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Is Food Addictive?

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THE SCIENCE OF FOOD ADDICTION

Can a doughnut act like a drug?

By Rebecca Wolfson and Anja Strejcek for The Ration

Customers eating herring in the traditional Dutch way. The Netherlands, Rotterdam, 1937 Collectie Spaarnestad. photo: flickr (The Commons)

Jan, the vice president of a public relations firm, tried everything she could think of to lose weight. The 58-year-old, who declined to share her full name, tried the traditional route with various diets, including Weight Watchers. She also tried more extreme techniques, such as demanding that her husband threaten her with divorce if she did not lose weight. None of it worked. Then in 2003, she found herself in the hospital with a life-threatening blood clot in her leg, which doctors said was the result of her obesity. She survived the clot, but it did not cure her of the desire to eat until she was full—and then eat some more.

While recovering from surgery at home in Sacramento, Calif., she continued to sneak food. “I was like an alcoholic,” she said. “I couldn’t stop.”

As soon as her family left the house, she said she would crawl downstairs and binge on anything she could find. It was not until months later, when she called herself a “food addict” aloud and in front of other people for the first time, that she began to recover control of her eating.

In recent years, some scientific research has suggested that food can be addictive, much like drugs or alcohol. But the term “food addiction” and the notion that humans could be addicted to something they need for survival is controversial among health experts.

UNDERSTANDING SO-CALLED “FOOD ADDICTION”

There is no scientific consensus on how the term “food addiction” should be defined, or whether the medical community should consider food an addictive substance at all.

The Food Addiction Institute, a non-profit organization that tracks research in the field, defines food addiction as a chemical dependence caused by changes in the brain in reaction to the biochemistry of a specific food, several foods, or volume of food.

For a substance to qualify as addictive in the medical profession it must meet certain criteria. The American Medical Association identifies four such criteria for a substance to be considered addictive: bingeing, withdrawal, craving and sensitization. Sensitization means that if you expose an animal to one substance, it will have a heightened neurological response to a second substance. For example, an animal that is already addicted to sugar would have a higher likelihood of becoming addicted to cocaine or another drug of abuse.

To date, neither the American Medical Association nor the American Psychological Association has recognized “food addiction” as a disease or psychiatric disorder, which has potential consequences for treatment. Food addiction is not included in the American Psychiatric Association’s current Diagnostic and Statistical Manual of Mental Disorders, the DSM IV. However, binge eating disorder, which is characterized by frequent episodes of extreme over-eating, often followed by feelings of guilt, is set to be included in the fifth edition, which will be released in 2013.

While a handful of researchers argue that foods, most notably sugar, are addictive, many scientists have chosen to wait for more research on the neurological effects of food on the brain before they embrace the term. Plus, food addiction can stigmatize obese individuals, according to Joseph Frascella, director of the National Institute on Drug Abuse’s Division of Clinical Neuroscience & Behavioral Research. To soften the stigma, health experts have started using the more benign sounding “food and addiction.” “It’s a subtlety,” said Frascella, “but it moves the focus from the individual to the food.”

EVIDENCE

Regardless of the terminology, an increasing number of scientific studies suggest that food, like drugs or alcohol, can indeed have addictive qualities. The Food Addiction Institute has compiled a bibliography of 2,733 peer-reviewed studies on aspects of food addiction. Human genetic research, animal studies, brain imaging and biochemical studies of the digestive processes all indicate that some people could experience addictions to food. There are more than 70 million food-addicted adults in the U.S. according to estimates by David Kessler, professor of pediatrics epidemiology and biostatistics at UC San Francisco Medical School and a former commissioner of the U.S Food and Drug Administration.

Leptin

Studies of the hormone leptin present some of the strongest human evidence for food addiction, according to Kent Berridge, a professor of psychology and neuroscience at the University of Michigan who has studied how pleasure from food is generated in the brain.

Leptin regulates appetite and tells people when they’re full. An extremely small proportion of the population is born without the leptin gene. These people feel as if they are constantly starving.

Researchers at Addenbrooke’s Hospital in Cambridge, England, recorded a case of a leptin-deficient girl who ate enormous meals and constantly demanded snacks. After a year of leptin treatment, she lost weight and reported that she no longer felt constantly hungry. Berridge called leptin-deficient people “proof of the logical possibility that something like a food addiction exists.”

While very few people are born without the leptin gene, ongoing research indicates that many more could be leptin-resistant. Researchers say leptin therapy, like the therapy that was administered to the leptin-deficient girl, could be a promising treatment for obesity in the future.

Pleasure Rewards

Dopamine is a neurotransmitter — a chemical messenger — in the brain that is linked to the reward system. In 2001, Gene-Jack Wang, chairman of the Brookhaven National Laboratory Medical Department, and Nora Volkow, director of the National Institute on Drug Abuse, published an influential study in the prominent British medical journal, The Lancet, which examined brain images of obese people. The study found that the brain’s ability to register dopamine was significantly lower in some obese individuals. “We did not expect a result like that,” Wang said. The study suggests that some people might overeat to counterbalance low levels of dopamine, one of the chemicals in the brain linked to pleasure.

“Animal studies indicate that most, if not all, drugs of abuse increase levels of dopamine in part of the brain — the reward system, the nucleus accumbens,” Frascella said. “We know that food increases dopamine, too.”

