How Junk Food Works

Ex-FDA chief offers clues to food addiction.

It is a perplexingly common experience: You open a bag of cookies, intending to have one or two. An hour later, the bag is empty, and your self-loathing is at its peak.

But compulsive overeating is not a character flaw, according to David Kessler, former head of the Food and Drug Administration. It is, rather, a “biological challenge.”

Readers may remember Kessler from his anti-cigarette and food product labeling crusades during the Clinton administration. In his forthcoming book, The End of Overeating: Taking Control of the Insatiable American Appetite, Kessler notes that while food took over his brain, the foods in question were not carrots, apples and green leafy vegetables. “Conditioned overeating,” as Kessler dubs it, is driven by a biological drive to eat high-fat, high-sugar foods even when we are not hungry. Moreover, such foods are cheaper than more healthy alternatives.

What Kessler describes in his book is a system of reward-driven eating abetted by a food industry fully aware of the biological attraction exerted by salt, fat, and sugar. Kessler himself is no stranger to this attraction. “I have suits in every size,” Kessler writes, according to a report by Lauren Neergaard for AP. “Once you know what’s driving your behavior, you can put steps in place.”

Kessler has also served as dean of the medical schools at Yale and the University of California at San Francisco. On the book’s Amazon site, Michael Pollan, author of In Defense of Food, calls Kessler’s book “a fascinating account of the science of human appetite, as well as its exploitation by the food industry.”

It is becoming increasingly clear that fat and sugar in combination are capable of producing a dopamine-driven surge of intense pleasure in people with a propensity for addictive behavior. Mice that have been genetic altered so that they lack the ability to taste sweet foods still prefer sugar water to regular water. (See my post on Dopamine and Obesity.) Kessler provides additional evidence that certain forms of overeating qualify as legitimate drug addictions. Just as it is with, say, cocaine addicts, the supersaturated reward pathways of the brain do not have effective mechanisms for signaling: “That’s enough. Stop eating.”

It may seem obvious in retrospect that the same mechanisms that make it so difficult for many drug addicts to “just say no” would also function in the case of addicted overeaters. What happens is similar to the flooding of reward circuitry that occurs in cases of what we might call “compulsive overdrugging,” otherwise known as addiction. The food industry, according to Kessler, has figured out what works, has packaged fat-and-sugar foods in products that scarcely even have to be chewed, and it has priced these products to move.

Yale university conducted studies in which “hypereaters” were given the odor of chocolate during an MRI scan. Normal eaters get used to the odor and habituate rapidly. Hypereaters find that the odor of chocolate becomes more demanding and overpowering with time. And even drinking a complete chocolate milkshake did not quell the craving.

According to Publisher’s Weekly, Kessler’s book, set to be released on April 28, “provides a simple food rehab program to fight back against the [food] industry’s relentless quest for profits while an entire country of people gain weight and get sick.”

Photo Credit: Neurological Correlates

"Mood Foods"

Why addicts crave sugar and starch.

James Langton of Clearhead.org.uk recently sent me a fascinating article about food and addiction. The technical bulletin from Sure Screen Diagnostics, Ltd., the U.K.'s leading provider of medical and drug testing services, focuses on the age-old and endlessly fascinating connection between addiction and sugar foods (See my post, “Drug Foods and Addiction”).

Entitled "Mood food and Addiction," the technical bulletin asserts that "drug users, alcoholics and those with addictive tendencies routinely resort to certain psychoactive foods between fixes to regulate their mood." Moreover, "certain foods might reduce withdrawal symptoms... the pantry is a veritable 'psychodelicatessen.'"

While some of the conclusions are highly speculative, most of the article is on more solid ground in its discussion of the "psychopharmacology of everyday foods."

Sweet foods and fruits can mitigate or eliminate cravings, the author says, and examples of this are abundant in the addict and treatment communities. Abstinent cigarette smokers sometimes find that "a piece of fruit or something sweet" can banish cravings by temporarily and partially restoring dopamine and serotonin levels.

In an unconscious effort to raise brain levels of serotonin and dopamine, drug users often discover that doughnuts, cakes, ice cream, soft drinks, and other sugar foods can lessen withdrawal symptoms. As evidence, we are far more likely "to see a user with a bar of chocolate in his hand than a sausage roll."

