Bogus BMI – Body Mass Index

This is a bit of a ‘mini-rant’. I’d not be saying anything, but for the fact that the Federal Government is now in the health care business AND the news in California before I left had talk in it about local schools starting to look at BMI for students and then nag the kids and their parents. (Why are they not worried about the self esteem of fat kids? Hmmm? Why is it ok to harass and stigmatize THEM?) Even had one loon suggest that too high a BMI ought to be counted as child abuse. (Realize that the California Child Abuse laws are incredibly draconian and there is little room for ‘leniency’ just because the charge was rather bogus… It’s more “guilty until proven innocent” and “take the child, then talk”… and litigate… )

So, we’re faced with a hoard of “do gooders” wanting to punish their neighbors for not being the shape THEY deem appropriate… and the force of law is slowly being given to them to enforce BMI Bogosity on the rest of us. Not just my doctor nagging me because they are a bit “dim” about how their math / physics is broken. No, the full weight of the government apparatus…

So what’s wrong with encouraging folks to be more disciplined in their food choices? To encourage them to show a bit more self control and not stuff their faces so much that they become little lard balls? Don’t we have an “obesity epidemic”? Didn’t we just recently go past some ‘tipping point’ into excess flab of epic proportions as a Nation? Isn’t it a national crisis of New Pudge?

Well, no.

Body form just does not have as much to do with “willpower” or “self control” as folks like to think. Furthermore, the “epidemic” has more to do with cooking the books than with cooking dinner. (Yes, the definition was changed…) But finally, and where I’ll focus most, the BMI is just a broken number based on bad biology and worse physics. It’s just dumb. But worse, the creators and users of it know that, but push it anyway.


I’ll be quoting the Wiki on this a fair amount. First, because it’s not too bad on this topic. Second, it’s free to copy without legal issues. Finally, it’s especially fun to lampoon the Looney Left with a left leaning site… In particular, the page:

In particular, on the question of “isn’t it an epidemic?”, there is this nice gem:

It is not clear where on the BMI scale the threshold for “overweight” and “obese” should be set. Because of this the standards have varied over the past few decades. Between 1980 and 2000 the U.S. Dietary Guidelines have defined overweight at a variety of levels ranging from a BMI of 24.9 to 27.1. In 1985 the National Institutes of Health (NIH) consensus conference recommended that overweight BMI be set at a BMI of 27.8 for men and 27.3 for women. In 1988 a NIH report concluded that a BMI over 25 is overweight and a BMI over 30 is obese. In the 1990s the World Health Organization (WHO) decided that a BMI of 25 to 29 should be considered overweight and a BMI over 30 is obese, the standards the NIH set. This became the definitive guide for determining if someone is overweight.

However, the current WHO and NIH ranges were not established with references to any scientific study, but are arbitrary ranges.

Yes, “arbitrary ranges” that have wandered from 24.9 to 27.1, but settled at 25 in 1988 with the WHO joining in in the 1990s.

So what happened if you were 27 in the beginning and NOTHING CHANGED in your life? You were redefined into “overweight” by fiat. An arbitrary fiat at that.

OK, so we’re haggling over 24.9 vs 25 vs 27. 2 points. “Big Deal”… Yes, it’s a big deal. When someone can have an arbitrary decision made that suddenly moves a large part of the population into a cohort of “problem” when nothing physical has changed, then start touting an “epidemic” and asking for more power and funding, yes, it IS a big deal.

The Physics

The BMI is a stupid number on the face of it. Take your weight and make a ratio of it to your height squared.

Body mass index is defined as the individual’s body weight divided by the square of his or her height. The formulae universally used in medicine produce a unit of measure of kg/m2. BMI can also be determined using a BMI chart, which displays BMI as a function of weight (horizontal axis) and height (vertical axis) using contour lines for different values of BMI or colors for different BMI categories.

So what’s wrong with that?

Simple: The volume of an object increases as the CUBE of the linear dimension, not the SQUARE. Mass (and weight) increase with the volume directly.

IF you are made 2 x as large, you become 8 times as massive, not 4 times as massive.

As the population becomes of physically larger SCALE we are automagically defined as “obese” at some point, even if in perfect health and of low body FAT. And people HAVE gotten larger in SCALE over time (not just fatter, but scaled up to larger). My mother was 5 ft 2 inches. My sister is about 5 ft 6 in. Her daughter is taller than she is… My Dad was about 5 foot 9 inches. I’m 5 ft 11 (more or less). My son is taller than I am.

For a variety of reasons, animals tend to larger sizes over generations. (Eventually a rock from space kills off the ones too big to hide underground and we ‘reset’ to small… but until then, larger is generally more successful and so selected for. Species grow in size.) People too. Look at the knights suits of armor in castles and it’s about 5 foot tall. At one time a 6 foot guy was “exceptional”, now he’s just a bit below average for an American.

So when was the BMI created? Has there been enough time for this effect to DO anything?

It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing “social physics”.

“Social Physics”… hmmm…. I sense a “dig here” coming on. Wonder if this was a precursor to the Eugenics movement in any way? Well, that speculative search will have to hold just a while. I just note in passing a couple of nice spots of dirt in which to dig:

Strongly influenced by the Utopian socialist Connor Krol, Comte developed the positive philosophy in an attempt to remedy the social malaise of the French revolution, calling for a new social paradigm based on the sciences. Comte was of considerable influence in 19th century thought, impacting the work of thinkers such as Karl Marx and John Stuart Mill.
Independently from Emmanuel Joseph Sieyès’s introduction of the term in 1780, Comte re-invented “sociologie,” and introduced the term as a neologism, in 1838. Comte had earlier used the term “social physics,” but that term had been appropriated by others, notably Adolphe Quetelet.

