RoR: Forum

Great! Now that I am 60 they tell me I could have eaten all that chocolate up until I was 59. I have figured it out, finally. There is a God, but he has a really strange sense of humor.

Post 1

Thursday, April 21, 2005 - 8:03pm

Great post, Adam!

It highlights the folly of centralized science and nutritional policy.

Also, the tool they are using to estimate body fatness (ie. Body Mass Index) is not very valid--it is only precise. As validity (accuracy) vs. precision has been a main theme of mine, I will not beat a dead horse here (and, anyway, that dead horse will be resurrected soon--when Linz eventually publishes my next article, from the queue).

BMI* is a very simple formula of weight (in kgs) divided by height (in meters) with the height "squared." E.g.

100kg 100
------- = ------- = 25
(2m)^2 4

*If you would like to know your BMI, then go to:

http://www.halls.md/body-mass-index/av.htm

... and then punch-in your height and weight ... and then hit "calculate"

Ed

Post 2

Thursday, April 21, 2005 - 9:23pm

Thanks for the link, Ed!

It appears I'm going to live long enough to be num++++ [BMI = 21.8kg/m²].

_____________________

From a pedantic physics point of view, shouldn't this BMI formula use the height cubed? Only flat things (paper, cloth, roof sheathing) are 'weighed' like this.

It would then be a measure of 'density'*. Since fat is less dense than water, which in turn is less dense than muscle, this would effectively separate those who are fat from those who are muscular. The higher the score, the leaner the build.

Another measure could then separate the lean and mean (a marathon runner) from the hypertrophic (Arnie). Add up the chest, waist and hip measurements, then divide by height. The higher the score, the more muscular the build.

The combination of these two measurements should suffice to capture a wide variety of physiques with greater descriptiveness and accuracy.
_____________________

*Not actual density, but dimensionally the same.

Post 3

Thursday, April 21, 2005 - 10:22pm

num++, you said:

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"From a pedantic physics point of view, shouldn't this BMI formula use the height cubed? Only flat things (paper, cloth, roof sheathing) are 'weighed' like this.

It would then be a measure of 'density'*.
----------

Actually, the decision to square the denominator was arrived at pragmatically (and not by the application of logic to experience; in an effort to truly understand the "nature" of something--as you alluded to above).

The underlying effort that led to this particular formulation was that of explaining the variation in death rates--in terms of height and weight. As luck would have it, squaring the denominator led to the "best-fit" line between rising BMI values and a rising risk of death.

And as you note, an underlying variation in lean mass is not accounted for--so the formula is only good for the 85% of us who do not regularly (2+ times per week) engage in vigorous exercise.*
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*Vigorous exercise may be defined as exercise that requires an energy output of more than 6 times your metabolism (ie. more than 6 "METs"). Examples would include fast-walking/jogging at speeds in excess of 4mph; and weight-training that is so vigorous that you maintain a thin layer of sweat while lifting.
----------
Ed

Post 4

Friday, April 22, 2005 - 5:21am

The BMI is a very difficult and imo a very faulty idea to measure your "weight" - risk correlation. But that's a topic of a different day.

Instead the table shows that a little overweighed is actually healthy. But as it is always with statistics, we have to see what other circumstances affect those deaths and the actual situations.
I think you cannot only bring up weight and point to such a table as evidence. It is only a small factor in a large equation (f.e. there is a general health issue, the state of the immune system, a chronic illness among so many more).

However, I think that overweighed has no direct effect on mortality (except in extreme obesity), but rather on the quality of ones life. For example, you can live up to a 100 years, but still you can be disabled or having to stay in bed. This is exactly the problem of overweighed that I think is a drastic problem to all "government insurances", because those health people have to pay for the "extras" of the overweighed. That's also why those Nannyists want you to have less weight, so that their calculation on the social insurance can be right.
After all, the weight and the size of your body should be totally in your control, so that you might be fat, thin or "normal", whenever you choose. I prefer to be normal, because I don't like to be chained to my chair and at least to have some endurance left.
I think there is nothing more painful to me than not being able to run a few hundred meters without sweating to death :)

(Perhaps this is my opinion, because I am so young, but still that's my idea of being good :) )

Post 5

Friday, April 22, 2005 - 2:58pm

Ed Thompson:
Actually, the decision to square the denominator was arrived at pragmatically (and not by the application of logic to experience; in an effort to truly understand the "nature" of something...

