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Body mass index is a ratio of a person's weight to height. Thanks to simple calculations, doctors determine the lack or excess of muscle and fat tissue in the body, which allows timely initiation of weight correction procedures. Thanks to the calculator below, you will also find out how much your weight corresponds to your height. This will help you choose a diet if necessary, normalize physical exercise and so on.
Body Mass Index Formula
In 1869, the eminent Belgian mathematician/sociologist Adolphe Quetelet first proposed a formula for measuring body mass index. It was he who considered that to derive a coefficient by which one can estimate the fatness/thinness of a person, it is enough to divide his weight in kg by the square of his height in meters. In other words, to find out the body mass index, the formula looks like this:
Let's try to calculate: suppose that a woman comes to us, whose height is 1.64 m and weight is 75 kg. To calculate her BMI you need 75/1.64*1.64=27.89. As you can see in the table, this is pre-obesity. That is, our hypothetical lady urgently needs to reconsider her lifestyle or nutrition system.
However, this BMI result should not be considered always correct. After all, when calculating, we did not take into account what kind of life the woman leads (what if she is a professional athlete - a wrestler or boxer with well-developed muscles?), and we also did not take into account the age of the lady.
Therefore, Adolf Ketele’s formula for measuring body mass index can only be used to obtain primary coefficients. To do this, use a calculator.
If the result of the calculations shows that it’s time for you to lose weight, use the advanced BMI calculator.
Body mass index norms
As already mentioned, the norm of body mass index is a conditional value. So, for people with an asthenic physique, a BMI of 24 points may mean pre-obesity, and for a professional athlete, a BMI of 27 may be normal. However, approximately, you can still rely on the indicators approved by WHO.
I would like to note that the body mass index norm is calculated not only for adults, already physically mature men and women, but also for children. It is very important to monitor the child’s weight, since deficiency and excess weight can lead to serious illnesses and deviations in physical development.
How to calculate your ideal weight?
Knowing the body mass index norm, you can calculate your ideal weight. To do this, you should multiply the optimal BMI result (19-24) by the square of your height in meters. Do the calculations manually or use this calculator.
Many of us are familiar with the following formula for calculating ideal weight: “height minus 100.” Men were required to subtract another 10% from this figure, women were required to subtract 15%. There is some truth here, however, this technique does not take into account the personal characteristics of a person, such as age and physique (fat weighs less than muscle). Therefore, it is worth discarding the remnants of the past and paying attention to an objective indicator.
Body mass index was developed by statistician Adolphe Ketele from Belgium in 1869. to determine a person’s weight category: from excess weight, obesity, underweight for your body or normal. BMI helps assess how a person's weight corresponds to their height. Thanks to this indicator, you can get closer to the ideal. Calculations are based on the empirical relationship between height and weight. To calculate your BMI, you need to know your height and weight. BMI is calculated using the formula “weight divided by height squared.” Weight is calculated in kilograms, height – in meters, respectively, body mass index – in kg/m². For example, with a weight of 60 kg and a height of 1.66, you have an indicator of 21.77, which indicates normal weight.
- less than 16 – there is a pronounced lack of body weight;
- from 16 to 18.5 – weight deficit;
- 18.5-25 – normal weight;
- from 25 to 30 – pre-obesity;
- 30-35 – obesity I degree;
- from 35 to 40 – II degree obesity;
- more than 40 – III degree obesity.
- For women: underweight – less than 19; norm – 19-24; excess weight – 24-30; excess weight – 30-40; obesity – over 40.
- For men: underweight – less than 20; norm – 20-25; excess weight – 25-30; excess weight – 30-40; obesity – over 40.
- It is believed that the ideal BMI for the fairer sex is 20-22, for men it is between 23 and 25.
- If your BMI is normal, but you see from yourself that not everything is in order with your figure, that is, there is excess weight and sagging body, you are recommended to focus on physical exercise. Hold off on the diet for now.
- According to statistics, people who have a body mass index in the range of 18-22 live longer.
- A BMI above 25 is not a very good indicator; in this case, it is recommended to seriously think about losing weight and bring your weight back to normal. Even losing 10% of your total weight will help reduce your risk of obesity-related diseases.
- The calculation of BMI, as well as the determination of other relative indicators, in practice requires some adjustments. For example, its value is affected by the thickness of muscle mass. One indicator can be obtained for both a dense person and the owner of a toned athletic figure. The high BMI of professional athletes, of course, does not indicate obesity, but is explained by developed muscles.
- The use of body mass index for children is not recommended.
- It is dangerous to use calculation results as a basis when making a medical diagnosis.
It is extremely difficult to determine by eye the ideal weight for yourself. But if you evaluate the ratio of your weight and height and calculate your BMI, you can understand how close you are to the ideal.