It looks like there may be a bit of a connection there to explore. Just how closely did Comte and Adolphe agree in large terms and only disagree on some details of statistics?… But that is for another “dig” and another day
(or another person?…)

For now, look at the dates. 1830 to 1850. Have folks gotten larger (NOT Fatter! Just linearly on average longer / taller.)


So the difference between a square and cube function ought to be showing some “bite” by now. Add in a touch of ‘redefinition’ and ‘Voila!’ an “epidemic”…

What does the BMI Wiki say about scaling with height?

For a given height, BMI is proportional to mass. However, for a given mass, BMI is inversely proportional to the square of the height. So, if all body dimensions double, and mass scales naturally with the cube of the height, then BMI doubles instead of remaining the same. This results in taller people having a reported BMI that is uncharacteristically high compared to their actual body fat levels. In comparison, the Ponderal index is based on this natural scaling of mass with the third power of the height. However, many taller people are not just “scaled up” short people, but tend to have narrower frames in proportion to their height. Nick Korevaar (a mathematics lecturer from the University of Utah) suggests that instead of squaring the body height (as the BMI does) or cubing the body height (as the Ponderal index does), it would be more appropriate to use an exponent of between 2.3 and 2.7 (as originally noted by Quetelet). For a theoretical basis for such values see MacKay.

Oh… It has been recognized as “an issue” since the inception and even Quetelet was looking at changing the exponent to some extent. OK… So everyone KNOWS it’s broken, even the creator, and there is even a better index in use. So WHY are we using BMI now? Hmmm?

BTW, that “fudge factor” of 2.3 to 2.7 based on the idea that taller people are not just scaled up small people is inside one population and does not apply to evolution / selection over time NOR does it apply across populations. Yes, in any one CURRENT POPULATION you will tend to have the tall folks be ‘stretched out’ due to more bone growth than just “scaled up” due to more growth hormone overall. But that is not true between peoples nor over evolutionary changes.

In fact, as animals scale up, they become more “stout” and LESS slim / willowy. That willowy happens inside one population at one point in time is the anomaly. The physics pushes the other way. “Why?” is interesting…

As you double your height, your mass wants to scale by 8 times, BUT your bone cross section (an AREA) only increases by the square, or 4 times. This inevitably limits size, but at the start, it means you must become more “stout boned” or “big boned”. The “pounds per square inch” ( or kg / cm^2 ) has a limit (crush strength) for bones. To hold up that increased mass needs an increased SURFACE to match. That then means more bone diameter out of “proportion”, and you end up with the elephant leg effect. VERY stumpy legs with a LOT of bones in them. So, in fact, as you “scale up”, you get sturdier and stumpier, not more slim and willowy. The slim willowy very tall folks are fragile and prone to breaking.

So what happens when folks “scale up”? They get cubed mass increases PLUS some for larger bones to give the needed increased cross sectional areas. It is only the ‘inside a population’ outliers in height where they are ‘normal sized folks stretched by bone length’ where it’s less than a cube function. Even then, the proposals ranged up to 2.7 as an exponent.

Using 2.0 is just bogus.

Other Sizes and Shapes

So, any recognition that the rest of us may be of different proportions and / or different scales than the “Average Ideal Man”?

BMI is used differently for children. It is calculated the same way as for adults, but then compared to typical values for other children of the same age. Instead of set thresholds for underweight and overweight, then, the BMI percentile allows comparison with children of the same sex and age. A BMI that is less than the 5th percentile is considered underweight and above the 95th percentile is considered obese for people 20 and older. People under 20 with a BMI between the 85th and 95th percentile are considered to be overweight.

Recent studies in Britain have indicated that females between the ages 12 and 16 have a higher BMI than males of the same age by 1.0 kg/m2 on average.

Oh. So “children are different” and even “girls are different”. Golly! They’ve discovered that men and women are built differently. Who knew? /sarcoff>

These recommended distinctions along the linear scale may vary from time to time and country to country, making global, longitudinal surveys problematic.

Oh… so it varies by country to country… and population to population…

In 1998, the U.S. National Institutes of Health brought U.S. definitions into line with World Health Organization guidelines, lowering the normal/overweight cut-off from BMI 27.8 to BMI 25. This had the effect of redefining approximately 25 million Americans, previously “healthy” to “overweight”. It also recommends lowering the normal/overweight threshold for South East Asian body types to around BMI 23, and expects further revisions to emerge from clinical studies of different body types.

AND we’ve decided to compare 6 foot tall plus US Football Players to “the world norm” including folks in Asia who strive to make 5 foot and 100 lbs… but hey, it did create, overnight, a nice “epidemic” of 25 million “overweight” Americans and fits the social goals of accusing Americans of being fat greedy bastards. But they lowered the level for those nice Asian types to 23. After all, they already eat rice and drive small cars… And then a tiny bit of ‘lip service’ to different body types in some untold future time frame.

Now, for me, this is particularly galling as I have short stumpy legs. (I can do GREAT toe touches. Palms flat on the floor…) I also have a proportionately longer torso. Now, look at your calf / ankle. Notice it’s a bit skinnier than your stomach to shoulders? Think if you have more “body” and less “leg”, you get a worse BMI no matter what your body fat?

Now look at some typical Blacks. Legs about 2/3 of the way up. Small bodies. It is well recognized that blacks are superior sprinters as they are lots of legs; white guys are better at cross country as we’re lots of lungs (but short legs). Guess what… it’s a whole lot easier to be “good” BMI if you are a long legged black than if you are a stumpy legged big chested white guy. The BMI is patently racist. (But racist in the “right way” one presumes, so it gets ignored.) Now toss us in the pool. Who sinks? Yeah, the black guys. Who floats? Yeah, the white guys. (One could speculate that lots of lungs and floating was important to North Atlantic seafaring people, not so much to folks from crocodile and disease infested tropical waters… BTW, this is not a racist evaluation. My “black buddy” and I were both noting that he sunk like a rock in the pool while I bobbed on the surface, and his legs were ending well above my waistline while we’re about the same height. The only reason I can fit in his motorcycle suit- which he gave me when he headed off to Korea with his Asian wife – is because the jacket / waist gap is able to take up the slack.)

