Photo from Mount Royal, Frisco, Colorado.

"That is happiness; to be disolved into something complete and great. When it comes to one, it comes as naturally as sleep." - Willa Cather

Thursday 10 June 2010

Body Composition Analyzer

(The title of this blog post should preferably be read aloud in the computer-generated British woman's voice in Austin Powers who says "Commencing warm liquid goo phase")

So, I spend most of my time these days working in a Clinical Biochemistry Department. In the corner of an examination room sits this piece of equipment, which is used on all of the participants in the study I am working on, called the TANITA Body Composition Analyzer. It's most important function is that it measures % body fat. For those who haven't tried something similar, you stand on it barefoot and grip some metallic handles and then little electrical currents are sent through various areas of the body, the resistance is measured and % of various tissues determined. You have to enter your height and whether or not you are "athletic" and it weighs you and figures out the rest.

After I was done doing eye examinations the other night, I figured it was time to take my shoes off and give the TANITA a try. I'd never had my % body fat measured, so wasn't really sure what to expect.

Needless to say I was a bit shocked to see 10.9%. Seemed quite low, but I wasn't about to complain. I mean for those of you who have seen me in real life, you know I look like a pretty normal woman. I had always thought of 10% as the lowest a woman could possibly go before she actually turned into a man.

Anyway, the MOST remarkable thing about the printout I received and the reason I am actually writing this, is it told me the optimal measurement for me would be 27% (!). Is a woman my age with 27% body fat healthier than I am? The actual "healthy range" for women ages 20-39 is 21-33%. Of course the confounder is most of my fat is not fat, it is muscle (to be more precise, I have 5.75 kg of fat, 44.8 kg muscle and 2.4 kg of bone). So women who have a lot of muscle and little fat, but normal or close to normal BMI are still healthy. You didn't need SLG to point this out, though. So why is it that the WHO/NIH who made these guidelines can't figure it out? Well, it goes back to a large study done by Gallagher in 2000 in the American Journal of Clinical Medicine, where they converted the normal BMI range to normal % fat range. He admits that they basically had no subjects in the low normal or below normal BMI range (!), so they couldn't make reasonable caclulations there.

Readers, don't be fooled into thinking that % body fat below 21% is unhealthy. In fact, don't be falsely reassured if your % body fat is in the upper end up normal. It is not clear how exactly % body fat correlates with BMI or how % body fat correlates with longevity. But I have subsequently read that most competitive female runners/triathletes have a % body fat between 10-15.

Let's look at some pictures I found on Then you can probably figure out for yourself what's healthy and what's not.

First, woman? man? steroids? What IS hiding uder that bikini? And you can't tell me that I need to look like this to get to be a faster runner.

Now take a look at Miss 11% above. No, despite what you're thinking, that is not me. HA! Just kidding. How is it I have the same body fat percentage as her? Could the answer lie in les boobs (yes, that should be pronounced in French)? All I can say is thank God I don't look like that.

I actually think I look almost EXACTLY like miss 18% :). Right, SR?
Now, getting back to the WHO % body fat guidelines. Miss 25% and miss 30% are well within the "healthy" range according to the WHO, whereas Miss 18% (and even Miss 20%) is not.

Edit (thanks, Meghan Hicks): It is difficult to know which of these women is healthiest. But I think it is wrong that the WHO implies that women with less than 21% bodyfat are unhealthy and that women with 30% body fat are healthy based on a rough estimate from normal BMI to % body fat. I am also having difficulty finding how % body fat can be used as a determinant of health or as a determinent of fitness among elite athletes, when the measurement seems to be, at least to a certain extent, affected by breast size.

Running Song of the Day: Airplanes by Local Natives


Anonymous said...
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cherelli said...

ha, interesting. a few years ago when i played competitive squash I used to ocasionally step on the Tanita scales and be around 13% - and I really felt at my healthiest then - I did a lot of strength and anerobic work back then. Sort of glad I don't have one of those machines around at the moment. And yes I think the society "norms" are a bit skewed. Hey they've even adjusted clothes sizes in the US so people don't feel bad about looking like Miss 30%...mind you 100 years ago Miss 30% was probably considered the "ideal female figure"!!

Danni said...

Ha I'm not sure how accurate those things are.

