Should BMI be Scrapped as a Measure of Health?
Dave at the Crisper Blog says it's time to scap the Body Mass Index (BMI) as a way of calculating obesity or health. I have to say that I agree. My BMI is fairly low (20) but I've had heart problems and BMI seems to have little correlation to the amount of actual body fat one has--a linebacker who has huge muscles and little body fat could easily be obese by the standards of BMI.
I recently had my body fat tested--you know, when they pull out the body fat calipers
and pinch different areas of your body to see how much fat you have--I was amazed at how high mine was. I won't bore you with the exact percentage, but let's just say that my body has a lot in common with a 200 pound woman. I have no idea why my body fat is so high--the lowest it has ever been (17%) was after I gave birth to my daughter. I have always been a bit of an anomaly so I don't take these tests too seriously. Unfortunately, many insurance companies and doctors do and this makes for a lot of discrimination against people who are in otherwise good health and not necessarily obese.
I recently had my body fat tested--you know, when they pull out the body fat calipers
and pinch different areas of your body to see how much fat you have--I was amazed at how high mine was. I won't bore you with the exact percentage, but let's just say that my body has a lot in common with a 200 pound woman. I have no idea why my body fat is so high--the lowest it has ever been (17%) was after I gave birth to my daughter. I have always been a bit of an anomaly so I don't take these tests too seriously. Unfortunately, many insurance companies and doctors do and this makes for a lot of discrimination against people who are in otherwise good health and not necessarily obese.
posted by Helen at 7:20 AM
24 Comments:
The only accurate way to find your BMI is to go get dipped. It's all about comparing the volume you take up as compared to your weight. I don't use one of those BMI scales because I always get the feeling it is going to be inaccurate. I've never in my life felt body fat calipers to be anywhere near precise.
However, I don't need to tell anyone that muscle is much denser than fat. The weight scale doesn't tell the whole story. If one judges their health by merely using weight as a factor, they may not understand that they have an unhealthy amount of fat and not enough muscle. The BMI is just fine, but it is the methodology that needs to be consistent.
You do not get your BMI by getting dipped. You get your body fat percentage by getting dipped. BMI is just (weight/(height squared)) you just need to know those two variables to calculate it. When being dipped you get an estimation of body fat percentage based on your average density. You get dipped to find out your volume. The weight is then divided by volume to calculate the density and the density is plugged into a formula (either Siri or Brozek) to estimate BF percentage. And yes BMI is useless as a health indicator as it completly misses the distinction between muscles and fat. BF% is a much better indicator but since it is harder to estimate than BMI many physicians just do not bother.
And body calipers are not very precise but if the user is consistent in method they can be very helpful to detect changes in BF% which can be very useful. Some people starting a fitness program comlain that they are not losing weight but their body composition is changing rapidly as they lose fat and gain muscle. Calipers can be very useful to make them realize what is actually happening.
All I know is that you are an awesomely beautiful woman, visually and spiritually. The nanny state has long since invaded the medical profession, to all of our detriment.
While BMI isn't perfect, it is really useful for the vast majority of people. Too many people lifting weights is not the big American health problem.
the bmi was made for the insurance companies in the 20's or 30's, based on the insurance policies, not the health of everyone, just those that could afford the insurance..
this is the modern stuff
but it was based on
http://en.wikipedia.org/wiki/Body_Mass_Index
It was invented between 1830 and 1850 by the Belgian polymath, Adolphe Quetelet during the course of developing "social physics
In 1998, the U.S. National Institutes of Health brought U.S. definitions into line with WHO guidelines, lowering the normal/overweight cut-off from BMI 27.8 to BMI 25. This had the effect of redefining approximately 30 million Americans, previously "technically healthy" to "technically 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
** so someone in 1998 went to sleep technically healthy, and woke up over weight..
**
Individuals who are not sedentary - especially athletes - as well as children, the elderly, the infirm, and individuals who are naturally endomorphic or ectomorphic (i.e., people who don't have a medium frame) are ill-fitted to assessment using the BMI. Or to state the problem more accurately, the BMI measurements at which these people may be underweight, overweight or obese are different from sedentary mesomorphs whose ages are between about 20 and 70.
**
i disagree bobh, it is not useful, there are massive differences, in sizes and health through race, country, if your an ectomorph, or a endomorph. then again theres the muscles, then.. theres ages, then theres.. and.. and. and..
all based on 130 year old information, then insurance agents.
To Mercurier:
So comparatively recent epidemiological studies showing a positive correlation betweeen relatively low BMI and long life and good health are bogus, right??
Or do you just believe that if a correlation coefficient isn't one, then it must be zero?
