Body mass index (BMI)

Body mass index is a way of checking whether your weight is too much or too low in relation to your height. Height is measured in meters and squared. Weight in kilograms is divided by the square of height in meters. This gives body mass index. BMI of 18.5 to 25 is considered as normal. 25-30 is overweight and above 30 is obesity. Obesity has been graded according to BMI as Grade I: 30-34.9, Grade II: BMI 35-39.9 and Grade III obesity as BMI above 40.0.

How is the risk of obesity classified in this scheme?

Low risk: Grade I

Moderate risk: Grade II

High risk: Grade III

Is BMI the only measure of obesity?

No. There are other measures like waist size and waist hip ratio. The risk of obesity not fully based on BMI alone. Other risk factors for disease of the heart and blood vessels like genetic factors, smoking, high blood pressure, blood sugar or cholesterol and sedentary lifestyle also enhance the risk. Moreover, many of these risk factors are inter-related in that one predisposes to the other.

When do you consider bariatric surgery (weight reducing surgery) depending on BMI?

Bariatric surgery like gastric bypass (bypassing the stomach) or reducing the size of the stomach so that you can’t take much food at a time, are considered when the BMI is above 40. But it may be also considered in those with other risk factors when the BMI is above 35. But every attempt should be made to bring the BMI with lifestyle modifications before bariatric surgery is considered.