January 11, 2010 • 20 mins
In this episode of Stuff Mom Never Told You, Molly and Cristen take a look at current ways of measuring obesity. They discuss the most common formula, Body Mass Index (BMI), in detail, from its origins to its flaws.
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Speaker 1 (00:00):
Brought to you by the reinvented two thousand twelve Camray.
It's ready. Are you welcome to stop Mom Never told You?
From housetop works dot com. Hello, and welcome to the podcast.
I'm Kristen, I'm Molly, so Molly. It's after the holidays.
(00:23):
We have gotten survived the holidays season, you do know,
Martin Luther King Day's coming up. I know, thank goodness,
another another holiday to look forward to. But it's around
the holidays that around this time, especially after the holidays,
with New Year's resolutions and everything, we start kind of
assessing our weight, our physical fitness, seeing what trouble spots
(00:44):
we might need to work on. Which brings to mind
a little measure called body mass index. Yeah, and it's
pretty easy to find out your own body mass index.
You go online, you google this, You'll be will enter
your weight and your height and find out a number
that's between eight and thirty five ish is. It's sort
of like that where the calculations kind of run and
(01:05):
if it falls within a certain range, then you're considered normal, overweight,
or obese. Yeah, and this seems like a pretty pretty
quick simple assessment of your weight, but there was some
controversy earlier this year about how one university was using
bm I to determine whether or not students could graduate. Right.
(01:27):
This was at Lincoln University in Pennsylvania. It was the
in part of two thousand nine who probably heard about
this story. Uh, The school was requiring students with the
body mass index of thirty or above to take a
fitness course in order to graduate, and this raised a
lot of controversy about whether, you know, it's a school's
responsibility to tell a person that they might have a
(01:48):
health problem. Um. You know, students were saying that this
shouldn't be a requirement to graduate, that their academic records
should be UM. But one of the factors that always
comes up, I think when b m I is involved
is that it's not the most accurate thing. Now to
make sure that they are really getting students who they
considered obese, the school went on to measure the students waste,
(02:08):
hoping that that would weed out people like athletes who
have um higher weights but are still healthy for their heights. Right,
because people with really high b m I s and
the overweight and obese category might be at a higher
risk for things like heart disease and type two diabetes.
So the college was arguing that, hey, we're trying to,
you know, do this for our students better health in
(02:29):
the future. UM. But we recently found out that because
there is so much hubbub surrounding this issue, to school
just basically dropped it. But the issue of whether or
not b m I is actually a good predictor of
health is still pretty controversial. So let's talk about it.
Do you want to talk about all the ways we
(02:49):
can measure obesity, Kristen, Yeah, let's talk about like what
exactly the b m I formula is and go from there.
So the b m I, your b m I is
your weight divided by your height squared times seven and three. Now, wait,
that all depends on whether you're doing metric system right
or just standard. Yeah, this is this is just I
(03:11):
hate metric. Yeah, this is this is you know for
people in the in the US of A UM hate metric,
like Molly anti metric, Molly new nickname. Um, that's the
that's the formula. And there there's another formula for the
metric system, which I think it's actually easier. I don't
think you have to do anything with seven. Oh, three
probably is metric is far easier and makes a lot
(03:32):
more sense. However, that is the so that's to be
in my formula. But like you said, there are a
few other, even more reliable ways to assess your your
body fat content. Now we just mentioned that Lincoln would
measure a student's waste and this is known as the
waiste to hip ratio, which is getting a lot of
attention lately as a hip ha ha ha new way
(03:54):
to measure ob cit. What you do here is you
take a tape measure and you you measure your waist
at its smallest point and your hips at their largest point.
Divide them and you should get a ratio. And they
don't know yet what the perfectly healthy ratio is, but
they're saying that if you're a female, if the ratio
is less than one, then generally you're you're okay. So
(04:18):
we've got we've got b m I, we've got waste
of hip ratio. We also have the old pinch test. Okay.
That's basically where you take the some calipers to measure
the folds of skin in certain spots in your body.
