Family based treatment

Return to Exercise and Eating Disorder Recovery in Teens During FBT

Excessive exercise is often a component of various eating disorders, including anorexia nervosa, bulimia nervosa, atypical anorexia, OSFED, and subclinical eating disorders. It is a symptom that affects up to 80% of those with an eating disorder (Quesnel et al., 2023). By expending energy, exercise may contribute to the negative energy balance that may trigger and maintain an eating disorder. In the case of anorexia, increased exercise can be a biological response to the restriction.

Activity-Based Anorexia in Rats

When researchers restrict rats’ food intake while allowing them unlimited access to a wheel, many of the rats become hyperactive and start running excessively. Paradoxically, these rats continue running rather than breaking to eat during the short intervals of time food is available. If not rescued, they will literally run themselves to death.

These rats display the confusing behaviors observed in many people with anorexia nervosa. We would expect that rats—and humans—who are eating very little would become tired and rest more. Yet these rats become hyperactive. Similarly, people with anorexia often increase their activity even in a state of malnourishment. And this symptom appears even in younger children with anorexia who may not be able to verbalize that they are intentionally trying to “burn calories” or change their bodies the way that adults can logically explain their exercise. Their activity may appear to be more fidgety than goal-directed. As with the rats, there likely is no conscious attempt to burn calories, but the activity appears to be driven by a drive that gets turned on by the negative energy imbalance of restricted intake.

Risks of Exercise for People with Eating Disorders

For people with eating disorders, exercise can be dangerous. People with eating disorders who exercise may put themselves at increased risk for a number of serious medical complications. These can include low energy availability, cardiovascular complications (leading to potentially negative outcomes, including fainting and cardiac arrest), electrolyte abnormalities, problems with biomedical function markers (such as hypothermia and hypoglycemia), dysregulation of sex hormones, and low bone mineral density (leading to fractures and ultimately osteoporosis).

When Can My Teen With an Eating Disorder Return to Exercise?

There are 4 main considerations regarding returning a teen with an eating disorder to exercise:

  1. Safety: Is it even safe for the person with the eating disorder to exercise?
  2. Energy balance: Can they continue to gain weight or maintain weight if they add activity?
  3. Leverage: Will the inclusion or exclusion of exercise help facilitate recovery?
  4. Symptoms: How is exercise contributing to eating disorder symptoms?

These considerations vary across the different phases of Family-Based Treatment (FBT).

Exercise during Phase 1 of FBT

In Phase 1, weight gain and cessation of eating disorder behaviors is usually the most urgent need. By definition, bodies are nutritionally compromised. During this phase, I normally recommend stopping all traditional exercise and physical activity.

The application of our considerations for not allowing exercise is pretty clear.

  1. Safety: Often it’s not safe. Teens who are malnourished often have low heart rates, They may be orthostatic and at risk of fainting and are at greatest risk of breaking bones.
  2. Energy balance: Faster weight gain is always better. We don’t want to risk slowing down the rate of weight gain by expending any more energy than we must. In fact, sometimes we want to reduce all activity and restrict the teen to bed rest.
  3. Leverage: By not allowing life as usual, we send the strong and important message that the teen is unwell and needs to recover in order to return to activities. While it may not be initially personally motivating (because for teens, delayed rewards are hard to comprehend), over time it can provide motivation for continued recovery. If we give back activity too soon, this can often backfire later on because what motivation is there for the teen to complete all meals more quickly if they are fully back in their lives?
  4. Symptoms: When the exercise is a symptom of the eating disorder and the task during this phase is to stop eating disorder behaviors, exercise needs to be prevented.

Restricted Activity

In Phase 1, teens, like the rats, usually need their parents to save them from death from overexercise. It can be hard to take away something that seems positive in so many ways. However, I can reassure you that it is a life-saving gesture to stop the compulsive and intense exercise and even sports that seemed fun before the eating disorder took hold. Your teen literally feels compelled to exercise and you are giving them permission to rest and recover by requiring them to stop. This typically requires pulling out of all sports, dance classes, individual workouts, movement-related activities, and PE.

The Nature of Exercise

If this is truly compulsive exercise that occurs when the teen is showering, or at night when others are sleeping, parents may need to take more drastic measures. These may include requiring open doors, taking doors off hinges, 24-hour supervision, or having the teen sleep in the same room with them. The compulsion often decreases on its own with full nutrition and weight restoration, but sometimes parents must use other strategies—such as exposure and response prevention—to stop compulsive movement.

Any movement in this phase should be very gentle and preferably playful. For example, if it’s safe and weight gain is progressing and vitals are okay, after a few weeks we might consider the reintroduction of low-aerobic social activities such as bowling or miniature golf or gentle short walks with a parent. I discourage arduous or team sports during Phase 1.

Many treatment programs and parents offer walks as daily rewards for meal compliance. While I don’t love setting up walking as a reward for eating—we should not send the message that these activities should offset one another—sometimes it’s hard to find other motivations. Getting out of the house, for any reason, can be a big motivator for some teens. In this case, walks should be gentle and done with a parent (and potentially dogs too).

Exercise in Phase 2 of FBT

In Phase 2, when weight is fully or mostly restored, eating disorder behaviors (including excessive exercise) are successfully managed, and meals are going smoothly (with little resistance), the considerations change.

