What Does Habit Have To Do with Anorexia Nervosa?

If I were to ask you if you eat low-fat, low-calorie foods, you would probably say yes. If I asked you if you do it a lot, you would probably say yes. But if I were to ask you if you do it without thinking, or if it would require effort not to do it, you might say yes, but you might not. And if I were to ask if it makes you feel weird to not do it, you would probably disagree. How much you agree or disagree with each of those questions can characterize whether eating low fat food is a habit for you.

The idea that some behaviors or sets of behaviors (that is, routines) may be habits is intriguing to scientists across disciplines. Some social scientists have studied the kinds of behaviors that go into energy balance (like eating behaviors or physical activity). They have learned that some routines are more habitual than others; the more habitual the routine (or the higher it rates on a metric termed “habit strength”), the harder it might be to change the pattern. One way to think of “self-control” is that it describes one’ ability to choose the behaviors you want. That is, if you are the habit of getting up and having a cup of coffee, it takes “self-control” to get up and have a glass of juice instead.

Controlled experiments have shown that at times of stress, this type of “self-control” is actually low. Presumably to conserve some type of cognitive resources, an individual relies more on the behaviors that have high habit strength during these times. Consider the example of eating popcorn at the movies, which was the targeted habit in one of these studies. A person who has a strong habit of eating popcorn at the movies (that is, someone who orders it frequently) will eat the popcorn even if it doesn’t taste good. That individual is even more likely to eat the popcorn if they have had a full day of engaging conscious effort in other tasks (like preparing for an exam or work presentation).

The field of cognitive neuroscience has also made great strides in understanding the brain circuits that underlie behaviors that persist even when the outcome is no longer desired. Animals learn to associate a particular cue (like entering a cage) with a particular behavior (press the lever to get food), and after a while of this kind of learning, they will continue to show the behavior even when the reward has lost its value. That is, even when the animal is clearly full and has stopped eating in one cage, if you put it in the cage where it learned to press the lever, it will press the lever anyway. This behavior – responding to a specific cue even when the outcome of that response is no longer rewarding – is the neuroscience definition of a habit. Neuroscience experiments have shown that this behavior depends on particular brain regions and circuits involving the dorsal striatum. Among humans, neuroscientists have also shown brain circuits involving the dorsal striatum are active when habits are created in the lab.

What does any of this have to do with eating disorders? And specifically, with anorexia nervosa?

The work from these fields converges to suggest hypotheses about the neural basis and characteristics of behaviors that keep occurring even when they are not useful – persistent, maladaptive behaviors, such as are seen in eating disorders. Specifically, for the individual for whom choosing low-fat foods has very high “habit strength,” perhaps dorsal striatum neural systems are engaged to a greater extent. If so, this has implications for both behavioral and medical treatments.

At the Columbia Center for Eating Disorders, where we conduct clinical research with individuals with eating disorders, we have developed a decision-making task that captures an individual’s food choices in an experimental paradigm. The selection of low-fat foods is a behavior that is a core problem in anorexia nervosa, as it is the inadequate food intake that leaves patients starved. The starved state, in turn, contributes to the medical, behavioral, and psychological symptoms of illness (Walsh 2005).

Our Food Choice Task has been shown to be a good way to measure the types of decisions about food that individuals with anorexia nervosa make: a persistent preference for low fat foods. Even when patients with anorexia nervosa begin treatment (and in fact, well into the recovery process), they continue to struggle with these decisions.

This program of research is one of the most exciting new directions in understanding anorexia nervosa. We have capitalized on the most up-to-date findings from cognitive neuroscience to be able to ask the truly key neural systems question – what is driving food choice? Individuals with anorexia nervosa can be so different from each other in so many ways. And yet, they are so remarkably predictable in their food selections. Even when their body is starved, and their hormones are signaling that they need calories and fat, they keep choosing a snack like a rice cake instead of the bread & oil.

As we study this paradigm with patients in our clinic, we are evaluating the many factors contributing to these unhelpful food choices. In one of our neuroimaging studies, we were able to directly assess the brain circuits that underlie these maladaptive choices. In our behavioral research, we designed an experiment to test the degree to which stress, or depletion of cognitive resources, relates to the selection of low-fat foods and/or the strength of the habit in food choices. To learn more about our results, check out our paper, Neural Mechanisms Supporting Maladaptive Food Choices in Anorexia Nervosa (Foerde et al., Nature Neuroscience, 2015) and this related NY Times article, Anorexia May Be Habit, Not Willpower, Study Finds.  

Going forward, we aim to use this program of research to directly evaluate the role of emotions in making habitual food choices. That is, do people make better choices when they feel less anxious or depressed?

Through scientific study, we also hope to identify new neural targets for medical treatment development. And, we aim to further clarify which components of new behavioral and psychological treatments are most likely to help individuals stop using old habits (and why), and start making new ones.

For more information on this study or other current studies (and treatment options) at the Columbia Center for Eating Disorders, please call us at 646-774-8066.

An earlier version of this post appeared on the blog for the Global Foundation for Eating Disorders on July 2, 2014.

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