How BMI Scales Work

BMI or Body Mass Index scales are popular scales used to calculate individual's body fat index. BMI scales use a technique called Bioelectrical Impedance Analysis, or BIA to measure the fat in a person's body. BIA does this by submitting a small unnoticeable electrical current through the body. This current is completely harmless. Since fat is a poor conductor of electricity compared with water, the current passes through fat and bone tissue significantly slower than it does through tissues void of fat, like muscles. Normally, the scale is one you step on, like a traditional body weight scale. In these instances the electrical current is sent up through one leg, through the entire body, and down the other leg. Due to this current's slow moving tendencies through fatty tissues, experts use BMI scales to measure a person's body fat with these machines. Fat-free muscle in the body and body density is detected by the amount of resistance the electrical current has when it passes through the body.

Ultimately, these scales actually measure body density. A formula is then applied to your body density measurements to determine fat percentages in the body. When determining body fat percentages, most scales and formulas take a variety of factors into account. These complex formulas generally account for age, sex, height, activity levels, and gender. These scales are not always 100% accurate but they are very convenient for measuring and monitoring changes in fat in the body, so utilizing BMI scales over time is an ideal way to measure fluctuating levels of fat in the body.

Before stepping on a BMI scale it is important to recognize some of the factors that can skew the BMI scale results. Since water is the main component in muscle and tissues it is an important component in the BMI the measurement process. Therefore the measurements can be thrown off if the individuals have taken part in excessive alcohol consumption, heavy exercising, or sweating. Essentially excessive dehydration can and will deter the BMI scale's ability to accurately ready body fat levels, and this fact should be taken into consideration by individuals using these scales.

Another factor that can ultimately affect the BMI scale's ability to register accurate body fat measurements, occurs when individuals use the scale during vastly different body-temperature situations. If you've just finished sweating or working out and step on a BMI scale the reading is going to be much different than if you were outside in freezing cold weather and then decided to use the scale. Body temperatures are different during different times of the day in general not only in extreme examples, so attempting to measure BMI around the same time each day the scale is used will provide individuals with the most accurate results possible.

It's also important to stick to the same machine when performing BMI measurements over time. Switching scales can also display different results and may give individuals an inaccurate portrayal of the actual changes in their body fat levels.

Ultimately, BMI scales are effective tools, if used properly, consistently, and most importantly over time to measure changes within the body's fat levels. When these scales are used as they are intended to they can provide reliable reference points for individuals striving to decrease their body fat levels and maintain a healthier overall body.