Body mass index and its calculation (calculator and table)

What is BMI?

BMI - body mass index (from English BMI - Body Mass Index), an indicator reflecting the degree of relationship between height and weight. Based on the obtained figure, we can conclude whether body weight is sufficient, insufficient or excessive. It is widely used in therapy in the treatment of diseases associated with excess weight, allowing you to select the required direction of treatment.

The indicator, the calculation formula, the interpretation of the data obtained - all this was developed by the Belgian scientist A. Quetelet in the nineteenth century. His research was finalized by the World Health Organization and now calculating this value is the first step towards losing weight. You can calculate your body mass index yourself. This skill is useful for people after a diet for self-control.

Why know your body mass index?

It is used to find out the risks of diseases. WHO states the Mean Body Mass Index (BMI) that excess weight increases the risk of type 2 diabetes, coronary heart disease, breast, uterine, colon, prostate, kidney and gallbladder cancer.

On average, 2.8 million deaths and 35.8 million disabilities are associated with excess weight worldwide per year.

WHO believes that for good health, every person should strive for an index of 18.5–24.9. The risk of disease increases between 25 and 29.9, and after 30 it increases significantly.

How to calculate your BMI?

Body mass index is calculated individually for each person. The value of this coefficient depends on weight, height, age. There is a special online calculator that allows you to determine your body mass ratio. You will need to enter your height and weight information. The computer will give the exact value. This is especially convenient for determining BMI at home.

You can determine the index yourself, manually. It is calculated using Adolphe Quetelet’s formula: I = m/h², where m is body weight, h is height in meters .

Let's look at an example:

1. It is necessary to calculate the body mass index for a man 185 cm tall whose weight is 94 kg.
2. Let's start calculating BMI by squaring height in meters (to do this you need to multiply the number by itself): 1.85×1.85=3.4225.
3. Divide the weight in kilograms by the resulting value: I=94/3.4225=27.47.

27.47 is the obtained index value. The BMI formula is quite simple; getting the coveted value is not difficult. The question remains - what does it mean?

BMI calculator

Enter information about the person for whom you want to find out the body mass index. To do this, fill out the fields below and click the “Calculate” button.

Age must be between 18 and 100!

Height must be a number greater than zero!

The weight must be a number greater than zero!

How to weigh a child correctly

Very young children are weighed on special scales, which can be either cup or electronic. Children up to one year old can be weighed lying down or sitting. At older ages, measurements are usually taken while standing. It is better to weigh yourself only in underwear or without clothes at all. Otherwise, the readings may be distorted up to half a kilogram.

The best time to weigh yourself is morning. It is best to carry out the procedure before eating, immediately after emptying the bladder and intestines. After eating, the weighing results will again be incorrect.

Decoding data: BMI table

Everyone's body mass index is different. The BMI norm is also calculated based on specific indicators. It is important to know what a specific number means. The BMI table for women, men and children will help you understand this issue. It was compiled by obesity experts WHO (World Health Organization).

The classification of obesity by BMI is quite superficial, however, it allows you to choose the direction of treatment and will be the impetus for contacting a weight loss specialist.

It is recommended to look for a BMI calculator based on age, since the norm largely depends on this indicator.

What to do if your BMI is higher than normal

A Quetelet index value of more than 25 units indicates the presence of extra pounds and the need to make changes to your usual lifestyle, because your health is directly related to the presence of excess body weight. The degree of severity of the measures taken depends on how much the Quetelet index is greater than the ideal:

• if the result is 25–30 units, it would be reasonable to exclude fatty and sweet foods from the daily diet;
• with a value of 30–35 units, it is worth adding feasible sports or exercise 2–3 times a week to adjusting the diet;
• an indicator exceeding 35 units requires contacting a nutritionist, a sharp reduction in the number of calories consumed per day, enrollment in a health group or other classes with an instructor.

BMI: what to pay attention to?

It is not possible to make an accurate diagnosis based on BMI. You will need to undergo a comprehensive examination under the guidance of a weight loss specialist. It is important to know: losing weight will not be effective without changing your habits. Only an experienced psychotherapist will help you find the causes of weight gain and get rid of them. Then you will be able to maintain the result obtained, gain harmony with yourself, self-confidence, and improve your health.

Body mass index may not be accurate. The BMI formula does not take into account the location of fat deposits: folds on the abdomen, visceral fat, may indicate the presence of diseases of the internal organs, serious problems with hormonal levels, and the functioning of the thyroid gland.

That is why you should not blindly believe the number; it is better to contact the specialists of a weight loss clinic. Here they will appreciate:

• body type;
• localization of fat deposits;
• thickness of fat folds;
• ratio of fat and muscle tissue.

This approach, in combination with the work of a psychologist, is recognized by experts as the most effective and correct.

