Body Fat Calculator
There are three main ways to calculate your body fat. Using a home body fat scale, skinfold calipers or hydrostatic weighing. Each method has it's pros and cons.
Body Fat Scales
How they works:
Body fat scales use bioelectrical impedance to measure your body fat percentage. A low-level electrical current is passed through your body and the "impedance", or opposition to the flow of the electrical current, is measured.
Pros:
- They measure body fat quickly and conveniently
- They are easy to use and have at home
Cons:
- Impedance levels can be altered by many factors besides body fat. Factors such as the amount of water in your body, your skin temperature and any recent physical activity can adversely affect the results
- Studies have shown variances as high as 8 percent when using the bioelectrical impedance
Callipers
How they works:
You take pinches of your skin at three points on your body and calculate the fat percentage from those readings.
Pros:
- Most studies have shown that they are very accurate
- They are affordable, simple to use and have at home
Cons:
- Difficult to do it on your own body. You may need professional assistance
Hydrostatic Weighing
How it works:
The examiner first calculates your body density by measuring the amount of water you displace when you immerse yourself in water. Then a formula is used to calculate body fat based on your body density.
Pros:
- The most accurate way to calculate body fat
Cons:
- Expensive
- Inconvenient
- Time consuming, cumbersome, complicated and difficult to find
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As I told Mel the other day, I use this bad boy, Omron HBF-306 Body Fat Analyzer:
The best part is that you get both BMI and body fat readings. It also stores your stats.
Last check, my body fat was 38.2, which puts me in the Obese category. Using the formula from yesterday, weighing in at 194 with 38% body fat, let's see what a reasonable weight loss goal for this fat fighter "should" be shall we?
I'm a 194lb woman with 38% body fat. My blanket goal is to lose 60lbs.
My initial body fat is: 73lbs (194lbs x 0.38) [holy shyte!]
My lean body mass is: 121lbs (194lbs total weight - 73lbs of fat)
My goal to lose 60lbs puts me at 134lbs, which may not be realistic.
At 134lbs, I'd have 121lbs of lean body mass and would only be carrying 9lbs or aprox 10-13% body fat. From yesterdays chart, unless I'm an Olympic athlete in training, this is a very low percentage.
A better goal might be to initially reduce my body fat from 38% to 30%:
194lbs x 0.30 = 58lbs of body fat
121lbs of lean body mass + 58lbs = 179lbs goal weight
To achieve this "acceptable" range of 30%, I'd need to lose only 15lbs of fat (73lbs body fat - 58lbs body fat = 15lbs), reducing my scale weight from a current 194lbs to 179lbs. Then, based on how I look and feel at that point, I can shoot for a lower body fat percentage, say going from 30% to 25% or losing 14lbs to weigh in at 165lbs.
3 months from this week, we shall check revisit our goals.
That shall be my first goal weight: 179lbs, 30% body fat. What's yours?
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6 Comments
08.10.06 | renee commented: heh, i'm a camel and tend to drink upwards of 4 liters of water on day, for the most part. i noticed something else, a few years back, when i'd do free trials @ gyms, they all used calipers, in recent years, the last 2-3, they use the omron thingy, even my current gym, golds, whipped it out. for the most part, the #'s are consistent w/what i use @ home, give or take a point or 2.
for the life of me, i can't get a handle on the calipers 
08.10.06 | iportion commented: I want to get some Callipers.
I think the body fat scales wouldn't work as well as thwe tried and true things.
08.11.06 | Bryan commented: As a professional personal trainer I think that sometimes we get to obsessed with % body fat and BMI.
Calipers are always a problem with people who are heavily overweight as fat moves and it is difficult to get exactlt the same site, especially between testers Also, the tables are not wholly accurate for present day populations and do not allow for racial characterisatics.
The hand-held devices have proven to be innacurate. In our business we use bio-impedence but with tags that are fitted to the ankles & wrists. People lie down to avoid the problem of pooling of body fluids.
As I say, I only use this information a s a guide. The best measure is whether your clothes fit better and you can sustain areobic activity or functional exercise you could not manage before. 
08.11.06 | iFitandHealthy commented: I tend to agree with Bryan, but if you really want to know your body fat percentage, the "gold standard" test is hydrostatic weighting. I wrote about it a bit in Is President Bush Too Fat?
08.13.06 | Nancy commented: Here there is still and this procedure:
for the men normal weight - this is its increase after minus 110;
for the women - its increase after minus 105
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Tom Venuto (author of Burn the Fat, Feed the Muscle) recommends the Accu-Measure skinfold caliper, which an individual can use without additional help in the privacy of their own home. (Search for Accu Measure at http://www.bodytrends.com/default.asp ). I think the deal with the Omron or other bioelectrical impedance measures is to make sure you're well-hydrated. The people at the health fair told me that their accuracy is also effected if you're on your period.
I still have to get to a sporting goods store to see if they have one....