I was recently reading a fascinating article by Dr. Guido Frank in the journal Physiology and Behavior. The article is Open Access, so you can download it here, but I asked Dr. Frank if he would mind being interviewed about the article and the thinking behind his model. He said, “Yes!”Bulik: Dr. Frank, you recently published a fascinating article in the journal Physiology and Behavior called “Motivation to eat and not to eat – The psycho-biological conflict in anorexia nervosa. I thought our blog readers might be interested in hearing your theory only translated a bit for us non-neuroscientists. You start your article out by presenting the “core conflict” in anorexia nervosa which you claim that all individuals with anorexia nervosa (AN) have in common “a discrepancy between their conscious motivation for how much they want to eat – or rather restrict food intake – versus the body’s need to stay at a healthy and sustainable body weight.” Let me start out with a simple question, your theory is primarily about traditional low weight AN, correct?
Frank: Yes, that is correct. The model revolves around the changes in the body that happen during weight loss and that in most of us would trigger eating. However, in anorexia nervosa those changes are ineffective in promoting eating and rather drive the vicious cycle of food restriction.
Bulik: At the root of your model and the origins of AN in a person is the desire to lose weight. How does that start?
Frank: The desire to lose weight can start for many reasons, just wanting to better in sports, wanting to eat healthier, or after for instance abuse experience not wanting to feel the body. This is what I call the conscious motivation to change eating. This change in eating may or may not be accompanied by the wish to lose weight. However, cutting out certain high calorie foods together with more exercise typically leads to weight loss.
Bulik: So, lots of people have a desire to lose weight, but people with AN seem to get stuck in this weight loss trap. I understand how the drive to lose weight can start, but what makes it continue?
Frank: Weight loss is then associated with the desired change in eating behavior and becomes an obvious sign of “success”, which reinforces the original goal of changing eating habits. People who develop anorexia nervosa typically are very hard working and have the desire to do things right. Those traits together with the fear of losing this accomplishment, reinforces (encourages) continuing to cut out foods.
Bulik: Dr. Frank, you know that we at UNC do a lot of work on the genetics of eating disorders. How do genes play a role in your theory?
Frank: Genes, I believe, play a central role in the transition from the desire to eat healthier or lose some weight to developing anorexia nervosa. Genetic predisposition including having a temperament that is more on the anxious side and striving for perfectionism, may mediate the transition to anorexia nervosa, to the extreme drive for thinness and body dissatisfaction, and eventually body image distortion.
Bulik: OK so you have someone with a desire to lose weight, and they feel rewarded by successful weight loss, and they might have a genetic predisposition to anxiety or perfectionism, but doesn’t their body feel terrible when they are in a starvation state?
Frank: Exactly, and that will be part of a vicious cycle to lose control over weight loss. The body responds to weight loss with sensitizing hormones and neurotransmitters receptors to stimulate eating. This physical component I would call the unconscious motivation to eat and gain weight. The person then experiences this body-driven motivation to eat, which goes against the original conscious motivation to “eat healthy” which has by now been associated with weight loss, which triggers anxiety and reinforces the cognitive control over eating.
Bulik: OK so we’re back to anxiety again. If I am understanding you correctly, the first desire to lose weight can come from all kinds of reasons, then maybe a genetic predisposition to anxiety or perfectionism might contribute to the transition to anorexia nervosa from dieting, and now you are talking (almost psychodynamically) about a conflict between an unconscious (physically driven) desire to eat with the conscious desire to lose weight or remain thin. Am I summarizing this correctly?
Frank: Yes, in fact when I developed this neurobiological model, I was chuckling to myself as I was indeed reminded of the classic Freudian conflict that leads to dysfunctional behavior. Back to the biology, when we eat but suddenly the proverbial tiger stands in front of us, we have to suppress the eating drive and stop eating quickly and run to preserve our life. This circuitry is set in motion by fear, directed from a brain region called the ventral striatum (a dopamine rich area) to the hypothalamus, and it involves dopamine, a brain neurotransmitter. The fear of weight gain, we believe, triggers this mechanism and suppresses eating. However, more control over eating and food restriction further drive the body to stimulate eating, which further triggers anxiety and further stimulates food avoidance, and now you are stuck in a vicious cycle.
Bulik: So how do you break out of this vicious cycle?
Frank: There are several key goals to accomplish to successfully treat anorexia nervosa. First, I think it is important to help patients and their families understand that this is a complex illness with a distinct biology behind it. This helps get this out of the realm of the mysterious to a more understandable problem that can be treated. Second, weight gain is key including learning to eat again and maintaining a healthy body weight. This can be a long and difficult process. Third, it is important that folks learn to live their life and replace the focus on anorexia nervosa with truly positive directions so that the anorexia nervosa “voice” becomes less and less important. Lastly, we are working on developing medications to make psychotherapy more successful and recovery from anorexia nervosa easier.
Bulik: So, this is all about low weight AN. As you know atypical AN is in the news a lot lately. Although I don’t love the name, it refers to individuals who have all of the symptoms of AN (the psychological and behavioral symptoms) and their bodies are essentially starved, but they are not at low weight. Does your model apply to them?
Frank: Our research data suggest that the brain responds differently in underweight anorexia nervosa compared to individuals who are diagnosed with the “other specified eating and feeding disorder of the anorexia nervosa type” without underweight. So far it seems that the brain gradually changes with weight loss, making the underweight group the most difficult to recover. The psychological and behavioral symptoms without low weight can still be severe and interfering with life, of course. In those individuals the body feedback may be less of a factor, although we are currently studying whether for instance the amount weight lost also changes the body and brain, even without being underweight by our typical criteria. I am hoping that the next few months will bring us some clarity for this question.
Bulik: Anything else you would like to add to help the readers of Exchanges to understand your model?
Frank: I just would like to emphasize that while anorexia nervosa is difficult to treat and recover from, it is possible to recover. I would like to encourage everyone with anorexia nervosa not to give up. Every person is different and needs individualized treatment plans, but our increasing understanding of the illness will eventually help develop more effective treatments. I also would like to mention that the term “illness” does not imply in my mind that medication will be the only answer to treatment. I rather belief that the combination of meal support and psychotherapy, facilitated and catalyzed by specific medication, will be the most effective treatment as long as we have not identified biological or genetic “switches” that we can turn off to stop anorexia nervosa from developing.
Bulik: Thank you Dr. Guido Frank of the Departments of Psychiatry and Neuroscience of the University of Colorado.