please empty your brain below
“... likely because lung capacity is not proportional to body size”.

I thought that exercise increased lung capacity, & that fitness might be an indicator of better outcomes. Maybe that doesn’t affect corona recovery rates - yet to me that’d be counter-intuitive.

Toni | 04.06.20 - 7:53 a.m. | #

Just Googled Joe Marler, the England prop forward, height 1.83m, weight 120kg= BMI 35.83. Obese, theoretically, just damned large (and strong) definitely. Lung capacity, no idea, but suspect huge. I suppose BMI is, as you say, a rough and ready indicator.

J. | 04.06.20 - 8:00 a.m. | #

I have an intense dislike of BMI for the reason that it's so crude.

Before lockdown I was a regular swimmer, totting up about 8.5km in three sessions a week. Since lockdown I've moved to cycling. I installed an app so I could track my progress, and since 1 April I've done 50 rides and cycled 1011km.

But I'm 180cm in height and 96kg in weight and therefore overweight. I have been "overweight" for years. I have been told I need to lose weight by doctors for years. I get rather fed up of being judged purely on this quite ridiculous metric.

The NHS BMI calculator even has a thing allowing you to put in how "active" you are. Active being doing "60-150 minutes of exercise a week." It's irrelevant to the calculation but it says something to me that there isn't an option for doing more than 150 minutes...

Andrew Bowden | Homepage | 04.06.20 - 8:19 a.m. | #

A large waist size is linked to a higher risk of type 2 diabetes and cardiovascular problems. So this means it could also be linked to severity of COVID-19 as well.
An explanation of abdominal obesity here

Martin | 04.06.20 - 8:30 a.m. | #

I was a skinny child and as a skinny adult I hovered around 10.5 stones for many years, dipping just under 10 stones after an operation at age 33. However this all changed when I was in my late 30s and went on a business trip to the USA for two weeks and came back with a large tummy and since then my natural slimness has disappeared!

My own non-scientific opinion is that people's build differs. Whilst possibly just in the safety zone (around 12st 4lb at last reading) looking at my tummy makes me think that there is still some room for improvement and I am carrying excess weight around.

Half a physicist | 04.06.20 - 8:33 a.m. | #

Obviously not a Government priority at the moment, but this post reinforced to me how I wish they'd finish the metrication project started so many decades ago, instead of stopping halfway!

Tim W | 04.06.20 - 8:44 a.m. | #

By coincidence I read this blog post from a statistician yesterday. It's a good overview of BMI, which was never meant to be anything but one health indicator out of many, and rather a rough and ready one. If you are on the borderline of being overweight, then that's where you are.

freerangestats.info/blog/2020/02/23/bmi

Tony | 04.06.20 - 8:45 a.m. | #

It's a measure of a society, not individuals. Body fat percentages are far better to judge a single body. You and Johnson may well end up with the same numbers as BMI respectively, but it'll be more relevant.

toby | 04.06.20 - 8:52 a.m. | #

It seems there is a lot of concern over your height. This is rather easier to measure than weight and requires no advanced technology. Just a cornflakes box, a ruler, a pencil and a wall. Just for comparison what is your height using the cornflakes method, and resultant BMI? Also bear in mind that your height reduces during the day.

Freddie | 04.06.20 - 8:54 a.m. | #

I wouldn't be surprised if the Prime Minister was shorter than 5 foot 9. I saw him in an airport queue 7-8 years ago and my impression was that he was really quite notably short, which wouldn't be true of 5' 9.

Also, I echo Tim W's comments.

Will | 04.06.20 - 8:57 a.m. | #

I’m worrying more about my waist measurement having ticked up a size or two over the last decade, than whether or not my BMI is marginally above or below some arbitrary number. I’d like to get into my old clothes but I fear I might never manage it. “Eat less, exercise more” is easier to say than do, I find.

But more than that, I’m worrying about my daughter who has needed professional support in the past to encourage her to eat more, because her weight fell far too low, and whether there is a risk that behaviour might return.

