The nanny state and BMI B.S.

[Amber]

The nanny state strikes again. Matt's school sent a fat letter home to me. They say his BMI is in the obese range.

"Your child was weighed and measured...blah blah blah...height 48.25 inches, weight 64 pounds, BMI 95th percentile. Your child's weight category is obese."

I love Penn & Teller's "Bullshit". They have a great episode on Obesity.

Obesity 1/3
Obesity 2/3
Obesity 3/3

When he was 6 months old, exclusively breastfed little roly poly chubba baby and weighed in at 30 pounds I would have given you obese. But now? No way. The kid is a tank.

Dear Public School System:
My kid doesn't need soy milk to screw up his endocrine system, and if he were any more active he'd need a hamster wheel. But thanks for wasting your time, my time, and some trees.
Best,
AB

[JoJo]

Let me guess - Matt is in 4th Grade. When my daughter was in 4th grade, I received the letter stating that they were measuring BMIs at school but that we did have the option of opting out but that you had to inform the school nurse to do so. I did because my feeling is that my daughter's weight/BMI is no one's business but hers, mine and her doctor's.

This is a state manadate measurement and it is part of the effort to track childhood obesity statistics and what areas of the state have a greater number of overweight children and tie that statistic to economic conditions of the area. Yet beyond sending letters home like yours, the state does not do much else to help the situation.

[Amber]

Let me guess - Matt is in 4th Grade. When my daughter was in 4th grade, I received the letter stating that they were measuring BMIs at school but that we did have the option of opting out but that you had to inform the school nurse to do so. I did because my feeling is that my daughter's weight/BMI is no one's business but hers, mine and her doctor's.

Nope, 1st grade with no notification or option to opt out.

[Tony1941]

BMI being one of my favorite topics to discuss with physicians, I did a quick review of my files and Wikipedia and submit the following.
1. Ancel Keys, the inventor of BMI, specifically states that it should not be used for individual diagnosis.
2. I did a quick study of the Celtics roster to determine their BMI. One would assume that professional athletes that run back and forth would have BMIs within the desired range.
BMI Celtics 2011 Roster.pdf
Please note KG is overweight and the Shaq is Obese

3. Body builders with body fat % below 4% will have BMIs well over 30.
4. The optimal BMI for longevity is between 26 and 28. i.e. If you want to have a long life, you should target your BMI to be between 26 and 28.

Please note that insurance companies use BMI to exclude coverages and of course medical professionals selling bariatric services will also use BMIs to generate business.

I would not lose any sleep or be overly concerned by these fat letters. I would suggest that you discuss the health of your child with your doctor.

Body mass index
http://en.wikipedia.org/wiki/Body_mass_index
From Wikipedia, the free encyclopedia (11/14/2010)
While the formula previously called the Quetelet Index for BMI dates to the 19th century, the new term "body mass index" for the ratio and its popularity date to a paper published in the July edition of 1972 in the Journal of Chronic Diseases by Ancel Keys, which found the BMI to be the best proxy for body fat percentage among ratios of weight and height; the interest in measuring body fat being due to obesity becoming a discernible issue in prosperous Western societies. BMI was explicitly cited by Keys as being appropriate for population studies, and inappropriate for individual diagnosis. Nevertheless, due to its simplicity, it came to be widely used for individual diagnosis, despite its inappropriateness.
However, BMI has become controversial because many people, including physicians, have come to rely on its apparent numerical authority for medical diagnosis, but that was never the BMI's purpose; it is meant to be used as a simple means of classifying sedentary (physically inactive) individuals with an average body composition. For these individuals, the current value settings are as follows: a BMI of 18.5 to 25 may indicate optimal weight; a BMI lower than 18.5 suggests the person is underweight while a number above 25 may indicate the person is overweight; a BMI below 17.5 may indicate the person has anorexia nervosa or a related disorder; a number above 30 suggests the person is obese (Al C) (over 40, morbidly obese).

