For Cari Banks, one of the hardest things to say no to is food.
"I could eat half a pack of Oreos and milk and consider it nothing," she said. "I would eat it, pretty much without thinking."
But new research shows Banks' sweet tooth could actually be more like substance abuse.
Dr. Joe McClernon at Duke University studies the brains of people who are addicted to drugs, such as the nicotine in cigarettes. He says that for many obese people, junk food can trigger the same response in the brain.
"You can see activation when smokers are looking at pictures of people smoking, and the same thing when overweight individuals look at food cues," said McClernon, an associate professor in the Department of Psychiatry and Behavioral Sciences at Duke University Medical Center and director of the Health Behavior Neuroscience Research Program. "We see activation in areas involved in visual attention.
"We also see activation in both cases in a region called the striatum," McClernon added. "It's the part of your brain that tells you whether something is something you want to go after, or if it's something you want to avoid. But it's also the part of the brain that's involved in learning habits."
A new study by researchers at the Scripps Research Institute in Florida found similar results in rats. Pleasure centers in the brains of those 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.
"Your brain reacts almost identically to [that of] a cocaine addict looking at cocaine," said Dr. Louis J. Aronne, a clinical professor at Weill Cornell Medical School and former president of The Obesity Society. "And the interesting thing is that someone who is obese has even more similarity to the cocaine addict. ... In many ways, they can be addicted to junk food."
For Banks, the trigger foods are mostly high fat and high calorie. She has been trying to fight her cravings for three months, eating a special low fat diet as part of a Duke study funded by the Atkins Foundation.
"It was a month into the diet that I could eat one slice of pizza and be OK with that one slice and not have to eat half the pizza," Banks said. "Or eat half a cup of ice cream and not have to eat half the gallon."
Obesity researchers believe treatments used for addiction recovery may hold promise in fighting obesity.
"We know that people can learn new ways to live that are healthier," McClernon said. "That's part of the challenge right now is developing new techniques and new diets that help people learn those new ways of responding to food."
So what can be done to break the junk food habit before it gets out of control? Dr. Eric Braverman, a professor of neurosurgery at New York Presbyterian Hospital, offers these tips:
Instead of sugar, try using Stevia, a high-fiber, no-calorie sweetener. According to the World Health Organization, no more than 10 percent of calories should come from sugars. That translates to a maximum of 12 teaspoons of sugar in a 2,200-calorie diet.