Do You Know Your BMI?



Obesity is an epidemic in many countries, and China’s diet is changing so quickly that the obesity rates here are also rapidly climbing. One popular tool to assess your own weight — and your subsequent risk category for heart disease and diabetes — is to figure out your Body Mass Index, commonly known as BMI. It’s a very simple calculation, height (meters) / weight (kg) squared.

Enter your height and weight in the above table. Your BMI score means the following:

UnderweightBelow 18.5
Normal18.5 – 24.9
Overweight25.0 – 29.9
Obesity30.0 and Above

Doctors use this BMI number to assess a person’s risk for diseases such as heart disease and diabetes (see the table below). The BMI test does have some controversy as many feel it isn’t accurate enough, especially for very muscular persons whose BMI may be artificially high since muscle is heavier than fat (see more details here). Many doctors feel that abdominal waist circumference is more accurate to assess your obesity risks. The bottom line is that you should know either your BMI or your waist circumference risk — both is better. Your doctor should also calculate this during your annual physical checkup.

The bottom line: however imperfect the test, BMI has been validated in countless studies and can give a fairly good idea of your obesity and health risks. Plus, it’s free and you can do at home without seeing the doctor!

Classification of Overweight and Obesity by BMI, Waist Circumference, and Associated Disease Risks

Disease Risk* Relative to Normal Weight and Waist Circumference
Men 102 cm (40 in) or less
Women 88 cm (35 in) or less
Men > 102 cm (40 in)
Women > 88 cm (35 in)
Underweight< 18.5
Normal18.5 – 24.9
Overweight25.0 – 29.9IncreasedHigh
Obesity30.0 – 34.9IHighVery High
35.0 – 39.9IIVery HighVery High
Extreme Obesity40.0 +IIIExtremely HighExtremely High

*     Disease risk for type 2 diabetes, hypertension, and CVD.
+     Increased waist circumference can also be a marker for increased risk even in persons of normal weight.

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