  1. Safety: By definition, reaching Phase 2 indicates that the teen is at or near a healthy weight, and behaviors like purging are managed, so medical markers should be stabilized. An ED-knowledgeable physician should still provide clearance for return to more formal physical activity; this is the time when it is usually safe to add in more physical activity.
  2. Energy Balance: The practicality requires ensuring enough energy intake to cover any additional movement.
  3. Leverage: By starting to allow some return to activities, you are helping the teen to build their life back and to see that recovery has advantages. You can help them build a life worth living. By Phase 2, teens are usually more logical and receptive to the idea that certain behaviors are required to allow them to do things they want to do.
  4. Symptoms: If you’ve successfully interrupted exercise urges during Phase 1, the eating disorder’s drive to exercise should be decreased. It will thus likely be easier to discern which activities are a true interest versus being in service of the eating disorder.

How to Reincorporate Exercise During Phase 2

I do believe parents should return teens to activity during Phase 2, while they are still providing oversight of food too. The plan for doing this is similar to that of returning control over food to the teen, which is another major focus of Phase 2. In the case of food, I encourage parents to think about what an age-appropriate

level of independence should look like for a healthy teen of that age and start gradually working toward that goalpost. I encourage parents to go slowly in giving back independence over food. For example, they may start by giving a choice between two equivalent options for a snack. Or they might allow the teen to plate their food with corrections. Too often control over food is handed back too quickly and teens lose weight.

Similarly, regarding exercise, you can think ahead to what the maximum level of activity you expect your teen to return to (based on the teen’s pre-illness level of activity) and gradually ramp up activity towards that endpoint. In some cases, it may not be safe or desirable for a teen to return to the level of activity they maintained prior to the eating disorder.


Where to Start

A great place to start is PE class, as long as it’s not too intense. I usually recommend that we start with activities that were enjoyed before—and not co-opted by—the eating disorder. The key here is monitoring the activity and how they respond to it. For example, when reintroducing running, we should not allow a teen to just start running on their own. Parents should monitor and limit the time of the activity. If the teen becomes upset when told it is time to turn around, this is an important indicator. It can also be helpful to monitor how the teen feels about re-engaging in the activity. You might ask periodically whether triggers are coming up and if so, how they are managing them.

Understanding Motivations

Often the motivations for activities become more apparent as the teen’s mental health improves. For example, in Phase 1 I often observe a rather rigid insistence on returning to prior sports or an insistence on freestyle aerobic activity (like running) or strength training. This compulsion loses steam during Phase 2. Teens frequently say things like, “I’m not interested in biking anymore; that was not fun,” or, “I don’t really like running. That was the eating disorder.”

Another way to call the eating disorder’s bluff is to require the addition of a “refuel” snack to compensate for the potential energy lost from added movement. In my experience, this tends to weed out those teens who are in it just for the calorie burn. When they learn the activity will require more food, they sometimes lose immediate interest. Some teens, having let go of the activities that the eating disorder was obsessed with, successfully develop other passions such as music or art, and sometimes this presents a surprising opportunity.

The Difference Between Eating Disorder-Driven Exercise and Joyful Movement

It is also important to understand that exercise driven by an eating disorder is qualitatively different than joyful movement. How do you know when exercise is safe and not driven? Some cues:

  • The person is able to express benefits or enjoyable aspects of the movement beyond calorie-burning or exercise euphoria
  • The person is willing to do other things that go against the eating disorder (such as have an extra snack) in order to participate in the activity

An important goal is to help your child develop a healthy relationship with movement. This can reduce their risk of relapse.

Always Go Cautiously When Adding Back in Activity

When adding back movement in Phase 2, it’s best to start with shorter sessions a few times per week and gradually add session length as well as frequency. This helps to prevent a sudden increase in activity from causing weight loss. For example, for a teen returning to a club soccer team that practices four times a week for 90 minutes and plays games on the weekends, I recommend starting with two shorter (45- or 60-minute) practices. If things are going well, after a few weeks we can increase to three practices per week, and so on.

Every few weeks we can add more time, or another day, until the teen is back to full participation including games. This requires them to continue to do well and the treatment team has made the decision that it is safe for them to return to that activity. The gradual buildup of activity allows parents to manage the teen’s energy balance with weekly weighing and adding appropriate intake if needed.

We often find that teens returning to sports need more food even than they needed in Phase 1. This is one reason we discourage reducing calories once an initial target weight has been reached. If we restricted activity during Phase 1, we use Phase 2 to gradually bring the teen up to their intended maximum level of physical activity while continuing to monitor weights to ensure they remain in energy balance.

Exercise During Phase 3

Since this is a short phase and the teen is already eating independently, exercise is usually returned before Phase 3, but we can continue to monitor it with less oversight in Phase 3.

Finally, it is important to consider that there might be some activities to which it may never be safe for a person with an eating disorder to return. Team sports are relatively safer than solo endurance sports. Some very intense activities with high energy requirements may remain too intense. Some other sports with strict weight or body size or shape, requirements (like ice skating, ski jumping, or ballet) may provide additional challenges. A person with a history of an eating disorder may need to do additional work in therapy before resuming such activities.

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Quesnel DA, Cooper M, Fernandez-Del-Valle M, Reilly A, Calogero RM. Medical and physiological complications of exercise for individuals with an eating disorder: A narrative review. J Eat Disord. 2023 Jan 10;11(1):3. doi: 10.1186/s40337-022-00685-9. PMID: 36627654; PMCID: PMC9832767.

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