A look in the mirror, often this is critical. Am I too fat, too thin or about right? Do I need to lose weight or gain weight? Questions around their own weight are everyday life for many people. The Body Mass Index (BMI) is a mathematical formula that can be used to calculate a measurement for evaluating one’s own body weight. But what exactly does the BMI say?
Calculate BMI – here’s how!
If you deal with the topics of weight, weight loss or health you will always meet the BMI. Almost in all online and print media BMI calculators are offered to determine its own BMI value. This is calculated according to a mathematical formula, which is composed of one’s own body weight divided by height squared. BMI = weight (in kg) : height
2
(in m)
With our BMI calculator you can easily calculate your BMI yourself. The BMI was developed by the mathematician Adolphe Quetellt in the 19th century. So although the BMI enjoys great popularity today, it is by no means new.
What does the BMI value say?
Using tables, the calculated BMI can now be used to determine whether one’s weight is in the normal range or in the zone of overweight or underweight, that is, whether one should lose or gain weight. Regardless of age or gender, the BMI is always calculated according to the same formula. However, the values allow different interpretations, which is why there are different BMI tables. Thus, in some guidelines, in addition to height and weight, gender and age are also taken into account.
BMI table according to WHO
According to the much-used classification of the World Health Organization (WHO), the normal weight is a BMI of 18.5 to 24.9, underweight would consequently be given at a BMI below 18.5, overweight starts at a BMI above 25 and from a BMI of 30 the weight would be in the range of obesity.
| BMI | Classification according to WHO |
|---|---|
| under 18.5 | Underweight |
| 18,5 – 24,9 | Normal weight |
| 25,0 – 29,9 | Overweight |
| 30,0 – 34,9 | Obesity grade I |
| 35,0 – 39,9 | Obesity grade II |
| from 40.0 | Obesity grade III |
BMI table according to DGE
A BMI table that also includes gender is, for example, the classification of the German Nutrition Society (DGE):
| Female | male | Classification according to DGE |
|---|---|---|
| under 19 | under 20 | Underweight |
| 19 – 23,9 | 20 – 24,9 | Normal weight |
| 24 – 29,9 | 25 – 29,9 | Overweight |
| 30 – 34,9 | 30 – 34,9 | Obesity grade I |
| 35 – 39,9 | 35 – 39,9 | Obesity grade II |
| from 40.0 | from 40.0 | Obesity grade III |
BMI table according to NRC
The US National Research Council (NRC) BMI table defines the ideal BMI depending on age:
| Age | Ideal BMI according to NRC |
|---|---|
| 19-24 years | 19-24 |
| 25-34 years | 20-25 |
| 35-44 years | 21-26 |
| 45-54 years | 22-27 |
| 55-65 years | 23-28 |
| over 65 years | 24-29 |
BMI calculator for children
Given significant increase in children with overweight in recent years, it is very important to pay attention to a healthy ratio in the weight of children. The BMI calculator can also be used for children, the table values are then based on the standard weight of the respective age. There are various BMI tables (so-called percentile tables) for girls and boys. But especially for children it should apply that the weight can also vary according to growth spurt and age. Since children should never be prescribed a diet to lose weight on their own authority, it is advisable to consult the pediatrician in case of weight problems.
Praise and criticism for BMI
BMI values are very popular in science as well as research, they also serve as a guide for doctors.However, this is exactly how the BMI should be viewed; it is a guideline value, not a generally valid value, which alone can provide information about the normality and state of health of the weight. Criticism is directed at the BMI above all in the fact that it can give no information about the composition of muscle and fat tissue by its calculation. In the case of a bodybuilder, for example, who has an enormous build-up of muscle, the BMI would indicate a value which, according to the table, would indicate overweight. An active athlete with a high muscle mass would therefore have a high BMI, although there are no oversized fat stores. Likewise, a high BMI value cannot automatically also be used to draw specific conclusions about an increased risk of cardiovascular disease, for example.
Include fat distribution
Certainly, being overweight poses an increased risk to one’s health. However, not only the number of kilos are decisive, but also their respective distribution in the body provides information about whether losing weight would be advisable. You can use our fat distribution calculator to find out what your waist-to-hip ratio is. Ultimately, a doctor should always be consulted if the value is in the overweight or underweight range. A physician can provide detailed information about the health status of your body and weight through other measurement tools, as well as identify related risk factors.
Conclusion: body mass index as a reference value
BMI can provide information as a guideline and control for one’s weight and health. However, possible consequences (for example, diet to lose weight) from the result should always be discussed with a doctor.