My twins "flunked" the BMI fat test in high school. The boy was a standout on the school soccer team who taught himself to do handsprings and backflips. The girl was a size 0 who has been dancing since she was 5 years old. Everyone I know describes them as being thin, or skinny.
they also show that a higher bmi had a less death rate, than a normal BMI.
which is even more recent.. as in last week.
http://www.news-medical.net/?id=19530
Body mass index (BMI) - the commonly used measure of obesity - cannot reliably predict the outcome for patients with heart disease, concludes an Article in this week's issue of The Lancet.
This is because BMI is an unreliable indicator of obesity, say the researchers.
Doctors already know that obesity is a risk factor for developing heart disease. However, how obesity affects people with established heart disease has been unclear because previous studies have had contradictory results.
To investigate, Francisco Lopez-Jimenez (Mayo Clinic College of Medicine, Rochester, MN, USA) and colleagues combined data from 40 studies involving about 250,000 people with heart disease; the average follow-up was four years. Most of the studies used BMI as a measure of obesity.
The investigators found that patients with a low BMI had a higher risk of death than those with a normal BMI. Overweight patients had better survival and fewer heart problems than those with a normal BMI. Obese people who had had bypass surgery had a higher death rate when compared with people with a normal BMI, while severely obese people had a higher risk of a heart-related death but not death from other causes
**
This if from the Lancet THE medical magazine.
http://www.thelancet.com/journals/lancet/article/PIIS0140673606692222/fulltext
This meta-analysis does not provide new information, but some useful implications can be drawn from it. BMI can definitely be left aside as a clinical and epidemiological measure of cardiovascular risk for both primary and secondary prevention. The contribution of body fat to cardiovascular risk is a matter of integrated basic, clinical, and epidemiological research, to which retrospective analysis of existing databases could hardly add relevant insights.
***
the lancet is the magazine that has all the new discoveries, and that doctors read.. you do have to sign up for it.
What is their definition of "low BMI". As I recall, it was in the range of 15-17. The supposed optimum range is 18-21. The "normal range" is between 20 and 25. Also, if you look further, I think that you'll find that obesity is strongly correlated with death due to the consequences of type II diabetes.
What is their definition of "low BMI". As I recall, it was in the range of 15-17. The supposed optimum range is 18-21. The "normal range" is between 20 and 25. Also, if you look further, I think that you'll find that obesity is strongly correlated with death due to the consequences of type II diabetes.
As a 28 year old woman, I entered a medical weight loss program. Upon admission, my body fat percentage was measured by dipping and by electical current transference. Imagine everyone's surprise that my body, with a BMI of 40, was only 23% fat. I wasn't athletic; I'm muscular by nature. Years and many pounds later, I'm still frustrated by the health industry's reliance on BMI. I would have to lose muscle mass or lop off an arm to cross the border between "overweight" and "normal weight".
Also, people with with very low BMI (1) smoke cigarettes at a higher rate than the population as a whole (one reason for smoking, especially among young women, is to supress appetite) and/or (2) tend to have low BMIs because they are already ill.
the word strongly correlated, meaning its possible or could be a coincidence. hypertension can cause type 2 diabetes,
http://www.centerforeatingdisorders.com/myths.html
Body fat is unhealthy
Actually, some body fat is essential and beneficial. For example, fat on the thighs and hips are reported to lower the risk of cardiovascular disease and type 2 diabetes, especially for women. A certain amount of body fat is necessary for normal body
Weight loss improves health & lengthens life
Weight loss does not necessarily improve health or lengthen life. In fact, yo-yo dieters and those whose weight fluctuates throughout their adult lives are twice as likely to develop cardiovascular disease and type 2 diabetes than people who remain overweight.
http://www.centerforeatingdisorders.com/myths.html
and what are the exact figures of type 2, from 10 years ago to now.. is there a difference.. u try to find the data..
i am overweight i know it, but i know if i lost weight i would yo yo, up down up down, and thats dangerous for anybody, as you put on more weight.
the BMI doesnt take into account,
genetics, race, culture, body composition, sex, metabolic rates (endomorph/ ectomorph). and evironmental factors too, and medical (allergies etc,illnesses no related to being fat)
financial(cheap food are more fattening expensive is healthier can you afford to eat all the healthy options all the time).
they are making so called links, with 2 disparete studies, people suffering more from type 2, and people are getting fatter, NOT the same study. but they put them together.
**writer tries to argue that a conclusion drawn from a specific condition also entails that we can conclude the specific condition by knowing the general situation, then s/he is converting a conditional. Argument using this fallacy take the form If A then B, therefore if B then A.
"If my cat is like all cats, then all cats are like my cat."
