Bioelectrical impedance analysis (BIA) is a commonly used method to estimate body fat and water content by electrical technology.  BIA basic principlesThere are many human body fluids ions, which are of electrical conductivity. The current has better transmission performance in the fluid with smaller resistance. Fluid is a conductive medium, so the body is equivalent to the conductor, with resistance; cell wall is equivalent to capacitance, because the cells are to internal and external conductive fluid, but was separated from the cell wall, so it has capacitance; there is almost no inductance inside the human body. If regard human body as a conductor, the amount of water will reflect body resistance; The more water content, the bigger the body resistance.The human body composition can be divided into water (Body water), protein (Proteln), body fat (Body Fat), Inorganic (Mineral) four. Although these elements in the human body  are with some individual differences because of different gender, but generally is 55:20:20:5 ratio. Thus, in these human ingredients, if you know the body of water content and body fat content, you can separately work out the amount of each of these four components.In human body analysis, the volume conductor can be seen as the body of water. The length of the conductor is regarded as the body's height, the resistance rate is the body water resistance value per unit volume. The electrolyte solution is quantitative per unit volume in human body, so the resistivity of the human body is a constant, as long as the measuring device with a measured impedance value of the body's resistance to obtain the body water content:Of course, the measuring device accuracy and calculation determines the precision measuring result of body water content.


Body Mass Index

Body Mass Index (BMI) is a number calculated from a person's weight and height. BMI provides a reliable indicator of body fatness for most people and is used to screen for weight categories that may lead to health problems.BMI is more helpful than weight in assessing degree of overweight. BMI is a measure of weight for height. It stands for body mass index. It's the internationally accepted classification for overweight and obesity using 18.5-25 as a normal or healthy BMI, 25-30 the overweight range, 30 and above the obesity range. You may need to talk to your doctor and find out if your weight is a medical problem. Your doctor may suggest a healthy eating or physical activity to improve your health status.