When people eat highly palatable—sweet, salty and fat—foods, taste buds in the tongue respond by sending signals to the brain reward circuitry. Studies show that these foods blunt the dopamine receptors in parts of the brain. This means that some people may need to eat more to reach the same level of pleasure, Frascella said.

Many subsequent studies have supported the idea that food is physically addictive, including one published in April in The Archives of General Psychiatry. Researchers at Yale University’s Rudd Center for Obesity Research and Policy took brain scans, or MRI’s, of people they deemed to be food addicts through a 25-point questionnaire, and showed them images of a chocolate milkshake. The scientists found that the parts of the brain associated with anticipation and craving were activated by the image. Furthermore, actually tasting a milkshake was associated with decreased activity in the part of the brain that makes people feel full, or stop eating.

Paul Johnson and Paul Kenny, neuroscientists at the Scripps Research Institute in Florida, found that rat brains react similarly to junk food as they do to drugs. Their study, published in March 2010 in Nature Neuroscience,involved implanting electrodes in rats’ brains. Some of the rats were given healthy diets, others were given limited amounts of junk food diets, and the last group was given unlimited amounts of junk food. Johnson and Kenny discovered that the rats on junk food diets needed more and more junk food stimulation to reach the same level of pleasure and reward as the rats on healthy diets.

THE SKEPTICS

Many scientists are reluctant to use the term “food addiction.” Gene-Jack Wang, the author of the 2001 dopamine study, prefers instead to refer to the umbrella terms “food and addiction,” or “refined or processed food addiction.”

Barry Levin, an obesity researcher and professor of neurology and neurosciences at New Jersey Medical School, is also wary of the term. While hormones like leptin and insulin impact brain function, imaging studies still don’t prove cause and effect. “People draw conclusions based on the function of the brain, and it’s fairly meaningless as far as I’m concerned,” said Levin. Researchers who study addictive behavior often refer to the decrease of dopamine receptors in the brains of obese individuals, said Levin. “It’s interesting, but doesn’t tell you that’s what drove them to be that way.”

“There is this release of chemicals in your brain that may be similar to what you see with cocaine,” said Ronna Kabatznick, a professor of psychiatry at the University of California-San Francisco who thinks that “food addiction” is perhaps too grave a term for the situation. “But you see that with shoppers, with love, in many different circumstances. The question again is: what is the behavioral element? You still have a choice, even though those circuits might be going wild. How are you going to respond to them?”

WILLPOWER V. BIOCHEMISTRY

Food addiction has nothing to do with willpower, according to Anne Kathrin, a psychologist who has written several books about food addiction. Brain chemistry is always stronger than willpower, and the body’s chemical cravings will always overrule individual resolve.

Once the combination of chemical events in the brain is set in motion, a chain reaction takes place, Kathrin says. “Over time the pleasure center of the brain changes so that it requires even more of the substance that triggers it.”

Those susceptible to food addiction might start by eating a piece of pie for dessert every day. After a while they want a bigger piece, and then they might want some cookies and ice cream, too. Over time, the addiction grows stronger and they will have to eat more often, says Kathrin.

Selena Bartlett is the director of Preclinical Development at the Gallo Center, a University of California San Francisco-affiliated research center that focuses on the impact of addiction on the brain. She says people have as much control over their food addiction as they have over their height. In other words, none.

Some people get angry over the term “food addiction” because they feel it gives overeaters an excuse for their behavior. “They will say, ‘I’m not addicted to food, why should you be?” Bartlett said. “I’m not addicted to alcohol, why don’t you say, ‘no’? I just say, ‘no,’ why don’t you say, ‘no?’”

Bartlett is in the initial stages of testing a drug that would help people control compulsive eating. In a recent rat study she tested ezlopitant, a drug that blocks the action of substance P, a neurotransmitter that is believed to play a role in the reward system. In the study, rats given ezlopitant showed decreased motivation to consume water sweetened with sugar, water sweetened with saccharin, and an alcohol solution. Other researchers are looking at leptin as a potential therapy for food-addicted people.

THE IMPLICATIONS

In his book The End of Overeating, former FDA Commissioner David Kessler explains how the food industry creates and markets sweet, salty and fattening food, so that people keep coming back for more. As a society, Kessler writes, “we can identify the forces that drive overeating and find ways to diminish their power with comprehensive labeling, public education campaigns, regulation of marketing and new perspectives on what kinds of behavior are acceptable and appropriate.”

Many self-described food addicts end up in 12-step addiction recovery programs modeled after Alcoholics Anonymous. Overeaters Anonymous has about 5,000 weekly meetings across the U.S.

Soon after returning from the hospital a friend suggested that Jan join Food Addicts in Recovery Anonymous, known by participants as FA. The program is one of the stricter food addiction groups, emphasizing abstinence from trigger foods, and requiring members to adopt an eating plan and have a former food addict sponsor. Within three months of joining, Jan lost about 50 pounds.

Today, she is healthy-looking and fit. She weighs her meals three times a day, and has returned to her full-time job. For now, her eating is in check, and she’s convinced that FA saved her life. But, like an addict, the only way for her to stay safe is for her to abstain from her trigger food, sugar. Even the smallest taste of a cookie might set her back on the path of uncontrolled eating, she says.

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