Body Mass Index
Doctors use the body mass index (BMI) as a simple way of assessing whether a patient needs to lose weight. The calculation is based on comparing a person's weight with their body height. It applies equally to men and women.

You can quickly see the BMI assessment for your body on the chart below.

Alternatively, you can calculate your own BMI. Divide your weight in kilograms by the square of your height in metres, or divide your weight in pounds by the square of your height in inches, then multiply by 703.

People with BMIs between 19 and 22 live longest. Death rates are noticeably higher for people with indexes 25 and above.

Category BMI range -kg/m2
Starvation less than 14.9
Underweight from 15 to 18.4
Normal from 18.5 to 22.9
Overweight from 23 to 27.5
Obese from 27.6 to 40
Morbidly Obese greater than 40

The BMI is not infallible. For instance, it is possible for a healthy, muscular athlete 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.