'sensory specific satiety,' the rate at which a food product loses its appeal as it is being eaten.

"That's an expression that says when food has one overriding flavour, if it's attractive, it will be really attractive to us initially, but then we'll get tired of it really fast," Moss said. "And so these companies make a concerted effort to make their foods not bland, but really well blended."

That's so people don't get too full too fast, and stop eating too soon. "If the taste builds too much, consumption will stop … and snacks need to be eaten non-stop until the packet is finished," Thornton Mustard wrote, back in 2002. He was a food industry consultant who revealed, early on, some of the secrets of the food industry, in a book called The Taste Signature Revealed. He wrote that fullness or satiety, is "quite a serious enemy for a product."

Mustard claimed he could help food companies design foods that were guaranteed to be "more-ish," which he defined as a quality that made a consumer want to eat more. It helped, he advised, if the food was easy to chew.

"If people had to chew the food to extract the flavour enjoyment, it would take longer to eat, be better digested, and the feeling of being full reached far sooner. People would need to consume less," he wrote.

Thornton Mustard has retired and couldn't be reached for comment, but Chris Lukehurst is continuing his work through The Marketing Clinic, the consulting company that Mustard founded.

"So people read that book, and we've been contacted by people saying, can you really do this? Because we've got a problem and we think you can solve it," Lukehurst said.

On the art of "more-ishness," Lukehurst explained it this way. "Some products, like most savoury snack products, want to be continually more-ish, so at the end of each product, they want you to reach out for the next product and put it in again, and they often achieve that by having an intense taste at the front of the mouth, and that dies off quickly, and so by the time you've finished each mouthful, you're looking to re-taste what you've lost."

Chocolates tend to be round to create a pleasant, melting sensation in the mouth. (Martial Trezzini/Keystone/Associated Press)

The crunch is also crucial, Lukehurst said. "It's partly the noise, the noise amplifies, through the jaw bones connected to your ears, and you can hear the crunch quite loudly when you bite. But it's also the physical requirement to chew on something and crunch it. It just distracts you and pours your mind onto what you're eating."

The importance of "crunch" was confirmed in a study funded by Unilever where the scientists tested whether people's perception of a chip was altered by the sound it made when they bit into it. The researchers concluded that "the potato chips were perceived as being both crisper and fresher when … the overall sound level was increased," indicating another possible way to control the perception of the product, although, the authors wrote, "consumers are often unaware of the influence of such auditory cues."

It also helps if the food dissolves quickly in the mouth, tricking the brain into believing that no calories have been ingested. It's called "vanishing caloric density."

"What happens is that your brain gets fooled into thinking the calories have vanished and you're much more apt to keep eating before the brain sends you a signal …you've had enough," author Michael Moss said.

The ultimate goal is the bliss point. "The company's researchers have learned to study their products, fiddle with the formulas until they hit that very perfect spot of just enough and not too much sugar to create what they call the bliss point," he said.

Melt-in-the-mouth appeal

Food scientists have even studied the architecture of the mouth. In a paper published in the Journal of Biomechanics, scientists from the Nestlé Research Center examined the "detection mechanisms in the oral cavity," to study how well the mouth could detect the thickness of a plastic disc placed on the tongue. The researchers created a model that would predict the load exerted on the disc when it was deformed by the tongue.

Three years later, Nestlé announced a new chocolate with a shape based on the geometry of the mouth, that hits "certain areas of the oral surface, improving the melt-in-mouth quality while simultaneously reserving enough space in the mouth for the aroma to enrich the sensorial experience," the press release announced.

It's a clue to understanding why chocolates tend to be round. It seems consumers don't enjoy a piece of chocolate as much if it has sharp edges. "Absolutely, we're looking for chocolate to be comforting, to be a really pleasant, lovely experience in the mouth," Chris Lukehurst said. "Melt is a very soft, soft experience, and if it's got sharp corners, you're really spoiling that and setting the consumer on edge slightly, before they get the melt. Much better if it's nicely rounded and they're already comforted and enjoying it first."

And whatever happens on the tongue triggers a response in the brain. That's why neuroscience is the next frontier for the food industry. Francis McGlone was a pioneer when he left academia to work for Unilever, one of the world's largest food companies, back in 1994.

"I think I was the leading edge of something which I think is going to become far more prominent," McGlone said. After more than a decade of industry research, he's back in academia, but he remembers his time in the food industry fondly. "As a basic neuroscientist, I was able to look at the mechanisms that drove preference for various types of food," he said.

What are those drivers of food preference, in McGlone's opinion? His answer sounded familiar. "I am afraid we find high fat, high sugar, high salt foods very appealing," he said.

"Salt, sugar and fat are the three pillars of the processed food industry," Michael Moss said. "And while the industry hates the world 'addiction' more than any other word, the fact of the matter is, their research has shown them that when they hit the very perfect amounts of each of those ingredients … they will have us buy more, eat more."

When Moss began working on his investigation into the science of food processing, he was sceptical of concept of food addiction. "Until I spent some time with the top scientists in the U.S. who say that yes, for some people, the most highly loaded salty, sugary, fatty foods are every bit as addictive as some narcotics," he said.

Francis McGlone made a similar point in a television program for the BBC, when he put a British chef into a functional magnetic resonance imaging machine, (an fMRI), fed him chili, and took images of his brain, which showed how the burn from the chili peppers triggered the release of endorphins. "The consequence of that low level of pain is that it floods the brain with its own natural opiates, so you can see another way of kicking up a pleasure system," McGlone said.