If you are going to persist in being obsessed you should really get a DEXA scan, which will give you an accurate BF% -- I've had one done. And my BF % is, coincidentally, 27% -- and I suspect I am actually healthier than you. :-) I'm not sure how exactly we would have a "health-off" though.

Danni said...

Also, those pictures don't make sense though because i am leaner than the woman who is supposedly 25%. Also, my TANITA scale at home says I am 22-23% FWIW. But the DEXA doesn't lie!

Olga said...

hey, what happened to my comment?

Diana said...

I stepped on one of those things once at the Sharper Image when I was in college (maybe it was a less advanced/accurate kind), and I loved how low my body fat percentage was. That was back when I was working out for crew twice a day and was all muscle. I'm not sure I completely believed the scale, though, because each time I stepped on it I got a different number. :)
It does surprise me that the WHO and NIH give a range of up to 33% as healthy but below 21% as unhealthy. I'll have to go read the study to see what factors they used to come to that conclusion. Healthy gets thrown around as a state we should try to achieve but what that actually means seems so vague and hard to pin down most of the time.
It's also interesting that the guidelines given by these organizations don't correspond at all to Western society's image of an "ideal" body. Unless, of course, most of that 33% is in your boobs.

Olga said...

OK, so much for typing for 10 minutes...all got deleted. I'll try again. It might be drier, less emotional:) First of all, all conductivity-based machines have an error based on water content in the body at any given time. Secondly I don't think you are 11% fat, with all due respect. Third, I had my fat measured by 4 different methods at one time span, and it was quite different. What would be the best? Die and have it all cut out and weighted. Don't think we'd go such dramatic measures though:) We can choose from these methods: I'd still say DEXA is the closest (scientifically speaking), as well as CT. As for the pictures - I like one at 20%, but if she puts more muscle (say, steal it from a girl at 15%). I like muscle. But I like curves too. And yes, not so long ago the golden standard was the last woman, that what was inspired poets and artists. But of course those women weren't trying to get faster at a marathon:) So, it kind of depends on who are you talking to and the priorities. I truly don't know how to impliment "standards" to the general public. to where we are not obsessed, yet not get into "oh, it's just a little bulge, nothing srious" and before you know it, the bulge gets over the top. I have no clue. I really wish I did. I do think there is a difference between OCD and perfectionists. As well as between "I am not obsessed" and "I don't care" type.

SteveQ said...

I must like being the fish out of water on your blog. When I ran in college, I remember having skinfold measurements taken and I came in at 17% (6'0" and 132 lbs., mind you). Underwater weighing came in at 10% - and that was considered the gold standard - rather than the 3-4% that was probably correct.

For me, % bodyfat and waist measurement are directly proportional (sorry ladies, it only works for men). If I ever get back into that pair of "skinny pants" I kept, I'll be 6 kilos lighter.

From the photos, 11% to 20% appeals most to me visually, but 8-9% and 25% are fine. 30%...yeah, 30% is okay too, but I had to think about it.

SteveQ said...

btw- the bad red hair dye in the one photo is a plus.

Meghan said...

I think all of these women look beautiful, all in different ways. It's amazing to look at a gamut of body types and to realize the variability (naturally occurring and modified by our hard work) of the human body.

I think it's super silly to judge who is healthy, who is not based upon apparent body fat percentage in pictures. Lord, who knows from where these bodies come from! Who in these pictures eats healthy, exercises well, sleeps enough, and experiences mental stability? These and so much more are what most people would judge a person to be healthy, or not.

I THINK A WOMAN WITH 27% BODY FAT CAN BE COMPLETELY HEALTHY! Sealegs, I really like you and the way you explore issues, but I think you're doing women a huge disservice by implying that women who have an average amount of body fat are possibly unhealthy.

Olga said...
circa 1999
2008, more muscle, same fat % (for a bit, at least)
BMI? Far apart. Weight? 15 lbs difference.

SteveQ said...

Thank you, Meghan, for being the voice of reason.

Olga said...