Andrew | 04.06.20 - 9:06 a.m. | #

I echo your comments Will... I am always surprised how short Johnson looks behind the lectern at the press briefings, particularly when he's appearing alongside Professor Valance.

And regarding the BMI thing, I think the calculations fail to take into account bone mass. I had a friend who was average height but had shoulders like Johnny Weissmuller and could never be skinny, no matter how much dieting he did, simply because he was "big-boned".

Richard | 04.06.20 - 9:16 a.m. | #

I have short legs - 26 inch inside leg. This means my BMI index works out too big. 5' 3", 11st 12lb - 29.4. Nobody would describe me as obese and doing several miles walk a day (even now) I lead a very active life.

davews | 04.06.20 - 9:16 a.m. | #

As Tony says, if you're on the borderline of overweight, then that's where you are. It's a fuzzy category.
I have, however, taken up your suggestion made recently of regulating my biscuit intake on any day by whether I was under or over an arbitrary set point on my morning weigh-in that day. Very effective. And a BMI of 25 is a good way of choosing that set point. For me, anyway.
I got separated from my scales by lockdown. And drifted unknowingly upwards. New scales have now made urgent action necessary.

Malcolm | 04.06.20 - 9:35 a.m. | #

BMI is a weird measurement, because it's units are that of pressure (kg/ m^2).

Perhaps when BMI is high enough, the pressure is great enough, your skin pops like an over inflated balloon.

David (@DTL) | Homepage | 04.06.20 - 9:36 a.m. | #

David: the unit of pressure is N/m^2 or kg/(m s^2).

anonymous | 04.06.20 - 9:46 a.m. | #

I am 5'9. I have met Boris Johnson twice when he was mayor, and he seemed shorter than me (on both occasions!).

timbo | 04.06.20 - 10:08 a.m. | #

BMI is an inaccurate measure, especially for taller people, as taller people don't just gain in height squared (2 dimensions) they will also gain in depth. BMI isn't a 3D measurement

For example I'm 6'2 and my mother 5'4. I have longer legs, but my leg bones will also have a greater circumference meaning that the "healthy" weight gain will be more than the length^2 difference suggests.

Mikey C | 04.06.20 - 10:14 a.m. | #

I'm very close to you in height and weight, though 10 years younger. Or rather, was close. I used to bob back and forth over the 25 BMI, mostly staying under but occasionally over.

Then I started on the statins. I put on 5 kilos over a few months and then levelled off. Looks like my new normal is "overweight". :( (lockdown has added one extra kilo to that, but I expect it to go once I'm more active)

Chz | 04.06.20 - 10:40 a.m. | #

If you measure your height in the morning, you will be taller than in the evening as gravity compresses the spine during the day.

So your BMI will increase during the day with constant weight.

Mike | 04.06.20 - 10:58 a.m. | #

I did pilates-type exercises for a year and gained (back) half an inch of height. This half inch is now causing me to waver between two BMI categories - rounding up gives a result that is more flattering to the ego!

E1W-er | 04.06.20 - 11:14 a.m. | #

Nice to do the calculations and find I have a BMI of 20.9, right in the middle of the healthy range.

DGD | 04.06.20 - 11:38 a.m. | #

In good news my weight this morning was 12 stone 2, so today's post is almost irrelevant. Almost.

diamond geezer | Homepage | 04.06.20 - 11:59 a.m. | #

I'm not sure of my height either (I'm sure I'm being worn down) but either way my BMI is between 22.5 and 23.3.

Like you, I have also lost weight since lockdown - one whole, hard-won pound! On the plus side, it marks a steady drop of 9 lbs since Christmas!
Even at that weight I was still just in the green section but I don't feel I'm a healthy weight.