** this is what they are doing or of cum hoc ergo propter hoc,
**This fallacy ignores the possibility that the two things might be unrelated, having different causes, and that their simultaneous appearance was coincidence. This fallacy also ignores the possibility that the two things appeared at the same time for some yet unknown third cause, the common origin of both. Just because two things occur at the same time does not necessarily mean one caused the other. Coincidence does not prove causation.
**
(Full disclosure: I was extremely overweight for over a decade. My weight is now squarely in the middle of the BMI recommendation for my height.)
While BMI is may not be the be all and end all answer to what a person should weigh, it does give a standard rule of thumb for a person to shoot for. I am a 6'0" male the weight range the BMI scale for "normal" is 35 pounds wide.
While BMI may not be the best gauge of "health" it is a decent gauge for what the "average" person should weigh. I find it interesting when people say the scale is just flat wrong they tend to use athletes who are obviously way outside the norm to bolster the case. A NFL linesman or NBA star is hardly an average person.
As people age their healthy weight tends to increase. Depending on the if it was controlled for in the study the reason people with lower BMI values may tend to have higher mortally rates has to do with their overall health. They may well be lighter because of health issues.
I would never argue that BMI is a good approximation of overall health, there is far more to being healthy than just a healthy weight. It is also not healthy to assume that because a person weighs more than the BMI scale suggests, that they are in the same physical shape as Terrell Owens. Unfortunately most over weight people use examples like Duante Culpepper as an excuse to convince themselves they are not over weight.
Health comes from eating well, exercising regularly and regular checkups to detect issues as early as possible. Throwing out the BMI scale will do next to nothing to change the overall health of society. No mater what arbitrary scale is used people will always point to the exceptions to provide validation for their beliefs.
An area of concern for us is the "skinny fat" girls who have the right size jeans, but less muscle mass than we would like.
The only way to get through their heads is with calipers.
The good news for the skinny-fat is all they really need to do is watch fat intake and hit the weight room -- good advice for anyone.
You could stand is a room and argue about the validity of the test, but the above poster was correct in that repeated body-fat measurements are a good guide to how well you are doing at reducing body fat. Make sure you use the same method each time -- don't bounce between the electrodes, calipers, and water displacement. They rely on different models of body composition.
My 2 cents.
h.
there are many more studies on the feast/famine idea, how in a famine (lack of food), you lose weight, but in a feast you eat the body puts on more weight for the next famine.. thats fact..
a lot of so called fat people eat less than some thinner people. oh but the fat must be lazy coz they are fat, they cant lose weight they must be slobs, this is typical of the puritanical idea of american diet industry. there is no diet that ever works, some of the diets are technically starvation rates of calories. you in the west on these diets are effectively starving yourself to death.
and how exactly does an external measurment determine health.. i could say let me measure your nose divided by your tongue, if its 1 then your healthy, if not your sick.
this is all about external appearances, how can that determine health, as soon as u say oh this person with a larger tongue or fat hips, outward appearances have NOTHING to do with inner health.
I wouldn't assume linebackers (or other football players) have high BMI's butlow body fat. Football players are typically badly over-weight by any measure and die younger, on the whole, than other American men. This is at least partially due to the fact that football players are highly specialized and are rarely complete athletes.
Ok,Mercurior. It's late and I'm in a good mood, let's engage.
Body composition is not about "outward appearance" -- precisely the opposite, as I mentioned above. There is great discussion about the value of body composition numbers as real numbers describing precisely how much of your body mass is fat. The view of body composition is evolving from a 2-part model (fat and non-fat) to a 3-part model (fat, non-fat tissues, and bone density). Science shows the 3-part model is more accurate, but the bone density testing is expensive. Professionals are recommending clients who need to monitor body fat percentage choose a method and monitor that number in relation to other performance factors. The number, in isolation, is nearly meaningless.
However, while the number itself is nearly meaningless, the construct represented by the number is important. Skin-fold measurements can show progress toward a lean-mass goal. Dieting is not recommended, but rather healthy eating is emphasized in addition to increasing load-bearing exercise to encourage the development of lean body mass.
Unless you are anticipating famine, fat mass is useless tissues that have to be supported. The support of those tissues is subjecting your body to unhealthy physical stressors.
As you have stated many times previously, you are overweight but your other indicators of health are perfectly in line. Good for you.
For others who are concerned about their health, skin-fold measurement can be a more accurate and satisfying way to measure progress than weighing in.
but its not about concious decisions, your body does its own things, there have been studies on fat people, and thin people and yo yo dieters,
it is part of the nature of humans, that in times of plenty you put more stores into fat production, to stop you from dying in famines, it is a genetic/biological FACT
***
One function that’s biologically built into our brains is the job of ensuring that we get enough food, and the right kinds of food, to survive," Hagan says. "When we starve ourselves to lose weight, or go on some crazy diet that’s all fruit or all protein or all carbohydrates, our brain feels deprived. So its response is to increase our levels of the natural chemicals that create hunger, and to decrease levels of the chemicals that make us feel sated.