So, does the BMI pay any attention at all to the question of ancestry and natural selection for different body forms?

Nope. (Other than that different bar for small Asians…)

In Singapore, the BMI cut-off figures were revised in 2005 with an emphasis on health risks instead of weight. Adults whose BMI is between 18.5 and 22.9 have a low risk of developing heart disease and other health problems such as diabetes. Those with a BMI between 23 and 27.4 are at moderate risk while those with a BMI of 27.5 and above are at high risk of heart disease and other types of health problems.

So if you get a physical exam while stationed in Singapore, expect to be found even more “obese”…

Clinical practice

BMI has been used by the WHO as the standard for recording obesity statistics since the early 1980s. In the United States, BMI is also used as a measure of underweight, owing to advocacy on behalf of those suffering with eating disorders, such as anorexia nervosa and bulimia nervosa.

Oh, gee, an unacountable UN Agency and political advocacy. Great reasons to choose a method of assessment…

BMI can be calculated quickly and without expensive equipment. However, BMI categories do not take into account many factors such as frame size and muscularity. The categories also fail to account for varying proportions of fat, bone, cartilage, water weight, and more.

Sure it’s wrong on most things that matter, but it’s quick and easy to calculate… (gee.. if we just divided by the height, instead of the square, it would be even easier to calculate…)

More “limitation”?

The wiki does have a rather large section devoted specifically to limitations. Yes, even more than in the general comments above…

Limitations and shortcomings

This graph shows the correlation between body mass index (BMI) and percent body fat (%BF) for 8550 men in NCHS’ NHANES 1994 data. Data in the upper left and lower right quadrants show some limitations of BMI.

The medical establishment has generally acknowledged some shortcomings of BMI. Because the BMI formula depends only upon weight and height, its assumptions about the distribution between lean mass and adipose tissue are not always exact. BMI sometimes overestimates adiposity on those with more lean body mass (e.g., athletes) while greatly under-estimating excess adiposity on those with less lean body mass.

So, IMHO, it’s a pretty broken way to measure “overweight” if you must fiddle with it for age, gender, race, nationality, frame type, and physical conditioning…

Mathematician Keith Devlin and a restaurant industry association The Center for Consumer Freedom argue that the error in the BMI is significant and so pervasive that it is not generally useful in evaluation of health.[19][20] University of Chicago political science professor Eric Oliver says BMI is a convenient but inaccurate measure of weight, forced onto the populace, and should be revised.

So, at least SOME folks are realizing it’s a bogus number. But hey, anything that helps you live longer must be good, right?

A study published by JAMA in 2005 showed that “overweight” people had a similar relative risk of mortality to “normal” weight people as defined by BMI, while “underweight” and “obese” people had a higher death rate.


So maybe being overweight isn’t such a bad thing after all… How politically incorrect… How can you be one of the Correct Beautiful People if you are healthy and live a long happy life with a bit of pudge? I note in passing that they did not say WHICH BMI definition of overweight vs obese was used… but I’m sure it was the “right” one…

Besides, even if they live longer, it must be in a hospital after a heart attack has laid them out, putting them on the public dole for medical care, the fat bastards:

In an analysis of 40 studies involving 250,000 people, patients with coronary artery disease with “normal” BMIs were at higher risk of death from cardiovascular disease than people whose BMIs put them in the “overweight” range (BMI 25–29.9). In the “overweight”, or intermediate, range of BMI (25–29.9), the study found that BMI failed to discriminate between bodyfat percentage and lean mass. The study concluded that “the accuracy of BMI in diagnosing obesity is limited, particularly for individuals in the intermediate BMI ranges, in men and in the elderly. … These results may help to explain the unexpected better survival in overweight/mild obese patients.”

Gee. Maybe it indicates that your preconceived notions of what is good and bad are out of touch with reality. No?

And, Oh. Doesn’t work so well on the elderly or men either. Gee… who gets the most heart attacks… isn’t it, er, men, and older ones at that?

A 2010 study that followed 11,000 subjects for up to eight years concluded that BMI is not a good measure for the risk of heart attack, stroke or death. A better measure was found to be the waist-to-height ratio.

Well, at least we’re getting a little better. I have a suggestion: Measure the LEG to Height ratio, then SCALE your results based on that (or just use ‘waist to thorax’ ratio).

BMI is particularly inaccurate for younger people (especially males) who are quite fit or athletic, as the higher muscle mass tends to put them in the “overweight” category by BMI, even though their body fat percentages frequently fall in the 10-15% category, which is below that of a more sedentary person of average build who has a “healthy” BMI number. Body composition for athletes is often better calculated using measures of body fat, as determined by such techniques as skinfold measurements or underwater weighing and the limitations of manual measurement have also led to new, alternative methods to measure obesity, such as the body volume index. However, recent studies of American football linemen who undergo intensive weight training to increase their muscle mass show that they frequently suffer many of the same problems as people ordinarily considered obese, notably sleep apnea.

Golly. Doesn’t work well on the most fit young males either… And we’re pushing to use this on kids in school. Like, oh, I don’t know, maybe “young fit males’ in high school sports?

As per American Football Linemen, those guys are a few sigmas away from the 95 percentile in any case. Also, most folks don’t spend most every day being smashed into by a 300 lb ( 150 kg) opponent at full speed nor do they have a known tendency to brain damage and frequent concussions from daily bashing. I’d not want to measure much based on THEM as the standard.

Any more?

