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Eating Disorders

Should You Exercise During Recovery From Anorexia? Part 1

The physiology and psychology of exercise in illness, recovery, and beyond.

By Karen Photiou and Emily Troscianko


Is it bad for me to keep exercising once I embark on recovery? Could it be good for me? Do I risk compromising metabolic or hormonal normalisation if I keep going with it? Will I overshoot my final bodyweight more or less if I carry on exercising? Will I be more likely to gain fat rather than muscle if I don’t exercise during weight restoration?

These kinds of question are extremely common in people contemplating or beginning recovery from anorexia. Compulsive or excessive exercise is often a significant component of anorexia and other eating disorders. One study suggested that 80% of people with the restricting subtype of anorexia may engage in compulsive exercise (Dalle Grave et al., 2008), and the terms anorexia athletica or hypergymnasia are sometimes used to describe cases where the exercise component of a restrictive eating disorder is particularly pronounced. You may also have heard the term female athlete triad. A physical condition involving low energy availability (often thanks to disordered eating), amenorrhea (i.e. absence of menstruation), and reduced bone density, this is a common consequence of overexercise and underweight. A more comprehensive term, relative energy deficiency in sport, or RED-S, has now been introduced to include men too, and to convey that the ‘triad’ is in fact a syndrome with a complex network of effects on physiological function, health, and athletic performance, all deriving from low net energy availability (Mountjoy et al., 2014, 2018).

Excessive exercise is often central to how eating disorders take hold and retain their grip: in many cases it compromises treatment, contributes to relapse, and is part of the emotional and cognitive fabric of the disorder (Goodwin, 2010, p. 3). Compulsive and excessive exercise may serve many anorexic functions: it may be a means of burning calories, exacerbating weight loss or otherwise exerting control over one’s body; it may be a form of self-punishment; and/or it may be a way to reduce anxiety or mitigate depressive symptoms. It often disguises itself as a life-enhancing thing, but the disguise is just that:

I am usually told in no uncertain terms by many with eating disorders that they are not exercising to try to limit any weight gain. They assure me, and everyone else, that it has nothing to do with body image or food intake at all. They are merely exercising because they love it; it makes them feel strong and healthy; and it improves their mood.

Studies unfortunately suggest that you are desperately trying to believe your own advertising when you swear that the exercise you do is all good. (Olwyn, 2013)

Formal treatment for anorexia and recommendations for independent recovery usually apply the simple principle that physical activity should be minimised to allow all calories consumed to support weight restoration and other aspects of ‘nutritional rehabilitation’ after starvation (e.g. Marzola et al., 2013). Alongside these physiological reasons to avoid exercise, continuing exercise before making significant progress in recovery could be psychologically damaging by maintaining the obsessive-compulsive aspect of the disorder.

The energy-balance and the psychological argument both make intuitive sense. But on the other hand, at some point the recovery process must also involve establishing a healthy relationship with movement, activity, and our bodies: although structured exercise and sport need never be part of your life if you don’t want them to be, just like food itself, functional physical activity is not something one can simply abstain from post-recovery, and the dividing lines between necessary and unnecessary movement are blurry, just like those between beneficial and compulsive movement. So the real question is not a single all-or-nothing question: should I engage in physical activity at all during recovery? It’s really a set of pragmatic sliding-scale questions:

  • Where is the boundary between necessary functional exercise and optional exercise and what are the benefits and risks of doing one or the other?
  • What kinds of movement, activity, exercise, or sport are more or less likely to be helpful or harmful?
  • How do physiological versus psychological risks and benefits stack up?
  • And how do the answers to these questions change during illness, recovery, and post-recovery?

Formulating answers to these questions is something I’ve been meaning to do for years, and this pair of posts (Part II is here) is a long-overdue attempt to do so. To tackle them I’ve gratefully teamed up with a doctor (specialising in paediatrics), Karen Photiou, who also has a personal history of anorexia, from which she has now almost recovered. She has kindly and expertly helped me process the many arguments made about the physiology of exercise in eating disorder recovery, as well as contributing insights on the psychological side of things based on her own experience and those of many others with whom she has shared and discussed the recovery journey.

In this first post we start with the physiology and then move on to the psychology. And then in the sequel we offer some practical suggestions for how to exercise, or not, in your own recovery. Our focus will be on anorexia and other restrictive eating disorders, but many points will apply more broadly across the eating-disorder spectrum.

Starvation, hormones and exercise

A common argument for wanting to continue to exercise in recovery is thatexercise is a healthy pursuit, with the associated concern that refraining from physical activity during weight restoration would equate to becoming ‘unhealthy’ or ‘unfit’. This harks back to societal concerns about the ‘obesity epidemic’ and the assertion that doctors are always telling people they need to take more exercise (and eat less sugar/fat etc.) to reduce their risk of heart disease, type 2 diabetes and all manner of other modern-world afflictions. The evidence on which these recommendations are based is shaky at best, but the message is pervasive nonetheless.