Statistical device
The BMI is generally used as a means of correlation between groups related by general mass and can serve as a vague means of estimating adiposity. The duality of the BMI is that, whilst easy-to-use as a general calculation, it is limited in how accurate and pertinent the data obtained from it can be.

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. The categories also fail to account for varying proportions of fat, bone, cartilage, water weight, and more.

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. This can be contrasted with group insurance policies which do not require medical underwriting and where insurance admissibility is guaranteed by virtue of being a member of the insured group, regardless of BMI or other risk factors that would likely render the individual inadmissible to an individual health plan.

Limitations and shortcomings
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.
The medical establishment has generally acknowledged some shortcomings of BMI. Because the BMI is dependent only upon weight and height, it makes simplistic assumptions about distribution of muscle and bone mass, and thus may overestimate adiposity on those with more lean body mass (e.g., athletes) while underestimating adiposity on those with less lean body mass (e.g., the elderly).
A 2005 study in America showed that overweight people had a similar relative risk of mortality to normal weight people as defined by BMI, while obese people had a higher death rate.
...
A further limitation relates to loss of height through aging. In this situation, BMI will increase without any corresponding increase in weight.
As a possible alternative to BMI, the concepts fat-free mass index (FFMI) and fat mass index (FMI) were introduced in the early 1990s.

Body Fat Vs. BMI
From Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Body_fat_percentage
There are several methods to measure body fat such as
Body fat percentage
A person's body fat percentage is the total weight of the person's fat divided by the person's weight and consists of essential body fat and storage body fat. Essential body fat is necessary to maintain life and reproductive functions. The percentage for women is greater than that for men, due to the demands of childbearing and other hormonal functions. Essential fat is 3%-5% in men, and 8–12% in women.
Recommendations
Different cultures value different body compositions differently at different times, and some are related to better health or improved athletic performance. Levels of body fat are epidemiologically dependent on gender and age. Different authorities have developed different recommendations for ideal body fat percentages, such as these from the American Council on Exercise:
Description Women Men
Essential fat 10-13% 5-8%
Athletes 14–20% 6-13%
Fitness 21–24% 14–17%
Average 25–31% 18–24%
Obese 32%+ 25%+
Essential fat means that level below which physical and physiological health would be negatively affected.

Measurement techniques
A living person's exact body fat percentage generally cannot be determined, but there are several techniques, which can be used to estimate it to a good degree of accuracy.

Near-infrared interactance
A beam of infrared light is transmitted into the biceps. The light is reflected from the underlying muscle and absorbed by the fat. The method is safe, noninvasive, rapid and easy to use.

Dual energy X-ray absorptiometry
Dual energy X-ray absorptiometry, or DXA (formerly DEXA), is a newer method for estimating body fat percentage, and is commonly cited as the current gold standard for body composition testing.

Expansions
There are several more complicated procedures that more accurately determine body fat percentage. Some, referred to as multicompartment models, can include DXA measurement of bone, plus independent measures of body water (using the dilution principle with isotopically labeled water) and body volume (either by water displacement or air plethysmography). Various other components may be independently measured, such as total body potassium.

Body average density measurement
Prior to the adoption of DXA, the most accurate method of estimating body fat percentage was to measure that person's average density (total mass divided by total volume) and apply a formula to convert that to body fat percentage.
However, this method gives highly reproducible results for individual persons (± 1%), unlike the methods discussed below, which can have an uncertainty up to ±10%. The body fat percentage is commonly calculated from one of two formulas (_ in g/cm3):
_ Brozek formula: BF = (4.57/_ _ 4.142) _ 100[7]
_ Siri formula is: BF = (4.95/_ _ 4.50) _ 100[8]

Bioelectrical impedance analysis
The bioelectrical impedance analysis (BIA) method is a more affordable but less accurate way to estimate body fat percentage. The general principle behind BIA: two conductors are attached to a person's body and a small electric current is sent through the body.
Anthropometric methods
There exist various anthropometric methods for estimating body fat. The term anthropometric refers to measurements made of various parameters of the human body, such as circumferences of various body parts or thicknesses of skinfolds.