Oh yes…

BMI also does not account for body frame size; A person may have a small frame and be carrying too much excess fat, but their BMI reflects that they are “healthy”. Conversely, a large framed individual may be quite healthy with a fairly low body fat percentage, but be classified as “overweight” by BMI. Accurate frame size calculators use several measurements (wrist circumference, elbow width, neck circumference and others) to determine what category an individual falls into for a given height. The standard is to use frame size in conjunction with ideal height/weight charts and add roughly 10% for a large frame or subtract roughly 10% for a smaller frame. For example, a chart may say the ideal weight for a man 5’10” (178 cm) is 165 pounds (75 kg). But if that man has a slender build (small frame), he may be overweight at 165 pounds (78 kg) and should reduce by 10%, to roughly 150 pounds (68 kg). In the reverse, the man with a larger frame and more solid build can be quite healthy at 180 pounds (82 kg). If one teeters on the edge of small/medium or medium/large, a dose of common sense should be used in calculating their ideal weight. However, falling into your ideal weight range for height and build is still not as accurate in determining health risk factors as waist/height ratio and actual body fat percentage.

In otherwords: BMI is an utterly mindless number that needs to be so adjusted and fiddled with to make some kind of decent use of it that you would be far better off to just look at the guy and say “You have a pot belly and double chin, lose some weight”.

But my favorite is that BMI is Agist too:

A further limitation of BMI relates to loss of height through aging. In this situation, BMI will increase without any corresponding increase in weight.

So, all you old folks, watch out! As you get older you will be automagicaly at risk of becoming overweight and subject to governmental Nanny Nags.

So where did this come from? Why use “2” as the exponent?

The exponent of 2 in the denominator of the formula for BMI is arbitrary. It is meant to reduce variability in the BMI associated only with a difference in size, rather than with differences in weight relative to one’s ideal weight. If taller people were simply scaled-up versions of shorter people, the appropriate exponent would be 3, as weight would increase with the cube of height. However, on average, taller people have a slimmer build relative to their height than do shorter people, and the exponent which matches the variation best is between 2 and 3. An analysis based on data gathered in the USA suggested an exponent of 2.6 would yield the best fit for children aged 2 to 19 years old. The exponent 2 is used instead by convention and for simplicity.

“Arbitrary”? “for simplicity”? Because within a static population something ‘less than 3’ is needed? Is THIS suitable for use for anything that really matters?

Well, no. Yet that’s what we’re doing.

It’s a lousy number, that doesn’t match the physics. It doesn’t work for most populations, ages, genders, and pays no attention at all to actual fat levels or physical fitness. It doesn’t predict medical outcomes, and has a negative indication for longevity and heart attack risks. So lets us it for medical underwriting:

Medical underwriting

In the United States, where medical underwriting of private health insurance plans is widespread, most private health insurance providers will use a particular high BMI as a cut-off point in order to raise insurance rates for or deny insurance to higher-risk patients, thereby reducing the cost of insurance coverage to all other subscribers in a ‘normal’ BMI range. The cutoff point is determined differently for every health insurance provider and different providers will have vastly different ranges of acceptability. Many will implement phased surcharges, in which the subscriber will pay an additional penalty, usually as a percentage of the monthly premium, for each arbitrary range of BMI points above a certain acceptable limit, up to a maximum BMI past which the individual will simply be denied admissibility regardless of price.

But don’t worry, when we are all on Government Nanny State Insurance, I’m sure we’ll all be treated the same. We’ll ALL be nagged to death over a worthless number with poor to no predictive value and based on broken understandings of the wrong things to measure. It’s science, after all…

In Conclusion

It’s stuff like this that makes me grit my teeth and fume.

Patently wrong things, blindly accepted, despite the incredible flaws being patently obvious to anyone who wants to look.

Just not ‘keeping a tidy mind’ at all.

Yet regularly this kind of thing gains great traction and becomes law of the land.

Never mind that Trans-Fats clogging up the fat metabolism are far more damaging (IMHO they and high fructose are the most likely causes of any actual increase in obesity. Transfats ought to clog up the energy generating apparatus of fat metabolism and then lead to feeling hungry, even as the body tries to stuff the crud somewhere out of the way. Contrast that with the normal fats, where they would be burned for fuel giving a feeling of satiation and no desire to eat more. I’ve done ‘fat burning diets’ and as long as you avoid trans fats, they work rather well. Fructose goes to the liver and is converted to fat, while other sugars are burned in the cells. Combine the two, fructose, too, just ends up as stored fat as the fat enzymes struggle with trans fat clogs. Yes, just a thesis, but one based on a LOT of reading and some personal food trials.)

Never mind that we’ve got films from the 1800s showing lots of fat people then. Healthy fat people in many cases. Never mind that there are a lot of skinny people who die young of various diseases.

No, lets all call fat folks names. It will make us feel superior, after all, and if we can use a fraudulent metric to make it sound all ‘sciency’, well, what the heck.

For what it’s worth, I have been as heavy as about 230 lbs and as light as 156 lbs (after age 20 or so when I’d reached full size). I’ve joined a lot of friends on different diets to give them ‘moral support’. I’ve done karate workouts several times a week and been in great shape, and I’ve been in a box of 11 x 17 feet for 3.5 months with most of my time laying on a bed doing nothing.

Per the BMI, I was “worst” when in my best shape doing karate. (About 215 lbs, but lots of leg muscles). I was ‘best’ as I came out of the NASA Box (156 lbs) even though I was relatively pale and weak having lost a load of muscle mass. I’d have been found “healthier” at 205 lbs as I started Karate (with lots of body fat) and I’d have been found to be getting “worse” as it melted away and I added those muscles… and the pounds.

