What is body fat percentage
The term body fat percentage determined as total mass of body fat divided by total body mass and multiplied by 100. Fat essential part of your organism and it is one of important energy source, helps your body to protect internal organs. Also it’s an important part of body structure that helps the body maintain the necessary level of warm. And finally it’s an important part of endocrine system which helps absorb some nutrients and produce important hormones.
How to calculate your body fat percentage at home
Calculate body fat percentage from BMI
Body mass index or BMI is an index based on body mass in relation to your body height and allow to classify weight related health risk for person. To calculate your body fat percentage through BMI you need to use next formula:
BF(%) = 1.39 x BMI + 0.23 x age – 10.34 x gender – 9
Where age equal 0 for female and 1 for male
Try our body fat percentage calculator to get your own results from BMI.
Methods for measuring the percentage of body fat using a meter are based on a statistical model and essentially evaluate body density. The percentage of body fat itself is obtained through applying the Siri Brozek formula to existing results. It follows from this that this methods carries the error of two different statistical models at once.
A big plus in this case is that it is much more convenient to take several measurements of the body than to immerse people in water, go somewhere or buy expensive equipment.
Here is the list of most popular methods for measuring your body fat percentage using tape:
- Us Navy Method
- Covert Bailey
For example in case of US Navy Method you need to use next formulas:
Men BF(%) = 86.010 x log10(abdomen – neck) – 70.041 x log10(height) + 36.76
Women BF(%) = 163.205 x log10(waist + hip – neck) – 97.684 x log10(height) – 78.387
All measurements in inches
Our body fat percentage calculator may provide you with most accurate values for this methods.
Skinfold Caliper is a device that measures the thickness of the folds of your skin. By making measurements in various parts of the body, you can accurately determine the percentage of fat.
Here is the list of most popular methodologies for measuring your body fat percentage using caliper:
- Jackson/Pollock 3-site caliper
- Jackson/Pollock 4-site caliper
- Jackson/Pollock 7-site caliper
Visit our body fat percentage calculator for caliper tool it will provide you with most accurate values for these methods.
How to measure body fat percentage other techniques
Underwater weighing also called Hydrostatic weighing and is based on principle of Archimede which tells us that a buoyant force acts on a body immersed in a liquid equal to the weight of the volume of liquid displaced by the part of the body immersed in this liquid. Using this principle allow you to measure body fat percentage, because the density of fat mass is around 0.9 kilograms per litre, when the fat free mass density such as muscle and bone is 1.1 kilograms per litre.
So first of all the person is first weighed at scales. Then this person is lowered into a large container of water on special scales and then asked to exhale all the air, this is important to obtain more accurate results. This procedure is repeated several times, usually 3 times. Then, using the obtained data and special algorithms, they calculate the weight of fat and muscle mass and determine the percentage of fat contained in the human body.
This method of measurement of measure body fat percentage is accurate enough. The measurement error for this method is 4%. Main error factor in measuring of body density using this method is due to the presence of various gases in the cavities of the body and lungs.
Another factor which is related not so much to measurement error as to user convenience is the fact that for measurements a person needs to be completely immersed in water and at the same time expel all oxygen, and this whole procedure is repeated several times. Not everyone will like it.
Air displacement plethysmography
Whole-body air displacement plethysmography or ADP. In this case, used a special device called Bod Pod. The principle of operation of this device is somehow similar to underwater weighing, only in this case air is used instead of water. This device measures the volume of the body based on the physical relationship between pressure and volume.
First of all measured the volume of an empty camera of the device, then the volume of the camera of the device with a person inside. Person’s volume is obtained by subtraction of values. Then persons value allow to calculate overall density of the body and the relative proportions of body fat and lean body mass.
This method allows you to quite easily and quickly get fairly accurate values of the percentage of fat in the body, but it has its drawbacks in the accuracy of calculations. Disadvantages are manifested in extreme values of the percentage of body fat, for example, for obese people, you can get an underestimated result of up to 3%, and for very thin people the result is overestimated to 7%
Bioelectrical impedance analysis
The essence of this method is that two electrodes are placed on the human body, usually on the person’s hand and foot. Then a very weak electric current is passed through the body and the device specifically reads and analyzes the signal attenuation. The amount of resistance in this case helps to determine the percentage of fat in the body, since adipose, muscle and skeletal tissue have different levels of resistance to electricity. Muscles have good conductivity because they contain about 70% of water, while fat practically does not contain water, and therefore is a poor conductor.
The accuracy level of this method is influenced by several different factors, for example:
- Precision of device for measuring resistance
- The level of hydration of a person, if a person drank water before measurement, this may affect the accuracy of the result
- Whether you ate or not before test
- Exercise activity may affect the accuracy too
Ultrasound measurement of subcutaneous fat thickness is one of the most accurate and at the same time expensive methods. For measurements, special devices are used that are based on the use of tabular values of the speed of sound in body tissues and analysis of signals to determine the thickness of fat. By measuring the thickness of fat in various parts of the body, you can calculate the estimated percentage of fat in the body.