There’s something sinister about combining stress and diet," Hagan says. "When laboratory rats are placed under stress, they’ll binge on food even though they’re not hungry and not underweight. There’s bound to be a good biological reason for animals to behave as they do, and in these cases it seems to be an adaptive mechanism. Whether you’re running from a predator or dealing with a difficult boss, the body signals you to store up food so you’ll have fuel if you encounter the same threat again
But a tantalizing, and little-known, factor in this equation is that lab rats only binge under stress if they’ve been deprived of food at some point in the past–if, say, they have ever been on a diet. And though the reasons are unclear, the same is true of humans.
"The strongest predictor of who will overeat when stressed," says Hagan, "is not body weight or build or gender, but whether they are dieters. No one knows how stress and dieting connect to cause binge eating, but we recently received funding from the National Institutes of Health to investigate neurochemical changes in our animal model of binge eating, which should help us understand the process."
**
http://main.uab.edu/show.asp?durki=63280
so you are going on looks, about a person without knowing the history, the genetics how is that better. my mum lived through the 2nd world war in the UK, and she buys a lot of food and stores it, why, coz she was used to starvation, and stores up stuff, this is an outside representation of what happens in your body.
it is KNOWN, have a word with some biologists, there are many things in us that we have no control over, the body has its own safety mechanism for survival, the problem is the brain tries to over ride this, but doesnt suceed so the body over compensates and u do it again.. thats why yo yo diets are generally fatter than if they stayed the same.
read about the thrifty gene sydrome
http://www.chestjournal.org/cgi/content/full/122/3/774
very technical,
Teleologic considerations have given rise to the hypothesis that the metabolic syndrome is a remnant of evolutionary development under the pressures of a "feast-or-famine" existence. The theory holds that one or more "thrifty" genes emerged that act to conserve energy during times of famine. Examples of this include reducing thermogenesis or inhibiting pregnancy and lactation. The genotype also should enable the maximal storage of energy during times of plenty in the form of adipose tissue rather than glycogen since this type of energy storage provides more sustenance during periods of starvation.6 The thrifty genes thus afford a survival advantage when the food supply is highly variable. However, this theory holds that the survival advantages of the genotype become liabilities when energy supplies are abundant and remain so. The metabolic syndrome results, and survival is impaired. Several putative mediators have been identified in support of this theory. One of them is leptin, which is a 167-amino acid protein produced by adipocytes and a variety of other tissues. Leptin has been shown to suppress hypothalamic neuropeptide Y in mice,7 and, since neuropeptide Y stimulates appetite and thermogenesis, it is involved in a useful negative feedback mechanism. The ob gene has been identified as encoding for leptin, and the db gene as encoding for a hypothalamic leptin receptor in mice, and similar genes have been located in humans.8 Interestingly, mice that are heterozygous for defective ob or db genes live longer when fasted than do normal mice, thus demonstrating the kind of survival advantage necessary for a thrifty gene.8 Other possible mediators of the thrifty genotype are insulin receptor substrates (particularly insulin receptor substrate-1), phosphoinositide 3-kinase, hormone-sensitive lipase, endothelial lipoprotein lipase, mitochondrial uncoupling proteins, tumor necrosis factor (TNF)-, glycogen synthase, and others.8
I have a younger sister who would probably be considered obese by any standard but who seems to have more stamina and health than women half her weight. Whilst she is at least a couple of inches shorter than me (I'm 5'6") and would admit herself that she needs to lose some weight (and is doing so), I think that if she were to drop to the weight recommended according to her BMI and accepted medical theory then she would have lost too much weight. She seems at her healthiest at around 9-10st, looking slightly plump but healthy.
Knowing that UK Doctors have already admitted that the Recommended Weekly Alcohol figures were plucked out of thin air it wouldn't suprise me if a similar technique was used for BMI.
Rather than having a 'target weight' mentality doctors should be encouraging an overall healthy lifestyle. There are plump people stressing themselves out over nothing while thinner looking people have arteries that look like the inside of a 200 year kettle. This only encourages the body-fascists who are spawning new and exciting kinds of eating disorders as we discuss this.
To keep your body healthy you have to reduce your body weight and ensure that it is with in the BMI range (BMI between 18.5 and 24.9). Exercise and well balanced diet are the best ways to prevent many diseases caused by over weight. Weight control methods can help you to keep your weight within normal BMI range. http://www.phentermine-effects.com
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