This is not a fun test to take. Molly and
I can speak from experience, I had to take a
pinch test, uh in I believe it was eleventh grade
(04:41):
in health class in high school, and uh traumatized you
sound It wasn't traumatizing to me. The idea of you know,
going to gym class and having your fat pinch was
not a good idea of to you know, for sixteen
and seventeen year old girls. But that it's another way
to do it. But it's not very accurate. That's the
(05:02):
thing is, if it's just some gym teacher who's borrowing
the calipers from the health department, you can get a
vastly incorrect reading. Uh we're reading in US Musical Report
that let's say you've got body fat um or that's
what the caliper shaw that you have. That could be
anywhere from two to twenty eight. You know, just a
big margin of error if you're not using the pinchers
exactly right. So something that's a little bit more accurate
(05:25):
according to US mus Normal Report is something called the
bioelectrical test. And this is where a technician will attach
electrodes to one hand and one foot and they run
a harmless specify harmless radio frequency pulse through your body
to measure its water content. I mean space age space age,
but again it's not doesn't I guess no way of
(05:46):
measuring body fat is going to be tons of fun.
But I can't imagine having radio frequency running through me
would be good. Um, but this isn't a lot of
health clubs, medicine clinics. It's not very it's not very available.
Let's say to the general pulp like, also not very available.
It's something called the bod pod. This is my favorite
one I would love. It's an egg shaped chamber and
(06:09):
you climb in, you sit there for twenty seconds, and
it can measure air displacement and tell you exactly how
much body fat you have. So bod pods pretty spot
on with this seems like so far it's sort of
the golden standard. And as most things that are the
golden standard are, it's very expensive and so it's only
a few hospitals. It's really not available to the general public,
(06:29):
which is why the general public is still left finding
a body mass index calculator online and using that to
figure out how much body fat they have. Now for
the last test, Smalley, the immersion test. This one seems
like the most pleasant one. To do, because you basically
just get in a pool of water and get dunked
a few times. Uh. First you will expel all the
air from your lungs and uh and they dunk you
(06:51):
in a pool half a dozen times. And it says
that under or overestimates your body fat by only one
percentage points. So still pretty accurate. Yeah, is, but you
know that's just the recipe for the worst day ever
to me jump to make a jump in a pool
for an hour and then here how much body fat
I have? Like, if that's not a recipe for overreading
(07:11):
ice cream, I don't know what it is. But if
you've had any of those tests, I want to hear
about them, if you've been in a body pod, I
want to know how cool it is. But here's my
question to Molly. We have all of these other ways
to assess body fat that are much that are very accurate,
that are far more accurate. But Molly, my question is,
we have all of these different options for measuring body
fat and a lot of which have far more accurate results. However,
(07:35):
b m I is still our go to measure, right,
That's what they're using at Lincoln. When you ever you
read articles about health risk, heart disease, things like that.
People are always going to say, look your b m I,
But why why are we looking at bm I? Well, Molly,
should we go back in time? Perhaps it's my favorite
thing to do on this podcast, tell the story of
(07:56):
the body mass index, which is actually a little more
it's more interesting than than this probably sounds at this
point listeners. So because there's someone involved named Adolph wheat
Lit Wheatlet, and he's from Belgium, and all good stories
start in Belgium. So he's the one who came up
with this equation eighteen thirty two, not because he had
this overwhelming desire to study obesity, but because he was
(08:19):
doing this study on normal man. That means he was
looking at everything about man that was average to figure
out just what the most perfectly average man would look like,
from his arm length to his level length, to his obesity.
And I think that we should know that we got
all of this great information from an article on slate.
So Queetlet went around collecting all of his data from
(08:41):
several hundred countrymen, and he found that there were correlations
between a man's weight and height. Basically that your weight
is going to be proportional to your heights. Say, you know,
if I'm uh ten taller than you, I'm probably gonna
wait ten percent more than you as well. So if
he makes this pretty decent finding, but it's not like
Dr Stitch bonded immediately to say, oh quite like you've
(09:02):
discovered how to measure this, it kind of sits dormant
for a while. Yeah, because but back then, doctors weren't
really linking illness to obesity. Um, the first large scale
studies of obesity and health didn't start until early in
the twentieth century with the rise of insurance companies. I
find this really interesting because in all this talk of
(09:24):
healthcare form, you know, I mean, you kind of wonder
if we could save a lot of healthcare costs by
coming out and telling people, hey, you're unhealthy, you need
to change your habits, which is what Lincoln was trying
to do the school. So just better than in mind
when you think about what organization's role is and telling
people that they're unhealthy. But here's what the insurance companies do.