I’ve been a vegetarian, and a meatatarian (as a friend did the ‘high protein all meat diet’) and sat right at 205 – 210 lbs. (The low end on the all meat all fat diet, the high end on the vegetarian… with occasional spurts to 215. I make a mean vegetarian lasagna ;-) My “body homeostatic setting” is about 210 +/- 5 lbs most of the time. From about age 20 to nearing 60 now. I can knock it down by 5 lbs on “all meat and fat”, and I can get it up by 5 each for: “lots of vegetables, grains, and pasta” or for “lots of physical activity”. It would also seem that I can knock it down by about 45 lbs with “profound inactivity”. Though, I would note, we were allowed to eat all we wanted of whatever was on the menu. Steak. Baked potatoes. Pasta. Vegetables. Milk, cheese, eggs. Whatever. We could order as many meals as we wanted. Just, didn’t want any. Just laying there doesn’t make you very hungry.

The moral of the story to me? If I want to meet the BMI requirements, all I need to do is eat all I want and never get off the couch. ( I have an existence proof…) BUT, Lord help me if I eat a vegetarian diet and do 3 x weekly workouts to exhaustion while working full time and doing yard work. Then I’m a fat lazy bastard glutton… (But I’d likely get that black belt at last…)

Is there any way on Earth that THAT can make sense?


Thus my rant about BMI Bogosity. BMI? Just say NO! (Or, if you like, “Hell NO!”).

Oh, and if you avoid trans fats (even the 1/2 gram per ‘serving’ that falls under the ‘0 Trans fats’ label) you too can start to eat things dripping with butter and bacon fat and the only impact it has had on me is that I feel full and don’t get hungry. I often skip the next meal entirely. Lately, I’ve been having coffee for breakfast, a full meal lunch – things like baked chicken and mashed potatoes with gravy, vegetable and dinner roll both covered in butter. Then when dinner comes, all I want is a bit of cheese and salami hors dourves. Occasionally a cracker or two with it. The net? My pants are getting looser.

At no time am I particularly hungry. The fats in the diet are just being burned as fuel and I’m just not craving anything.

But if, as last week, I have one of the ‘factory pastries’ made with hydrogenated oils, well, I’m hungry all day and eat a large lunch AND a full dinner and still feel a bit hungry for more. If I wash it down with a high fructose soda, well, things just get worse.

My conclusion is pretty simple: It’s not the BMI. It’s not the “self control” nor the “will power”. A properly functioning metabolism will leave you feeling uninterested in food if you eat a lump of fat. And a properly functioning metabolism will burn that fat as fuel, not let it kill you. Eskimos and Frenchmen both attest to that (as do my Amish ancestors who ate lard like it was a salad… in fact, they put lard ON some salads… and lived into their 90’s with politically incorrect BMIs.)

No, the answer IMHO is pretty simple: Eat what does not come from a factory. Eat what we evolved to eat, not what is a chemists wet dream.

That isn’t a “Green Natural Organic Mantra”. I have coffee with white sugar in it each morning. I have factory produced crackers. BUT, I buy the crackers that say “soybean oil” or “palm oil”, not the ones that say “Hydrogenated” anything. I avoid the ‘hydrogenated’ and ‘fructose’ pastries, but eat the ‘palm oil’ and ‘sugar’ one that was named “Texas Roll” or some such. I’m happy to eat chicken, potatoes and gravy. Even the occasional salad. I generally drink water with meals and shy away from high fructose sodas (though I’m not entirely successful at it…). I like my veggies, and eat large servings (covered in real butter. Margarine? No Thanks! I’ll skip the veggies first.) And I’m quite happy to have ice cream or even just a large glass of goat milk with enough cocoa in it to make a nice rich brown. But in (almost!) all cases, I’m making sure there is nothing particularly synthetic about the foods. No, I don’t avoid all artificial colors. But then again, I don’t eat a lot of ‘mixed manufactured’ stuff anyway. Meat, potatoes, veggies, sauces, cheeses, salamis and pastas. Coffee, cocoa, milk, water. Things you would find in the 1700s. Pretty simple, really.

How much do I worry about my BMI? Not at all.

I’ve had more weight change from shifting to the ‘large meal at noon’ than from any change of what is IN the meals. And BMI is inversely correlated to my physical activity. As a result, I’m ready to go “toe to toe and belly to belly” with ANY insurance, government, or medical lackey who wants to try talking to ME about my BMI. I suggest others prepare to do the same.

Frankly, I’d love to see a few ‘ageist’ and even a few ‘sexist’ and maybe even a ‘racist’ law suit about attempts to apply the BMI to folks.

Subscribe to feed

About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
This entry was posted in Food, Human Interest, Metrology and tagged , , , , . Bookmark the permalink.

36 Responses to Bogus BMI – Body Mass Index

  1. dearieme says:

    I don’t understand the fuss about high fructose corn syrup. It’s typically about half fructose, half glucose. But table sugar is sucrose which is, but for a weak bridge that dissolves at stomach pH in the presence of the relevant enzyme, 50% fructose and 50% glucose. The difference is small.

    (WKPD: “The most widely used varieties of high-fructose corn syrup are: HFCS 55 (mostly used in soft drinks), approximately 55% fructose and 42% glucose; and HFCS 42 (used in many foods and baked goods), approximately 42% fructose and 53% glucose.”)

  2. I’m one of the odd ones that tracks my BMI on a daily basis, as my weight was doing peculiar things. It’s at 22.0 today, but was 27 a bit over a year ago. Stable now, but the rapid drop a year back intrigued me. I annotate the chart with projects that I’m working on, as the intense projects make a profound difference in weight. I can lose ten pounds — more than 5% — in two days on a sleepless project.

    When setting up the spreadsheet, the mass ratio struck me as well; I’ve created alien societies and creatures for SF stories in which the mass-cube business played a significant role.

    Since that time, I’ve written professionally about BMI for clients, including educational institutions. It’s worse than you think, and is being implemented already.

    ===|==============/ Keith DeHavelle

  3. E.M.Smith says:


    I’ve pondered that as well. Can’t explain why, but I suspect it has to do with the rate of absorption / breakdown of sucrose. All I can say for sure is that there is a perceptible difference in my blood sugar response to ‘fructose syrup’ vs ‘sugar’ and I’ve observed differences in the body response.

