Just been having a bit of virtual fisticuffs on Facebook.

There’s always one or two who like to pipe up with a cheeky comment.

Which I then have to reply to and it goes back and forwards, grrr.

At least it gives me some fodder for this blog.

Let me explaineth…

I just posted a link to the BMI calculator on one of me websites.


It’s a simple tool that the docs use to assess whether you’re in a high risk category for several diseases like heart disease, diabetes, etc.

You wouldn’t think there is any harm in this, but a few peeps took offense.

Mostly saying that the BMI scale is pants.

No use at all, apparently.

Now, I’m not saying it’s perfect by any stretch, but it’s an easy and unobtrusive tool that Mary and Jim down the road can use.

Let me break this shiznit down.

The BMI scale tells you whether you’re at risk of certain diseases, which you can then seek further medical advice on.

People are inherently lazy, which makes BMI attractive as it’s as easy as plugging in your weight and height and pressing enter into one of the many apps online.

Or if you prefer to do the math just divide your weight by your height squared.

Once you’ve got your number you can then use a simple set of ranges to show where you fall relative to the general population.

These ranges might be a bit crude and don’t take into account body frames, muscle or gender but they at least give us a guideline to work with.

Obese: 30>
Overweight: 25>
Normal: 18.5-25
Underweight: 18.5<

Now, the problem my social friends had on ye ol’flakebook is that BMI doesn’t take into account individual body type.

I totally agree.

Take me for example, I’m currently at 24.8 on the BMI scale.

Knocking on the overweight range.

I’m not panicking though, as I know muscle ways more than fat and I’m an active guy.

This is where BMI falls down.

Whilst BMI is a reasonable estimator of obesity and disease in regular Joe’s, it’s a little bit shoddy when it comes to predicting risk in people with lots of lean muscle or in fact, little muscle aka ‘skinny fat’ people.

It therefore, doesn’t hold true for everybody.

At the same time there is a good chunk of the population that it does.

So as I said up top, the BMI scale is by no means perfect, but I still think it can be used as a basic tool to assess risk.

And if you find yourself outside of the normal range (18.5 – 25) or just want to dig a little deeper into your health you can either pop down to the docs or use an alternative methods such as body fat % or the waist to hip ratio (WHR) to see whether your BMI paints a true picture.

You can buy body fat % scales/monitors that are able to distinguish between fat, lean tissue and water and give you a rough body fat %.

Although, I’m a little bit dubious of these scales due to the fluctuations I’ve seen on a day to day basis.

For this reason I prefer to use body fat callipers to measure my own body fat %.

You’ll need someone in the know to help you with the callipers and it also helps if you’re not be shy about them pinching your fatty bits (love handles, back and arms).


Age Underfat Healthy Range Overweight Obese
20-40 yrs Under 21% 21-33% 33-39% Over 39%
41-60 yrs Under 23% 23-35% 35-40% Over 40%
61-79 yrs Under 24% 24-36% 36-42% Over 42%



Age Underfat Healthy Range Overweight Obese
20-40 yrs Under 8% 8-19% 19-25% Over 25%
41-60 yrs Under 11% 11-22% 22-27% Over 27%
61-79 yrs Under 13% 13-25% 25-30% Over 30%


Alternatively, you’ve also got the waist-to-hip-ratio (WHR) which you can do yourself with a tape measure.

Simply measure your waist (belly button) and then your hips (widest point round your butt).

Divide your waist measurement by your hips measurement and bingo.

Anything over 0.90 for guys and 0.85 for the ladies is considered a problem.

So, there you go: The good, the bad and the ugly of BMI.

Hopefully it helps clear a few things up and people see both sides of the coin on this topic.

Any questions or comments just fire away…

Leave a comment





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Gavin Walsh
Gavin Walsh

A British fitness and fat loss magician that helps men and women lose the jelly from their belly pronto. Gavin is the head coach here at Body Fixers and has been featured in the likes of Men's Health, Women's Health and Men's Fitness, as well appearing on British TV several times with delightful nuggets of fitness and fat loss wisdom.

    2 replies to "BMI: The Good, The Bad & The Ugly"

    • Russell

      Pretty balanced response Gavin. You’ll never win a fight on FB with a smart arse who’s just been on a course!
      BMI has its flaws but is a good first indicator and is ideal for the average jo. I believe it was used as more a measure of surface area that body comp.
      Keep spreading the love. Russell

      • Gavin

        Easy Russell, appreciate your comment. Don’t worry, I’ll keep banging out the love :)

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