The problem with BMI calculators

Do you know your BMI? Do you care? Whilst I absolutely agree that being healthy and fit is important, and, whilst these things are personally important to me, I honestly think that it can be really dangerous to solely focus on either the scale or what your BMI is.

Photo by Anna Tarazevich from Pexels

What is BMI?

So what is BMI? BMI stands for Body Mass Index. It is a measure that uses your height and weight to work out if your weight is healthy. The BMI calculation divides an adult’s weight in kilograms by their height in metres squared. For children and young people aged 2 to 18, the BMI calculator takes into account age and gender as well as height and weight.

So what’s the problem?

The problem is that if you are going off BMI alone you can create a huge problem and give yourself or others a false perception of the reality.

I can’t remember the reason, but when I was 15 I was told what my BMI was. It must have been some sort of health check because I remember sitting in a room with a lady in a blue uniform. I don’t remember what she told me my BMI was but she pointed to the chart which said I was in the obese category. I was mortified. Totally mortified.

I was a size 8 at the time. I wasn’t skinny and never have been but I was fit and active from horse riding, cross country running and going to fitness classes with a friend. Yet, here was this women, bursting out of her blue uniform telling me I was obese and needed to do something about that.

I did. I started throwing my lunch in the bin at school, saying I wasn’t hungry at home and doing hundreds of sit ups in my room at night. It didn’t take too long before my grandmother, who looked after me and my brother after school figured it out. She was furious – not with me but with what I’d been told. I was able to talk myself out of this extreme behaviour before it became a problem, but I always wondered how many people couldn’t do that. How many teenage girls had that woman in the blue uniform spoken to?

The next time I had my BMI measured was as part of a health check in one of my first jobs during my early twenties. I was a size 10 and I had been training hard for a marathon. I was running, going to the gym 5 days a week, and swimming in lunchtimes. I was probably the fittest I’ve been in my life. BMI said OBESE!

Photo by Anna Tarazevich from Pexels

Given I knew more about this by my early twenties, I challenged the health professional about this. I asked her if she would have said I was obese when I walked in. She said she would not have said that. She thought I looked athletic and healthy – so why then was there a recommendation on my sheet that I needed to lose weight? She never really gave me an answer, other than, that’s what they were told to do!

I’ve sometimes thought back to that time and laughed at how ridiculous that whole conversation was. Don’t get me wrong, there have been multiple times in my life when I’ve wanted to lose weight. I’ve never been skinny and I have always had to work at my figure. I’ve always exercised which means that to actually make a difference I have to constantly vary what I do. To ‘change’ my body I have to lift heavier, vary the exercises and run faster over short distances. I used to joke that I must be the only person who can train for and run a marathon and not look any different. I don’t think I’ve ever been totally satisfied with where I am, I’m always trying to improve, but at the same time I don’t think that I have ever been obese either.

Photo by Olya Kobruseva from Pexels

The big issues

BMI takes no account of waist size, which is proven to link to obesity. It takes no account of bone mass, water or muscle in individuals and it is an outdated approach. The BMI was introduced in the early 19th century by a Belgian mathematician. The formula to give a quick and easy way to measure the degree of obesity of the general population to assist the government in allocating resources.

If the BMI calculator is used alongside other indicators of health and wellness then I think that is fine, but surely as a stand-alone tool this can’t be relevant.

Your thoughts

What are your thoughts about using the BMI? Do you think it still has a place?

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