The chief problem with all statistically derived formulas is that in order to be widely applicable, they must be based on a broad sample of individuals. Yet, that breadth makes them inherently inaccurate. The ideal statistical estimation method for an individual is based on a sample of similar individuals.

[rcweir]

I think of it this way. For most medical conditions there are a range of diagnostic procedures. They vary in their cost, their accuracy, their intrusiveness, side effects, etc. I think we're all familiar with cheap, somewhat accurate screening techniques, that if they come up positive, trigger more lab work for more expensive or more intrusive techniques to confirm the initial indication. So think of BMI as the quick and cheap diagnostic tool. Will it give some false positives? Certainly. But it starts the conversation.

[Tony1941]

Nope, 1st grade with no notification or option to opt out.

Enclosed are two charts that show the relationship of BMI to percentile.

girlsbmi.pdf

boysbmi.pdf

You should note that a boy with a BMI of 19 would be at the 95% level.
All it means is that the population that he was compared with had BMIs lower than 19.
It is obvious from the pictures that you posted your son is not a fatty.

IMHO The notice should have contained information about the composition of the baseline population and the implication of the percentile reported.

If the baseline population was composed of Asians which tend to have smaller bone structure then most European descendants would have high percentiles. On the other hand if the baseline were children of the Danish extraction, your son would have been lucky to be at the 50%. The Danes aka Vikings are big dudes and very muscular. I have worked with Vikings who stood 6'6" plus and weigh well over 300 lbs. Their strength and endurance while working at Thule, Greenland with temperatures ranging from zero to minus 20F amazed everyone.

[Tony1941]

I think of it this way. For most medical conditions there are a range of diagnostic procedures. They vary in their cost, their accuracy, their intrusiveness, side effects, etc. I think we're all familiar with cheap, somewhat accurate screening techniques, that if they come up positive, trigger more lab work for more expensive or more intrusive techniques to confirm the initial indication. So think of BMI as the quick and cheap diagnostic tool. Will it give some false positives? Certainly. But it starts the conversation.

Unfortunately most medical professionals have no idea of the origins of the BMI. The author/inventor of the BMI specifically states that it should not be used for individual diagnostics.
If the body fat % needs to be used in a diagnosis there are more accurate methods. At the current time, Emerson hospital is using BMI to make recommendations to patients on the bariatric surgery. Why? Emerson has recently constructed a bariatric surgery section.

Of course, diet and exercise will not only cause the patient to lose weight but would enhance the overall muscular and aerobic structures of the patient at a lower cost and lower health risk.

[Amber]

I think of it this way. For most medical conditions there are a range of diagnostic procedures. They vary in their cost, their accuracy, their intrusiveness, side effects, etc. I think we're all familiar with cheap, somewhat accurate screening techniques, that if they come up positive, trigger more lab work for more expensive or more intrusive techniques to confirm the initial indication. So think of BMI as the quick and cheap diagnostic tool. Will it give some false positives? Certainly. But it starts the conversation.

I have done 20-55 mile bike rides and I can push around more weight in the gym than many guys I know. As of my physical 2 months ago, my fasting blood sugar and HDL/LDL are all in the normal/healthy range. Would I like to be a Stepford Wife Size 6? Sure...but it doesn't mean that because I am not I'm doomed to have a quadruple bypass, either.

Maybe if the state is so worried about the health of our kids they should tell the teachers' union to go bite it, give all of the K-5 kids an extra 30 minute recess every day; and stop calling corn, rice, and nacho chips a healthy school lunch.

[DanD]

Just one more example of out of control government. What a huge waste of precious taxpayer dollars.

[Tony1941]

Just one more example of out of control government. What a huge waste of precious taxpayer dollars.

Dan, I wold chalk this one up to ignorance. i.e. The devil made me do it.

As you can see from my brief post (The original post was 28967 characters, forum limit is 10,000 characters) that anyone who uses BMI for a diagnostic tool is either ignorant or is trying to sell you a very expensive service.