In order to decide whether someone is “thin” or “fat”, doctors usually use the Body Mass Index (BMI) as a standard. Body Mass Index is a simple index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults. It is defined as the weight in kilograms divided by the square of the height in metres (kg/m2).
For example, an adult who weighs 80kg and whose height is 1.75m will have a BMI of: 80 / (1.752) = 26.12
To decide whether that number is include in underweight, normal, or overweight, let’s check this table below, which is an international classification for BMI from World Health Organization (WHO):
| Classification | BMI(kg/m2) | |
| Principal cut-off points | Additional cut-off points | |
| Underweight | less than 18.50 | less than 18.50 |
| Severe thinness | less than 16.00 | less than 16.00 |
| Moderate thinness | 16.00 – 16.99 | 16.00 – 16.99 |
| Mild thinness | 17.00 – 18.49 | 17.00 – 18.49 |
| Normal range | 18.50 – 24.99 | 18.50 – 22.99 |
| 23.00 – 24.99 | ||
| Overweight | 25.00 and above |
25.00 and above |
| Pre-obese | 25.00 – 29.99 | 25.00 – 27.49 |
| 27.50 – 29.99 | ||
| Obese | 30.00 and above | 30.00 and above |
| Obese class I | 30.00 – 34.99 | 30.00 – 32.49 |
| 32.50 – 34.99 | ||
| Obese class II | 35.00 – 39.99 | 35.00 – 37.49 |
| 37.50 – 39.99 | ||
| Obese class III | 40.00 and above | 40.00 and above |
BMI values are age-independent and the same for both sexes. However, the BMI table has a weakness of the inability to differentiate whether a person is overweight or just has an over-size muscle as a result of regular exercises. BMI, although not a perfect method for judging someone’s weight, is often a good way to check the obesity risk, which is quite accurate for most person.
So, how much is your BMI? Remember that being obese will put you at risk for coronary artery disease, and high blood pressure, among others. Start a diet program immediately if your BMI is near or over 30.
Diet and exercise are the safest and most natural ways to lose weight. However, there are a lot other methods that give more instant results, all with its own benefits and risks. Among those weight reduction methods are liposuction, diet pills, or operation of lap band surgery (or gastric banding), which is one of the safest weight loss operations.
I think BMI is really helpful to measure if we are Under or over or at with right body weight. And measuring body weight is especially useful if you are putting in the effort and commitment required to achieve your goals.