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Obese – or Just Overweight?

For some of us, reading an official definition of obesity is, well, a little insulting. It’s not like we don’t know that our bellies are bulging and that our favourite jeans from 10 years ago are 10 sizes too small for us now.

But I like to look at it from a slightly different angle: if I was diagnosed with a serious illness, one of the first things I’d do is go and learn as much as I could about it. I prefer to understand the beast that has hold of my body – or my life – so that, at the earliest opportunity, I can outsmart it, or at the very least, come to terms with it.

Knowledge, as we all know, is power.

So, in the interests of handing you as much power as I can, here’s a quick and simple guide to obesity, minus all the dire health warnings that usually come as part of this discussion.  I’m not going to pretend there aren’t health implications – but the problem is they’re always weighted down (pun intended) with all sorts of guilt implications as well. And we can do without those, thank you very much.

This is the first, necessary part of an overall program of posts that will look at how the body works, how it gains weight and why – all from a purely physiological point of view.

Unfortunately for us, all the really good websites that provide this information are put together by doctors and are exceptionally clinical – which is why I haven’t just pointed you to them. While obesity is indeed a medical, social and economical issue, for me, it’s also about real people – us.

In this post, we’ll cover that clinical definition of obesity and its cousin, overweight. Just remember as you read through this – these definitions, the numbers and everything do NOT represent the whole picture. And if you keep reading, you’ll find a handy tool you can download at the end. If your goal is weight loss, then this is a great tool for you.

Definition of Obesity

According to Obesity.org, obesity is an excess of adipose tissue – which is a clinical way of saying that obesity is defined as an excess of fat tissue. Yeah, I know, groundbreaking, huh?

The terminology is important however, because accurately identifying the type of tissue means that doctors can predict how it will behave under certain circumstances – such as the over-production of insulin, which can lead to insulin resistance. That’s a good thing for you and your health.

Another important thing to consider when looking at this clinical definition is what it doesn’t tell you. For example, it’s not telling you that:

  • Obesity is a crime or a sin
  • That it’s god’s revenge on you for something in your childhood
  • That it’s something you should hate yourself for
  • That it’s something society should hate you for
  • That it means you should suffer in misery

These, of course, play into a whole host of mind games obesity plays in your head which makes the purely clinical definition a little hard to swallow. As I said however, this is only where the story begins, not where it ends.

Am I Obese or Just Overweight?

This question is actually one of the most important you can ask as it impacts on the impact of your excess weight. It also impacts on your options.

The answer is all wrapped up in the contentious subject of BMI otherwise known as Body Mass Index. Obesity is defined as being 25% or more over the maximum desirable weight for a woman’s height or 20% or more in men.


Body Mass Index is a measuring system devised decades ago. It basically puts together your height and weight and tells you a number that says how much body fat you are carrying.

The World Health Organisation uses this measurement when they talk about obesity rates around the world. Like Obesity.Org, their information is full of dire financial warnings meant for governments who are expected to wave their magic wands and fix it – so don’t go to those sites hoping for understanding and compassion and a few weight loss tips*.

There are problems with using the BMI as a one-stop shop to gauge obesity. Dr Steven B. Halls lists the issues with BMI as these:

  1. Body Mass Index changes with age, obviously in children but also in adults.
  2. Women and men are physically different, so why should adult men and women have exactly the same BMI?
  3. Short adult women have higher BMI than taller women.
  4. Race/ethnicity and nationality affect body composition and BMI.
  5. Muscular people, athletes and bodybuilders particularly, have high BMI values, but are not fat.

One of the other problems with BMI is that it’s very fiddly to calculate. It’s okay if you use kilograms: Divide your weight in kilograms by your height, squared.

Yep, I know – most of us haven’t squared something since we were in primary school. Plus, if you weigh yourself in pounds, you have to first convert the number to kilos before the calculation will work.

Which is why I created this handy tool.  This is simply a little spreadsheet that does all the calculations for you – no matter if you use kilos or pounds, meters or feet and inches!

Click here to download it.

Feel free to share this tool around to anyone you think might like to use it.  Remember – this is just part of the picture, and we’ll cover the rest of it in coming posts.

If you’d like to know more about the clinical side of things, Virtual Medical Centre is a good starting point. But really, there’s no better reference than you own doctor.

*Don’t go thinking these websites are bad, despite the lack of ‘humanity’ in the way they present their information. Remember the audience they’re writing for – they do have very important roles, so if you’re interested, please do go and have a look.


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  1. Laura says:

    I do sometimes wonder how badly the statistics on the extent of the “obesity epidemic” are skewed by the use of the BMI tool. It would be interesting to see if some studies have been done that adjust for these factors.

    My husband has a BMI that puts him in the obese category, but almost all of that is muscle. I imagine that as compared to 50 years ago there are many more muscular people around as we have replaced a lot of incidental exercise and sports with going to the gym and lifting weights.

    1. Mackenzie says:

      Hi Laura

      Thanks for your comments.

      I know that BMI makes no sense if you are especially muscular. The more sensible guides I’ve read have acknowledged that. But it does make you question just how helpful it is if you have to keep making exceptions. And what if you’re very strong but also overweight? I would like to see a better tool developed that was more helpful.