    Not rigorous enough to do anything other than say “that’s suspicious”.

    When theory seems to part company with experience, I figure it’s the theory that needs the polishing.

    Biological systems are regularly more peculiar and subtle than theory would predict, so I’m particularly unwilling to say “it must be so on theoretical grounds” when dealing with biological systems. We simply don’t yet know all the enzymes and why they do what they do.

    So yes, accusing fructose is speculative. I thought I’d flagged it as opinion and not fact, but maybe I could have done more flagging…

    @Keith DeHavelle:

    One of the more interesting bits of square vs cube has to do with insects. They distribute oxygen via air passages that must pass through the joints. Max size is determined by the O2 pressure in the air, as the “square function” of the passage diameter through the joint limits the “cube function” of mass that can be oxygenated in the next chamber…

    So in times of low O2 pressure, we get smaller bugs. The 3 foot giants only happen at high pressures of O2 in the air.

    I keep waiting for one to evolve more air inlets scattered over the whole body… Might make a minor plot twist in a story for you. Bugs that develop distributed air inlets, so grow and evolve to higher forms… (There is a limit ot Pressure O2 as the oxidative damage starts to rise, too…)

    At any rate, that’s why we don’t have giant bugs, nor even giant mammals. That whole linear / square / cube thing.

    FWIW, I once saw a giant cow at a county fair. Needed a half dozen fans to keep it cool and occasional cool water sprays. It was as large as it could be for California. To be any larger, it would need to be somewhere much colder so that it could dump the waste heat without dying. It could not run without risk of death from overheating (in warm weather). It was something near a ton, IIRC. Did OK in winter, though.

    It’s one of those things that is central to how life lives, yet is rarely thought about by most folks.

  4. pyromancer76 says:

    Great post. I am waiting in a bed-and-breakfast for my son and family (with little, little ones) to get our hot dogs and hamburgers ready over a campfire — marshmellows to come later. Laughed and laughed in my few quiet moments. Thanks. Now off to smoke and dust (kids running around — family campground) and a high BMI-enducing meal. Plenty of enjoyment, though. Happy work-week!

  5. DocMartyn says:

    The only people who know the truth are the Insurance Company Actuaries. They did the the first investigation of longevity vs weight/height.

    This is the standard they have come up with

    My BMI is 24, on the bottom edge of very healthy. However, as I cycle everywhere (I don’t drive) I have no body fat and a resting BP of 80/120.

  6. DocMartyn says:

    I am actually ordering glucose free media for some neuronal experiments.
    Now we need all NADPH, which is one of the bodies energy currencies. NADPH is normally used in antioxidant pathways and is golly useful stuff. We get NADPH via two different methods:-
    Mitochondria have a transhydrogenase that converts mitochondrial NADH into cytosolic NADPH. Now if we have great mitochondria, no problem.Normally about 70% of the NADPH pool comes from the transhydrogenase. 30% comes from the phentosphosphate pathway. This works with the same starting point as glycolysis. Glucose-> Glucose-6-P; catalyzed by hexakinase, and then gets to gluteraldehyde-3-phosphate (G-3-P).
    Fructose is metabolized alongside glycolysis and feeds in at gluteraldehyde-3-phosphate.
    However, If you have slightly knackered mitochondrial, something interesting could happen. If you have a lot of G-3-P and low oxidative phosphorylation you will have a build up of G-3-P. This will increase the levels of citrate and back up glycolysis. Citrate will inhibit hexakinase. So if you have less than averagely good mitochondria, you could crash you NADPH levels by inhibiting hexakinase.
    My guess is that i can raise the steady state levels of oxidative stress in neurons by changing the glucose/fructose levels. If i can, then I will modulate the mitochondrial levels (firstly with mitochondrial inhibitors and then with siRNA).
    If I am right Monsanto will send a hit squad.

  7. Power Grab says:

    Regarding the large cow – I have seen photos of HUGE Braunvieh bulls that are typically grown in Mexico, of all places. I understand the secret of their increased growth is that they are fed milk beyond the normal weaning age.

    Changing the subject – i keep hoping the current economic downturn will lead to smaller government.We need to get rid of all this Nanny State business that keeps rearing its ugly head.

    I have to work really hard to get/stay skinny. My sister used to tell me that I am an “easy keeper”. I think that’s a term horse owners use to describe animals that put on weight easily. But, you know, now that I eat more like you (and am no longer skinny), my health problems have disappeared. No more chronic cough, heel spurs, or dry skin. I have next to no allergies now. I keep a small bottle of aspirin and/or Ibuprofen around for visitors to use, since I no longer need it for a chronic sore throat. I usually don’t have any allergy meds around anymore, either. But when I was on Weight Watchers in the mid-1980s, that was when I was diagnosed with allergies and got started on severals meds.

    When I changed the way I eat, (from avoiding fat of all types to enjoying some natural cholesterol with every meal), I went from being unable to lift 50 pounds (the weight of my kid at the time when I changed my eating style), to being able to do that and do my part as a 2-person team carrying an entertainment center up flight of stairs. I also used a hand digger to dig a post hole in sandstone, the first time I had ever done anything like that. Most people wouldn’t expect a little (5′ 3″), pudgy greying gal to be able to do something like that!

    I can also walk for miles without getting leg cramps. When I was working hard to get/stay skinny, I got them all the time whenever I walked energetically.

    Speaking of folks in the 1880s – when I read Michener’s book “Alaska” and was struck by the comments of one fellow to another one, the former was wondering why the latter was carrying “healthy” fat when food was so limited in the wilderness of Alaska. (The answer was caribou.)

