An earlier submission on the same topic. The BMI (Body Mass Index) is a metrication success story because, as far as I know, the values have existed in metric only. Yes, there were the feeble attempts to redefine BMI as "*divide your weight in pounds times 705 by the height in inches squared*" but the number was always the same, the "metric" one. It is certainly more appealing to USMA members to know BMI as "your mass (kg) divided by your height squared (m²)."
When I incorporated the BMI calculation in my classes some 35 years ago, the average values in the U.S. were 27.8 for man, 27.3 for women. (I wrote those numbers on the blackboard for everyone to compare theirs - a scale and a tape were provided for that purpose.) Recently, I came across an article in *Nutrition Today *that reported that the ideal BMI for U.S. man is 21.9 to 22.4, average 22.2, and for women 21.3 to 22.1, average 21.7. Besides that, there is an international standard that states: Anyone 25.0 and over is *obese*, while anyone 18.5 and under is *underweight* (why not "skeletal," or something equivalently repulsive to the term "obese," I wonder). The article then focuses on the most interesting subject related to BMI - the beauty pageants. A survey of Miss America winners from 1922 to 1999 exhibits a more or less steady lowering of the number from 22 the first year to 18 a decade ago with a puzzling jump back to over 20 subsequently. The lowest was 16.9 in the late 1980s. As for all women in the U.S., today, the average is 28.4, average Miss America contestant is 19.3 and Barbie Doll is still at 13.7, unchanged since 1959. I trust you will sleep better knowing about this metric success of kg/m². But there is more to this story. It illustrates what I have been telling my students: "With SI implemented, we will not need to pronounce units." Explaining, I would use the BMI example. And add that one may need prefixes with some values but not the units because, in SI, only one unit exists for any measurement. Thus if one knows from the context what the subject is, such as grocery shopping, the prefix is sufficient, in this case the kilo. The BMI illustrates my maxim: not even the prefix is needed. Everybody uses BMI numbers without ever seeing the unit or feeling the need for identifying it. Similarly with tire pressure gages I saw in Europe - a scale only; no unit, no prefix on the dial at all. If it is tire pressure it "obviously" is in kPa. Stan Jakuba On Sat, Jun 30, 2012 at 10:17 PM, Bill Hooper <[email protected]>wrote: > The BMI interpretation from the Center for Disease Control and > Prevention is: > *BMI* > *Weight Status* Below 18.5 Underweight 18.5 – 24.9 Normal 25.0 – 29.9 > Overweight 30.0 and Above Obese > (The SI units used for BMI in this table are kilograms per square metre, > kg/m².) > > This info is from: > > http://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html > > > Bill Hooper > mass = 71.8 kg > height = 1.8 m > BMI = 22 kg/m² > > > ===================================== > > On Jun 29 , at 9:00 PM, Pierre Abbat wrote: > > On Thursday 28 June 2012 16:49:20 Carleton MacDonald wrote: > > Me, unfortunately, right now, 98.3 kg, 1.79 m: > > > 98.3/1.79 = 54.9162 > > > 54.9162/1.79 = 30.679 > > > BMI is 30.679. > > > What's unfortunate about a BMI? Mine is 36 (81/1.5²) and that seems to be > where my body likes it. > > You should state yours as 30.7 or 31. Your mass can vary by a kilogram one > way > or the other throughout the day, so there's no way you can get five > significant figures in a BMI. > > Pierre > -- > ve ka'a ro klaji la .romas. se jmaji > > > > > > > > > > >