Before you fight those hated extra pounds, you should find out at what weight your body will feel comfortable in terms of health. To objectively assess your own weight, determine whether or not you have overweight, it is necessary to calculate the body mass index - an indicator that shows the optimal level of body weight in a particular case.
Excessive or high levels of weight contribute to the development of heart disease, cardiovascular disease, and other serious illnesses. The body mass index, or BMI, was developed by Belgian sociologist and statistician Adolphe Ketele in 1869. That is why this indicator is also called the Ketel index.
Body mass index (BMI) is calculated using the formula: Body mass index (BMI) = m/p 2, where
M – mass in kilograms, P – height in meters squared. For example: your height is 1.64 meters, your body weight is 60 kilograms. We square 1.64 meters - we get 2.6896 m 2. Divide 60 kilograms by 2.6896 m 2. Rounding the value, we get 22.3. This indicator will be your weight indicator. By the way, in this case it is within the normal range.
Body mass index (BMI) calculator
Body Mass Index (BMI) Table
| Classification | BMI | Health Risk |
| Anorexia nervosa, severe underweight | less than 16 | Very tall |
| Lack of weight | from 16 to 16.9 | High |
| Low body weight | from 17 to 18.4 | Elevated |
| Normal weight | from 18.5 to 24.9 | Absent |
| Overweight | from 25 to 29.9 | Elevated |
| Obesity I degree | from 30 to 34.9 | High |
| Obesity II degree | from 35 to 39.9 | Very tall |
| Obesity III degree (morbid) | more than 40 | Extremely high |
Normal body weight is the average value, that is, the value that is observed in specific group people (same height, gender, age, etc.). However, the magnitude normal weight The body is quite individual and depends on a number of factors (constitution type, gender, race, age, height, etc.). There is no dispute about gender and height. But regarding age, according to most scientists, weight completely stabilizes around the age of twenty-five. It is at this age that the weight corresponds to the norm. And this is where controversy arises. After all, body weight is not constant, it grows by about eight percent of the norm in most people, except for people in old age (during this period, weight decreases slightly). Therefore, the norm is considered to be the weight that is observed more often. But he's not perfect.
It has also been proven that the type of constitution greatly influences body weight. Three body types are taken into account:
- Normosthenic type, which is characterized by proportional body size and harmonious development of the musculoskeletal system.
- The asthenic type, which is characterized by a slender body and weakness in the development of the muscular system, while, when compared with the normosthenic type, in this type the longitudinal dimensions of the body and chest prevail over the dimensions of the abdomen, and the length of the limbs prevails over the length of the torso.
- The hypersthenic type is characterized by good fatness, has a long body and short limbs, and the transverse dimensions of the body and abdomen are relatively greater than the dimensions of the chest.
Normal body weight averages for assessing overweight and obesity are approximate. They can be calculated more accurately only by determining percentage adipose tissue in the body. Only the muscle and fat components of total body mass can truly show that excess weight is a consequence of obesity or due to highly developed muscles. But in reality, this question arises only if there is an insignificant excess of the norm. In addition, the standards for the percentage of body fat are quite individual character. When calculated by any method, the indicator has a significant error.
When determining normal weight, factors such as place of birth, race, and climatic conditions in which their ancestors lived (heredity) are of particular importance. It has been proven that the concept of a biological norm for a North American differs significantly from a similar characteristic for a resident of Europe, Australia or Africa. Therefore, each population of people should focus on its own indicators of normal body weight.
Before you actively lose weight, you need to understand what you really need: you want to get rid of extra pounds or slightly correct your figure. It is important to take into account weight and fat distribution various parts bodies. To do this, you need to divide your own waist size by your hip size in centimeters. If the obtained value is above 0.8, you need to think about it, since excess fat at the waist is more dangerous than its deposits on the hips and buttocks.
According to research data, the risk group includes women whose waist circumference exceeds 88 centimeters, and men whose waist circumference exceeds 102 centimeters. But here one thing should be taken into account important point, no fat at all female body will not function normally, so there is no point in completely getting rid of fat. Is it dangerous! After all, it is in this layer of fat that women have estrogens, which are responsible for their well-being and also maintain the elasticity and youth of the skin.
What is body mass index and how to calculate it for women by age is a very popular topic, one might say hackneyed. Slimness today is actually synonymous with beauty and certainly an integral part of health. Insufficient weight, as well as excess weight, negatively affects the functioning of all organs and systems of the body. But how do you know if your weight is within the normal range? After all, the concept of norm will be different for people of different genders, constitutions, and ages. The most accurate formula today is considered to be the one used to calculate body mass index. Still calculating your ideal weight using the formula “height minus 110”? This is correct, but not for everyone. After all, you don’t take into account many important indicators, for example, body type and age. Body mass index helps to calculate your ideal weight much more accurately. Let's figure out what it is.
What is body mass index (BMI)?