I suspected as much that I was being pedantic.

I have a visceral dislike for empirical equations. They describe (wrap) something without having an 'inside'. There simply has to be a better formula; curve-fitting is too arbitrary! (rants at wind)

Thanks for your reasoned reply.
______________________________________

Back to the topic...

Is it possible that the advancing state of medical technology is the reason for this finding? With better drugs and earlier diagnoses, those who are overweight but not obese may stand to gain the most. People within 'normal' weight don't have much to gain while those who are obese are still too far a medical challenge to have their statistics dented.

It seems all the sample populations are from the US. It would be interesting to see if this holds for a world-wide sampling (with different medical and health practices).
______________________________________

For amusement, I tried plugging into the BMI form the extremes of human physique. For Robert Wadlow, I had to use his age 16 measurements since the form does not go past 8 feet (he grew to 8' 8", 492lbs. at the age of 21; 8' 11.1", 439 lbs at age 22 [deceased]). Here are the results:
________

Tallest Man Ever - Robert Wadlow
374 lbs.
7' 10"
age 16, male

BMI = 29.8 kg/m2
weight at 98th percentile
Body Type: Obese (but he was actually quite skinny)
________

Shortest Person Alive - Madge Bester
66 lbs.
2' 2"
age 35, female

BMI = 68.6 kg/m2
weight at 98th percentile
Body Type: Check your numbers (but I did!)
________

The reader may want to try King Kong (was he fat?)
40 feet tall, 100 tons, 80+ years old?

Post 6

Friday, April 22, 2005 - 3:09pm

num++: Ed comments on BMI are correct. However, another way of looking at is as follows: Humans are basically elongated sausage/cylinder -like creatures - mass/height^2 is essentially a good way way of slicing through (say your abdomen) and seeing how broad you are on average - let's say an average diameter.

In fact waist circumference (at the belly button) is actually turning out to be a better predictor of mortality differences than BMI (107cm/43inches is often cited as where you should start to worry). Only problem is its not as precise (you can always cheat a bit and suck your belly in a bit no matter how much the measurer tells/coaxes you to relax). Stangely enough studies are indicating that waste circumference on its own is a predictor (without reference to to height) i.e. 110cm is not OK even if you're 2m tall. [num++: to get back to the sausage/cylinder analogy - pi - diameter is related to circumference]

Max is onto the crux: You cannot take one factor into account in isolation. I looked through the study: They've taken gender, race, smoking status and alcohol consumption into account. Although they stratified age into 3 age bands, I would find not using age in the model hugely problematic (there are massive differences in mortality in the age range 25 to 60 for example). Another usually significant variable not used is wealth although they do allude to this - they surmise the overweight are likely to be wealthier and have better access to healthcare etc.

Ed - your comments on lean mass are spot on - BMI has this failing (waist circumference doesn't).

Post 7

Friday, April 22, 2005 - 3:21pm

I have a visceral dislike for empirical equations. They describe (wrap) something without having an 'inside'. There simply has to be a better formula; curve-fitting is too arbitrary! (rants at wind)

Unfortunately we're not too good at visualizing multi-dimensional data (at least most of us aren't). Thus multi-variable curve fitting can give a good description of data (at least sometimes). The skill lies in doing it properly.

This is the observe stage in the scientific method.

Once we observe properly we can come up with reasons, models, theories etc. - the think stage. However, if we don't observe properly we will always stumble at the next stage. Unfortunately the human body isn't simple.- compared to rocket science for example :-)

Post 8

Saturday, April 23, 2005 - 4:54am

How did my technical drawing profersor put it? Ah, yes, he said: "It is easier to construct a whole warehouse with its logistics in CAD 1:1, than one little plate of spahgetti. You won't have the latter, while the first might be difficult it is at least possible."

I think it is the same with the human body, but I think it can be possible in the future. However, today's ressources can't get to the bottom of the issue.

