Tanita vs. 3-site method

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On my Tanita scale (without athlete mode) my BF fluctuates between 16 and 18%.

Using a skinfold caliper and the three-site method, I get a consistent reading of 8.5 - 9%.

Now, what gives? I know that Tanita scales are not very precise, but TWICE the bodyfat of the skinfold method?!

Do any of you also own Tanita scales? What is your experience with scale vs. skinfold?

And BTW, is the 7-site method really worth the hassle, especially when you're more concerned about BF changes than absolutes? Have you found any major differences between 3-site and 7-site method?
 
Tanitas will change according to your hydration. This includes how much and what you ate, when you last urinated, glycogen stores, and how much water you're holding.

A 3-site caliper measurement is also only as good as the measurements and the formula. These formulas usually don't work too well for me.

Just use them as reference points.
 
IMO any fat measurement other than underwater weighing should be used as a gauge of change over time, not as an accurate number.
The athlete mode on the Tanita is closer to the skinfolds method for us. I've got a Tanita, and in the athlete mode my fat percentage is less than the skinfolds method. Go figure.

Also measuring at the same time each day (which I'm sure you're already doing), in the morning before eating or drinking and after going to the bathroom is a good time.
 
Thanks for your replies.

I'm pretty consistent about the time I measure BF. Unfortunately, My Tanita scale doesn't have an athlete mode. I got it from my father, who, after buying the scale, found out he couldn't use it because he has got a pacermaker, and so he gave it to me.

So, I'll just continue with the three-site method, which is fairly convenient with the ExRx online calculator. I'll have the Tanita as reference anyway.
 
I'm curious, what's the value in using the 7 site method for testing body fat? I've been using it every 2 weeks to try to gauge my body fat loss. I'm wondering if it's significantly more accurate than the 3 site.
 
For men, I have found the following formula to be the most accurate:
BD = 1.0990750 - 0.0008209*S + 0.0000026*(S^2) - 0.0002017*B - 0.00005675*Q + 0.00018586*R
S: sum of chest, abdominal & front thigh skinfolds (in mm)
B: age (in years)
Q: waist circumference in cm (at the umbilicus level)
R: forearm circumference in cm (at its widest point)

And then:
BF = (4.95/BD - 4.50) * 100

It's more accurate than the formula used in the ExRx calculator. ExRx says I'm 6-7%... Yeah, right.

BIA devices assume a certain density of the human tissues in order to interpret the electrical current that passes through the body. For athletes, they just use a different number in the equation (they assume a higher density of the fat free mass). But this is completely useless for a bodybuilder with a minimum level of muscle mass, since it is impossible to estimate the density of a bodybuilder's body. How much is muscle and how much is bones and water ? So, these devices will never be accurate for bodybuilders.
 
There are also more than 1 formulas for the 7 site method. Again, the most accurate is the one that takes into account the waist and forearm circumference:

BD = 1.101 - 0.00041150*S + 0.00000069*(S^2) - 0.00022631*B - 0.000059239*Q + 0.000190632*R

S: sum of chest, mid-axilla, triceps, subscapular, abdominal, suprailiac, & front thigh skinfolds (in mm)
B: age (in years)
Q: waist circumference in cm (at the umbilicus level)
R: forearm circumference in cm (at its widest point)

Should be a little more accurate than the 3-point.
 
[b said:
Quote[/b] ]BIA devices assume a certain density of the human tissues in order to interpret the electrical current that passes through the body
Click to expand...
most methods of BF assume a standardised density, which is the problem with navy, YMCA, skinfolds, underwater weighin and BIA. All methods also have problems with hydration, including DEXA.

But those formulas, especially the 3point +waist and wrist give the best correlation to BF measured by underwater weighing. Well out of hte JP formulas anyway.
 
[b said:
Quote[/b] ]most methods of BF assume a standardised density
Click to expand...

True, but with calipers you are not limited to the Siri two component model (which assumes a density of 0.901 gr/cc for fat mass and 1.10 gr/cc for lean mass). There have been lots of models, for whites, blacks, Asians, adolescents, older people etc.
Perhaps future BIA devices may allow us to program the densities too. This would be nice.
 
Thanks for all the feedback again. micmic, I'll use your formulas once in order to see which of the two initial BF percentages is more accurate (visually, I'd estimate my BF around 12%).