Diet and exercise recommendations made by medical professionals to the general population as a whole DO NOT apply to people in recovery from anorexia. (They also don’t apply to many other ill people who, likewise, either have to remind themselves of this fact and resist the widespread pressure, or risk exacerbating their illness.) Attempting to use the health argument to justify a behaviour that is contributing to energy deficit during starvation and thus helping perpetuate a life-threatening illness is classic eating-disorder logic. It is highly unlikely that your motivation for going out for a run at 5 am in the cold, dark, wind, and rain is to benefit your health. If you are suffering from anorexia, you are not going to develop heart disease or type 2 diabetes by resting as you weight-restore. And there will be plenty of time for fitness once you are fully recovered, if you want there to be.

So, let’s have a look at the evidence – is exercise healthy for those in recovery from anorexia?

One basic problem with exercise during starvation is that it puts even more physical stress on an already weakened body, exacerbating endocrine adaptations to malnutrition and energy deficit. A vicious cycle develops, centred on dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, which is responsible for production of reproductive hormones in both women and men.During starvation, hypothalamic production of gonadotropin-releasing hormone (GnRH) decreases to pre-pubertal levels. This leads to reduced production of luteinising hormone (LH) and follicle-stimulating hormone (FSH), which in turn leads to decreased synthesis of oestrogen and testosterone. In women, this often (but not always) results in cessation of menstruation (amenorrhoea), an indication of extreme physiological stress. Although this clear physiological marker is obviously not applicable to men or post-menopausal women, the underlying hormonal dysfunction and resultant adverse consequences are the same.

Additional hormonal adaptations take place in response to chronic energy deficit, which have serious adverse effects on bone health and body composition. Low levels of growth hormone (GH) and insulin-like growth factor (IGF-1), and high levels of the stress hormone cortisol, cause rapid reduction in bone density and changes to the microarchitectural skeletal structure. This leads to an increase in fracture risk that may be irreversible (Fuqua et al., 2013). Additional consequences include increased catecholamines and ghrelin, and decreased leptin and thyroid hormone (Allaway et al., 2016).

All these hormonal changes collectively result in high levels of blood glucose and cholesterol, causing problems for the cardiovascular system. Adverse affects on body composition also ensue, with excess cortisol contributing to wastage of lean muscle tissue and fat accumulation with preferential deposition around the midsection. So ironically, the long-term physical consequences of continuing to exercise while malnourished are precisely the opposite of what your exercise may be intended to achieve: an increased ratio of fat:lean tissue and a reduction in bone mineral density (Mountjoy et al., 2014).

Excessive exercise may also have a negative impact on your metabolism: the chemical processes by which your body uses food for energy and growth. The basal metabolic rate in response to the energy deficit (Loucks et al., 2003). Essentially, the metabolic rate slows down to conserve vital energy in the context of chronic over-expenditure.

Most research in this area has been done with athletes. Energy deficit has been found to correlate with decreased basal metabolic rate in female endurance athletes (Melin et al., 2015), whilst increasing training over 4 weeks in rowers of both sexes led to a significant reduction in basal metabolic rate (Woods et al., 2017). Women with an energy deficit brought about through diet and exercise have been shown to lose less weight than predicted over a 3-month period, again with a significant reduction in basal metabolic rate (Koehler et al., 2017). In this context, adequate rest and energy intake through good nutrition is essential to redress the balance and allow the metabolism and the rest of the body to heal.

When the body is nutritionally stressed and hormonally depleted, exercise exacerbates the physiological consequences of anorexia. Once nutritional rehabilitation has taken place and energy intake is consistently sufficient, however, the effects of physical activity are more positive. This means that good nutrition, weight restoration, and normal hormonal physiology are crucial to deciding whether, in purely physiological terms, exercise is safe and advisable. And the presence or absence of menstruation is a good first clue as to whether ‘normal or abnormal hormonal physiology’ is what you’re dealing with.

This point can be demonstrated by considering the effect of exercise on bone health. Osteopenia (mildly lowered bone mineral density) and osteoporosis (more severely lowered density) are common effects of restrictive eating disorders, and once osteoporosis is present, the risk of bone fractures is significantly increased. Once fractures have occurred, pain often remains even after healing, becoming more pervasive as the bones incur more damage.

The role of exercise is critical here. In the presence of adequate estrogen or testosterone, exercise increases bone density (Ackerman et al., 2012). In the presence of HPA dysfunction, however, exercise exacerbates bone loss. Studies of athletes with HPA dysfunction consistently show impaired bone density compared to athletes with normal menstrual cycles and healthy controls (e.g. Christo et al., 2008; Nazem and Ackerman, 2012).