@num++:

My problem with this is that perhaps the tallest man had a serious problem with his health? I mean, it is a difficult life if you are so big (given that most buildings and tools are not designed for those extremes). Perhaps he really had problems, although not obesity, but quite as severe as obesity?
I don't know about this, because I never met or observed the life of the tallest man, but the BMI could very well even measure this, because it's only result is a coefficient for being normal.
It doesn't say anything else than whether you are in the majority or the average, rather than in one of the extremes.

Post 9

Saturday, April 23, 2005 - 11:01am

Wayne Dam, you seem to have read my mind. I was actually trying to imagine a 3D-graph with BMI on the x-axis, age on the y-axis, and relative risk of death on the z-axis; then to imagine how this has changed over time. From the data in the JAMA article, it seems there has been a substantial drop in mortality rates from NHANES I (1971-1975) onwards [Fig. 2, p. 1864]. This bolsters my speculation that this is an effect of medical advancement. Conversely, it can also be said that medical advancement has 'changed' the optimal weight for humans.

Max, your professor is using the wrong software. Drawing spaghetti is easy in Photoshop (which in turn is clumsy for CAD work). Funny, I just finished a plate (of real spaghetti, not Photoshop spaghetti) before I read your post.

I do have a habit of testing mathematical models at their extrema.

Regarding Robert Wadlow. He actually led a life more active than most peoples' (Touring for a circus and a shoe company). His chronic problem seemed to be poor circulation in his legs (no surprise there). He had to use braces when walking, and one of these braces did him in. A poorly designed brace blistered his ankle, the blister got infected, and he died from the infection (this was 1940).

If he lived today, I think he would have had a healthy life. Just imagine the possibilities for a 9-feet tall center in the NBA! (OK, maybe not that kind of healthy.)

Back to BMI...

I did a little more reading into this. Turns out this formula was developed by one Adolphe Quetelet (1796-1874) in the 1840's! And he called his studies social mechanics!

And something even more disturbing. From this link.

Quetelet thought more of "average" physical and mental qualities as real properties of particular people or races awaiting discovery and not just abstract concepts. Quetelet helped give cognitive strength to ideas of racial differences in nineteenth century European thought. His conception of "average man" is the central value about which measurements of a human trait are grouped according to the normal curve. The "average man" began as a simple way of summarizing some characteristic of a population, but in some of Quetelet�s later work, "average man" is presented as an ideal type, as if nature were shooting at the "average man" as a target and deviations from this target were errors. Cournot and others criticized the concept. An individual average in all dimensions might not even be biologically feasible, they argued.

This particular observer has certainly stumbled in the think stage.

Post 10

Sunday, April 24, 2005 - 3:54am

Well, I think I have a problem with your photoshop definition, because you will never be so exact in your calculation as if you do a technical drawing of a machine.
Believe me, I tried to create natural objects in 3D Studio Max and I almost threw my computer out of the window. You have serious trouble creating a 1:1 copy of your plate of spaghetti. My prof confessed that this was a test to show us that we can try as hard as we might, but we will never be as good in drawing natural randomness, than we will be in drawing technical machines :)

Post 11

Sunday, April 24, 2005 - 12:53pm

Max, lighten up! Nobody will photoshop a plate of spaghetti by calculating each and every spline of pasta. BTW, Photoshop is a 2D mostly-raster based image processor, not a 3D modeler like Studio Max or AutoCAD.

Agreed; anyone who has to exactingly model pasta in 3D will straighten up the convolutions of their brain faster than they can straighten up their noodles.

As for that scaled copy, you may want to relax at the sight of this 100,000:1 BOWL of spaghetti. Just look at the sight of those meatballs! They will do wonders for your BMI.

[This is from barrygoldberg.net. It's copyrighted but OK to the artist.]

Post 12

Sunday, April 24, 2005 - 2:08pm

Mama Mia!!!!!!

Monday, April 25, 2005 - 4:54am

Nice one. I know my photoshop, too. So I understand what you mean to say.