Prediction accuracy based on BMI

And although the index is often used in medicine, more and more information is emerging about its inaccuracy. Several facts can be cited that cast doubt on the choice of the formula as the best tool for determining excess weight.

1. BMI does not determine the actual percentage of muscle and fat.

The disadvantage of the formula, as well as its advantages, is its simplicity. As a result, the BMI of a muscular athlete may coincide with that of an obese, untrained person. With the same height and weight, the percentage of fat, appearance and, accordingly, health risks can vary significantly. Studies of hundreds of people showed that athletes often showed an index of excess weight, and women with clearly extra pounds were within the normal range.

Another study of 13 thousand people showed similar information. Using bioimpedance analysis, scientists compared BMI with actual body fat percentage. The index showed obesity in 21% of men and 31% of women, while a more accurate scientific analysis showed 50% of men and 60% of women. We can say that in approximately every second case, the body mass index gives incorrect information, reassuring an overweight person.

2. BMI does not take into account gender and age

In order to conduct large-scale research, the scope of the index was deliberately made universal. But the volume of fat in men and women differs by about 10%. Is it right to apply the same criteria to different genders?

Age changes the proportions of muscle and fat tissue in the body. Over time, metabolism slows down, muscle tissue begins to break down, and fat tissue begins to accumulate. Correct conclusions require taking into account both the person’s gender and age. According to statistics, BMI in men is higher than in women.

3. BMI does not take into account the three-dimensionality of a person.

Oxford professor Nick Trefenthen also doubted the ability of the BMI formula. According to the scientist, it does not take into account the real structural features of the human body. In it, height and weight change nonlinearly. As a result, the formula considers short people to be slimmer and tall people to be denser. Trefenthen adjusted the formula so that it gave correct results:

BMI = 1.3 × weight / height 2.5,

where body weight is measured in kilograms and height in meters.

Nevertheless, the creator of the formula himself considers it imperfect, like any other formula in general - the human body has too complex a structure and shape.

4. Change in BMI norm

Over the past 30 years, the “normal” body mass index has changed several times. If before 1998 in America the threshold value was 27.8 kg/m2, then after 1998 doctors began to consider 25 kg/m2 as such. A small change in the standard resulted in 29 million Americans being considered overweight.

10-second BMI test

A quick calculation of body mass index is based on your waist size. The following algorithm will help you measure correctly:

1. It is recommended to take measurements on an empty stomach using a measuring tape.
2. Before this, it is not recommended to drink or eat food.
3. Waist circumference is measured at the narrowest point of the body, approximately 2-3 centimeters above the navel.
4. Do not over-tighten or loosen the tape.

Based on the obtained value, we can draw a conclusion about the condition of the body, the presence or absence of excess weight. This is a good way to exclude visceral or central obesity, which is recognized by experts as the most dangerous.

Men

The rates for men and women are different. The optimal value for men is about 94-95 centimeters. If the obtained value is more than 102-103 centimeters, it is recommended to immediately contact specialists at a weight loss clinic to determine the true reasons for the appearance of extra pounds and get rid of them.

Excess weight is dangerous for men for several reasons:

• the risk of hypertension and coronary heart disease increases;
• the risk of heart attack and stroke increases;
• psycho-emotional disorders occur;
• There are problems in intimate life: decreased sexual desire, decreased erection, infertility.

Ignoring this indicator can aggravate the course of many chronic diseases and lead to the emergence of new ones.

Women

For women, a value over 80 centimeters is already considered dangerous. When volumes increase to 88, the risks of many diseases increase significantly, such as:

• phlebeurysm;
• cardiovascular changes;
• apnea;
• arthritis;
• risk of being diagnosed with infertility;
• disorders of the central nervous system;
• hormonal imbalance, menstrual irregularities.

It is important to start treatment on time. Statistics show that only 2-5% of people are able to lose weight at home. The best option is to contact a weight loss clinic specialist. A comprehensive technique developed by professional doctors and psychotherapists will help you get rid of excess weight once and for all.

Waist/hip ratio

Another way to assess body condition is to determine your waist-to-hip ratio. This requires taking two measurements and dividing one number by the other. The calculation is quite simple, the question remains - how to interpret the result?

• a value above 0.95 for men indicates overweight;
• for women this value is less and is 0.8.

This calculation is considered the most optimal, since it takes into account the presence of fat deposits in the abdominal area.

Calculation of excess weight using BMI

Based on the calculation of body mass index, the treatment strategy for obesity is determined. In some cases, a change in diet or training is sufficient, in others, the help of a psychologist or medication is enough. But in most cases, an integrated approach is required, a special technique used in weight loss clinics.

In this case, the technique is based on BMI, takes into account existing risk factors, chronic and current diseases, and lifestyle. This approach is recognized by experts as rational and safe for health.