The troubling truth about the BMI…

According to the internet, the words ‘BMI’ and ‘healthy’ go hand-in-hand. What if I were to tell you that that couldn’t be farther from the truth?

While the body mass index (BMI) scale is widely used by medical professionals today, it has a troubling history and needs to be reconsidered as a measure of health.?

Here’s what you need to know:

Until the early 1900s, doctors saw weight gain as a normal part of ageing. What changed perspectives wasn’t based on scientific evidence but rather a cultural preference for thinness.

At that time, the flapper was the beauty ideal - straight, slender lines, youthful, no curves. Patients started asking doctors for weight loss advice, which is why medical offices today have scales.?

Around this time, life and health insurance companies started using height-weight tables to categorise people as ‘normal weight’, ‘overweight’, and ‘underweight’.

For this they used the Quetelet index which was developed by a Belgian astronomer in the 1830s to see if the law of probability applied to humans at the population level.?

The BMI, as it’s now known, was never meant for clinical use but instead as a statistical exercise.

What’s Challenging? about BMI as a measure of health?

The equation was created using strictly white, European bodies that don’t represent ethnic size and shape diversity.?

Neither does it factor in age, sex, body size, fat distribution, or behaviours and lifestyle. But because insurance companies profit off charging a premium for ‘overweight’ BMI, they push the narrative that larger bodies have a higher mortality risk. In reality, more representative data samples prove that ‘overweights’ have a lower mortality risk than ‘normal’ and ‘underweights’.

What’s more, in 1998, the National Institutes of Health changed the threshold for what was considered a ‘normal’ BMI causing millions of Americans to become ‘overweight’ overnight without having gained a pound.?

This change was based on a report funded by pharmaceutical companies that make weight loss drugs.

The outcome of this origin story is that fat now gets exaggerated as a health risk.?

What research actually shows is that while there may be a correlation between fatness and disease, that doesn’t equal causation. Taking into account that many studies published on nutrition are industry-sponsored, it’s important to be careful with how we interpret the reports.?

Many commonly held beliefs about weight are simply not true - like ‘obesity’ causes type 2 diabetes, heart disease, and stroke.

Correlations between two things can be caused by a confounder, or a third factor, such as weight discrimination, stress management, access to healthcare, etc., that affects both of them.?

So If Not BMI Then What?

Blaming fatness for disease is like blaming yellow teeth for lung cancer without looking at smoking as a cause of both.

So how do you effectively measure health if the subject is more nuanced than you thought?

Fitness - Mental and Physical

The death rate for women and men who are thin but unfit is at least twice as high as for their fatter counterparts who are fit. Fitness reduces anxiety, blood pressure, the risk of dementia, depression, heart disease, stroke, type 2 diabetes, several cancers, and improves sleep quality and bone health.

Physical fitness doesn’t have to look like militant hour-long sweat sessions. Find an activity, maybe something you did as a kid, that revives your inner child. Something that brings you absolute joy that you can lose track of time while doing.

Try substituting the word ‘exercise’ for ‘playing’ and see what new activities you’ll try with that mindset shift.

Look at your own internalised fatphobia and the ways it’s influencing your relationship to food and your body. Rather than approaching eating by external rules (time, portion size, calories, etc.), trust your body’s cues of hunger, fullness, and satisfaction and let them be your guide.?

Releasing food rules to treat your body with dignity and respect can be a challenging transition for those who’ve only ever known the diet mentality.?

If you are looking for support with this, feel free to schedule a call with me HERE and we can discuss where you are currently at and which one of my programs would be suitable to help you to cultivate a healthy relationship with food and exercise - without diet culture and unhelpful messaging on what health should be.

Until next week,

Denise