BMI and Glycemic Index: (Not what you think)
Fess up. I’ll bet you already think you know what I’m going to talk about- the connection between the glycemic index of the foods you eat and your BMI.
Right?
Nope.
These two measures- glycemic index and BMI- have something else in common.
They’re both extremely inaccurate and incomplete measures of the thing they purport to be measuring.
What got me thinking about this is today’s New York Times article (quite good) on BMI and it’s limitations. The BMI (body mass index) basically looks at two variables- height and weight. Using these two variables, it calculates a single number which is supposed to tell you if you are overweight, underweight or “just right”. (For those who are interested, underweight is less than 18.5, overweight is between 25 and 29.9 and obese is over 30). The BMI has the advantage of giving you your info in a single number so you don’t have to wade through those old Metropolitan Life “height and weight” tables. The BMI number is equally applicable to either sex.
Anyone see a problem so far?
Let me give you a hint.
Sylvester Stalone, at fighting weight, in the amazing shape he was in for Rocky 19, or whatever that last movie was, has a BMI of over 30.
I haven’t measured him, but I’m willing to bet that Ronnie Coleman, the current Mr. Olympia, is off the charts. Serena and Venus Williams would probably be rated “obese”. So would any well muscled athlete, policeman, Marine and half the personal trainers in America.
Why?
Because BMI does not take into account body composition.
A 5'7" 175 pounder with 3 percent body fat would rate the same BMI as a 5'7" 175 pounder with 33% body fat. So while BMI gives a little bit of an indication of whether or not you’re healthy, it’s only one tiny piece of the equation and misses some of the most important data.
Which brings me to the glycemic index.
Just as the BMI doesn’t take into account body composition, the glycemic index doesn’t take into account portion size. The glycemic index uses a standard portion of 50 grams of “available carbohydrate” (non-fiber) to measure the effect of a food on blood sugar.
That’s great, but irrelevant.
Why? The typical available (non-fiber) carbs in a plate of spaghetti at the Olive Garden is about 200. The typical number of available carbs in a carrot is about 3. So to compare the “glycemic index” of carrots with that of spaghetti (carrots are higher) tells you precisely nothing about the real life effect of the food on your blood sugar.
(For years, a misunderstanding of this measure has caused well-meaning nutritionists to give weight loss clients the rather ridiculous advice to avoid carrots).
That’s why I’ve abandoned glycemic index for the much better glycemic load, which does take into account portion size.
And why I’d love to see a BMI-like measure that took into account body composition.
Is there a moral to the story? Only this: Single numbers- and single facts- rarely tell the whole picture in health.
Just as in the rest of life.
Right?
Nope.
These two measures- glycemic index and BMI- have something else in common.
They’re both extremely inaccurate and incomplete measures of the thing they purport to be measuring.
What got me thinking about this is today’s New York Times article (quite good) on BMI and it’s limitations. The BMI (body mass index) basically looks at two variables- height and weight. Using these two variables, it calculates a single number which is supposed to tell you if you are overweight, underweight or “just right”. (For those who are interested, underweight is less than 18.5, overweight is between 25 and 29.9 and obese is over 30). The BMI has the advantage of giving you your info in a single number so you don’t have to wade through those old Metropolitan Life “height and weight” tables. The BMI number is equally applicable to either sex.
Anyone see a problem so far?
Let me give you a hint.
Sylvester Stalone, at fighting weight, in the amazing shape he was in for Rocky 19, or whatever that last movie was, has a BMI of over 30.
I haven’t measured him, but I’m willing to bet that Ronnie Coleman, the current Mr. Olympia, is off the charts. Serena and Venus Williams would probably be rated “obese”. So would any well muscled athlete, policeman, Marine and half the personal trainers in America.
Why?
Because BMI does not take into account body composition.
A 5'7" 175 pounder with 3 percent body fat would rate the same BMI as a 5'7" 175 pounder with 33% body fat. So while BMI gives a little bit of an indication of whether or not you’re healthy, it’s only one tiny piece of the equation and misses some of the most important data.
Which brings me to the glycemic index.
Just as the BMI doesn’t take into account body composition, the glycemic index doesn’t take into account portion size. The glycemic index uses a standard portion of 50 grams of “available carbohydrate” (non-fiber) to measure the effect of a food on blood sugar.
That’s great, but irrelevant.
Why? The typical available (non-fiber) carbs in a plate of spaghetti at the Olive Garden is about 200. The typical number of available carbs in a carrot is about 3. So to compare the “glycemic index” of carrots with that of spaghetti (carrots are higher) tells you precisely nothing about the real life effect of the food on your blood sugar.
(For years, a misunderstanding of this measure has caused well-meaning nutritionists to give weight loss clients the rather ridiculous advice to avoid carrots).
That’s why I’ve abandoned glycemic index for the much better glycemic load, which does take into account portion size.
And why I’d love to see a BMI-like measure that took into account body composition.
Is there a moral to the story? Only this: Single numbers- and single facts- rarely tell the whole picture in health.
Just as in the rest of life.
1 Comments:
Such a cozy place to visit!
- www.jonnybowden.com 8
07 car civic honda
buy used car
car undefined used
used car bergen
used car oakland
used car greensboro
used car raleigh
used car killeen
used car vallejo
used car tacoma
Post a Comment
Links to this post:
Create a Link
<< Home