Body Mass Index - Norms? How it is determined - formulas and tables

Body Mass Index - Norms? How it is determined - formulas and tables

Body Mass Index - Norms? How it is determined - formulas and tables
Body Mass Index - Norms? How it is determined - formulas and tables

According to the World Health Organization, the average body mass index of Russians is 26.2. Although this figure is only slightly higher than the norm, Rosstat reports2 that almost 40% of the population has symptoms of obesity and over 21% - obesity.

At the same time, only a third of Russians have a normal weight (body mass index in the range of 18.5 - 25). In the article below, read how to correctly calculate the BMI (and whether you should do it at all) - as well as what body weight is the norm.

//  Body mass index - what is it?

Body mass index

Body mass index is a measure of the ratio of a person's body weight to his height. Despite the fact that the classical methods for calculating BMI do not take into account gender and age (as well as the structure of overweight itself or its distribution on the figure), they give a general understanding of the situation.

The main goals of the body mass index are to facilitate the conversation between the nutritionist and the patient about the presence of obesity, as well as to give an understanding of the general health of the population. In particular, high BMI is associated with an increased risk of diabetes, heart disease and vascular disease2.

However, it is important to emphasize that the calculation of BMI gives very general numbers - and can not be used to determine the optimal weight of a particular person. For example, at a height of 170 cm, a weight in the range of 53.5 - 72.3 kg will be considered "normal" - for both men and women.

Who invented it?

A simple mathematical formula (the so-called "Kettle's formula"), derived by the Belgian scientist Adolf Kettet in the mid-19th century using a statistical method, is used to calculate the body mass index. Most online BMI calculators are based on it:

  • ITM = m / h  2  ,

where   m   is body weight (in kilograms) and   h  2   is human height (in meters), squared.

BMI - tables and graphs

BMI - tables and graphs

After calculating the body mass index, it is necessary to compare the obtained figure with the tabular data. A low BMI indicates a lack of body weight, and a high BMI indicates a possible presence of obesity. You can also use the graphic shown in the photo above.

//   Body mass index:

16 or less Severe deficit
16 - 18.5 Insufficient weight
18,5 - 24,99 Norm
25 - 30 Overweight
30 - 35 Obesity
35 - 40 Severe obesity
40 and more Severe obesity

How do I use the information?

The hard part about the body mass index is that it shows only part of the big picture. For example, muscular athletes (due to their higher muscle mass) will have a high BMI - without being obese.

However, a body mass index above 30 is definitely a good reason to visit your doctor for more detailed health advice. In this case, it will be useful to determine the blood sugar level (to diagnose diabetes) and measure the waist circumference (helps to identify the metabolic syndrome).

Standards and guidelines

On the one hand, the WHO warns that high BMI may be associated with overweight and health-related complications. The most common recommendation is to maintain a weight within the "normal" body mass index.

On the other hand, this does not mean that being within the norm is a universal characteristic suitable for absolutely everyone. In fact, the range of "normal" weight is about 10-15 kg - without taking into account age, gender and body structure.

That is, if your doctor talks about the need to reduce BMI, he is talking exclusively about the need to reduce excess fat. It is simply not possible to use a BMI to determine the exact "ideal" weight.

Additional data

In addition to measuring waist circumference (indicating the presence of internal  abdominal fat  ), modern nutritionists have a number of ways to determine the percentage of body fat - after all, it is on the basis of this indicator that the diagnosis of "obesity" is made.

In turn, the norms for the percentage of fat depend on gender and age - if the figures in the range of 25-30% for men indicate the presence of obesity, then for women this is a characteristic of the average ("Normal") level of fat .


Calculating body mass index is the first step in diagnosing overweight and possible obesity. However, BMI cannot help you calculate your "ideal" or "normal" weight - it requires gender, age and body fat percentage to be taken into account.

Information for informational purposes only. It should not be used for diagnosis or treatment.