To BMI or NOT to BMI

BMI - The ever-contentious way of being measured - healthy, overweight, obese class I, II, III or even Underweight.

I have felt the need to discuss this for quite a while and just put some logic and science to this issue for a while.

This is a bit of a long read so please bear with me here, as this issue needs a bit of background and base information for you to understand what this is all about.

Before I get into, Why BMI? I need to explain a bit more about BMI and what it stands for.

Each one of us are built and made differently and rightly so - can you imagine how boring life would've been if we all looked the same, so we differ in shape, size and height.

Saying that being unique does not give us the excuse to dismiss being healthy and of healthy weight. How to we calculate the healthy weight?

That is where BMI comes in - Body Mass Index.

Body Mass index is the measurement whereby scientifically the average person gets measured as underweight, healthy weight, overweight, Obese. Most of us categorize under average population and only 5% of the population do not.

Let me explain the above statement - The ONLY people that do not fall under that category is if you are an ATHLETE (definition: a person that does sport either for a living or trains more than 20 hours a week) and have a bodyfat of less than 10% in males and less than 15% in females and the rest is pure muscle


Yes, there is a but to that statement - I can assure you MOST of that 5% that have the "I'm outside the norm" ticket will be within 5-8kg of their healthy BMI weight category and the other few % will be in a strong man type of sport.

I can tell you they monitor their body composition very closely and their body fat % to stay within the suggested parameters and a lot of them are only outside their healthy range for a short while inside or outside competition phases.

I have heard every excuse in the book over the years of dealing with nutrition clients as to why they think being in your BMI scale is too thin...

Frankly, society, social media, TV and everything in between has been feeding us such a skewed sense of what is healthy that the moment we see someone within their healthy BMI weight range we criticise "you are too skinny" and then there is the other end of the scale " you are too fat".

Each person has an average of 15kg within the healthy BMI scale from Bottom to the top, so that does give a lot of room for the term "healthy weight".

Being within your BMI Scale (healthy fat and muscle balance) will not require you to have hip bones protruding, cheek bones popping or anything other of the skewed perceptions out there.

Having a healthy BMI Range, allows your bone structure to carry you (its load of muscle, organs and water) as it’s intended to do - WITHOUT having to carry too much strain when we exercise or do normal activities.

We need to look at BMI like a truck that has a minimum and maximum load. That healthy range is your minimum and maximum load your body and joints are built to handle and over that is classed as the classification rightly says "overweight"

What happens to a truck when it’s overloaded? The vehicle axles and load body can break, and essentially that is what happens to the human body. The human body is quite a masterpiece though and it adapts to load and then keeps functioning, but we must understand that anything higher than your BMI of 24.9 will put additional strain on your joints.

By now I can see a few of you reading this frowning and saying prove it…

I only need to explain the implication of impact on some of your joints to bring my point across.

Your, back, hips and Knees – these are the most injured joints of all, and they hurt first in a lot of instances…

For every 1kg you weigh you have 2-4kg of impact on your lower extremity joints when you are actively moving walking etc and running but for this example lets just stick to moving and walking.

Let’s do the math…the average 60kg female therefor has a whopping 120kg of impact if we factor it by 2kg and then when you run, we have a factor of up to 4kg that is a whopping 240kg of force going through your lower extremities.

Now if your skeletal structure is built to withstand the maximum force of 240kg you are at your top end of your BMI of 60kg, can you now understand why adding weight above that classes as overloaded.

NOW we come to the grey area of the BMI 25-29.9 the Overweight class - yes for someone that does non-impact exercise this can be ok, because we only factor by times two or three BUT the moment we add impact, our system directly overloads. AND therefore, most of the ATHLETES – like bodybuilders etc that are in the 25-29 BMI Class don’t do impact Cardio at all!

To get back to our truck example – when a truck is loaded at the right capacity going uphill will be hard but not impossible and then obviously the lighter his load the easier it will go uphill. Our bodies are the same, it won’t be impossible, but it will be significantly EASIER!

I have been throwing some numbers at you in the last paragraph and to put this all-in perspective I am going to explain these numbers to you.

BMI has different classifications according to the age, weight and height.