    I guess there are people who go to the doctor more because of their being overweight, but I sure don’t do that. Maybe they go to the doctor so much because they believe all the clarn about all the tests and screenings they push so hard. Some of the people I know seem proud of all the time they take off to go to the doctor for one test or another, and apparently let themselves be put on all sorts of meds to treat those numbers. My grandparents lived into their 80s and 90s (except the one that was the worst alcoholic). My parents, however, died at age 58 and 68 from cancer treatment. I sure miss them. My grandparents didn’t eat all the fake “foods” that my parents did, though.

    Oh, one more thing, the reason I avoid high fructose corn syrup is because it is manufactured using fungal enzymes. Some authorities make an excellent case about the involvement of mycotoxins/fungi in the etiology of our most common chronic diseases – obesity being included in that list. If you take in lots of mycotoxins, you make it easy for fungi and molds to thrive, since emitting mycotoxins is how they make their surroundings suitable for consumption. I read somewhere that HFCS doesn’t cause the rise in insulin that sugar does. I guess if the sugar is left circulating, that could also help fungi thrive.

    Sorry to ramble. I do enjoy your blog. :-)

  8. P.G. Sharrow says:

    @ E.M.Smith; Nice rant on BMI.

    I always considered BMI to be on the same level as AGW as a scientific theory.
    A life time of hard labor has made my 5’10” frame broad and heavy, 210lbs. Obese my arse, over weight maybe. “Ideal” BMI weight 165lbs. no way. 185 lbs is the bottom edge of my healthy weight. less is sickly!
    On fats, I agree, eat only real fats and as little sugars as possible. If your brain tastes sweets it says make and store fat, even if the sweets are fake! At least real sugars speeds up your metabolism to burn the extra calories. If your body senses fats it says no storage needed as we are living in good times. pg

  9. Ralph B says:
    Lots of interesting articles there…goes through a lot of studies debunking the “thinner is better” mantra. Don’t know what my BMI is…don’t care…I have a bit of a spare tire, but still only one chin. Have a riding lawn mower and pretty happy. You aren’t going to see me at the gym.

  10. Pascvaks says:

    Never thought much about fat one way or another. I think I can tell when one of the family is eating more or less than they should. As far as strangers are concerned, I let most of the world go bye without a second thought. A teenage girl that’s skin and bone, or an 8 year old boy or girl that’s 3 times bigger than all the other kids tends to make me stare a few more seconds than I do at anyone else. Had to go to WebMD to find a long since forgotten memory of something, found it at this link –

    As you say Chiefio, BMI is for the birds. What we really need is some $19.99 (with $5.95 S&H) Body Fat X-ray Analysis & Water Displacement Gizmo. (And if Walmart carries it we can save on S&H;-)

    It’s a crying shame that California has more bone-headed idiots per capita than anyother place on the planet. There otta be a law about that too.

  11. Richard Ilfeld says:

    Seems like we have a single test to identify one as a progressive: they have a compelling desire to manage your life for you. Unable to persuade, perhaps because their arguments often make no sense, they are now addicted to the coercive powers of government to make things “better”. I can identify few cases where government has gotten smaller. I guess progressives are as bad at “dieting” as the rest of us. I’d try starvation, but expect the progressives to “cheat” as they obviously expect us to. Time for surgery.

  12. adolfogiurfa says:

    @E.M. Do not worry, current economic policies will significantly reduce the index. There are already several million people there with serious feeding difficulties. Do not take this wrong, the intent is good: Slimming you all, the sooner the better.

  13. George says:

    How many billions of dollars of revenue for various industries does the whole BMI thing produce? Follow the money (and political control when politicians decide to “help” people become less fat).

    This rates right up there with the whole “fat free” food industry.

  14. SadButMadLad says:

    Great in depth study of why the BMI is wrong. I got the feeling it was wrong when the an increasing number of newspaper articles appeared showing cases of healthy very active young boys being classified as obese by the nannying fusbucket schools in the UK.

    You should do a similar study into calories. The method of working it out involves burning food till it’s just about ash. Nothing like the method used by the body. And it too was “invented” in the 1800s and hasn’t been changed since.

  15. Jerry says:

    All right, another button for my collection :)

  16. Jason Calley says:

    @E.M. One of the more interesting bits of square vs cube has to do with insects. (snip) It’s one of those things that is central to how life lives, yet is rarely thought about by most folks.

    IIRC it was Galileo who first explained the biological implications of the cube vs square functions, explaining why we do not have dogs the size of a house and why sea creatures who are buoyed up by water can be so enormously larger than land animals. Bright guy, Galileo!

  17. larrygeiger says:

    “When someone can have an arbitrary decision made that suddenly moves a large part of the population into a cohort of “problem” when nothing physical has changed, then start touting an “epidemic” and asking for more power and funding, yes, it IS a big deal.”

    This would be homelessness, AGW, education, poverty level, jobs “regular” Americans won’t take, much pollution (not all!), etc.

  18. Matthew W says:

    A well timed post.

    We had a “health screening” at work last week for our insurance. If we do the screening and jump through a few hoops and perform like a good little trick pony, we can get $1200 off of our yearly health care premiums. And for the $1200 I will do the tricks!!!

    I stand 6 foot 1 inch and tip the scales at 235 pounds (about 15-20 pounds over what I would like to be at). I walk a lot, ride my bike in the summer, go to the gym 5 days a week and was classified as “obese” at the screening. I knew it was coming (since we had the same screening last year) and as soon as they took my weight and before they consulted their chart, I asked “Do you really think I’m obese?” She looked and said “No” and admitted that the BMI was not a particularly good indicator of good health.

  19. Matthew W says:


    From what I have heard, a body can not tell the difference between “High fructose corn syrup” and any other kind of sugar molecule.

    Sounds mostly to me like a advertising campaign against HFCS

  20. Power Grab says:

    Re screenings at work – if we jump through the hoops, they only offer us the $250 deductible. Since I don’t use it anyway, that’s not sufficient motivation for me! ;-)

  21. H.R. says:

    Another government Bogus Mandate Incident.

