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Why BMI does not necessarily mean good health in 10 bullet points

Why BMI does not necessarily mean good health in 10 bullet points 960 640 Janie

BMI stands for Body Mass index. Health resources state that:

“It is used to give you an idea of whether you’re underweight, overweight or an ideal weight for your height. It’s useful to know because if your weight increases or decreases outside of the ideal range, your health risks may increase.”

But how true is this?

onesmBMI defines us as a number – it is based on our weight and height. Just like body weight it suggests that when we hit a certain number that we will be healthy. There is nothing empowering or solution-focused about this. It does not provide us with any information about why we are this number – our GP just tells us we need to be that number to be “healthy”.

twosmBMI can vary by gender, age and ethnicity – we are all individuals with different genetics, environments and biochemistry. How can a number be the same for all of us?

threesmBMI is not very kind to shorter people – because the “healthy” range proportionally is much smaller. Being 5 foot or under does not give much leeway for “health”.

foursmBMI focuses on body weight instead of health – since height is not able to be manipulated, the only variable is therefore body weight. And it doesn’t focus people on healthy ways to lose weight, it just focuses them on losing weight in any way they can to hit that number.

fivesmTherefore BMI promotes short term weight loss solutions – it pressures people to reach for meal replacement shakes, miracle supplements, crash diets or pharmaceutical intervention. If they lose weight this way their GP will still tell them “good work” because their BMI has come down. But no one talks about how their BMI is likely to increase even more as soon as they go back to normal eating.

sixsmYou can have a “healthy” BMI but be very unhealthy – there are a growing number of people who are being called “skinny fat”. These people have a healthy BMI, but they can have a large amount of invisible or visible visceral fat around their abdominal organs. They may be on their way to becoming diabetic or having a chronic disease but their BMI is good (probably due to a faster metabolism). These people are lulled into a sense of false security – their GP tells them their BMI is fine and they are healthy, so they continue making poor dietary and lifestyle choices until disease catches up with them.

sevensmLikewise BMI considers some very healthy people to be overweight – Geoff has a BMI of 26.5 which is considered overweight. If you have seen Geoff this will make you scratch your head because he certainly doesn’t look overweight in anyway, but if he went to his GP he might be told to lose weight. BMI does not take into account what makes up body weight – is it muscle or fat? If it is a lot of fat then there is a problem. If it is lots of muscle – like Geoff – then a high BMI is actually good! Many professional athletes are considered obese by the BMI scale!

eightsmSo BMI ignores the importance of muscle mass – more muscle mass means a higher resting energy expenditure, it means more balanced hormones, it means a larger amino acid pool for protein building, it means better strength, better balance and ultimately it means better quality of life. Ironically as you increase muscle mass your BMI may go up.

ninesmBMI is a number at a point in time which tells you nothing about its direction of movement – if someone who had a BMI of 35 has made changes to their lifestyle, has lost weight in a healthy way, has improved their health markers and now has a BMI of 30 then that is very healthy. But if they went to a new GP they would still be told they are unhealthy. Consider the other person who up until a few years ago had a “healthy” BMI of 25 but has hit middle age and their BMI has slowly crept up to 30. Should these people with the same BMI be considered to have the same level of health?

tensmWhat if your BMI is slightly high, but you eat well, you lead an active lifestyle, you feel great and your health markers are all good? What if you go to your GP and he tells you this (this is a real-life example): “You are just in the healthy range and can’t afford to put any more weight on”

Of what use is this? Are you going to start dieting to fit a number and perhaps slow down your metabolism? Are you going to start an intense exercise regime and feel fatigued all the time? Are you going to feel stressed about this which is ironically going to increase your cortisol, insulin and ultimately possible lead to increased body weight and hence BMI?


This woman had the same BMI before and after she started her health program. Do you think BMI is a good indicator of changes to her health? (http://paleozonenutrition.com/2012/04/25/what-does-your-body-look-like-on-the-inside-more-reasons-to-lift-weights)




Some better alternatives to BMI are:

  • Go to your GP and get your health markers tested. How is your insulin sensitivity? How are your inflammatory markers? How are your hormone levels?
  • Get a DEXA scan. How much muscle and how much fat do you have? Do you have dangerous invisible visceral fat around your organs? How strong are your bones?

These things will tell you more about your health than a number.