Body fat testing: methods & accuracy

IF the person is well trained, then it can be very comparable to underwater weighing. When I was in grad school we used calipers and then would use the hydrostatic method and I was usually within 1-2 percentage points of hydro method.

An alternative to underwater weighing is the BodPod. I was skeptical of these early on, but they seem to be pretty good.

22% for a female in you age range is the normal/healthy area. I would consider 12% to be the floor at which most women should be in terms of body fat content.

BodyFat wrote:

I am also very...curvy

well now, that changes everything

The average error for skinfold is +/-3.5 percent if they use the correct equation and skinfold sites. If you give me your athletic status (as of now), ethnicity, and age. I can send you the correct equation and skinfold sites recommended so you can see if they did it right. One word of caution is the average error for skinfold is 3.5% but the 95% confidence interval for skinfold is excess -8% to 12%!

The underwater weighing is the gold standard because of an average error of 2% but again this is only true if they use the correct set of equations. Again the 95% confidence interval for skinfold is excess of -5 to 7% (see references by Heymsfield sp?)

The optimal body fat percentage depends on your own physiology and how you maintain or achieve your body fat goal. The body fat lower limit for female athletes or optimal fitness is where you maintain your normal menstrual cycle.

You should not lower your caloric intake to point where your menstrual cycle becomes irregular/inconsistent or you drop your menstrual cycle altogether. Menstrual cycle irregularities begin to occur in females anywhere from 20% down to 8% for most females.

To really get a accurate reading of body fat is to undergo a multicomponent model method. This can be easily performed with a DEXA machine. The error is 1.2% and the confidence interval is very small less than 2.5%.

Ok first of all, I thought saying that I am curvy was a classier way of saying I have big boobs, but I guess it didn't translate :)

What does this mean: "Again the 95% confidence interval for skinfold is excess of -5 to 7%"? I'm confused about the lingo.

It sounds like you're obsessed about justifying your 150 pounds. Face it you're heavy. The way around it not by looking for numbers you like. Make the tough choices, eat less, change what you eat, run more.

I am disappointed in this board. This question has been up for three hours and no one has asked for pictures. Is the world coming to an end?

^especially after the curvy-ness...really expect more from the amonymous posters...

If you are top heavy then the best bet is the underwater weighing. The skinfolds will not be able to measure you body fat accurately.

In terms of "what does it mean". I will give it a shot. If you tested one hundred people with skinfold. The average error or mean error for the 100 people would be 3.5%. However, you would get a range of error values that spanned from -5 to +7% for 95 out of the 100 people tested.

I hope this helps!

dexa

There are many different caliper methods. 3-site is the most common, but also the most innacurate. A 7 site or even a 9 site method would be the most accurate.

Still, if you have a larger than normal chest (compared to your frame and other body fat) then the 3-site method would actually undermeasure you since 3-site is tricep, thigh, suprailiac.

The 7-site method includes:

tricep

thigh

suprailiac

subscapular

abdominal

midaxiallary

pectoral

The 7-site method can be a little uncomfortable for females given that the pectoral measurment is a diagonal fold taken midway between the nipple and the armpit.

Also, underwater weighing is the "gold standard" but still has an error of 1-2%. Caliper method has an error of 2-3%. Bioelectrical has an error of I believe 3-4% and the Near-infrared (Futrex 5000, light beam through your bicep) has an error of 5-6%.

Alan

lmb wrote:

I am disappointed in this board. This question has been up for three hours and no one has asked for pictures. Is the world coming to an end?

Fine, I'll do it. Pics and/or bra size, please? It's critical to... uh... determining... the best "exercises" to enhance your running abilities... yeah... that's it...

you are flat wrong. see heyward and wagner for reference. there is small error with each skinfold pinch. therefore when you take 7 pinches you increase the error exponentially over 3. that is why in some cases 3 site are recommended over 7 sites.

Runningart2004 wrote:

There are many different caliper methods. 3-site is the most common, but also the most innacurate. A 7 site or even a 9 site method would be the most accurate.

Still, if you have a larger than normal chest (compared to your frame and other body fat) then the 3-site method would actually undermeasure you since 3-site is tricep, thigh, suprailiac.

The 7-site method includes:

tricep

thigh

suprailiac

subscapular

abdominal

midaxiallary

pectoral

The 7-site method can be a little uncomfortable for females given that the pectoral measurment is a diagonal fold taken midway between the nipple and the armpit.

Also, underwater weighing is the "gold standard" but still has an error of 1-2%. Caliper method has an error of 2-3%. Bioelectrical has an error of I believe 3-4% and the Near-infrared (Futrex 5000, light beam through your bicep) has an error of 5-6%.

Alan

Alan, you are by far the most helpful and knowledgable poster. I appreciate reading your advice. It's a breath of fresh air amongst all of the crappy posts.

Thank you!

Alan is usually somewhat right but he is completely mistating the facts about skinfolds. His theory of 7 is better than 3 skinfolds is wrong.

Please see Heyward and Wagner "Applied Body Composition Assessment" You can preview the this book at Google books and head to the table with the recommended skinfold sites for women on page 151 (adult females) or page 168 (female athletes).

Go Long = Alan. Look at him respond to himself under another name. Next he'll come on and say "it wasn't me" like we'll believe him just because he says so.

Nothing new to add, since everybody else covered it well. Comparing to previous skin pinch measures may be difficult if the same sites weren't used or if the testers had different amounts of experience. Personally, I prefer the measurements which have multiple site, like the seven fold, but I honestly don't do skin pinches that often.

My experience is the BodPod is so-so. It has good days and bad days (despite being calibrated within a few hours of the test). I actually just tested a bunch of females for a class, and a bunch of them were coming out at 8-12%, and that was following all the procedures exactly, the right equations, etc. Just one example - lots of others, like testing a male at 8% and then 13% two minutes later, people coming in at 1.3%, etc. So, I am still pretty skeptical on it. When it works, it is great, but there are too many times I have seen it give really bad readings, and I've seen it on two different BodPods.

I tested a Div.I. women's basketball team using Bod Pod (during a period when it seemed to have an accruate streak) and most of the athletic looking females were somewhere around 18-22%, which sounds about right for team sports.