Body mass index is an indicator characterizing the ratio of height and weight. This also takes into account age and gender, which makes it possible to obtain differentiated data for different groups of people.
This indicator is used by doctors to assess the condition of a person’s body - the presence of obesity or dystrophy and their degree. Calculating BMI is quite simple; it can be done at home. Perhaps the BMI calculation result will be the starting point for you on your way to normal weight bodies.
The first BMI formula appeared in the 19th century, its author was the Belgian Adolphe Quetelet. Subsequently, many scientists worked on refining the formula, and today the BMI value can be calculated according to Quetelet, Brock, Breitman, Oder, Noorden, etc.
Most often, it is the basic formula that is used, in which the indicator is equal to the ratio of body weight to height squared (height is indicated in meters). For example, a woman with a height of 165 cm and a weight of 50 kg needs to calculate her BMI as follows: BMI = 50 * (1.65 * 1.65). The final BMI value is 18.36.
After this you receive a finished figure. As a rule, a weight between 19-25 is considered normal, but this is an average figure. It is not suitable for minors, elderly people or professional athletes. It turns out that just calculating the body mass index for a woman, even taking into account her age, is not enough to understand the state of her body. Indicators are deciphered using special tables.
What does BMI depend on?
Since the only indicators used in the calculation are height and weight, the final result only gives a general idea of the condition of the body.
It is quite obvious that the weight of a healthy girl at 20 years old and a woman at 55 years old with the same height is rarely equal. This does not mean that any of them “falls” outside the boundaries of normality. No, just to calculate BMI by age for a woman over 45 years of age, a basic formula is used, but a different interpretation of the results is used. For every 10 years of life (starting from the age of 24), the normal limit increases by 1 unit.
That is, normal BMI at the age of 19-24 years is 19-24, 25-34 years old - 20-25, etc.
Besides, appearance a person depends not only on the actual weight, but also on the ratio of the amount of musculoskeletal and adipose tissue. The normal BMI of athletes is much higher than that of untrained people with weak muscles.
The interpretation of BMI will also depend on your body type, which is determined by measuring your wrist circumference. This is how thin-boned, normal-boned and broad-boned types are distinguished.
Men have more muscle than women, which means their body mass index will be higher. The difference between men and women is visible at any age, so the calculation results for different sexes are interpreted using separate tables.
Why do you need to know how to calculate body mass index?
The feeling of one’s own fullness or thinness is very subjective; some consider themselves fat, being more than slim, while others do not consider the 10-20 kg of fat hanging on their sides to be extra. The BMI calculation was created to help you understand how prone you are to obesity and how much your weight fits into the average norm.
In medicine, calculating BMI is used to adjust drug doses, and in everyday life - to control body weight.
Of course, we all strive to look good and in the struggle for beauty we often go to extremes. For example, girls often drive themselves to exhaustion with strict diets or complete refusal to eat because they feel they are not thin enough.
Body mass index allows you to understand whether you are within the normal range and in which direction you should work on yourself - lose weight or, conversely, build muscle.
BMI not only helps determine the presence of weight problems, but also shows their extent. Depending on how much the BMI deviates from the norm, the types and intensity of exercise, as well as an individual diet, are selected.
Lack of weight is also fraught with serious health problems - metabolic disorders, water-salt balance, hormonal imbalances, vitamin deficiency, amenorrhea, osteoporosis. Complications due to these diseases can even lead to death, so it is very important to be careful about your weight and health.
At the same time, you should not blindly focus only on numbers - always analyze how comfortable you feel in your body, what symptoms or complaints you have. A slight deviation from the norm may be an individual feature of your body. If you are full of energy, feel good and are satisfied with your health, you definitely shouldn’t reshape yourself for the sake of numbers and indicators.
How to calculate body mass index for women based on age?
So, the standard formula for calculating BMI is suitable for young women aged about 20-40 years.
If you don't want to bother with squaring and dividing numbers, you can use a ready-made BMI table. The advantage of such tables is that there are different options for men and women, separate tables for athletes, pregnant women and women over 45 years of age.
For older women, there is a simplified formula for calculating BMI: height in centimeters minus one hundred. This is how weight is calculated for women of average build.
If your type is asthenic, subtract 10% from the result obtained. For hypersthenics, on the contrary, the result should be increased by 10%. Accurate measurements of height and weight should be taken in the morning on an empty stomach after visiting the restroom.
As a rule, in the morning our weight is less than “evening” by about a kilogram and a half (due to swelling and food eaten during the day), and our height in the morning, on the contrary, is a couple of centimeters higher due to the fact that the spine is in a horizontal position overnight “stretches”, the intervertebral cartilage returns to its normal state. But in the evening we are tired, the spine is compressed and, accordingly, our height is less.
Regardless of the formula for calculating weight that you use, if there are serious deviations from the recommended weight, it is necessary to urgently adjust your diet - on your own or with the help of a nutritionist.
