Basics of bodyfat measurement

[RottenWillow]

PART 1


Most of us are terrible at estimating subcutaneous bodyfat levels. Our idea of what lean or fat looks like is typically skewed in one direction or the other. In order to get a solid, reliable fitness baseline, I personally always recommend one gets a bodyfat estimate prior to embarking on a fitness routine.

Getting the baseline
This not only can provide a way to objectively measure your progress further down the line, but can serve as a big motivation boost (or heads up you're doing something wrong) after you've pursued your new program a few months. Getting that bodyfat level baseline estimate can also aid significantly in designing your diet and training program. A fatter body won't need as many calories as a leaner one because it has less lean body mass (LBM) relative to it's total bodyweight. Remember, your LBM is a big determinant of the amount of calories your body needs to maintain it's current weight. A person with a fatter body might need a bit more cardio to reshape the body, and the bodyfat estimate (which will give your LBM weight) can tell you how much extra, while helping you avoid the common pitfall of doing too much cardio.

Get a reliable estimate or it's useless
Or even counterproductive. Getting erroneous information can not only be disheartening, but misleading. You could end up with a diet and a routine inappropriate for your fatness level. It is essential that you get the very best estimate that is practical for your budget and your circumstances.



stay tuned for Part II, bodyfat measurement methods.

 

[RottenWillow]

PART 2


Choosing the best possible method
Methods of estimating bodyfat vary widely in terms of expense, ease of use, accurate, and privacy of testing. Let's look at the options starting with the most accurate.

*The DXA Scan-The current MackDaddy of accuracy, expensive, not widely available
Dual energy X-ray absorptiometry is a medical imaging test used to measure bone mineral density. It was developed primarily to aid physicians in diagnosing osteoporosis, but is now often used as a measure of total bodyfat. It's results are very accurate. If the machine indicates you have 21.4% bodyfat, you probably do!

The going rate will vary from one provider to the next, but figure at least a few hundred USD/Euro/Pounds for a single testing.


*Bod Pod-very accurate, expensive, not private or widely available.

These little high tech coffins use air displacement to estimate your bodyfat level. It's pricey, not widely available, and your results certainly wouldn't be private. It is however very accurate.

*Hydrostatic weighing-accurate, very inconvenient, not private, not widely available

This is the former gold standard of bodyfat measurement. It involves being dunked in a tank while suspended from what amounts to a giant fish scale. Lovely. Your dry land and submerged water weights are then compared. A fatter body will evidence a greater difference in weight between it's dry/water weights and this is the principle used to estimate the total bodyfat. This test is relatively inexpensive compared to the previous two methods, and is more accurate than the methods below.

*Skinfold Calipers-inexpensive, can be used privately, widely available, less accurate

They definitely aren't all the same. Let's look at the options.

If someone is testing you at your gym, first ask how experienced they are with testing and check to use what type of caliper they are using. It should be one of the following: Harpenden Skinfold Caliper, Lafayette Skinfold Caliper, or the Lange Caliper. The Slim Guide Skinfold Caliper is ok though much cheaper and less accurate than the others. A properly trained, experienced tester will use a ruler on your body to ensure he/she is measuring you in precisely the right spot and will mark their folds with a pen. Sounds invasive and a bit messy, but it's the way to be accurate and meticulous. Also, make sure you always have the same examiner test you every time to ensure consistency.

If you want to test yourself, this is the one to use.
Accu-Measure Body Fat Calipers. It's only $20 and regarded as being pretty accurate.

As for the fancy formulas used to estimate bodyfat levels, their results will vary hugely. Trying to calculate your total bodyfat with calipers is at the very best +- 4% in accuracy, meaning your 20% results means you could easily be 24% or 16%. That's a huge margin. So, what to do?

You might seriously consider not trying to plug your numbers into any formula at all. Instead note down your individual numbers for bicep, thigh, calf, etc and compare future measurements directly to those objective measures. If your thigh measure was 11mm on 2/1/10 and 8mm on 8/1/10, then you know you reduced subcutaneous bodyfat in that region. No guesswork involved.

However, if you really want to try the formula, here...
Scroll down about halfway for the Female Body Fat Calculator
Body Fat Calculator 6 formulas calculate your body fat percentage
The more data inputs the more accurate your result is likely to be.


*Bioelectrical Impedance Analysis- private and convenient, can be very inaccurate if not used correctly

These scales measure your body density in the same very general sort of fashion as DXA, though with far less sophisticated equipment. The weak electrical charge will pass through visceral and subcutaneous fat more quickly than bone and muscle, so the speed of transmission is plugged into a formula programmed into the scale to estimate your bodyfat.

The key here is to keep the testing conditions absolutely constant. Ensure the following conditions are the same every time you step on your BIA scale: room temperature, your level of hydration, that you haven't just been exercising, that your feet and the footpads of the scale are clean, that you are standing perfectly straight.

The BIA scale can be useful for tracking changes in your bodyfat, as long as you adhere to the proviso above. It's using the same formula every time to estimate your fat level, so even if it's inaccurate, it'll be consistent in how it arrives at that number.

There's that word "formula" again. A good scale will give you different profiles you can select based on your age and fitness level which allow it to pick the most appropriate formula for you. A more expensive scale is going to be a more accurate measure, so spend as much as you can.

Your body position, the amount of water in your body, your food intake, skin temperature and recent physical activity can all adversely affect the results of body fat scales.
Keep all the testing conditions constant if you want to accurately track your fat loss.

Again, to achieve accurate, consistent results, you must standardize the way you perform each test.