Sunday, 22 September 2013

Rant: BMI measures

I'm not a fan of the BMI scale. I just don't think that it is very accurate - and this is supported by facts and research. Now, before I go on, let me put a WARNING. The BMI (body mass index) scale is sometimes needed. For example, we use this all the time to help patients lose weight, to gain weight, and to monitor growth in children and teens. But what I am not fond of is the preoccupation with BMI, when really, we might be losing the bigger picture of things.

First, what is BMI? You can calculate yours by dividing your weight in kg by the square of your height in m. Generally, 18.5-24.9 is normal, less than 18.5 is underweight, and more than 25 is overweight. But what is wrong with this, you might ask? Well, all this measures is your height and weight. It does not take into account other factors, such as muscle mass. If someone with a lot of muscle used BMI, they would likely be in the overweight section. But are they overweight? No. They simply have more muscle, which makes their weight higher. But it is muscle, not fat; thus, they are not overweight. Let's consider another example. What about a child who genetically has bigger or thicker bones than others (yes, this is possible). Their bones will be heavier, but are they fat? No. Their bones just weigh more. But a clinican might not know this, and thus assume that the child is overweight. If we all used BMI in this way, we might mistakenly think that we are overweight and need to lose weight - when really, the measurement is not taking everything into account.

What about when helping ED patients? Many treatment facilities use BMI, as this is their only reliable predictor. Generally, patients are considered 'weight restored' if their BMI is 20+. I'm not arguing with this - I understand that BMI is needed as some way of deciding when patients have gained enough weight. But, really, everyone is different. Maybe I am healthy at a BMI of 22, and not 20. So why should my treatment team decide that I no longer need help for my eating disorder? What if I need to gain more weight than a BMI of 20 in order to be healthy? Or what if someone without ED has beena t a BMI of 18.5 their entire life. Are they sick? Probably not. This may be due to genetics, their way of eating/living, and other factors. Maybe this person does not need to gain more weight, unless other factors necessitate it. Should we force this person to eat more simply to gain more weight? If they are healthy and eating enough, probably not. Do you see why BMI is a 'gray' measurement to use? It is hard to determine when it is useful, and when it is not accurate.

However, I know that BMI provides us with some useful information, and that is why we still use it today. I'm not saying that this is wrong. I am simply giving a warning out there to people who use BMI. For some, this might create an obsession and possibly lead to ED. For others, their BMI may be in the overweight area when really, they are not overweight. For others, their weight may be lower and underweight on the BMI scale, even if they are healthy. For all patients with ED, however, recovering is more than just the BMI scale! I was weight restored quickly, but my thoughts and eating patterns did not improve for a while. So, please do not get stuck with the idea that as soon as your BMI is in the 'healthy' range, you are cured from ED. It is more than just the number. YOU are more than just a number. So, be cautious. Medicine/science/math can come up with theories and equations to help us, but that does not mean that all of these subjects/ideas are flawless.


  1. I am not a fan of BMI also
    I am athletic and I enjoy strong bulky muscles every where and my BMI is 30 yes but I am very healthy and strong.


  2. Good morning Marina
    As you know I am not a doctor or a nurse like you but I am a therapist.
    I counsel people to enjoy living happy life in moderation.
    I do counsel them re moderation in eating, playing ,work and also use moderations in their love and hate and their views of things.
    I agree with you BMI should not the main target of treating people but rather knowing people and helping them is the key.
    I always ask my self what kind of a person has the disease NOT what kind of a disease a person has.
    Look at you for example , you suffered terrible fatal disease but because of your personality ,perseverance ,honesty ,hard work etc. you recovered and now helping others .

    Excellent post Marina

    Kelly W

  3. I agree
    We are more than just a number.
    We are favoured by God as the best creatures.
    We are unique.
    Number may mean something but not every thing is numbered.

    I like your writings .


  4. I have same experience with my hospital staff re BMI.
    Yes my BMI is now still stable at 22 even I left out patient program and back to my school and my life.
    I do admit now I feel better ,more healthy and able to do much more in shorter time(so my be I was in denial when I was sick as you told me before)
    I do agree with you completely that ED recovery is not only weight restoration or BMI
    I do agree with you most important is one has to recover from ED thoughts, control and dispel all his tricks to scare us.

    I love this post as makes sense to me now
    I am 90% recovered from ED thoughts and working on the 10%
    I need your continuous support Marina

    Love Anne

  5. I agree with you Marina.
    My self despite my BMI is high I do feel healthy and energetic and have excellent prospect for my future.


  6. I like what you say Marina
    I am really not sure if I can reach BMI 22 .I am now 20 and feel the best as I ever been and I will do all the best I can to maintain this or go to 22 but under no circumsatnce I slide to lower than this.
    I had enough from ED tricks and now none of his tricks or thoughts that I can buy.
    Now I feel in control
    Thanks Marina


  7. I agree
    Living healthy and every thing in moderation is our best goal


  8. I completely agree with you.
    I have learnt this during my internal medicine and endocrinology rotation.
    Good Job Marina

    Medical student

    Medical student

  9. Even though I use and teach my diabetic clients about BMI but I do not take it alone. I assess the client as a whole and talk about healthy eating.
    I counsel them about Canadian food guide and tell them about Eat Right Ontario web site .

    RN .

  10. Marina
    Can you explain what did you mean when said

    "I ask what kind of a person has the disease and not what kind of a disease a person has."


  11. Antashia, I think Kelly meant that instead of generalizing the disease to every patient, we look at the patient and how the illness presents in them. For example, I had ED, and I was very thin but I did not purge., Others may also have ED but they may purge. Therefore, we need to look at the patient and not just the illness - because we are all different. I hope that helps!

  12. Thank you so much for clarifying this .
    I may also add that You had ED and you got yourself out of it (not losing one year of your school or a job or a relationship ,other may struggle with disease and loss.
    Thanks again Marina

    I enjoy your blog the most as I learn as if I am intertwining .


  13. Lots of information about BMI.
    I am learning.


  14. I agree with you.
    We need to focus on health rather than numbers.


  15. BMI is not flawless and every theory is subject to critical assessment. We always look at pros and cons of every theory.


  16. I think for kids up to 19 years they use the WHO growth charts not BM. BMI is technically for 20 and over

  17. I do not know what is your advise Marina
    I am a woman and I love to see and feel fat on my buttocks and breasts even if my BMI goes up.



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