BMI how much use it as a measure of obesity?

[mids2019]

Watching the rugby and Tom Curry at 6 foot and 17stone (back row) would be classified as obese under a BMI measure. The guy is obviously an athlete and the 17stone includes a lot of muscle mass which made me think how useful is BMI as a measure of obesity especially with men?

Is an MRI to determine volume of fat tissue the only accurate way of defining obesity or do we have just be subjective and visually determine obesity?

If they have a BMI of 35 and look fat, they are.

If they have a BMI of 35 and look like Tom Curry, they arent.

HTH x

BMI is true for the vast majority of normal people

I think that most people would be aware whether their high BMI is because they are an elite rugby player or not though.
I mean, yes, it’s a broad brush measure and certainly not perfect. But I do also think some people don’t like what their BMI is, and so bring out the “but a rugby player’s would also be high” argument when it’s not really relevant to them and their health.

I used to weight train and at 5’2 my BMI was 32 I now don’t weight train and my BMI is 30. There is a vast difference in my body composition and fitness levels between these measurements and the last 8 years.

i found tell you my body fat percentage at a BMI of 31 was 19% so it’s stands that the rest was water muscle and my organs!

so I think it’s like anything take it with a pinch of salt and if helps measure the population overall we need to accept that some won’t fit the measurements.

It's very useful because the vast majority aren't athletes.

A very useful guide for non-athletes, especially in conjunction with...

• mirror
• tape measurement
• a pair of jeans that fits perfectly when one is a weight one feels comfortable with.

The issue is when that BMI is used to screen people for medical treatment. Say your rugby player was a woman wanting fertility treatment on the NHS, she would get a blanket computer-says-no despite being in peak health and fitness.
That's why I'm so anti-BMI, there is no room for the individual.

BMI is a poor indicator and shouldn’t be used to decide medical treatment. It was designed for populations and not individuals.

BMI is a good indicator for the vast majority of us.

BMI is a health screening tool that can easily be used in many settings and while it’s not without its faults it is useful in certain situations. The gold standard for body composition measurement would be DEXA perhaps followed by CT but both carry radiation risks and the high costs and accessibility is not feasible for use for general population screening.

While BMI has many limitations, it’s very obvious when a high muscle mass is responsible vs excessive adiposity.

How many actual athletes do you know? I don’t think I know any personally so BMI would work for pretty much all of my acquaintances.

BMI is a useful risk indicator for the vast majority of the population. It's well known that it is not appropriate for use in many athletes due to their high muscle mass, but they account for a tiny percentage of the population. Waist circumference is arguably a better screening tool as it indicates visceral (abdominal) adiposity, which is known to be particularly risky.

There are many academic papers analysing the utility of BMI as a risk measure. The cut-offs of 25, 30 etc were in part chosen to be easy for the public to understand and remember but I think it's more useful to think of it as a continuous measure. It's not that someone with a BMI of 24.9 is healthy but 25.1 is not healthy. Rather it's a continuous scale, and a BMI of around 21 is healthiest for most people. There is debate over whether cut-offs should differ by e.g frame size or ethnicity.

I use it. I think it’s pretty accurate for most of us. I am overweight Bmi 28 and a14. I think the heaviest I’ve been was just over 30 and I was a big 16 and definitely feeling pressure in my joints, plantar fasciitis in my foot. Felt much better after I got weight down.