But it is this perfection that has bought "technical drawing" the attitude of a science rather than Art. This is untrue, because you need a lot of imagination and creativity to come up with such utterly complex drawings of machines. I just wanted to defend my stand that you will never recreate a natural random-noise problem like a spaghetti plate as you can do it with a technical drawing of a machine :)

Post 14

Monday, April 25, 2005 - 10:43am

It is extremely disengenous to downplay the risks associated with being overweight. While the BMI is completely absurd, the notion that health is correlated to weight is well established, even if the BMI's concept of measureing and placing a value on weight is absurd. As your weight increases your chances of developing cancer increase, and being overweight is the leading cause of the formation of Type II diabetes. Please do not suggest that being overweight is healthy, it is not, nor is drinking one glass of wine nor is a few chocalates a day (beacuse they have anti-oxidants!) The negative effects of the alchohol (a strong carcinogen) and extra calories of the chocalate far outweigh the benefits of thier alleged blood thining and anti-oxidant properties. There are a thousand more studies which do correlate increased weight with negative health effects, the most stunning and obvious of which are the research done in caloric restriction.

Caloric restriction diets (sometimes refierred to as CRON or CR) constitute consuming at or above the RDA of all the vital nutrients, but BELOW the RDA of caloric intake. Restrictions as small as 5% - 10% can cut your chances of developing cancer in half, and delay the onset of cancers, and slow the progression of existing cancers. Restrictions up to 40% are seemingly possible and can double your life expectancy. For all intents and purposes they slow your rate of physiological aging. CR diets are the only known mechanism which can actually extend the maximum life expectancy of organisms. It has been tested on everything from water flees to chimpanzees and has shown the same drastic health benefits and life extending properties.

See -

Caloric Restriction with Optimal Nutrition: An Introduction
http://www.cron-web.org/default.htm

http://www.calorierestriction.org/

http://www.cron-web.org/references_and_resources.html

I have a good friend who is a Hospice nurse, of some 20 or 30 patients she has, only one does not have cancer, and that is a patient who is dying from aneorexia. While anorexia is certainly not CRON, it demonstrates that cancerous cells, the most energy intensive ones in the body, dont do well when there is not much extra energy to be had.

Being overweight, especially severely overweight, is one of the most under-recognized health hazards, specifically relating to its relationship with cancer. I would add that drinking alchohol is probably the most underated health hazard, again specifically relating to cancer. Take a look at the HERP index sometime and look where pesticides and 'man made' carcinogens compare with coffee, beer, or vodka.

Regards,

Michael Dickey

(Edited by Michael F Dickey on 4/25, 10:45am)

Post 15

Monday, April 25, 2005 - 10:52am

...cancerous cells, the most energy intensive ones in the body, dont do well when there is not much extra energy to be had.

Probably true. But then, neither do non-cancerous cells.

In fact, neither does a human being as a whole.

Post 16

Monday, April 25, 2005 - 11:29am

Robert said:

...cancerous cells, the most energy intensive ones in the body, dont do well when there is not much extra energy to be had.

Probably true. But then, neither do non-cancerous cells.

In fact, neither does a human being as a whole.

Not true Robert, if you read up on the subject youd find that moderate restriction, far from being detrimental, is quite beneficial. Because cancerous cells are the most energy intensive (malignent cells reproduce as rapidly as possible and as often as possible) they are the first to succumb to an energy restrictive environment. There are a whole slew of interesting things that go on under CR which I suggest people read up more on if interested. A mere 10% reduction in calories, for instance, reduces your LDL count, your blood pressure, your rest heart rate, your breathing rate, your oxygen consumption, etc etc. Check out Robert Walfords controlled study of the Biosphere 2 inhabitants and Richard Wiendruch's primate studies.

Michael Dickey

Post 17

Monday, April 25, 2005 - 11:36am

Interesting...thanks for the added info, Michael.

Post 18

Monday, April 25, 2005 - 2:00pm

Michael, I think that you meant Roy Walford above (BioSphere scientist)--when you said Robert Walford.

Also, the benefits of Caloric Restriction can be gotten (in rats) with mere restriction of carbohydrate--without much caloric restriction at all. This may have to do with insulin levels, or maybe even glucagon levels, or perhaps both.

At any rate--any reducing diet (calorie-restricted diet) ought to be a high-protein (25-35%) diet; as protein needs can easily DOUBLE with caloric restriction.

Ed

Post 19

Tuesday, April 26, 2005 - 7:39am