Calculation of ideal weight according to the Quetelet index: by age, body weight and height

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.

How accurate does body mass index predict?

Despite the fact that BMI is still widely used in medicine, new evidence is emerging about its inaccuracy. Here are some facts that prove that body mass index is not the best way to determine whether you are overweight or not.

BMI does not show the actual percentage of fat and muscle

The formula is too simple. Thus, the BMI of a muscular athlete may coincide with that of an obese, untrained person. They will weigh the same, but their body fat percentage, appearance, and health risks are very different.

This was confirmed by a study of Body Mass Index as a Predictor of Percent Fat in College Athletes and Nonathletes of 439 people. The body mass index of athletes and untrained men often showed excess weight when there was none. Women with extra pounds, on the contrary, were within the normal range.

Similar results were obtained in a large-scale study, Accuracy of Body Mass Index to Diagnosis Obesity in the US Adult Population, involving 13 thousand people. Scientists compared the body mass index value and the actual percentage of fat obtained using bioimpedance analysis. BMI showed obesity in 21% of men and 31% of women, and analysis showed obesity in 50% of men and 60% of women.

Body mass index is wrong about half the time, reassuring overweight people.

BMI does not take into account gender and age

The index framework was made universal to make it more convenient to conduct large-scale research. At the same time, the amount of fat in women and men differs by an average of 10% Sex differences in human adipose tissues - the biology of pear shape, so it is incorrect to apply the same values ​​to both sexes.

In addition, the proportions of muscle and fat tissue in the body change. With age, metabolism slows down, muscle tissue begins to break down and fat deposits begin. Therefore, for correct conclusions, it is necessary to The effect of sex, age and race on estimating percentage body fat from body mass index: The Heritage Family Study take into account both the sex and age of the person.

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

Professor Nick Trefenthen from the University of Oxford questioned the current BMI formula. The scientist claims BMI (Body Mass Index) that it does not take into account the real features of the human physique and provides inaccurate data, since changes in height and weight occur non-linearly. Shows short people that they are slimmer than they are, and makes tall people believe they are fatter.

Trefenthen recommended a new calculation method, which, in his opinion, would give more correct results.

BMI=1.3 * weight (kg) / height 2.5 (m)

At the same time, the professor believes that any formula will be imperfect, since a person is too complex.

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!

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.

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.

The Quetelet index takes into account weight and height but not body composition.

Calculating the Quetelet index is the simplest way to give a rough estimate of the ratio of a person's weight to his height. It is this simplicity and accessibility that makes BMI calculation still popular, including in clinical practice.

In Russia, you can get a deferment from the army for as long as 6 months if your BMI does not fall within the target indicators

For whom is the calculation of the Quetelet index not applicable? First of all, these are older people and professional athletes, people who regularly train with weights and have a high percentage of muscle mass. In both cases, the result will be either underestimated - in the elderly due to a reduction in the volume of bone and muscle tissue, or overestimated - in people who train with weights due to the higher specific gravity of the muscles.

Despite the high error, the definition of the Quetelet index is used everywhere, incl. and in fitness testing. Now don’t be lazy and calculate your BMI yourself!

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.

Waist to height ratio[edit | edit code]

Some scientists believe [1] that the ratio of waist circumference to height is a more informative indicator than BMI.

Thus, a study was published in BMJ Open[2], according to which risk factors for cardiovascular diseases and metabolic disorders were identified in 35% of adults using the waist-to-height ratio (WHtR).

Margaret Ashwell, a research fellow at Cass Business School, and her colleague Sigrid Gibson, analyzed data from the UK's National Diet and Nutrition Survey (NDNS) between 2008 and 2012. The study found that people with high WHtR (>0.5) had more risk factors than when looking at their BMI alone.

A 2014 study[3] conducted at Cass Business School found that life expectancy in the presence of obesity can be better predicted by measuring the waist-to-height ratio (WHtR) than by using the conventional body mass index (BMI).