Body Mass Index – BMI

It is safe to say most of us have heard about it and a great many of us have probably used it at some stage in our lives. But is it actually reliable?

Some of you may already already have a firm belief about this and know the answer, but for those of you who don’t I will explain why it isn’t in a nutshell and what other method is better to use.


BMI  ISN’T the best method to determine if someone is overweight or obese as it can not distinguish the difference between muscle mass and body fat. That pretty much sums it up in a nutshell.

Think of it like this. Since BMI cannot differentiate between muscle mass and body fat it can allow someone who is an athlete score a rating of obese when they are obviously fit and healthy. For example most elite rugby players, who are staggeringly impressive athletes, will be regarded as ‘obese’ by the BMI system.

So what method can you use instead? Have you heard of waist to hip ratio?

The waist to hip ratio can identify abdominal obesity. All you need is a measuring tape. You can determine your waist to hip ratio very simply by dividing your waist measurement (cm) by your hip measurement (cm).

Below is a quick guide to getting these measurements.

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To get your Waist measurement:

-Measure directly against your skin.
-Breathe out normally.
-Make sure the tape is snug, without compressing the skin.
-Measure halfway between your lowest rib and the top of your hip bone, roughly in line with your belly button.

To get your hip measurement:

-Measure directly against your skin.
-Breathe out normally.
-Make sure the tape is snug, without compressing the skin.
-Measure so that it is at the widest point of your buttocks.
-Ensure the measuring tape is parallel around you.

A waist to hip ratio greater than:

-0.9 for men
-0.8 for women
indicates an increased health risk for cardiovascular disease, Type 2 diabetes, some musculoskeletal conditions and some cancers.

If your results indicate that your at a greater risk don’t panic. This just means that you have identified a risk and need to make some changes. What I recommend before doing anything is see a Doctor (local GP) to ensure it is safe.

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Then with your GP determine a healthy weight for you. Set this to be your long term goal. But remember to achieve this weight, lifestyle changes must be:

-able to be maintained for the LONG-TERM.

Aim for a healthy weight loss of 0.5-1kg per week to achieve your long term goal. If you need help be sure to visit a Dietician/Nutritionist and/or Personal Trainer.

Other methods to measure body fat percentage include using Fat Callipers or doing a Dexa scan. Dexa scan being the most accurate of all.

If you have any questions about this topic don’t hesitate to ask me here through my profile page or on my facebook page.

I’m a Personal Trainer, Fitness Role Model (Fitfluential Ambassador) and contributing Author for that specialises in many aspects of health/fitness including:

– Weight Loss
– Weight Gain (Hypertrophy)
– Nutritional Coaching
– Sports Conditioning
– Martial Arts

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