What’s wrong with BMIs?

So obesity… It is something else to talk about I guess when many of us are sick of hearing about covid all the time. Though maybe not now though as we know that there is a strong link. But it is true, there is a pretty pronounced problem in with obesity within the UK, but surely it is an exaggeration to say that almost two thirds of adults in the UK are either overweight or obese. Well according to BMI standards this is the case. But most people realise that there are going to be people who have a higher amount of bone or muscle mass compared to others of their size, and we know that BMI doesn’t account for this. Yet did you also know that mortality rates are much lower in both genders with a higher BMI? To the extent that “Among women, death rates declined from 18.6/1,000 person-years in the lowest BMI quintile to 13.9/1,000 person-years in the highest BMI quintile. Among men, death rates declined from 51.5/1,000 person-years in the lowest BMI quintile to 32.7/1,000 person-years in the highest BMI quintile.” So while BMI may be the best option we have, are we quite aware of the extent of the number’s of inaccuracies with it?

Why is BMI Used?

The concept of BMI was created back in the 1830s, by Lambert Adolphe Jacques Quetelet, a Belgian astronomer, mathematician, statistician and sociologist”. However it wasn’t until the 1980s when it “became an international standard for obesity measurement.” Gradually the public became more aware of it, as healthy eating programs were introduced and there was more education at schools surrounding this. Before then doctors still generally used a height to weight chart to measure whether someone was overweight or not, however they were generally aware that it wasn’t the most accurate means of determining health. But there is growing evidence and a growing belief that BMI may not be the most accurate way to judge whether someone is of a healthy weight or not, however it has continued to have been used, due to the expense and further inaccuracy of alternative attempts to determine whether someone is at a elevated health risk due to their weight. But whether a sufficient alternative can be found or not, it is important for everyone to recognize that BMI is not the most accurate means either…

The Classic Muscle Issue (as well as other things)

So the fact that someone who comes out as being “overweight” or “obese”, while having a very high amount of muscle is no new phenom. Instead “for years scientists have said that BMI can’t distinguish between fat and muscle, which tends to be heavier and can tip more toned individuals into overweight status, even if their fat levels are low.” It is expected that many rugby players would be obese according to BMI standards, and you can guess with any other sports people. Yet another thing, BMI isn’t going to measure is bone density. As BMI often list big boned people as being obese, according to the Harvard school of Public Health. With this it is harder still to see whether someone has a high BMI because of it, as it is something which many people are born with rather than something that is worked for and more visibly apparent, while like muscle, bone weighs more than fat!

But What Else?

Well so muscle is fine, but want to know what is always going to be bad? Fat: Fat, fat, fat. Um really? Like with the fats you consume which we think are always bad for us, though in reality some fats are actually healthy; the same is the case with the fat on our bodies. Because while an excessive amount of fat may lead to us developing various health complexities, there are different types of fat “which can have different metabolic effects on health” which “BMI doesn’t tease apart”. Also it obviously doesn’t read where fat is stored on the body, as in some parts of the body it is healthier to have more fat compared to others. As well, I think it would be a decent time to point out that literally every body needs fat, as fat plays a vital role in protecting our organs. Also did you know that our brains are made up of 60% fat!

Not everyone at a “healthy weight” is going to be Healthy either!

So it is fair to say that BMI can be a rough indicator, though there are going to be people within the healthy range who are either restricting or not eating the right foods. It is expected that those who are going to be older may fall into the healthy range, while some may have a higher proportion of fat, due to the reduction of muscle mass and bone density frequently experienced at that age. What’s more is that everyone’s optimal weight is at a different point along the BMI chart, and some people’s bodies at their best with varying amounts of fat. However if the person has been restricting then their bodies may still appear to be healthy according to BMI standards, but in reality their bodies aren’t going to be receiving sufficient energy. Therefore they could be at equal or greater risk of developing certain health adversities against someone who may be above a healthy weight according to BMI standards.

How this could be more damaging

So there are already strong weight body and weight standards to live up to in society. Firstly from social media and beauty magazines, as well as severely harsh standards in some sports like dance and gymnastics. Therefore if BMI is to become more prominent then there is the high risk that many people already weight anxious are going to become even more worried completely unnecessarily. Imagine for instance a teenager who attends dance and is already body image conscious partly due to the harsh image expectations associated with it! While already one in three UK teenagers are said to be “ashamed about their bodies” while nearly half of teenage girls have tried to lose weight by the age of 17.

Therefore I think the message behind this post is to be careful. Because though BMI looks can be effective and it doesn’t look as if it is going to be going anywhere quite yet. So while it’s fair to acknowledge it as a very rough indicator, we need to realise that it can also be very inaccurate while it can potentially be damaging to people’s mindsets around healthy eating and their bodies…

Sources: ethnicity facts and figures, Wikipedia, How stuff works, Medical news today, the guardian, sky news,