I still have my "baby belly" 19 years after the youngest was born and my waist is too big, and I haven't worn a swimsuit since 2003! As they say, there is a lot of room for improvement

Cornish Cockney | 04.06.20 - 12:00 p.m. | #

“contrary to expectations, I've actually lost weight under lockdown“

Bakeries and chip shops all closed. Would that make a difference?

dg writes: No.

Cheeky | 04.06.20 - 12:16 p.m. | #

BMI (along with smoking & drinking habits) are used by life insurance companies to assess your health. I'm built like a toilet block so my BMI is very high but you'd struggle to accuse me of leading an unhealthy lifestyle or being unfit. Yet, according to the life insurance companies, I'm a very high health risk so my premiums are very high to match.

Jon Jones | 04.06.20 - 12:29 p.m. | #

This is useful information for the DG spotters. I now know that I need to look out for someone between one or two inches shorter than me, and two to two and a half stone lighter.

I have always been on the overweight end, at one point reaching 20 stone. But I am trying hard to get down into "normal" before my next birthday.

Friar Sven | 04.06.20 - 12:36 p.m. | #

I have a theory that the lockdown is causing fat people to get fatter and skinny people skinnier. No way to test it, though.

Jimmy | 04.06.20 - 1:36 p.m. | #

After I retired in 2011 I began to put on weight; my GP advised some years later on bringing that down. Like me, he was wary of 'diets' because once you've reached a goal weight, what next? Many abandon the 'diet' and yo-yo on the weight.

The critical point about weight is not just when you weigh yourself (as earlier) but how often. My GP said only once a month as weight varies day to day.

My weighing routine is on the 5th or 6th of each month under exactly the same morning conditions. After I've had a morning cuppa, after a loo visit, before going into the shower.

The weight reduction regime is nicely simple. It's slow but effective; stick with it for permanent good results. I've slowly taken off 21 lb over several years, bit stalled at the moment, but the routines is basically:
1 - drink more water
2 - minimum 2 brisk half hour walks weekly, to work up a sweat, not to become breathless
3 - eat more veg
4 - cut down on carbohydrates (not 'out', he said as you still need 'treats', just severely ration them)

BMI's value is like car fuel consumption data in adverts - no car actually achieves those, just a comparison by a common standard.

Joel | 04.06.20 - 2:32 p.m. | #

Congrats on the weight loss DG, from personal experience going down is far harder than going up!

TomH | 04.06.20 - 3:15 p.m. | #

DG, if you're only hovering on the edge of overweight, I think you're doing well. I'm also hovering on the edge of the overweight category, but at the wrong end of the scale.
My doctor (as another commentator mentioned) suggested that the height / waist ratio is a more useful health indicator. (Using inches) your waist should not exceed half your height. Those heavy but trim rugby boys score well on that measure. I break this rule, but only by a small margin - phew.
Like yourself, I've also lost weight in lockdown (though only a little). I put it down to consciously doing exercise every day, as it was the only way to get some fresh air.

IslandDweller | 04.06.20 - 3:31 p.m. | #

That'll be it for the Creme Eggs then... ;-)

Gordon | 04.06.20 - 8:01 p.m. | #

Simples - just don't weigh yourself.

kev | 04.06.20 - 8:35 p.m. | #

IslandDweller, the units don't impact whether your waist is half your height - the rule is standard in any distance measure.

TomH | 04.06.20 - 9:15 p.m. | #

Any scale which suggests that Olympians like Sir Chris Hoy and Sir Matthew Pinsent are 'obsese' (and therefore unhealthy) when both of whom are patently not can't be worth much in terms of value.

Jordan D | 04.06.20 - 9:32 p.m. | #

@anon... That's what I get for trying to do physics before I've woken up.

David (@DTL) | Homepage | 05.06.20 - 10:07 a.m. | #

Came across this pertinent piece in the Metro [app] last night: How to use your bathroom scale to find the right weight loss strategy.

The article discusses a randomised control trial of a programme developed to help people lose weight:

E1W-er | 05.06.20 - 12:38 p.m. | #











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