They want to show their policy holders that yes, you
(09:46):
were costing us more if you're overweight. Because you overweight
people are dying earlier than those of a so called
ideal weights. You're more likely to get diabetes, you more
likely get heart disease, and we're paying out the nose
for that. So what these insurance companies need basically is
a quick function to show how body fat is related
to your heightened weight. Yeah, and they still and back
(10:09):
then they had like the caliper skin fold testing UM
and hydrostatic weighing with the basically the immersion tests that
that we mentioned. But it wasn't until nineteen seventy two
that the physiology professor an obesity researcher named Ansel Keys
published the Landmark Indices of Relative Weight and Obesity which
(10:29):
he studied seventy men in five different countries to assess
different heightened weight formulas that correlated to the best measurement
of their body fat percentage. And with this study he
found that Quainlets formula was the best. It was the best,
(10:50):
but he noted that it was the best at population
studies is a good way for doctors to get an
idea of how a certain population was um overweight or
not overweight. It was never meant to be used on
an individual diagnosis scale, right and and Keys was the
one who renamed Quitla's formula the body mass index, and
(11:10):
then five the National Institutes i FELL started defining obesity
according to b m I. And what I thought was
really interesting in this late articles. When the n i
H first started using body mass index to define obesity,
it was very specific in terms of gender and that
you could have UM b m I measure for a
(11:30):
woman and a man, and the numbers were different. They
were kind of um odd numbers, like twenty seven point
eight was a cut off for ABC. Wharas now everything
sort of on the five. That's how they determine if
you're overweight or not. UM. But then they just wanted
to sort of sound like standardize everything, and that means
that both men and women's b m I was measured
(11:51):
the same way, despite the fact that women have a
lot of more body fat and UM. Like I said,
everything became on the five, so it was easy to member.
I mean, you know, you knew as soon as you
hit thirty on your b m I that that was
a bad thing. So not only do we have this
measure that was originally intended for population studies rather than
individual diagnoses, we also have the NIH coming in and
(12:15):
sort of further watering down those standards. So we were
starting to see how the b M I might be
might not be the best predictor of your health because,
like you said, just to throw out a couple of things,
like b M I is the same for gender race.
There are some differences for children and teens, but for
the adult population, a b M I is a b
(12:38):
m I s bm I. It doesn't differ for men
and women. However, like you said, women have tend to
have more body fat than men, and at the same
b m I, older people will tend to have more
body fat than younger adults, which makes sense the mass exactly.
And then speaking of muscle mass, highly trained athletes who
are very muscular will probably have a very high b
(12:59):
m I that might put them in an overweight category
because it's just looking at body mass rather than differentiating
between fat and muscle. Right, So, you can find many
articles on the internet that just uh to cry down
with the b m I. It's not very accurate. Please
don't go on the internet and decide if your overweight
just based on a b m I. UM. A really
(13:20):
good example of how this can work against you was
a New York Times article from two thousand seven that
Kristen bound. It's called how does your waistline matter? Let
us count the ways ha ha ha um. And this
woman had a perfectly normal b m I. She didn't
have many risk factors for heart disease. But then her
doctor whips out a tape measure and does the old
(13:40):
ways to hit rate she and finds out that she
is actually in a high risk category for developing some
of these long term health problems. Now, while that New
York Times article highlights a couple of individual stories, I
think we should also know that there have been a
few large scale studies that have called the b m
I into question. For instance, there's on from a recent
(14:00):
one from the National Institutes of Health that compared people's
b m I s against results from the biolectrical analysis
that we talked about earlier, and it found, um for instance,
a big gender gap in these measurements, where where with men,
the b m I had a better correlation with their
(14:21):
with their lean mass, while in women the BF or
the bioelectrical test was a little more accurate predictor. And
they basically concluded that the b m I is is
pretty limited in how well it assesses obesity, and in
this case it missed more than half the people with
excess fat. And in addition, the Slate article also mentioned
(14:44):
a critique that was published in the journal Circulation that
said that since b m I is used in so
many of these large scale just health studies that we
that we see, and since b m I might also
not be very accurate, we don't know how the that's
affecting all of this health research that's going on. So
this could have a ripple effect in two areas beyond
(15:05):
just obesity. So basically, you can't trust your b m
I if it, I mean, it may not be showing
that you are overweight, and may be showing that you
are overweight and you're actually not. But it doesn't seem
to be going anywhere just because, as we said, it's
so easy. Anyone can check their b m I. So
um right now the big guidelines, even though the n
i H just found it's not the most accurate thing.
