Crack, cocaine, heroin … and pizza? You may have suspected your love of pizza is an addiction. Now a new study proves that's true.

Conducted by University of Michigan psychologists Erica Schulte and Ashley Gearhardt, and neuroscientist Nicole Avena from the New York Obesity Research Center of Columbia University, the study found that "highly processed foods … may share characteristics with drugs of abuse (e.g., high dose, rapid rate of absorption) … [and] appear to be particularly associated with 'food addiction.'"

The researchers ranked 35 different foods according to how problematic they are in terms of being addictive. Chocolate was number one, followed by ice cream, french fries, pizza and cookies. Cake, fried chicken, soda, cheese, pretzels and bacon were all in the top 20.

The researchers found that processed foods — which are generally higher in fat and glycemic load (a number that estimates how much a food will raise blood glucose level) than non-processed foods — are more frequently associated with eating behaviors that resemble addiction. The researchers note that consuming highly processed foods with high sugar and fat content signals similar changes to the neurological dopamine reward system as when drugs are being abused.

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(Table via U.S National Library of Medicine/National Institutes of Health)

"Processing appears to be an essential distinguishing factor for whether a food is associated with behavioral indicators of addictive-like eating," the researchers write. "Highly processed foods are altered to be particularly rewarding through the addition of fats and/or refined carbohydrates (like white flour and sugar)."

They point out that substances that are addictive are rarely in their natural state. Grapes, for example, only become addictive when they are processed into wine. Similarly, poppies gain their addictive properties only after they are refined into opium.

The researchers write:

“Food addiction” is characterized by symptoms such as loss of control over consumption, continued use despite negative consequences, and an inability to cut down despite the desire to do so. Addictive-like eating has been associated with increased impulsivity and emotional reactivity, which are similarly implicated in substance-use disorders. Thus, “food addiction” may share common behavioral attributes with other addictive disorders. Neuroimaging studies have also revealed biological similarities in patterns of reward-related dysfunction between “food addicts” and substance-dependent individuals. Individuals endorsing symptoms of “food addiction” exhibit increased activation in reward-related regions in response to food cues, consistent with other addictive disorders.

The study adds to the growing scientific evidence linking obesity and substance dependence, which has led researchers in the fields of biology, neuroscience and psychology to work collaboratively to investigate the role of addiction in eating disorders and problematic eating behaviors in general. In the United States, obesity continues to increase: By 2030, it is estimated that more than 85 percent of American adults will be overweight. Obesity-related health care costs are projected to increase from the current nearly 10 percent of national health care expenditures to 15 percent over the next 15 years.

In his 2014 autobiographic novel Sex and Crime: Oliver's Strange Journey, author Oliver Markus explores many forms of addiction through a series of relationships. He argued that the mechanisms of addiction are the same, whether it's heroin or food:

“Don't ever think you're better than a drug addict, because your brain works the same as theirs. You have the same circuits. And drugs would affect your brain in the same way it affects theirs. The same thought process that makes them screw up over and over again would make you screw up over and over as well, if you were in their shoes. You probably already are doing it, just not with heroin or crack, but with food or cigarettes, or something else you shouldn't be doing.”

Perhaps the old saying, "You can't have your cake and eat it too," should be amended: You can have your cake and eat it too — but you probably won't be able to stop.

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