Why we should NOT use BMI to diagnose eating disorders

Today’s post is a bit different from my usual content but I saw a story on BBC news yesterday which really stirred up emotion in me and inspired me to write. It was a young woman sharing her experience with disordered eating and being told by doctors that her BMI “wasn’t low enough to be anorexic” when she went to seek help. Here is the short video clip:

For those of you who haven’t read my previous posts about my struggles with disordered eating, I had an undiagnosed eating disorder throughout my teens and early twenties and lost my period for nearly 10 years due to being underweight for my body type. During this time I too was told by doctors that I was healthy because my weight was within the normal range and was led down the road of more and more tests to figure out why I wasn’t menstruating. This definitely prevented me from getting the help I needed and delayed my recovery by several years as I was able to keep kidding myself that I was healthy and continue with my unhealthy behaviours around food and exercise.

I still have anger inside me towards the medical system for failing to help me and I think it’s so important to share stories like these in the hope that they can help someone else who might be going through something similar. Disordered eating is something that so many women go through at some point during their life and often it is brushed under the carpet because obsession over our bodies, chronic dieting and exercising to lose weight is seen as just part of being a woman in today’s world. Using the BMI scale as a measure of disordered eating is so outdated and only continues this issue. Women and girls, like me in the past, who do become aware that perhaps they have a problem around food are often made to believe we “aren’t sick enough” to seek or receive support.

The BMI scale was developed around 200 years ago by a mathematician as a quick way of determining whether an individual is at a healthy weight for their height. It is usually seen as a chart of height vs. weight like the one below with marked ranges for underweight, normal weight, overweight and obese. However, it was never intended to be used as a formal diagnosis of health. It wasn’t developed by doctors but for some reason it has been adopted by the medical system and is still used, often without question, to this day.

According to most doctors, a BMI within the range 18.5-25 is considered “normal” but there are several major problems with using the BMI scale. The main one I want to highlight is that it doesn’t take into account the percentage of lean mass which consists of bones, organs and muscle tissue. So someone with a larger bone structure or more muscle mass can quite easily be considered overweight or even obese. Think football players or figure skaters who are often lean but extremely athletic and muscular, according to the the BMI scale many would probably need to lose weight to be considered healthy.. really?! How can a basic mathematical formula know what it healthy for your body type. All it is is statistics. On average, humans have less than 2 arms but does that mean that the typical human has less than 2 arms? Of course not!

What is healthy for our bodies depends on so many factors, including our genetics, the environment we are currently living in and what stressors we have in our lives. At certain times it’s healthier for us to hold more fat and at others it might be more advantageous to be leaner. Our bodies are smarter than we give them credit for. I look at photos of myself at my lowest weight when I was around a BMI of 18.5 and I wonder how any doctor could have thought I looked healthy. I was 20 years old but I looked like a child. There was nothing womanly or fertile about how my body looked at that time. I had hardly a scrap fat on my body, no breasts at all without a padded bra and my knees stood out a mile on my stick legs.

Of course, I didn’t look like the completely skeletal anorexic figures that you see, but I was clearly not at a healthy weight for my frame. It’s obvious to me now why I didn’t have my period. As women we need fat on our bodies to support a healthy pregnancy and to nourish a growing baby. I definitely was not eating enough to support my activity level and I was restricting food groups and specific “unhealthy” foods. I had a high level of cognitive dietary restraint meaning that I thought a lot about food and I was constantly controlling and denying my cravings. My body was sending me all the signals that it wanted to be at a higher weight, I would have crazy binge eating episodes because my body was starving for calories but I saw this as a lack of motivation or as emotional eating. I wasn’t underweight for my height so I didn’t see the problem.

This is the issue with the BMI scale, it lumps everyone in the same category and doesn’t account well enough for our bio-individuality or our bodies’ natural intelligence. Personally, I had to workout excessively and restrict my diet in order to maintain this weight which should have been a major red flag that it wasn’t my natural set point. Perhaps another woman could maintain this same weight naturally with little effort and could be healthy but that is not how my body was designed to be. But because I was so attached to the BMI scale and trusted doctors when they told me I was healthy, I carried on this delusion for too long. I’m sure there are so many other women (and men) stuck in this same false narrative, believing that their behaviours around food are healthy when in reality it is causing more harm than good.

When it comes to eating disorder diagnosis, I think using the BMI scale can be extremely dangerous. Especially today as the trend online is not just to be skinny but also to be fit and lean. There must be so many girls and women out there who are suffering in order to achieve a “perfect body” either by being overly rigid and restrictive around food or by over-exercising but they are at a normal BMI so they must be healthy, right? Wrong. Eating disorders are about so much more than physical appearance, they are mental disorders. Diagnosis should be based on thought patterns and behaviours and not on weight alone. If someone is focused on food to the point it is affecting their life, if they are afraid of certain foods or obsessed with losing weight, it doesn’t matter what BMI they are, they deserve help.

I understand that the NHS has limited resources and that they have to prioritise those who are at the highest risk. Being dangerously underweight can cause so much damage to the body and of course these people need to be under medical care, but for those who fall into the grey area of not being sick enough to receive support this can be a real problem. Disordered eating develops over time and generally the earlier it is diagnosed, the easier it is to recover. Eating disorder thoughts are like a fungus that enters your brain, sets down roots and spreads a network across your psyche. Rooting out all of the false beliefs, stories around food and your body and replacing them with healthy, helpful thoughts takes a lot of time and effort.

Putting off treatment because your weight isn’t low enough yet means falling further down a slippery slope and it can become harder if not impossible to achieve a full recovery. Eating disorders are already such a secretive disorder, drenched in shame and denial. Even when part of your mind realises there is a problem and wants to seek help, the disordered part wants things to stay as they are and will hold tightly onto any excuse to stay stuck. A healthy BMI is exactly that, a lifeline of denial for the eating disorder voice. I still have to deal with these thoughts today, even though I can recognise them and not act on them. I think this is partly because of my disordered eating being hidden and allowed free reign of my sub-conscious mind for so long.

I do believe that full physical and mental recovery is possible but it’s much more likely when these things are caught early and don’t go as deep. I definitely consider myself fully recovered now and have for many years but I don’t think that quiet voice will ever completely go away. As a nutritionist and yoga teacher, healthy and wellness is still a big part of my life but I am fully aware that I have to stay vigilant as it can be a fine line between looking after your health and obsessing over your health. It’s not like recovering from alcohol or drugs where you can completely abstain, you can’t recover from obsession with healthy eating by avoiding healthy foods.. that’s a recipe for disaster! However, my motto now is be healthy to live, don’t live to be healthy. Eat vegetables but also eat chocolate cake. Move your body but know when to rest. It might be cliche but balance is the way!

Over to you

Please like and share this post and help to spread awareness of this issue. Follow my blog for more posts on balanced health, yoga and nutrition for healthy hormones.

If you feel like you or someone you know is suffering with disordered eating, please please reach out for support. Don’t let having a healthy BMI get in the way of getting the help you need.

YOU DESERVE TO HAVE A HEALTHY, ACCEPTING RELATIONSHIP TO FOOD AND YOUR BODY NO MATTER WHAT!

BEAT: https://www.beateatingdisorders.org.uk/support-services/helplines

NHS: https://www.nhs.uk/conditions/eating-disorders/

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