It through its National Heart, Long and Blood Institute, has
(15:28):
sort of tried to bring the waste hip ratio more
into a three legged stool, if you will, the three
legged stool of assessing your risk for these long term
health conditions to try and figure out if you are
overweight is the b M I plus the waist circumference thing.
And then also just evaluing your risk factors. Do you
have things like high blood pressure, how's your cholesterol account,
(15:49):
how's your blood glu close? Do you have a family
history of this? Do you smoke? Do you exercise? So
hopefully we'll be coming to a more well rounded view
of how we can measure obesity in the future, particularly
at schools like Lincoln are going to try and dictate
graduation based on it. And it all goes back to Wheatlet.
So thanks Wheetlet for all your hard work, but unfortunately
(16:14):
Mr Queatlet, we have manipulated and misused your tool. But
maybe we're on the right path now. Maybe maybe maybe
that should be our health resolution for two thousand and
en to find a bod pode that's mine. So if
any of you fair listeners out there have access to
a bod pod, you should definitely email us at Mom's
(16:36):
Stuff at how stuff works dot com and make Molly
Edmonds is year. I don't know if it would make
my ear well, maybe a week of it. A day, yeah, okay,
a day make Molly stay with a bod pod And
speaking of listener mail, why don't we uh whant we
do some of that? Okay? So today christ we I'm
(16:57):
gonna read some emails about the women behind Santa Clause,
that podcast we did right before Christmas. And first off,
we need to thank many of the listeners. I'm not
going to identify any of them by name, because a
lot of people caught us on this one. Um, we
made fun of the Goody Santa Claus Catherine Lee Bates
article and uh, it sent me back to eleventh grade
(17:18):
English as soon as our listeners started writing in. But
goody is an abbreviation of the title goodwife. So back
in those days, I would have gone over to have
been like, Goody, conger, have you any cookies for me?
Today I would have said no, go home. Then we
would have burned you as a witch. Um. So yes,
thanks to all listeners who reminded us of that. And
(17:38):
now I think we're going to share some theories from
our listeners about what Mrs Claus's first name is. Yeah,
George wrote in, and he pointed out that in the
autobiography of Santa Claus by Jeff gwen Her name is Layla. Alright,
laws Heather wrote in and said that if you saw
the nineteen seventy special Santa Claus Is Coming to Town,
(18:01):
then in that show, it's a girl named Jessica who
saves Chris Kringel, a young, handsome red hair Santa from
burger Meister Meister. Burger Burger Meister is mean and cool
and does not let children have toys. Chris, who has
a human raised by Elves, gives toys to all the
kids and yes, a doll to Jessica. They fall in love,
flee the town, get married, and grew old and happy
and fat together. Chris learns his real name is Claus
(18:22):
and becomes Santa Claus. So that makes Mrs Claus Jessica Claus,
Jessica Claus. We've got Layla Jessica and this one for
Virginia will round out are a trio of name names,
and it is my favorite. I thought this was the
cutest story. We got started to other other suggestions. This
one just Jase Cake. So basically, Virginia was hanging out
(18:47):
around Christmas with her boyfriend and his ten year old
daughter at the time, and his daughter asked her what
Mrs Claus's first name was and she said, I didn't
want to tell her that no one had ever thought
to give Mrs Claus her own name, so I told
her that Mrs Clause was Merry Christmas, and she decided
to change her name when she married Santa. I also
told her that I guess she couldn't have hyphenated her
(19:08):
name to marry Christmas Clause, but Santa and she had
been married so long that people really didn't hyphenate names
back then anyway, So I thought that was pretty durable.
And if you guys have any emails you would like
to send our way with your thoughts, feelings, and comments,
send them on to mom stuff at how stuff works
dot com. And of course, during the week, you can
follow us on our blog It's how to stuff, and
(19:31):
you can learn more about obesity and health and the
right way to assess your weight. How stuff works dot
com for more on this and thousands of other topics.