Yeah, Meghan IS right - here if others come by, they would be directed to think unless you are skinny, you are a worthless creature (not only in athletics)...and we do LIKE you, girl.
I think we actually all display a tad (a big tad) of some kind of sickness too, since we keep coming back and commenting. It's like watching a gory show. We disagree, we try to voice a reason, but deep inside we know we won't get through. yet we keep coming back. The issues SLG raises are controversial at best, and we are drawn to it. Like, when you're (I am, for example) watching "Clean house" or "Hoarding" show, I am thinking - thank God I am never going to be close. Anyhow, SLG expresses her opinion. We create conversations and support continuation of such topics. Everything stays status quo:)

sea legs girl said...

I think the post came off a bit differently than I intended. So, Meghan, I am glad you commented, because I certainly don't KNOW which % fat is the healthiest and don't want to imply I do. I also don't in any way want to imply that thinner women are just BETTER or anything preposterous like that.

LK said...

I'll take the one between 18% & 20%, since that's what my wife looks like. BUT, I'd actually take her at any percentage because what really matters to me is that she is happy and healthy and that could be a much wider range than what I stated above. :)

Danni said...

No SLG, I think it came off how you intended:

"Let's look at some pictures I found on Then you can probably figure out for yourself what's healthy and what's not."

You were obviously using the pictures to try and show that a higher bf% is not healthy.

Michelle said...

I'm with Danni, Olga and Meghan on this one. I am also one of those who keeps coming back to this blog, despite being horribly turned off by some of what I've read. I don't know if SLG needs an ego stroke all the time or what, but the constant message that only skinny-ass girls can be healthy is beyond irritating. I am NOT skinny, never have been, but I am in better shape than most of my "skinny" friends. My new obsession is cycling, and I constantly kick my thin friends' asses on the bike. I really shouldn't be so insulted by this blog, but I find myself feeling that way more and more. And that sucks. :-(

sea legs girl said...

Danni & Michelle,

First I'm glad you guys comment honestly. And when I wrote that, Danni, about "you guys can judge", I knew 100% everyone would think the 8-9% body fat was unhealhty. I did not know what people would say about the women above that. But it IS ingrained in our society that muscular and thinner women are healthier, while it actually may not be true. I was curious to see what the responses were. I tend to think thinner and more muscular is healthier, or at least as healthy, but perhaps I'm wrong. I think it's an interesting point of discussion and it was definitely not my intention to offend anyone. So I am sorry if I did!!!

Michelle, I certainly didn't want to give the impression that "only skinny-ass girls can be healthy", though I guess it depends what "skinny ass" means. If "skinny ass" means normal weight, then yes I think that is healthier, but if "skinny ass" means under weight, than no, I don't think it is healthier.

sea legs girl said...
This comment has been removed by the author.
Katie said...

Cherelli's comment is spot on regarding US sizes! My entire grownup life I was a size 8 in stores like the GAP, and now I'm a size 4 (and weigh exactly what I always have)! I actually find it really irritating. And I do believe that says something about our society today.

As far as body fat percentage goes...I have absolutely no idea what is healthy. In my mind, I've always thought somewhere between 18%-20% would be ideal, but have no basis for that thought. Looking at the pictures you posted, I do find the miss 18 and miss 20 to be the most ascetically pleasing, although a bit more muscle on them would be nice.

I am surprised by the WHO guidelines. I do find it hard to believe that 30% body fat would be healthier than 18%-20%. The American Council on Exercise has slightly different guidelines or norms. From their chart it doesn't look like anything under 10% is necessarily considered unhealthy. Of course, I have no idea how they came up with their "norms."

Not that I want to sound judgmental, but a lot of the comments seem to indicate that miss 30 was probably the ideal way back when. I'm not sure if I agree. Women may have been curvier and less muscular, but I don't think they looked quite like that. I think this pic of Whitney Thomas is probably closer to what the ladies probably looked like a few decades ago. I have no idea what her body fat percentage is, but she looks pretty healthy...

sea legs girl said...

Hey thanks for your insight again, Katie. I debated brining up the American Coucil on Exercise guidelines, but then wasn't really sure how credible they were, so hesitated. Anyway, some council in America seems to differ with the WHO.

While I don't exactly know what used to be the ideal, I know that back when it was ideal to be heavier, the ideal was also that women never got any form for exercise. I think we have learned a few things about what is healthy for humans in the last 150 years (not that we are good at adhering to them).