We measure the body composition of every new patient using the state-of-the-art InBody520 machine. The InBody 520 utilizes the Direct Segmental Multi-frequency Bioelectrical Impedance Analysis Method (DSM-BIA Method) via a Tetrapolar 8-Point Tactile Electrode System to measure:
The InBody™ assesses body composition by applying varying frequencies of a low- level current to all four limbs of the body. By doing so, it is able to measure much more accurately overall lean body mass (LBM) than a device that utilizes a single frequency and applies it only to the legs. Then, by subtracting the LBM from the total body weight, overall fat mass and percentage can be calculated.
Weight is the first thing measured when standing on the InBody scale. However, weight alone does not tell you much about health of your body composition unless you also know your height and body fat percent.
Body Mass Index (BMI) is an older first attempt to correct for the shortcomings of just looking at weight. It corrects uses height to adjust the health implications of a person’s weight. However, two people of the same height and weight can have very different relative proportions of body fat and therefore very different body compositions. The normal range for BMI is 18.5-25 (kg/m2). The average is in the middle of this range at about 22 kg/m2. Using this range, a person is underweight for his height if his BMI is less than 18.5. He is slightly overweight if his BMI is 25-27 and obese if it is 27-31. Morbid obesity is defined as a BMI greater than 31. You can imagine, however, that a very muscular person can be considered obese by using a simple BMI estimation. Most Mr. Universe competitor would be considered obese, and some morbidly obese, by BMI standards when they in fact have very little body fat. BMI is only really useful for estimating if a person is underweight and in need of putting on some muscle. The most important determinants of the health of your body composition is the relative proportion of muscle to fat.
Lean Body Mass (LBM) is the total body weight minus the fat mass. The normal range for LBM is dependent on the height and gender of the subject being measured. For males, the standard LBM is the amount of LBM that would give a BMI of 22 and a body of 15%. For females, the standard amount of LBM is the same BMI (22) and a body fat of 23%.
Fat Mass (FM) is calculated by subtracting the LBM from the total body weight.
Percent Body Fat (%BF) is calculated by dividing the FM by the total body weight. The normal range for males is 10-20% and for females 18-28%.
Total Body Water (TBW) is what is actually measured to determine LBM. It is comprised of all the non-fat weight of your body, both intracellular and extracellular. When the electric current is applied to your body, the lower frequencies travel around the cells and the higher frequencies through the cells.
Intracellular Water (ICW) is a measure of the amount of your TBW that is contained within the cell membranes of your tissues. In young healthy tissues, a greater proportion of TBW is in the cells.
Extracellular Water (ECW) is a measure of the portion of TBW outside of your cells as interstitial fluid. It is equal to the TBW minus the ICW. As we age, more of our LBM is outside of our cells as “junk,” degraded proteins, etc. A temporary cause of increased ECW is edema, the swelling of the legs that can occur in certain disease states, and also at the end of a day of standing.
Extracellular/Total Body Water (ECW/TBW) is actually an interesting biomarker of aging. This ratio is a measure of the “quality” of your LBM. The lower the ratio, the healthier your LBM. It can help to diagnose the condition of sarcopenic obesity (high fat and low muscle), which might show a normal LBM, when in fact a higher than normal portion of it is ECW. Between 20 and 85 years old, the ratio gradually increases from 0.36 to 0.39. In certain disease states, the ratio can exceed 0.40.