Because at how stuff works dot com. Want more how
stuff works, check out our blogs on the house stuff
(19:52):
works dot com home page. Brought to you by the
reinvented tooth thousand, twelve Camry. It's ready, are you
Brought to you by the reinvented two thousand twelve Camray.
It's ready. Are you welcome to stop Mom Never told You?
From housetop works dot com. Hello, and welcome to the podcast.
I'm Kristen, I'm Molly, so Molly. It's after the holidays.
(00:23):
We have gotten survived the holidays season, you do know,
Martin Luther King Day's coming up. I know, thank goodness,
another another holiday to look forward to. But it's around
the holidays that around this time, especially after the holidays,
with New Year's resolutions and everything, we start kind of
assessing our weight, our physical fitness, seeing what trouble spots
(00:44):
we might need to work on. Which brings to mind
a little measure called body mass index. Yeah, and it's
pretty easy to find out your own body mass index.
You go online, you google this, You'll be will enter
your weight and your height and find out a number
that's between eight and thirty five ish is. It's sort
of like that where the calculations kind of run and
(01:05):
if it falls within a certain range, then you're considered normal, overweight,
or obese. Yeah, and this seems like a pretty pretty
quick simple assessment of your weight, but there was some
controversy earlier this year about how one university was using
bm I to determine whether or not students could graduate. Right.
(01:27):
This was at Lincoln University in Pennsylvania. It was the
in part of two thousand nine who probably heard about
this story. Uh, The school was requiring students with the
body mass index of thirty or above to take a
fitness course in order to graduate, and this raised a
lot of controversy about whether, you know, it's a school's
responsibility to tell a person that they might have a
(01:48):
health problem. Um. You know, students were saying that this
shouldn't be a requirement to graduate, that their academic records
should be UM. But one of the factors that always
comes up, I think when b m I is involved
is that it's not the most accurate thing. Now to
make sure that they are really getting students who they
considered obese, the school went on to measure the students waste,
(02:08):
hoping that that would weed out people like athletes who
have um higher weights but are still healthy for their heights. Right,
because people with really high b m I s and
the overweight and obese category might be at a higher
risk for things like heart disease and type two diabetes.
So the college was arguing that, hey, we're trying to,
you know, do this for our students better health in
(02:29):
the future. UM. But we recently found out that because
there is so much hubbub surrounding this issue, to school
just basically dropped it. But the issue of whether or
not b m I is actually a good predictor of
health is still pretty controversial. So let's talk about it.
Do you want to talk about all the ways we
(02:49):
can measure obesity, Kristen, Yeah, let's talk about like what
exactly the b m I formula is and go from there.
So the b m I, your b m I is
your weight divided by your height squared times seven and three. Now, wait,
that all depends on whether you're doing metric system right
or just standard. Yeah, this is this is just I
(03:11):
hate metric. Yeah, this is this is you know for
people in the in the US of A UM hate metric,
like Molly anti metric, Molly new nickname. Um, that's the
that's the formula. And there there's another formula for the
metric system, which I think it's actually easier. I don't
think you have to do anything with seven. Oh, three
probably is metric is far easier and makes a lot
(03:32):
more sense. However, that is the so that's to be
in my formula. But like you said, there are a
few other, even more reliable ways to assess your your
body fat content. Now we just mentioned that Lincoln would
measure a student's waste and this is known as the
waiste to hip ratio, which is getting a lot of
attention lately as a hip ha ha ha new way
(03:54):
to measure ob cit. What you do here is you
take a tape measure and you you measure your waist
at its smallest point and your hips at their largest point.
Divide them and you should get a ratio. And they
don't know yet what the perfectly healthy ratio is, but
they're saying that if you're a female, if the ratio
is less than one, then generally you're you're okay. So
(04:18):
we've got we've got b m I, we've got waste
of hip ratio. We also have the old pinch test. Okay.
That's basically where you take the some calipers to measure
the folds of skin in certain spots in your body.
