Exercise in Anorexics; Study Review


In my daily research I came across a study that sparked my interest today;

Impact of exercise on energy metabolism in anorexia nervosa- Zopfel et al 2013

Personally having suffered an excessive exercise component to my anorexia I am always looking at further understanding what I think is a key element to anorexia. I think that the food symptoms are often focused on in treatment and that the energy expenditure component is overlooked. I will briefly review this study and its findings in today’s blog.

The study looked at energy metabolism and psychological data in anorexics split into two groups; low level and high level exercisers. The researchers looked at Total Daily Energy Expenditure (TDEE) as made up of Resting Energy Expenditure (REE), Diet Induced Thermogenisis (DIT) and Energy Cost of Physical Activity (Exercise)

Aside from the conclusion which I have inserted below, the only really interesting point that I found in the results was that REE was lower for anorexics until it is adjusted for the lower body surface area and lean body mass, so ultimately anorexics REE is relative. I remember thinking about this type of thing a lot when I was anorexic. I weighed myself often, and kept a mental tally of every calorie that I consumed, the exercise machines at the gym told me how many calories I was burning. As my weight dropped, my calorie requirement estimation charts would tell me that my daily calorie requirement was lower. This would help my justify eating less to myself, so a strengthening argument for the anorexic in me. As my weight dropped, the calorie counters on the treadmills and exercise machines would report a lower calorie expenditure, thus justifying spending longer on them. For example, when I started university I was 130 lbs so I could burn 823 calories in a 60 minute run on the treadmill. Buy the end of my first term I was 120 lbs, so now I was only burning 759 calories if I ran at that same speed for 60 minutes. This resulted in me running longer, I upped my time progressively as my weight dropped to achieve the same number of calories burned per run. At 120 lbs, this looked like 115minutes on the treadmill.

Today, my non- anorexic brain would not work in this line of reasoning. I would see my reduction in body weight and calorific intake as a reason to exercise less rather than more. I just wanted to use this example to highlight the difference in my reasoning when I was anorexic.

Back to the study in question, they looked at only 12 participants (red flag immediately for such  a low number of participants in any study!) and the method consisted of interviews and self-rated questionnaires (including Eating Attitude Test) blood samples were also taken in the morning and the patents BMIs were taken. TDEE was calculated for 15 days.

So, basically this study only looked at 12 anorexics for 15 days. Hard to draw anything conclusive from that short a period of time and such a small group of people, but all research is interesting and the results I am sure have been useful. Here is the conclusion as published:

Taken together, our study shows that there are marked differences in energy requirement among AN patients. Over one-half of our AN patients reported high exercise levels directly related to weight control with an overrepresentation of the binge/purge AN subgroup. Bearing in mind their dramatically increased energy expenditure and levels of depression, this subgroup may benefit from a structured treatment program specifically addressing their hyperactivity supplemented where necessary with drugs derived from the group of atypical antipsychotic . Studies thus far with olanzapine in AN patients have shown some promise with respect to weight gain and improvement of depression, anxiety, aggressiveness, obsessive-compulsiveness and also safety 

In order to assess the actual energy requirements and more appropriately match treatment to patients needs in AN, it is important for clinicians to quantify both energy intake and physical exercise levels. A simple and expedient way to ascertain the latter before and during treatment would be the examination of the single item “What percentage of your exercise is aimed at controlling your weight” of the EDI-SC.

The first sentence here is a no brainer- there are marked differences in energy requirement among the general population, so that is not really telling me anything. I like it that they have been considerate of the binge- purge subgroup of AN and shown that the high level exercisers are dominant in this subgroup of anorexics. I personally found myself in this section as my exercise regime was so intense and relentless, often as high as 6 hours per day.  I agree that treatment should be different for this subsection, but then it is also my personal opinion that treatment should be different for every sufferer and every anorexic should be individually considered. Due to the disorder representing in psychological, behavioral and physiological elements to differing degrees in every individual I think all sufferers should be treated as unique cases.

The second paragraph in this conclusion is in my opinion vastly over-simplistic. Well, the first part is correct, yes, one needs to access the energy intake and physical exercise levels – so hallelujah …….but the idea that one can accurately gauge an anorexics level of activity from asking one simple question “What percentage of your exercise is aimed at controlling your weight?” boggles my mind. Firstly, for at least 8 years of my illness had I been asked that question I would have lied about the amount of exercise that I was actually doing, then I would have lied about why I did it, so my answer to that question would have been a great misrepresentation of what was really occurring.  Second, when I was in a place to admit to excessive exercise, I still would never have admitted that I did it in order to control my weight. In fact, I would hold that there was some honestly in my claims that I did not exercise to control my weight, so I would have been truthfully claiming that I did not exercise in order to control my weight.

My point? In my experience, anorexia will lie in order to preserve itself. Self rating questionnaires are not particularly helpful. Second, even when telling the truth, I was conflicted and confused as to what my truth was and why I did what I did.

This study was useful as it looked at the make-up of energy expenditure in anorexics and the difference between the sub-groups that are represented within anorexia. I hope that larger and longer term studies will emerge.

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About Tabitha Farrar

I work as Head of Marketing for a software startup in Boulder. As a recovered Anorexia sufferer, I advocate for proper understanding of eating disorders in my spare time. On that note, I wrote a book about my own journey into eating again called Love Fat.

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