Body Mass Index? More like Barely Meaningful Integer…amIright?!

What’s this? A Blog post from the other side? No! I am, in fact, still alive. I have been taking time to learn more about the Size Acceptance movement and Health At Every Size as well as the important differences between the two. I’ve decided to dig even deeper (and blog about it along the way). This month I am learning about BMI and the results aren’t pretty.

IMPORTANT NOTE: TRIGGER WARNING: In this post I will be using terms like ‘obese’ as it is a term associated with BMI labeling. I will also be discussing metabolic health. It is important to note that health is not an obligation nor a ‘barometer of worthiness’ (as the lovely Ragen would say), nor is it always within your control. This blog is only meant to discuss the short comings of the BMI system and the effects it has on society and policy. Also, this is a really long blog post. Read it anyway.

Body Mass Index (BMI) is a mathematical formula used to generate a number based on the height and weight of an individual. This magical number is then supposed to determine things like health and longevity but instead determines things like whether or not you will qualify for health care, whether or not you will receive an evidence-based diagnosis and treatment from your doctor (read this! And this!), how much weight-based social stigmatization you will face, etc. Why is it so ineffective? Let me count the ways!

The ways:

  1. It’s the wrong tool for the job

The BMI system was never intended to measure individual health but was meant to measure and predict trends in large populations. Its inventor, was statistician/sociologist (read: not a medical doctor) and wouldn’t have been considered an expert in the medical field 200 years ago let alone today. Even the dude responsible for making BMI popular in medicine today explicitly stated that it was not appropriate for individual evaluation.

We have the ability to measure the metabolic health of an individual without profiling them by their appearance. If fitness level and behaviors are measured, a much more accurate and individualized picture can be established independent from weight and height. Why is the BMI system still used over other more accurate methods? Answer: it’s cheap, easy and profitable. Our fear and misconceptions about our health are making a lot of people very rich.

  1. Metabolic health is complex

BMI makes no concession for things likes muscle mass, bone density, body fat percentage, fitness level, etc. The idea that it can predict health when it cannot even account for these things is ridiculous. Body builders often complain that according to their BMI they are classified as overweight or obese! This may seem like a superficial complaint, but when it begins to affect your ability to qualify for health insurance, it becomes a serious issue. Sounds a little cash grabby on the part of the health insurance industry, doesn’t it?

The truth is that health is a complicated and multifaceted issue and profiling someone’s health by their size is both foolish and damaging. Angela Meadows notes that “thin people are not treated for conditions that doctors think they can’t have, fat people are treated for conditions they don’t have, and eating disorders rise exponentially in ever younger children.” In fact, studies show that a substantial portion of the population is misidentified when using BMI as a valuation of health. This results in sicker people not being treated and additional cost burdens to health care for people who are being treated unnecessarily.

  1. Weight is not a measure of health.

Time to prepare your surprised face! Fat does not equal unhealthy. Crazy, right? So all you concern trolls going, “OMG, BUT WAT ABOUT UR HEALTHZ!” can just take a breather. Seriously, stop. Weight and health are two separate issues and BMI only very weakly correlates these two factors.

Studies show that BMI only weakly predicts longevity and most studies actually find that ‘overweight’ and moderately obese people live just as long, or longer than ‘normal weight’ people. Also, obese people with type 2 diabetes, hypertension, cardiovascular disease, and chronic kidney disease tend to fair better than thin people with the same conditions. So why do doctors prescribe weight loss as a cure for these diseases?


The age old argument is that there is a higher correlation between obese people and certain diseases; but it is important to note the difference between correlation and causation (seriously, click that link; it’s hilarious). Did you know there’s also a correlation between reading ability and shoe size? Why is Michelle Obama not waging a war against illiteracy in the tiny footed?? Oh, wait, those are babies. We need to remember that when two things are correlated there is often a third factor at play. Dr. Linda Bacon notes that weight cycling and yo-yo dieting can increase risk for many obesity related diseases including hypertension, insulin resistance, dyslipidemia as well as poorer cardiovascular outcomes. She continues to note “that the association between weight and health risk can be better attributed to weight cycling than adiposity itself.” Other contributing factors to consider are socio-economic status, stress from size based discrimination and shaming, etc. Maybe it’s more complicated than fat=bad. Maybe there are lies, damn lies, and statistics. Maybe our solution to the ‘problem’ is actually the problem.

The absurdity of having such sharp lines drawn between healthy and obese was reinforced in 1998 when the CDC lowered the threshold for what is considered unhealthy causing 29 million Americans who were previously considered to be healthy to be reclassified as overweight from one day to the next. What’s interesting is the individuals responsible for this decision had direct financial ties to the diet industry. These people then advocated dieting for anyone who did not fit into the newly defined ‘ideal BMI’ category. I’m sure they just had our health in mind though, right?

  1. It feeds the hate fire!

BMI + Calories in/Calories Out myth + Ignorance = OMGDEATHFATZWTFBBQ!

I’ll break it down for those of us who had trouble with math. People believe that fat people are diseased (BMI) and that it’s a result of our own personal failings as humans (+ Calories In/Calories Out Myth) and that because they have been ordained the almighty rulers of your personal choices (+ Ignorance), we then get our so called ‘Obesity Epidemic’ (= OMGDEATHFATZWTFBBQ!).


People like to justify their size based prejudice with the “science” behind BMI. When it doesn’t work people think they just have to hate a little harder. If they are able to muster enough self-righteousness they will be able to shame us into either changing to fit in, dying or disappearing from sight. This is often sometimes perhaps occasionally not done with malevolence; these attitudes are so ingrained in our culture that people do not even realize how rude and damaging their behavior is.

The negative view of fat people is not only ineffective in producing thin people but also contributes to rising numbers in eating disorders. It distracts people from larger health issues; it discourages fat people from visiting their doctor for fear they will be discriminated against, and it discourages fat people from participating in healthful habits (and life in general). It also contributes to depression, stress levels and poor self-esteem. Perhaps more importantly, it effects public, medical, professional and insurance policy. There are laws protecting against nearly every other form of discrimination, but none to protect against size based discrimination.

What should we do?

Our focus needs to change from size to behaviors. Evidence shows that people reap the benefits of healthy behaviors independent of size or any weight loss. People can engage in healthful habits at any size! This is not to say that it is ok to police other people’s behaviors, but only that size is not and should not be treated as a limiting factor.

So speak up! Tell your doctor to give you evidence based medical care next time they tell you your BMI isn’t ‘ideal’! Post articles about Health at Every Size and Size Diversity Acceptance on social media! Think critically and do your research! Call people on their discriminatory behavior! Challenge people’s attitudes and assumptions! Let’s make this world a safe place for people of all sizes! RIOTS NOT DIETS!

-Amy out!


5 thoughts on “Body Mass Index? More like Barely Meaningful Integer…amIright?!

  1. I agree Amy – very well written. Marketing can convince people of just about anything. BTW, according to my BMI, I am too short! 😉

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