Walk This Way: Physical Activity in Anorexia Nervosa

Despite being at a dangerously low weight, clinicians have long observed that many people with anorexia nervosa are very physically active. When asked about their own levels of physical activity, patients report that they are more active than individuals without eating disorders. But are they really more physically active than those without an eating disorder? Or, do clinicians and patients just perceive that the patients are more active? And, what effect does physical activity have on recovery?

These were the questions that we sought to answer in a recent project and publication.

Study Purpose

In this study, we wanted to know:

• Are patients with anorexia nervosa more physically active than healthy individuals without eating disorders?
• How does physical activity level affect treatment outcome?

Study Methods

To answer these questions, we collected information from two groups: inpatients with anorexia nervosa (ages 15 to 40) receiving treatment in our program, and healthy individuals without an eating disorder.

To measure physical activity, participants wore a sophisticated activity monitor, like the one pictured below. It was attached to their chests, legs, and arms for three consecutive days. Healthy controls wore the activity monitor once, while patients wore it at three different time points:

1. when they were hospitalized and at a low weight,
2. while hospitalized, but restored to normal weight, and
3. 1 month after discharge from the inpatient program.

Key Findings

Were patients more physically active than healthy controls?

Once patients were back in the “real world”, one month after being discharged from inpatient treatment, they were more physically active during the day and less active at night than healthy controls.  

The activity monitor used in this study was fairly sophisticated. It differentiated different types of physical activity, from walking to jumping to running to fidgeting. In looking at the breakdown of different types of physical activity, we learned that patients with anorexia nervosa spent significantly more time on their feet (that is, walking, running, standing, jumping, and stepping up and down stairs) than healthy controls during the day. Even more specifically, time spent standing made a difference between the two groups.

Was physical activity related to treatment outcomes for patients with anorexia nervosa?

The more time patients spent on their feet once they were weight-restored on the inpatient unit, the more rapidly they lost weight in the year after leaving treatment. Other types of physical activity, such as fidgeting, were not associated with weight loss after treatment.

What Does It All Mean?

It’s important that these results be replicated before drawing too firm a conclusion. However, the findings do suggest that helping people with anorexia nervosa learn to minimize physical activity, be active in ways that do not compromise their eating disorder recovery, and rework some of their thinking about exercise are important treatment targets.

For example, clinicians should ask their patients about their involvement in a range of physical activity, and not just “exercise.” Patients may benefit from engaging in self-monitoring of physical activity, asking others for feedback on their level of activity, and challenging themselves to sit down or be still during or after certain activities, like meals or when riding public transportation.

If you or someone you know is struggling with an eating disorder, we encourage you to contact the National Eating Disorder Association or our program for referrals.

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