1. Body mass index 身體質量指數 Your BMI is an objective scientific measure, that uses your height and weight. You can calculate your BMI by dividing your weight in kilograms by the square of your height in meters. In other words the algebraic expression for BMI is: BMI = Kg / (m)2 One variable BMI fails to consider is lean body mass. It is possible for a healthy, muscular individual with very low body fat to be classified obese using the BMI formula. If you are a trained athlete, your weight based on your measured percent body fat would be a better indicator of what you should weigh.If you are a trained athlete, your weight based on your measured percent body fat would be a better indicator of what you should weigh

2. This page includes a simple “JavaScript” program to calculate your exact BMI (in metric measurements) and a height vs weight chart that will approximate your BMI (in english measurements). To use the program enter your height in meters and weight in kilograms, in the boxes below, and then click “Calculate.” For those unfamiliar with the “MKS” system, listed below are relevant unit conversion factors, and an example of english to metric unit conversion. ● BMI = 體重 (kg) / 身高 2 (m2 ) 體重 If your BMI is below 20: This indicates a lean BMI, which means you have a low amount of body fat. If you are an athlete, this can be desirable. If you are not an athlete, a lean BMI can indicate that your weight may be too low which may lower your immunity. If your BMI and body weight are low, you should consider gaining weight through good diet and exercise habits, to increase your muscle mass.

3. If your BMI is between 20 and 22: This indicates the ideal, healthy amount of body fat, which is associated with living longest, and the lowest incidence of serious illness. Coincidentally, it seems this ratio is what many individuals perceive to be the most aesthetically attractive. If your BMI is between 22 and 25: This is still considered an acceptable range, and is associated with good health. If your BMI is between 25 and 30: You are considered “Hefty” and should finds ways to lower your weight, through diet and exercise. You are at increased risk for a variety of illnesses at your present weight. You should lose weight by changing your diet and exercising more. If your BMI is over 30: This indicates an unhealthy condition, your excess “Prosperity” is putting you at risk for heart disease, diabetes, high blood pressure, gall bladder disease and some cancers. You should lose weight by changing your diet and exercising more. From ： http://www.phaster.com/unpretentious/bmi.html