This is not a fun test to take. Molly and
I can speak from experience, I had to take a
pinch test, uh in I believe it was eleventh grade
(04:41):
in health class in high school, and uh traumatized you
sound It wasn't traumatizing to me. The idea of you know,
going to gym class and having your fat pinch was
not a good idea of to you know, for sixteen
and seventeen year old girls. But that it's another way
to do it. But it's not very accurate. That's the
(05:02):
thing is, if it's just some gym teacher who's borrowing
the calipers from the health department, you can get a
vastly incorrect reading. Uh we're reading in US Musical Report
that let's say you've got body fat um or that's
what the caliper shaw that you have. That could be
anywhere from two to twenty eight. You know, just a
big margin of error if you're not using the pinchers
exactly right. So something that's a little bit more accurate
(05:25):
according to US mus Normal Report is something called the
bioelectrical test. And this is where a technician will attach
electrodes to one hand and one foot and they run
a harmless specify harmless radio frequency pulse through your body
to measure its water content. I mean space age space age,
but again it's not doesn't I guess no way of
(05:46):
measuring body fat is going to be tons of fun.
But I can't imagine having radio frequency running through me
would be good. Um, but this isn't a lot of
health clubs, medicine clinics. It's not very it's not very available.
Let's say to the general pulp like, also not very available.
It's something called the bod pod. This is my favorite
one I would love. It's an egg shaped chamber and
(06:09):
you climb in, you sit there for twenty seconds, and
it can measure air displacement and tell you exactly how
much body fat you have. So bod pods pretty spot
on with this seems like so far it's sort of
the golden standard. And as most things that are the
golden standard are, it's very expensive and so it's only
a few hospitals. It's really not available to the general public,
(06:29):
which is why the general public is still left finding
a body mass index calculator online and using that to
figure out how much body fat they have. Now for
the last test, Smalley, the immersion test. This one seems
like the most pleasant one. To do, because you basically
just get in a pool of water and get dunked
a few times. Uh. First you will expel all the
air from your lungs and uh and they dunk you
(06:51):
in a pool half a dozen times. And it says
that under or overestimates your body fat by only one
percentage points. So still pretty accurate. Yeah, is, but you
know that's just the recipe for the worst day ever
to me jump to make a jump in a pool
for an hour and then here how much body fat
I have? Like, if that's not a recipe for overreading
(07:11):
ice cream, I don't know what it is. But if
you've had any of those tests, I want to hear
about them, if you've been in a body pod, I
want to know how cool it is. But here's my
question to Molly. We have all of these other ways
to assess body fat that are much that are very accurate,
that are far more accurate. But Molly, my question is,
we have all of these different options for measuring body
fat and a lot of which have far more accurate results. However,
(07:35):
b m I is still our go to measure, right,
That's what they're using at Lincoln. When you ever you
read articles about health risk, heart disease, things like that.
People are always going to say, look your b m I,
But why why are we looking at bm I? Well, Molly,
should we go back in time? Perhaps it's my favorite
thing to do on this podcast, tell the story of
(07:56):
the body mass index, which is actually a little more
it's more interesting than than this probably sounds at this
point listeners. So because there's someone involved named Adolph wheat
Lit Wheatlet, and he's from Belgium, and all good stories
start in Belgium. So he's the one who came up
with this equation eighteen thirty two, not because he had
this overwhelming desire to study obesity, but because he was
(08:19):
doing this study on normal man. That means he was
looking at everything about man that was average to figure
out just what the most perfectly average man would look like,
from his arm length to his level length, to his obesity.
And I think that we should know that we got
all of this great information from an article on slate.
So Queetlet went around collecting all of his data from
(08:41):
several hundred countrymen, and he found that there were correlations
between a man's weight and height. Basically that your weight
is going to be proportional to your heights. Say, you know,
if I'm uh ten taller than you, I'm probably gonna
wait ten percent more than you as well. So if
he makes this pretty decent finding, but it's not like
Dr Stitch bonded immediately to say, oh quite like you've
(09:02):
discovered how to measure this, it kind of sits dormant
for a while. Yeah, because but back then, doctors weren't
really linking illness to obesity. Um, the first large scale
studies of obesity and health didn't start until early in
the twentieth century with the rise of insurance companies. I
find this really interesting because in all this talk of
(09:24):
healthcare form, you know, I mean, you kind of wonder
if we could save a lot of healthcare costs by
coming out and telling people, hey, you're unhealthy, you need
to change your habits, which is what Lincoln was trying
to do the school. So just better than in mind
when you think about what organization's role is and telling
people that they're unhealthy. But here's what the insurance companies do.
