A growing body of medical research at leading universities and government laboratories suggests that processed foods and sugary drinks aren't simply unhealthy. They can hijack the brain in ways that resemble addictions to cocaine, nicotine and other drugs.
"The data is so overwhelming the field has to accept it," said Nora Volkow, director of the National Institute on Drug Abuse. "We are finding tremendous overlap between drugs in the brain and food in the brain."
The idea that food may be addictive was barely on scientists' radar a decade ago. Now the field is heating up. Lab studies have found sugary drinks and fatty foods can produce addictive behavior in animals. Brain scans of obese people and compulsive eaters, meanwhile, reveal disturbances in brain reward circuits similar to those experienced by drug abusers.
Twenty-eight scientific studies and papers on food addiction have been published this year, according to a National Library of Medicine database. As the evidence expands, the science of addiction could become a game-changer for the $1 trillion food and beverage industries.
If fatty foods and snacks and drinks sweetened with sugar and high fructose corn syrup are proven to be addictive, food companies may face the most drawn-out consumer safety battle since the anti-smoking movement took on the tobacco industry a generation ago.
"This could change the legal landscape," said Kelly Brownell, director of Yale University's Rudd Center for Food Policy and Obesity and a proponent of anti-obesity regulation. "People knew for a long time cigarettes were killing people, but it was only later they learned about nicotine and the intentional manipulation of it."
Food company executives and lobbyists are quick to counter that nothing has been proven, that nothing is wrong with what PepsiCo Chief Executive Officer Indra Nooyi calls "fun-for-you" foods, if eaten in moderation. In fact, the companies say they're making big strides toward offering consumers a wide range of healthier snacking options. Nooyi, for one, is as well known for calling attention to PepsiCo's progress offering healthier fare as she is for driving sales.
Coca-Cola, PepsiCo, Kraft Foods and Kellogg declined to grant interviews with their scientists.
No one disputes that obesity is a fast-growing global problem. In the U.S., a third of adults and 17 percent of teens and children are obese, and those numbers are increasing. Across the globe, from Latin America, to Europe to Pacific Island nations, obesity rates are also climbing.
The cost to society is enormous. A 2009 study of 900,000 people, published in the Lancet, found that moderate obesity reduces life expectancy by two to four years, while severe obesity shortens life expectancy by as much as 10 years. Obesity has been shown to boost the risk of heart disease, diabetes, some cancers, osteoarthritis, sleep apnea and stroke, according to the Centers for Disease Control and Prevention. The costs of treating illness associated with obesity were estimated at $147 billion in 2008, according to a 2009 study in Health Affairs.
Sugars and fats, of course, have always been present in the human diet and our bodies are programmed to crave them. What has changed is modern processing that creates food with concentrated levels of sugars, unhealthy fats and refined flour, without redeeming levels of fiber or nutrients, obesity experts said. Consumption of large quantities of those processed foods may be changing the way the brain is wired.
Those changes look a lot like addiction to some experts. Addiction "is a loaded term, but there are aspects of the modern diet that can elicit behavior that resembles addiction," said David Ludwig, a Harvard researcher and director of the New Balance Foundation Obesity Prevention Center at Children's Hospital Boston. Highly processed foods may cause rapid spikes and declines in blood sugar, increasing cravings, his research has found.
Education, diets and drugs to treat obesity have proven largely ineffective and the new science of obesity may explain why, proponents say. Constant stimulation with tasty, calorie-laden foods may desensitize the brain's circuitry, leading people to consume greater quantities of junk food to maintain a constant state of pleasure.
In one 2010 study, scientists at Scripps Research Institute in Jupiter, Fla., fed rats an array of fatty and sugary products including Hormel Foods bacon, Sara Lee pound cake, Cheesecake Factory cheesecake and Pillsbury Creamy Supreme cake frosting. The study measured activity in regions of the brain involved in registering reward and pleasure through electrodes implanted in the rats.
The rats that had access to these foods for one hour a day started binge eating, even when more nutritious food was available all day long. Other groups of rats that had access to the sweets and fatty foods for 18 to 23 hours per day became obese, Paul Kenny, the Scripps scientist heading the study wrote in the journal Nature Neuroscience. The results produced the same brain pattern that occurs with escalating intake of cocaine, he wrote.
"To see food do the same thing was mind-boggling," Kenny said in an interview.