But from then on, I'll just go with my former methods because I hope that for detecting BF changes, they should be accurate enough (well, when I have achieved a significant decrease in waist size and an increase in lower arm size, I might try it again ;) ).

I want to do BF measurements on a regular basis and so I'm going to stick to methods which are as convenient as possible, even at the cost of some accuracy.

P.S.: micmic, I'm impressed! Your three-point formula puts me at 11,9%, which should be about accurate!
worship.gif
 
no formula is going to be precise, as such i just add up all the measurements and note whether trend is up or down.
i also mark each site on me with a marker pen so you're always getting the exact same site.
 
[b said:
Quote[/b] (flow @ April 25 2003,9:28)]On my Tanita scale (without athlete mode) my BF fluctuates between 16 and 18%.
Using a skinfold caliper and the three-site method, I get a consistent reading of 8.5 - 9%.
Now, what gives? I know that Tanita scales are not very precise, but TWICE the bodyfat of the skinfold method?!
Do any of you also own Tanita scales? What is your experience with scale vs. skinfold?
And BTW, is the 7-site method really worth the hassle, especially when you're more concerned about BF changes than absolutes? Have you found any major differences between 3-site and 7-site method?
Click to expand...
I really do not think either one is accurate for me. The scale gives me 21.6% or 19% depending on the time of the day. Using ther 7 point caliper test I get 12.3%. I would guess I'm between 15-16%.

Eric
 
[b said:
Quote[/b] (micmic @ April 25 2003,11:48)]For men, I have found the following formula to be the most accurate:
BD = 1.0990750 - 0.0008209*S + 0.0000026*(S^2) - 0.0002017*B - 0.00005675*Q + 0.00018586*R
S: sum of chest, abdominal & front thigh skinfolds (in mm)
B: age (in years)
Q: waist circumference in cm (at the umbilicus level)
R: forearm circumference in cm (at its widest point)
And then:
BF = (4.95/BD - 4.50) * 100
It's more accurate than the formula used in the ExRx calculator. ExRx says I'm 6-7%... Yeah, right.
BIA devices assume a certain density of the human tissues in order to interpret the electrical current that passes through the body. For athletes, they just use a different number in the equation (they assume a higher density of the fat free mass). But this is completely useless for a bodybuilder with a minimum level of muscle mass, since it is impossible to estimate the density of a bodybuilder's body. How much is muscle and how much is bones and water ? So, these devices will never be accurate for bodybuilders.
Click to expand...
Anybody have such an equation for women??
 
There are lots of formulas for women too. For example, for white women 18-55 yo:

BD = 1.1470 - 0.00042930*S + 0.00000065*(S^2) - 0.00009975*B - 0.00062415*C

where S is the sum of:
Chest skinfold
Mid-Axilla skinfold
Triceps skinfold
Subscapular skinfold
Abdominal skinfold
Suprailiac (or supraspinale) skinfold
Front thigh skinfold

all of them in mm

B = age in years
C = Gluteal circumference in cm

A simpler one:
BD = 1.0994921 - 0.0009929*S + 0.0000023*(S^2) - 0.0001392*B

where S is the sum of:
Triceps skinfold
Suprailiac (or supraspinale) skinfold
Front thigh skinfold

all of them in mm

B = age in years


After calculating Body Density:
BF for white women = [(5.01/BD) - 4.57] x 100

(Jackson-Pollock-Ward -1980)
 
Wow all of those formulas are great... how did you guys figure those out? Anyways my real question is this, i'm thinking about buying a tanita bf scale(w/athlete mode) for $40 online. I've heard that its not that accurate, then ive heard from someone in the archives that its second in accuracy only to hydrostatic weighing...how is it in measuring changes in BF? to be honest, i could care less what my BF% is in numbers, just that it decreases. In other words i dont care if my real BF is off. (it makes no difference to me if it says i go from 50 to 40 ... or 15 to 5 as long as the decrease is accurate) hope i didnt confuze anyone :confused: thanks
Keith
 
My advice would be to buy skinfold calipers. In order to track your progress, you should take at least some body measurements anyway, and it's just a small hassle to measure three skinfolds along with that (maybe once every one or two weeks). Daily BF calculation is unnecessary and will only distract you, as any differences are more likely due to inconsistencies in the method used than to any actual body composition changes. During my cutting phase in the last four months, the caliper has always provided good and reliable data, whereas the Tanita scale must be used at the exact same time of day under the exact same conditions (meals/hydration/potty) in order to deliver useful results.
 
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