But many ingredients in processed food have nothing to do with taste. They're there to reproduce a certain texture, to control the moisture level, to keep the various ingredients from separating and spoiling during the months that they will sit on the shelves.

Food companies seek the perfect spot of just enough sugar to create what they call the bliss point, says author Michael Moss. (Naum Kazhdan via Pulitzer Prize Board/Associated Press/New York Times)

"Absolutely, that's essential to the processed food industry, that their food be able to remain in a warehouse, in shipping, and then in the grocery story for weeks or months at a time," Moss said.

To mask the bitterness or sourness that the formulations can cause, the food industry uses flavour enhancers, invisible ingredients that trick the brain into tasting something that isn't there, and not tasting something that is there.

"Ingredients like that are kind of bundled under what may seem like relatively innocuous labels like 'natural flavours' or even 'artificial flavours,' when truly they are much more surprising when consumers really understand what it is," Bruce Bradley, the former food industry executive, said. "There's tremendous amounts of money spent behind creating tastes and smells that feel real but in reality are completely artificial."

'These products are designed to keep you coming back to eat more and more and more. They're trying to increase their share of your stomach.'— Bruce Bradley

Because without flavour enhancement, no one would eat it. "It would taste horrible, you'd want to spit it out," Bradley said.

Michael Moss was treated to a special taste test, while researching his book. "Kellogg invited me into their R&D department, and prepared for me special versions of their iconic products, without any salt in them at all. And I have to tell you, it was a God-awful experience tasting those things. Normally, I can eat Cheez-Its [crackers] all day long, but the Cheez-Its without the salt? I couldn't even swallow them. They stuck to the roof of my mouth. The real impressive moment was when I turned to the cereal, which, without salt, tasted like metal. One of the miracle things that salt adds to processed foods, it will cover up some of the off notes that are inherent to the food processing systems that they rely on."

Bruce Bradley says all of that processing takes food to a different place. "We're not talking about food actually being real anymore. It's synthetic, completely contrived and created, and there's so many problems about that because our bodies are tricked and when our bodies are tricked repeatedly dramatic things can happen, like weight gain" or endocrine disruption, diabetes and hypertension, he said.

What about the scientists who created these products? Moss says some of them are having second thoughts about their popular creations. "A number of the people I talked to invented these icons really in a more innocent era, when our dependence on processed foods was much less than it is now. And over time, they've come to regret how their inventions have come to be so heavily depended on by us. So yes, any number of these scientists are now looking for ways to help their companies improve the health profile of their products."

Appreciating the power of salt, fat and sugar in snack foods could help people from overdoing it. (Matt Rourke/Associated Press)

Bruce Bradley says he believes food companies are trying to make some changes. " think there's an element of it that's sincere. I've certainly worked on several products where there was a sincere effort to reduce the amount of sodium or sugar in that product," he said.

But he says there is only so much tinkering that can happen with the three basic building blocks of processed food. "To make these highly processed foods taste great, they require salt and sugar and fat, and so while there may be some very good intentions … it's just not in the cards to get a product that tastes really great."

Chris Lukehurst believes the food industry is making a mistake trying to formulate lower salt, sugar and fat versions of their popular brands while still hoping to match the original taste. Instead he says the food engineers should tinker with the crunch, the mouth feel and other sensory aspects to make consumers like the new versions better, for different reasons.

"What we would argue is don't try to make it taste the same, make it work better for the consumer. So when they're tasting this product, they may well notice a taste difference, but the emotional delivery they're getting out of it is at least better than it was before," he said. "Let's find what emotions are lacking when you take the fat out. How can we make those emotions up in different ways?"

Today's grocery shelves are filled with the promise of healthier snack foods. Cookies now sport a bright green label, claiming to be a "sensible solution." Chips boast about "the goodness of whole grains," and crackers proudly declare that they've been "baked," not fried.

Pressure on food industry

Bruce Bradley believes the food industry has simply identified a new market opportunity. "These companies are extremely profit-focused, as are all publicly held companies out there. It is a quarter to quarter profit drill," he said. "If the food industry can find a way to market it and make money off of it, I'm sure they will. But if, in the long term, it is decreasing the amount of food that they can sell, I don't see that as being an avenue that they will go down."

"There's huge and growing pressure on the food companies now, from consumers who are concerned about what they're putting in their mouths," Michael Moss said. "There's equal pressure coming from Wall Street, which is concerned about sales, and there's starting to be increasing attention paid by government regulators. I think you have all three of those converging on the food giants right now, and of course, what will happen remains to be seen."

Meanwhile, Moss has his own food cravings to fight. "I'm a huge fan of potato chips and I can overdo it like the next person," he said. "But what's really helped me is getting inside the companies and understanding how they formulate and perfect their product. I can see where they're coming at me and appreciate the power of the salt, the fat and the sugar in potato chips. And I think that helps me control my indulgence."

For Pat Guillet, back in her kitchen, determinedly chopping celery, there is little hope for relief. "If I had one spoonful of ice cream, I would want the whole tub," she said. "And there were times I ate the whole tub. And I would sit there and say 'I've gotta stop, I've gotta stop,' really feeling completely unable to act on what my brain is telling me."

That's why she is bracing for a lifelong battle with the sugar demons that lurk in the processed food aisle. "These foods are so addictive, so appealing, they give you a high and you feel better," she said. "And the thing many food addicts say is, long after the food causes us joy, long after it causes us misery, we still couldn't stop. It becomes hard-wired and it's very hard to overcome."

This is the first of two special features by health reporter Kelly Crowe on how industry designs foods so that we crave them.