Exposure in the treatment of Eating Disorders

Exposure therapy is widely recognized as a necessary (and sometimes sufficient) ingredient of treatment for most of the anxiety disorders including phobias, panic disorder, and obsessive compulsive disorder.  Anxiety is a core psychological feature of anorexia nervosa and bulimia nervosa.  However, instead of being afraid of heights, speaking in public, having a heart attack, or contamination, individuals with eating disorders are primarily afraid of food, eating, and shape and weight.

Both cognitive-behavioral therapy and family based treatment, two empirically validated treatments for eating disorders, employ exposure techniques.  Exposure works through the process of habituation, the natural neurologically-based tendency to get used to things to which you are exposed for a long time.   During exposure, habituation occurs as people acclimate to their fear and come to realize that nothing actually dangerous is occurring. Habituation promotes new learning of safety, tolerance of fear feelings, and extinction of the fear avoidance urge. 

In “enhanced” cognitive behavioral therapy for eating disorders (CBT-E; Fairburn, 2008), the individual is exposed to shape and weight by weekly weighing.  Individuals with eating disorders often have significant anxiety around being weighed so the weekly weighing provides exposure.  Some individuals weigh themselves excessively, which serves the purpose of a temporary reduction in anxiety, much as an OCD ritual does.  For these individuals, limiting weighing to once a week exposes them to tolerating the unknown between weighings.  Other individuals avoid weighing themselves at all; for those clients, weekly weighing provides controlled and regular exposure.

In CBT-E, patients are also exposed to feared foods.  Just as clients with phobias construct fear hierarchies, in CBT for an eating disorder, therapist and client make a “forbidden food list.”  The client is instructed to rank the foods they are afraid to eat in order of the degree of reluctance to eating them.  The list is then broken down into 4 groups of increasing difficulty.  Over the next few weeks the client is instructed to start introducing these foods into their diet, starting with the easiest and moving on to the most difficult.  The desensitization to forbidden foods is seen as necessary for recovery.

CBT-E also addresses other types of avoidance; for example, avoiding exposing one’s shape by wearing only loose clothing, or avoiding baring one’s arms.  It also addresses body checking and avoidance– similar to weighing, this can manifest as such extremes as either spending inordinate time in front of mirrors or refusing to look in mirrors at all.

While the mechanisms of treatment in Family Based Treatment (FBT) are not precisely understood, one theory is that FBT may work via exposure (Hildebrandt et. al, 2010).   In FBT, the patient is weighed weekly and the weight is charted to visually track weight gain over time, thus providing exposure to one’s weight.   A specific weight target is usually not given.  This serves the additional purpose of the patients having to tolerate uncertainty about a ceiling weight.

In a course of FBT, parents are instructed to “nourish their children according to their severe state of malnutrition, not according to the wishes of the anorexia.”  Because meals commonly take place 5 to 6 times a day during refeeding, this provides ample opportunity for exposure to food.  Anxiety usually skyrockets as parents take over the serving of food at the beginning of the treatment.  However, over time anxiety around eating reduces and meals become easier.  Because this happens in a naturalistic setting (the home environment instead of an inpatient unit), it is believed that the results generalize even better.  

In FBT, parents are left to choose the pace of the exposure to forbidden foods, whether they start with less challenging foods and move up the hierarchy or whether they go immediately for higher calorie foods which maximize weight gain but initially bring more resistance.   In exposure work, the latter is called “flooding,” and while it raises anxiety more in the short term, it also brings around faster results.

Once forbidden foods are reintroduced, it is important that individuals continue to eat these “scary” foods on a regular basis for a while.  The child does not have to eat these foods every day, but the scary foods have to be given enough that they no longer produce anxiety.   This reduces the fear pathways.  Children and adults who have regained their lost weight but not conquered their forbidden foods are at greater risk of relapse.  A child is not better until they can eat all the foods she or he used to enjoy without anxiety or hesitation.

In FBT parents are also encouraged to confront other eating disordered behaviors, such as wearing baggy clothing, cutting food into tiny pieces, and exercising excessively.  By preventing these behaviors, the family helps their child learn to tolerate the anxiety that is generated when the behaviors are not engaged in and over time, the anxiety decreases.

In both treatments for exposure to work, it must be done repeatedly and consistently.  Exposure work is by nature unpleasant because it generates the fear response and for this reason is often resisted by both parents and patients.  However, it is necessary for successful treatment.