For eating disorders specifically, an observational study comparing women with anorexia and amenorrhoea with a weight-restored recovered group whose menstrual cycle had returned to normal found that those who were still ill who exercised even moderately, including restlessly walking around, developed worse bone density than ill patients who didn’t exercise. After recovery, however, all exercise (including high bone-loading exercise) was associated with better bone density compared with not exercising at all (Waugh et al., 2011). So although these findings were only correlational not causal, excessive moderate bone-loading exercise (like walking, elliptical etc.) while ill may put people with anorexia at higher risk of low bone mass, whereas high bone-loading activities (like running) may enhance bone restoration after recovery. And overall the associations between inadequate nutrition, excessive exercise, hormonal dysfunction, and bone damage are incontrovertible.

Adding force to these observational studies, an experimental intervention involving weight-bearing and impact-loading exercise for post-menopausal women with osteoporosis recently demonstrated, for the first time, that severe bone density loss can be reversed (not just halted or slowed) through exercise (Watson et al., 2017). The participants were all otherwise healthy, including in bodyweight terms (the average BMI was around 24). So once everything else is back to normal, exercise can contribute to repairing the damage done by illness. Before that, it cannot.

We need to be very clear here that having a regular period should be viewed as no more than a bare minimum indicator of some form of hormonal balance. The point is that amenorrhoea is a red flag signifying extreme dysfunction – NOT that having a period means all is well. As discussed in this post, the presence or absence of a menstrual cycle in any individual at a given time is the result of a long evolutionary process wherein different survival constraints were in play, and so menstruation is only a crude indicator of the many contributors to health that we have the luxury of caring about now.

Resumption, or lack of cessation, of menstruation should not be taken as a green light to engage in intense exercise before full recovery: getting a period does not mean you can lace up your running shoes and sign up for a marathon to raise money for Beat. There are other very important and relevant physical and psychological factors to consider.

Anorexia has numerous serious physical effects in addition to those already discussed. Some of these, like bone density loss, are silent – and can be present at any weight. People with anorexia often feel well despite the existence of significant and dangerous medical problems, which may come to light only when the body is subjected to additional physical stress. The heart muscle can become wasted and weakened through starvation and unable to withstand the additional demands of increased activity. Exercise in the context of electrolyte abnormalities (which are particularly common in purging subtypes) can be lethal. Disturbances in potassium levels can induce dangerous heart arrhythmias and result in cardiac arrest and sudden death.

Excessive water consumption during endurance activity can cause fluid shifts leading to critically low sodium levels (hyponatraemia) and a severe form of brain damage called central pontine myelinolysis (CPM). Blood glucose levels can be very unstable during anorexia, with extreme highs (hyperglycaemia) and lows (hypoglycaemia) both observed. Hypoglycaemia can be exacerbated through exercise as blood sugar is rapidly consumed to provide the muscles with fuel, resulting in irreversible brain damage or death. If you know you have any of these medical problems, you should make sure they’re resolved before even considering reintroducing structured physical activity into your life. The catch is, you may not necessarily know.

The bigger picture: Careful exercise really can make you feel better

The upshot from the physiological evidence, then, is: if you’re underweight and amenorrheic, don’t exercise until you are weight restored and your period returns. But does this mean that you should lie in bed until this happens, and plunge straight back into a full high-intensity exercise schedule once it has? No, it doesn’t. Here we return to some of our sliding-scale questions: the question of what we actually mean when we say exercise, and the question of what benefits and risks we decide matter more to us.

In her recent book Sick Enough: A Guide to the Medical Complications of Eating Disorders (2018), medic and eating disorder clinic founder Jennifer Gaudiani argues that although ‘serious exercise is a privilege of full recovery […], movement during weight restoration makes recovery sustainable’. Gaudiani believes that physical movement should be part of the recovery process for all but the most physically depleted patients. She has observed that

very weak patients would brighten and glow as they saw rest, nutrition and expert physical and occupational therapy result in stronger, more independent bodies. They accepted nutrition and rest more readily because they saw improvements in their functional status.

In her clinic, Gaudiani recommends a slow increase in movement incorporating a variety of activities such as yoga, walking, and free weights, with rest days in between, and with additional nutrition if needed. She acknowledges this may contribute to some bone density loss in patients with HPA dysfunction, but feels that a sustainable plan involving movement can lead to earlier achievement of full eating-disorder recovery, which will have a better long-term overall effect on bone health.