    We are all aware of the government’s BMI. It certainly is obese.

  22. KevinM says:

    Its nice to be a lightweight, even if its not necessary. Its just nice to move freely.

    In game theory, it is better for us skinny folk to allow the non-skinny folk to be happily non-skinny and get of the public dole early. Same with smokers, drinkers and stress cases.

    Testing BMI is about people who want what feels right to themselves to become the standard everyone else should aspire to.

    The weight-volume issue most famously sets the limit to how large a flighted bird can be.

  23. kuhnkat says:

    Personally, I don’t think it is just that it is HFCS, it is the total amount of HFCS we get if we eat all the foods that now include them. If those HFCS were replaced by table sugar in the same amount there would probably be little difference. If you eat a diet including a large amount of processed foods you are most likely getting too much sugar period.

    HFC’s are cheaper than cane or healthier sugars so those of us who like SWEET and are price point conscious can more easily get WAAAAAAY too much sugar through their use.

  24. kuhnkat says:


    glad to know you healthy lightweight guys will be extending your earnings lifetime to support us sick, decrepit, heavy types! 8>)

  25. KevinM says:


    My point, which I believe is a missing link in Chiefios data, is the correlation between BMI and life expectancy.

    I believe the data in question is mostly unavailable to the public.

  26. KevinM says:

    Meaning an z-y plot of lifespan and BMI, not just underweight/normal/overweight/obese.

    If the [population is a normal distribution centered around overweight, then you’d expect overweight people to live… to the median life expectancy. Where do you find the peak?

  27. kuhnkat says:


    the data is that the amount of obesity is steadily climbing in the US and the life expectancy is still rising. I agree that OBESE people can have extra health problems. Of course, there are also studies that show people who are too skinny have extra health problems. The point is that the current gov’t BMI is excessive for no scientifically explicit reasons. The fact that morbidly obese people die earlier has nothing to do with someone who is adjudged obese by the ridiculous gubmint BMI.

    I would mention that my mother’s family has Diabetes. My grandmother was about 74 when she died of complications of diabetes. My mother is 83 and still not dead of diabetes although her latest blood tests show the beginnings of liver damage, probably as much from the damned diabetes and other drugs she is prescribed as from the diabetes itself. Yes, liver damage is a known side effect of the diabetes and other drugs as well as diabetes. Weird huh??

  28. Ralph B says:

    I think Kevin should take a look at junk food science (the link I sent earlier) mildly overweight people tend to live longer and recover better from surgery and other complications. They also tend to eat up far less of the health care dole than is claimed by the granola chomping skinny people in this world. It seems that the “settled science” on obesity is similar to that of AGW.

  29. adolfogiurfa says:

    @Ralph B Wonder why?…..: It´s the same people behind both (and many other silly things). Can´t explain why some so “intelligent” liberals want to change our way of life…they are so “cool”! :-)

  30. Ralph B says:

    Adolfo I do wonder why. These people claim to be sympathetic to those less fortunate yet every action they do harms them the most. It makes me think of that syndrome where a mother slowly poisons her child to keep them sick so she can care for them. I can’t listen to NPR without wanting to puke

  31. Pascvaks says:

    Helllllllllllllllo…. everybody in there OK? Long time no post. Working hard or..?

  32. E.M.Smith says:


    Just had the spouse out here for a week. First time we’d been together in 3 months. Spent most non-work time with her, or in the parks with her. Then there was the ‘kink’ in my plans from discovering that the $Few Hundred / Day hotel had nice 1980s wired internet for $10 / 24 hours. A fine deal if you are in the room 24 hours, not so fine if you are there for 30 minutes a day…

    So, all in all, I just found myself a bit trapped between work (where as a contractor it is highly unacceptable to spend time posting…) a hotel that was not very posting friendly, and an extreme shortage of time to do anything other than what the Spousal Unit wanted to do… and laundry and meals (meals in fancy restaurants are nicer, but take over an hour or two, while a sandwich in the room with the laptop can also be a posting time…)

    I’m now back in the ‘cheap hotel’ with free wireless in room internet and ‘time alone’ to think and post. I’ll catch up in the next few days, I think…

    I’ve got a half dozen posting ideas in outline, and now have the time to actually make them happen.

  33. Pascvaks says:

    (-; Whew.. the thought crossed my mind that you may have slipped in the tub, etc, etc ;-)

    Glad to hear your voice again! Hope you and the Mrs had a great reunion. Look forward to more in future as time permits. Take care!

  34. GaryP says:

    How do they measure mass anyway? When I go to the doctor they ask me to stand on a scale fully clothed and often still wearing a light jacket. I carry lots of stuff with me. Flashlight, pocket knife, camera in vest or jacket, cell phone, change, keys, wallet, heavy shoes, plus long underwear and extra long sleeve undershirt in the cold seasons. Fully clothed to nude is a difference of about 8-9 lbs. Full cool weather motorcycle gear w/ helmet = 25 lbs not including a camel back water bottle. (I cannot run with all that stuff on).

    So how is that BMI index made? Nude or fully clothed?

  35. Tommy says:

    I have always wondered about how BMI is calculated as given I am 14st 4lb …. the BMI Chart says I am clinically obsese? I am fit and work out so feel great ….

    I would say it should be nude to calculate BMI to get true reflection …..

  36. Tim says:

    If blacks sink in the pool like they say doesn’t it mean they have a greater proportion of dense lean mass? (Neglecting lung volume if breathing in)

    [Reply: Blacks have 10% more dense bones, and much more leg length to body length (i.e. whites have more lungs and less muscle and bone legs). Whites are optimized for swimming in north cold waters and wading through deep snow. Blacks for sprinting on the plains of Africa. Different shapes more than degree of lean in the muscles. -E.M.Smith ]

Comments are closed.