Complex carbohydrates, the bulletin asserts, do not have the same effect. Whole grain breads and starchy vegetables, unlike table sugar and white bread, do not have the same reinforcing impact on neurotransmitters along the reward pathway. "For that reason, they do not tend to be craved as much as sweets, even though they still satisfy [serotonin] 5-HT needs." Because simple sugars eaten in large quantities can cause blood sugar levels to drop below baseline, the result can be the abrupt return of drug withdrawal symptoms.

How does this work out in practice? The bulletin speculates, for instance, that “a amphetamine user who has exhausted his dopamine and noradrenaline levels, and feels depressed and unable to think straight, may be drawn to high-protein, tyramine-rich foods, such as a steak, pizza or a cheese sandwich and a glass of milk. An MDMA or "ecstasy" user experiencing fatigue... would probably crave something like fish and chips rich in carbohydrates, and a sugar-rich drink to temporarily bring the depleted 5-HT levels back up to normal." As for opiate users, foods such as whole milk, ice cream, and milk chocolate are appealing because they contain "biologically active opioid peptides.... It no doubt explains why a pint of full fat milk and a Snicker's bar is a perennial snacking favourite of opiate users."

As for chocolate (you didn’t think I’d forget chocolate, did you?), “the most widely preferred chocolate among the general population is not unsweetened dark chocolate with its higher drug cocktail, but sweetened milk chocolate suggesting that the majority of us may in fact be craving its addictive psychoactive sugars, fats and narcotic casomorphins more than anything else.”

In the end, the specific food preferences of addicts force us “to reconsider how fragile the food-drug distinction actually is.”

Graphic Credit: Anselm

dopamine

Food Addiction and Dopamine

Why your brain likes sweets.

The brain's ability to sniff out calories in the form of sugar depends upon sugar's drug-like effect on the dopamine-rich reward center known as the nucleus accumbens, according to a study published in the March 27 issue of Neuron. This tiny structure in the mid-brain is also the locus of reward activity for all addictive drugs.

In the study, Ivan de Araujo and colleagues at Duke University and the Universidade do Porto in Portugal demonstrated that lab mice lacking the ability to taste sweet foods still preferred sugary water to regular water. The genetically altered mice, lacking functional taste receptor cells for bitter and sweet, consistently chose to consume sugar water--even though they could not sense the sugar. (The lab animals were also prevented from smelling or sensing textural differences in the offerings.)

"Our findings suggest that calorie-rich nutrients can directly influence brain reward circuits that control food intake independently of palatability or functional taste transduction," the researchers wrote.

The findings offer new clues to obesity, and also bolster the contention that simple carbohydrate foods--because of their effect on reward pathways in the brain--can be addictive for certain people. As Tamas Horvath of Yale University's School of Medicine told Science News (sub. required): "This is a very exciting new element in how you get addicted to food. It doesn't even matter how it tastes."

In the same article, written by Amy Maxmen, study author de Araujo said: "The animal's reward processing systems were sensitive to changes in metabolism, not just flavor. This is a new system."

The "sweet-blind" animals did not go for the low-cal alternative, when they were offered water mixed with sucralose, otherwise known as Splenda. Low-cal sweeteners did not result in a similar dopamine boost along the reward pathways of the brain.

The brain's ability to "sense" calories may help explain why diet foods are often ignored in favor of sweets. As Ewan Callaway of New Scientist put it, "Anyone who has devoured a tub of ice cream in one sitting knows that delicious foods can override our body's pleas of 'enough.'" We have increased levels of dopamine in the nucleus accumbens to thank for that.

As De Araujo explained to New Scientist, "even when you do not stimulate the sensory pathways in the mouth you still have this reward signal in the brain."

In a preview of the article in the same issue of Neuron, Zane Andrews and Tamas Horvath speculate that "high-fructose corn syrup is an ubiquitous sweetener in American society.... It may be that fructose produces stronger activation of the reward system and that removing high-fructose corn syrup as a sweetener will curb some desire for these products."

Photo Credit: Biz/Ed

dopamine addiction