Can't put down the box of Oreos? There might be a compelling biological reason for that.
New research suggests that sugary, fatty treats can elicit the same reaction and activate the brain in a similar manner as cocaine and morphine, at least in lab rats.
Joseph Schroeder, an assistant professor of psychology and director of the Behavioral Neuroscience Center at Connecticut College, is expected to present the study, which has not yet been published, next month at the Society for Neuroscience conference in San Diego, Calif.
Oreos weren't specifically singled out for their ability to trigger a snack attack, they were just a handy device to get enough fat and sugar in the rat's habitat, Schroeder said.
A spokeswoman for Mondelez International, which owns Nabisco, the maker of the iconic sandwich cookie, cautioned people against associating Oreo with the findings since the cookies were used as "a proxy for a non-specific 'sweet' variable."
"While it may seem simple to bucket foods as 'good' or 'bad,' the reality is that foods are complex, and encouraging people to enjoy a balanced diet paired with physical activity is most important," the spokeswoman said in a statement.
The experiment was actually conceived by Schroder's neuroscience student, Jamie Honohan, to examine the effects of high-fat and high-sugar foods on the brain. Honohan said she is interested in examining the effects of high concentrations of fatty and sugary foods in lower-income areas where there tend to be higher rates of obesity.
"My research interests stemmed from a curiosity for studying human behavior and our motivations when it comes to food," said Honohan. "We chose Oreos not only because they are America's favorite cookie, and highly palatable to rats, but also because products containing high amounts of fat and sugar are heavily marketed in communities with lower socioeconomic statuses."
To examine how "addictive" high-fat, high-sugar foods could be, the rats were put into a habitat with two rooms. In one they were given an Oreo and in the other a rice cracker. Schroder and Honohan then measured the time they spent in each room to see their preference for the Oreo versus rice cake.
"Just like humans, rats don't seem to get much pleasure out of eating" rice cakes, Schroeder said.
The experiment was then repeated with other groups of rats being offered injections of cocaine or morphine in one room and saline in the other. According to Schroder, the researchers found that the rats had an "equivalent preference" for a room when it contained an Oreo as when they were given injections of morphine and cocaine.
Further examination of the rats' brains found that they had higher cellular activity in the "pleasure center" of their brain after eating an Oreo versus being injected with one of the drugs.
"That's the novel finding that applies to us," said Schroder. "We found that the high-fat or high-sugar food activated the brain to a greater extent than the cocaine or morphine."
A 2009 study by researchers at the Scripps Research Institute in Florida found the pleasure centers in the brains of rats that were fed high-fat, high-calorie food became less responsive over time -- a signal that the rats were becoming addicted. The rats started to eat more and more. They even went for the junk food when they had to endure an electric shock to get it.