They want to show their policy holders that yes, you
(09:46):
were costing us more if you're overweight. Because you overweight
people are dying earlier than those of a so called
ideal weights. You're more likely to get diabetes, you more
likely get heart disease, and we're paying out the nose
for that. So what these insurance companies need basically is
a quick function to show how body fat is related
to your heightened weight. Yeah, and they still and back
(10:09):
then they had like the caliper skin fold testing UM
and hydrostatic weighing with the basically the immersion tests that
that we mentioned. But it wasn't until nineteen seventy two
that the physiology professor an obesity researcher named Ansel Keys
published the Landmark Indices of Relative Weight and Obesity which
(10:29):
he studied seventy men in five different countries to assess
different heightened weight formulas that correlated to the best measurement
of their body fat percentage. And with this study he
found that Quainlets formula was the best. It was the best,
(10:50):
but he noted that it was the best at population
studies is a good way for doctors to get an
idea of how a certain population was um overweight or
not overweight. It was never meant to be used on
an individual diagnosis scale, right and and Keys was the
one who renamed Quitla's formula the body mass index, and
(11:10):
then five the National Institutes i FELL started defining obesity
according to b m I. And what I thought was
really interesting in this late articles. When the n i
H first started using body mass index to define obesity,
it was very specific in terms of gender and that
you could have UM b m I measure for a
(11:30):
woman and a man, and the numbers were different. They
were kind of um odd numbers, like twenty seven point
eight was a cut off for ABC. Wharas now everything
sort of on the five. That's how they determine if
you're overweight or not. UM. But then they just wanted
to sort of sound like standardize everything, and that means
that both men and women's b m I was measured
(11:51):
the same way, despite the fact that women have a
lot of more body fat and UM. Like I said,
everything became on the five, so it was easy to member.
I mean, you know, you knew as soon as you
hit thirty on your b m I that that was
a bad thing. So not only do we have this
measure that was originally intended for population studies rather than
individual diagnoses, we also have the NIH coming in and
(12:15):
sort of further watering down those standards. So we were
starting to see how the b M I might be
might not be the best predictor of your health because,
like you said, just to throw out a couple of things,
like b M I is the same for gender race.
There are some differences for children and teens, but for
the adult population, a b M I is a b
(12:38):
m I s bm I. It doesn't differ for men
and women. However, like you said, women have tend to
have more body fat than men, and at the same
b m I, older people will tend to have more
body fat than younger adults, which makes sense the mass exactly.
And then speaking of muscle mass, highly trained athletes who
are very muscular will probably have a very high b
(12:59):
m I that might put them in an overweight category
because it's just looking at body mass rather than differentiating
between fat and muscle. Right, So, you can find many
articles on the internet that just uh to cry down
with the b m I. It's not very accurate. Please
don't go on the internet and decide if your overweight
just based on a b m I. UM. A really
(13:20):
good example of how this can work against you was
a New York Times article from two thousand seven that
Kristen bound. It's called how does your waistline matter? Let
us count the ways ha ha ha um. And this
woman had a perfectly normal b m I. She didn't
have many risk factors for heart disease. But then her
doctor whips out a tape measure and does the old
(13:40):
ways to hit rate she and finds out that she
is actually in a high risk category for developing some
of these long term health problems. Now, while that New
York Times article highlights a couple of individual stories, I
think we should also know that there have been a
few large scale studies that have called the b m
I into question. For instance, there's on from a recent
(14:00):
one from the National Institutes of Health that compared people's
b m I s against results from the biolectrical analysis
that we talked about earlier, and it found, um for instance,
a big gender gap in these measurements, where where with men,
the b m I had a better correlation with their
(14:21):
with their lean mass, while in women the BF or
the bioelectrical test was a little more accurate predictor. And
they basically concluded that the b m I is is
pretty limited in how well it assesses obesity, and in
this case it missed more than half the people with
excess fat. And in addition, the Slate article also mentioned
(14:44):
a critique that was published in the journal Circulation that
said that since b m I is used in so
many of these large scale just health studies that we
that we see, and since b m I might also
not be very accurate, we don't know how the that's
affecting all of this health research that's going on. So
this could have a ripple effect in two areas beyond
(15:05):
just obesity. So basically, you can't trust your b m
I if it, I mean, it may not be showing
that you are overweight, and may be showing that you
are overweight and you're actually not. But it doesn't seem
to be going anywhere just because, as we said, it's
so easy. Anyone can check their b m I. So
um right now the big guidelines, even though the n
i H just found it's not the most accurate thing.
