“My doctor told me I am overweight" (original: mrsfitcoach on Instagram)

This is your periodic reminder that BMI is bullshit.

Ok, not really.

BMI can be useful for looking at population trends. Why? Because height and weight are two of the easiest statistics to collect if you ask millions of people.

Can you imagine asking millions of people what their body fat percentage is? Most people never have this measured and if they do, it’s often with very unreliable devices.

Therefore, whether we like it to not, BMI kind of wins by default. It’s VERY far from perfect, but it’s what we are stuck with until something better comes along.

But, it is important to realise that someone can be somewhat useful on a population level but not particularly useful on an individual level.

BMI can classify people as ‘overweight’ or ‘obese’ even if their body fat is low, if they have a lot of muscle mass, as demonstrated by this video. You could have the same BMI as someone else, but have completely different 1) body fat percentages 2) fat storage patterns 3) health statuses.

We all know that BMI doesn’t tell people the full picture when it comes to their body composition. We mock it when it misclassifies people.

But, this is a great opportunity to take this lesson one step further and emphasise that using BMI to make snap judgments about people’s health is also a dangerous game.

Because how many people fall on the ‘overweight’ spectrum at the Doctors office and immediately get lectured about their health, before the Doctor has asked any other questions about your physical activity levels, or performed any additional blood tests.

If we can all collectively agree that you can’t assume someone’s body composition based on their height and weight, we should also all be able to agree that your health is more multifaceted than how much you weigh.

Yet, this is still a controversial idea to some people *sips tea*.

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http://geni.us/EverythingFatLoss

References:
- Body Mass Index: Obesity, BMI, and Health: A Critical Review
- Comparisons of percentage body fat, body mass index, waist circumference, and waist-stature ratio in adults
- Indices of abdominal obesity are better discriminators of cardiovascular risk factors than BMI: a meta-analysis
- Central fatness and risk of all cause mortality: systematic review and dose-response meta-analysis of 72 prospective cohort studies
- Body-mass index and all-cause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents
- The performance of anthropometric tools to determine obesity: a systematic review and meta-analysis
- Do No Harm: Moving Beyond Weight Loss to Emphasize Physical Activity at Every Size