*Please note these are for adults of 18 and over*

**for Child classifications you can contact me for more information**

Underweight BMI of 18.4 and under

Healthy weight BMI of 18.5-24.9

Overweight BMI of 25-29.9

Obese is a BMI of 30 and over

Obese class I is a BMI of 30-34.9

Obese class II is a BMI of 35-39.9

Obese Class III is a BMI of 40 and over

There after you can go morbidly obese etc but you get the picture.

To Calculate your BMI, you take your weight in kilograms divided by your height in meters squared.

Where do you weigh in on your BMI?

NOW! I can see some rocks in the form of frowns and daggers coming my way already!!

I have been in the overweight category of my BMI for the last 2 years (Due to medication etc for an auto immune condition) running and doing my activities as normal and I have the injuries to show for it, stress fractures, lower back pain etc.

Before that I had a period of a couple of years where I was doing the same but at a healthy BMI and I had NONE of those.

My weight loss journey or my journey to a healthy weight, I should rather say has been anything but straight forward and being in a bit of an extra peculiar position of having an auto immune disease makes this journey anything but easy.

But keeping at it and doing my bit daily to get my body fat lowered to get that healthy BMI is the aim and will be achieved.

The most popular questions I get…

How do I get to a healthy body weight?

Closely followed by….

How fast can I get there?

This one I can answer here…how long did it take you to pick up the weight??? Not overnight…. exactly… I am leaving that one for contemplation….

Then the other questions come.

What do I have to eat?

Can I eat Carbs?

How much do I Eat?

Can I drink alcohol?

Can I eat cake and chocolate?


I can guide you through this journey individually, but I will elaborate on this statement.

What I am going to try and do is give you a broad outline of what it takes to get to a healthy weight and keeping it off.

First and foremost, you must eat less calories than you burn thus a caloric Deficit if you have weight to lose

If you are in the under-weight category (which is more common than you all think) you must eat more calories than you burn, caloric Surplus

If you are at goal weight you must eat at maintenance calories – thus eating as much as you burn – balancing out as we call it

Secondly it must be a healthy variety for your body to get all the needed macro, micro and Phyto nutrients (protein, carbs, fat, vitamins and minerals) That means eating from ALL the food groups in the correct ratio and keeping the rainbow in your plates daily.

Thirdly Hydration plays a vital role in either loosing, gaining or maintaining weight and this is a whole talk on its own but just know adequate hydration is KEY.

Th fourth factor is the movement and exercise. You will see I have put this last for a reason. The simple answer to this…it only plays a 5-10% role in your daily caloric usage and it gets grossly over estimated.

We are all sedentary - because of our type of work and lifestyles- even if you train 6 days a week - unless you sit down less than 5 hours a day you are classed as sedentary

lightly active people are those that stand for 4-5 hours a day and train 45-90min 4-5 days a week.

(More DAGGERS – oh my hat! How can you say that its true! If it, wasn’t we would not have a worldwide obesity problem.)

And lastly…SLEEP…yes…how much sleep do you get?

Hence why I go back to my combined answer


This brings me to the final loaded question of…

Will I be able to eat normal again?

The answer

...maintaining a healthy weight requires you to maintain a healthy lifestyle, and if you are under or overweight your “normal” way of eating is obviously not working

and then…

ABS ARE MADE IN THE KITCHEN…even the ones that don’t make that six pack that are covered with more cushioning than it should be.

How to maintain a healthy weight…Get this…and repeating this.

The first factor of caloric deficit, caloric surplus or caloric maintenance

Secondly…ABS ARE MADE IN THE KITCHEN…food of all food groups and all the variety in the right amounts.


That honestly is the key…making the better choice daily and if you feel you failed get up and do it again the next meal.

This can be as easy or as hard as you want to make it.

By this statement I am not saying never eat chocolates and cake again or never have alcohol again, you just must know the consequences of your action and how to mitigate them and handle them. This we discuss in detail when I coach you.

This is where I am ending this conversation.

To summarise.

To individualise this journey to a healthy BMI we must look at overall health and wellness, hormonal reactions, bodyfat percentage, food tolerances, life stressors and then how well your body functions in burning those calories. Trial and error and repeating simple actions.

I hope you now understand why I am passionate about aiming to maintaining a healthy BMI.

12 views0 comments