It through its National Heart, Long and Blood Institute, has
(15:28):
sort of tried to bring the waste hip ratio more
into a three legged stool, if you will, the three
legged stool of assessing your risk for these long term
health conditions to try and figure out if you are
overweight is the b M I plus the waist circumference thing.
And then also just evaluing your risk factors. Do you
have things like high blood pressure, how's your cholesterol account,
(15:49):
how's your blood glu close? Do you have a family
history of this? Do you smoke? Do you exercise? So
hopefully we'll be coming to a more well rounded view
of how we can measure obesity in the future, particularly
at schools like Lincoln are going to try and dictate
graduation based on it. And it all goes back to Wheatlet.
So thanks Wheetlet for all your hard work, but unfortunately
(16:14):
Mr Queatlet, we have manipulated and misused your tool. But
maybe we're on the right path now. Maybe maybe maybe
that should be our health resolution for two thousand and
en to find a bod pode that's mine. So if
any of you fair listeners out there have access to
a bod pod, you should definitely email us at Mom's
(16:36):
Stuff at how stuff works dot com and make Molly
Edmonds is year. I don't know if it would make
my ear well, maybe a week of it. A day, yeah, okay,
a day make Molly stay with a bod pod And
speaking of listener mail, why don't we uh whant we
do some of that? Okay? So today christ we I'm
(16:57):
gonna read some emails about the women behind Santa Clause,
that podcast we did right before Christmas. And first off,
we need to thank many of the listeners. I'm not
going to identify any of them by name, because a
lot of people caught us on this one. Um, we
made fun of the Goody Santa Claus Catherine Lee Bates
article and uh, it sent me back to eleventh grade
(17:18):
English as soon as our listeners started writing in. But
goody is an abbreviation of the title goodwife. So back
in those days, I would have gone over to have
been like, Goody, conger, have you any cookies for me?
Today I would have said no, go home. Then we
would have burned you as a witch. Um. So yes,
thanks to all listeners who reminded us of that. And
(17:38):
now I think we're going to share some theories from
our listeners about what Mrs Claus's first name is. Yeah,
George wrote in, and he pointed out that in the
autobiography of Santa Claus by Jeff gwen Her name is Layla. Alright,
laws Heather wrote in and said that if you saw
the nineteen seventy special Santa Claus Is Coming to Town,
(18:01):
then in that show, it's a girl named Jessica who
saves Chris Kringel, a young, handsome red hair Santa from
burger Meister Meister. Burger Burger Meister is mean and cool
and does not let children have toys. Chris, who has
a human raised by Elves, gives toys to all the
kids and yes, a doll to Jessica. They fall in love,
flee the town, get married, and grew old and happy
and fat together. Chris learns his real name is Claus
(18:22):
and becomes Santa Claus. So that makes Mrs Claus Jessica Claus,
Jessica Claus. We've got Layla Jessica and this one for
Virginia will round out are a trio of name names,
and it is my favorite. I thought this was the
cutest story. We got started to other other suggestions. This
one just Jase Cake. So basically, Virginia was hanging out
(18:47):
around Christmas with her boyfriend and his ten year old
daughter at the time, and his daughter asked her what
Mrs Claus's first name was and she said, I didn't
want to tell her that no one had ever thought
to give Mrs Claus her own name, so I told
her that Mrs Clause was Merry Christmas, and she decided
to change her name when she married Santa. I also
told her that I guess she couldn't have hyphenated her
(19:08):
name to marry Christmas Clause, but Santa and she had
been married so long that people really didn't hyphenate names
back then anyway, So I thought that was pretty durable.
And if you guys have any emails you would like
to send our way with your thoughts, feelings, and comments,
send them on to mom stuff at how stuff works
dot com. And of course, during the week, you can
follow us on our blog It's how to stuff, and
(19:31):
you can learn more about obesity and health and the
right way to assess your weight. How stuff works dot
com for more on this and thousands of other topics.
Because at how stuff works dot com. Want more how
stuff works, check out our blogs on the house stuff
(19:52):
works dot com home page. Brought to you by the
reinvented tooth thousand, twelve Camry. It's ready, are you
Stuff Mom Never Told You News
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Anney Reese
Samantha McVey
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