It wasn't that Kathleen Callahan couldn't lose weight.
"I've dieted myself up and down the scale gazillions of times," the 51-year-old nurse anesthetist says.
"I've done Weight Watchers, Nutrisystem and my own little starvation plans — you know, crazy stuff."
What she couldn't do was keep the weight off. Hunger was an emergency akin to a five-alarm fire, she says.
Thoughts of food filled her mind, and cravings made mincemeat of the persistence and willpower that had allowed her to complete a 105-mile bike ride and put herself through graduate school as a single parent.
"Sometimes I used to feel like I was on a bus with no driver, and it was taking me straight to the Italian restaurant and I couldn't get off, even if I wanted to," Callahan says.
Callahan is one of a small but growing number of Americans who believe that some foods exert an addictive pull on them, and that eliminating problem foods is a better solution than traditional "moderation." Using the eating plan in the best-selling book "Eat to Live," which eliminates or severely restricts foods such as doughnuts and pizza and consists mainly of vegetables, fruits and beans, she has lost 60 pounds, she says, and gained control of her eating.
In addition to "Eat to Live," which includes a chapter on food addiction as well as frequent references to author Joel Fuhrman's theory that "toxic hunger" is triggered by foods low in nutrients and fiber, there's the best-selling diet book "Wheat Belly," by William Davis, which claims that wheat is addictive for many people.
The science of food addiction has made rapid strides in recent years, with University of Florida College of Medicine assistant professor Nicole Avena and her colleagues showing that rats that binge repeatedly on sugar behave much like rats addicted to morphine or alcohol, exhibiting symptoms of bingeing, tolerance and withdrawal.
A 2001 study published in the Lancet found that obese people have abnormalities in brain dopamine activity similar to those seen in cocaine, alcohol and opiate addicts. And a subsequent study published in 2011 in the Archives of General Psychiatry found that that people with higher food addiction scores respond to pictures of a chocolate milkshake with more activity in brain regions associated with motivation to eat and less activation in brain regions linked with self-control.
Scientists also note the anecdotal evidence that food has addictive aspects.
"Haven't you experienced that there are certain foods that you don't even want to try because they are so powerful vis-a-vis their rewarding effects that you immediately want more?" says Dr. Nora Volkow, director the National Institute on Drug Abuse.
"So what more proof do we (need) than all of us having this experience?"
But the field of food addiction is still young, and the popular food plans that claim to fight addiction go well beyond the scientific findings, restricting foods such as corn, raisins and whole-grain breads and pastas, and encouraging drastic changes that some experts say probably aren't optimal.
Ashley Gearhardt, an assistant professor at the University of Michigan who co-authored the Yale Food Addiction Scale, a method of measuring food addiction, says she likes the basic idea of "Eat to Live," which derives at least 90 percent of its calories from unrefined plant foods, strictly limits processed foods and keeps meat to a minimum. "Eat to Live" encourages eating regular meals and places no limit on green and nonstarchy vegetables, fruits and beans.
Gearhardt's objection — and it's a big one in a world where most diets eventually fail —– is that people will find it hard to stick to such a restrictive plan.
"I think it's important in these eating-related situations where we don't have that much science yet to take incremental steps to test things out and see how they work for you, rather than jumping to extremes back and forth," Gearhardt says. "That binge-restrict, binge-restrict pattern is really problematic for a number of things, and one of those things is that it may set up addictive processes in the brain and in the psyche. It's kind of more what works for you on a consistent, lifestyle basis."
If you suspect you have food addiction problems, you may want to seek support from a therapist, a nutritionist or a support group, Gearhardt says. If you want to try eliminating problem foods, she suggests going slowly, maybe cutting out your top problem food and seeing whether you feel freed or frustrated before considering other food restrictions.
The few studies available suggest that maybe 25 percent of obese adults could be diagnosed as food-addicted.
Gearhardt's incremental approach doesn't appeal to Callahan, who tried "Eat to Live" on and off for a while before diving in 100 percent in April 2012 with the help of a motivational coach.