In Gaudiani’s view, forbidding people in recovery from undertaking any form of physical activity unintentionally reinforces the disordered perception that the sole purpose of movement is to burn calories and prevent weight gain. In this way, a policy of strict rest may inadvertently exaggerate the tightness of the links between exercise, weight, and calorie intake, giving credence to the complex and rigid calorie input-output calculations and calibrations that often characterize anorexia.

So the toss-up here is whether or not we prioritize longer-term potential benefits over short-term dangers: the possibly increased likelihood of full and swift recovery over the probably increased likelihood of some temporary bone damage. It’s a hard call to make, and making the right call depends on giving careful consideration to both the precise physical nature of the exercise being contemplated, and the care with which its possible benefits and risks are managed for you as an individual. This is an even harder line to tread if you’re recovering without intensive professional support, so – as we’ll go on to suggest in Part II – there’s a strong argument for keeping things simpler for yourself by abstaining from anything structured until you’re well on the way to fully recovered.

The even bigger picture: The psychology of compulsion and the dangers of setting conditions for weight gain

Like everything else about eating disorders, the costs and benefits of exercise are a combination of physical and psychological: we ignore either at our peril. When it comes to continuing exercise during recovery, the biggest psychological dangers are probably 1) leaving obsessive-compulsive aspects of the disorder unchallenged, and 2) setting conditions for weight restoration. And the two are intimately intertwined.

Anorexia always involves obsessive-compulsive rituals of some kind. Most often the central ones are food-related: immovable requirements (far beyond preferences) for time and place and other contexts of eating, for the type and amount of food itself, for the speed of eating, and so on. Often these requirements extend beyond the eating to encompass things that make it acceptable to eat – and exercise is the obvious candidate here: eating is not acceptable unless I’ve completed my daily workout, say.

For Emily, exercise was never a huge part of her anorexia.The rules were very food-centric, and although a bike ride did happen every day, it never got longer or more intense over the years, and although she fretted about exercise levels if she was away from home (and usually replaced cycling with something else, like walking), the desire not to spend too much time away from work prevented the exercise demands from spiraling as the food once had – one arguably positive example of one obsession trumping another, perhaps.

Karen Photiou
Source: Karen Photiou

For Karen, the same was true in her first episode of teenage illness, in which her anorexia was characterized solely by starvation, perfectionism, and obsessive academic work. Following weight restoration, she had a desire to move away from her former life as an over-achieving stick insect clinging to a radiator and took up running – with the intention of developing strength and fitness and learning to appreciate her body for its functionality rather than aesthetics. The aim was not weight loss, but anorexia can be a cunning shape-shifter. Over the years her running became increasingly frequent and intense, with rigid rules forming around timings and distances – all of which were disguised by the socially acceptable rationales of training for races, self-discipline, and remaining ‘fit and healthy’. Until her weight fell to a point below which she could no longer pretend (to herself or anyone else) that she was healthy or motivated by the attempt to be so, and she realised that missing a daily run or eating more felt impossible.

For both of us, having some time without any of these previously non-negotiable kinds of exercise was crucial in kicking the habit. Emily did it in an ad hoc way, as life started to expand and she was able to go on trips and spend time with people and let go, one by one, of all the aspects of her previously highly rigid solitary daily routines. Karen needed a period of complete abstinence from exercise to break the rigid rules and conditions and allow movement to become a choice, rather than a compulsion.

Some eating-disorder therapists and recovery coaches recommend a prolonged period of complete rest from both structured exercise and low-level movement for everyone in recovery, regardless of weight or exercise history. We broadly agree that a period of total rest is important for everyone. But there is no empirical evidence base on this topic, and there exist no specific, categorical recommendations for how long those in recovery should refrain from exercise. This is highly individual – the goal on the psychological side is to break any links between exercise and eating and allow enough time for any obsessive and compulsive elements to dissipate.

Karen Photiou
Source: Karen Photiou

So in summary, keeping exercising during recovery from anorexia is not a way to stay healthy. Healthy for you means resting while your body repairs itself, and not putting yourself at risk of any of the ways exercise can exacerbate the physical damage done by anorexia. Healthy for you means allowing your body’s fat reserves to be replenished, so they can return to playing the crucial regulatory role they’re meant to in a fully functioning endocrine system. Healthy for you means remembering that muscle mass can’t be effectively built up in conditions of nutritional deprivation. Healthy for you means knowing that the research on bodyweight overshoot (letting your bodyweight increase during recovery to a level beyond where it will ultimately stabilize) is nowhere near well advanced enough to predict how different activity levels may affect your overall weight gain, but that accepting you can’t know exactly where your weight will stabilize is necessary for full recovery.

What does all this mean in practice? In the sequel to this post, we go on to suggest some practical strategies for weaning yourself off whatever kind of exercise addiction may be part of your eating disorder. Read Part II here.


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