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Body mass index (BMI)

The body mass index is also called body mass index, body mass number or Quetelet-Kaup index and is a measure for evaluating a person's body weight in relation to their height. It is based on the classification of the World Health Organization (WHO).

Important is the following:

BMI only takes body weight and height into account. Age and gender are also taken into account when assessing normal, underweight or overweight. The muscle mass or fat percentage of the body are not measured and therefore not taken into account. In this way, only an initial rough assessment of a person's physical condition can be made. For example, someone with a lot of muscle mass can have a high BMI without actually being overweight.

The bottom line is that the BMI only serves as an indication of whether body weight is low, normal or high. In addition, the BMI cannot provide any information about the reasons for being under or overweight.

World Health Organization (WHO) BMI classification:

under 18.5: underweight

18.5 - 24.9: normal weight

25 - 29.9: Overweight

30 - 34.9: obesity (obesity) grade I

35 - 39.9: Obesity grade II

from 40: Obesity grade III

BMI in children and adolescents

Body Mass Index Biozoom Vitalitycheck, Biologisches Alter, Hautalterung, Gesund Ernähren, Vitamine

Unlike adults, BMI doesn't say much for children and adolescents, as body composition changes constantly and also depending on gender. However, in order to still be able to determine a BMI for children, so-called reference values were calculated, which take both age and gender into account.

Problems of overweight and obesity

According to the guidelines of the World Health Organization (WHO), a person with a body mass index of 25 or more is considered overweight, and a BMI of 30 or more is considered obese. A person becomes overweight or obese when they supply their body with more energy than they use in a day. Diet and exercise are two indicators that have a significant influence on body weight.

Possible consequences of being overweight or obese

Being overweight or obese doesn't just mean having a high body weight. The risk of serious secondary illnesses increases with increasing obesity and therefore the likelihood of dying earlier is greater than people with a normal weight. 

Almost all organs can be significantly negatively affected by so-called obesity. The following complications can occur due to obesity: 

  • Metabolic diseases such as type 2 diabetes or gout

  • Diseases of the organs, especially those that are susceptible to this, are e.g. B. Liver, kidneys and gallbladder

  • Infertility especially in men

  • Diseases of the musculoskeletal system, e.g. E.g. hips, knees, spine

  • Diseases of the cardiovascular system, such as atrial fibrillation, strokes or high blood pressure


In addition, being overweight often reduces your own well-being and quality of life. In addition, people who are overweight often suffer from restrictions, hostility and exclusion in everyday life. Of course, these are also triggers for stress or reduced self-esteem. This can significantly increase the risk of developing mental illnesses such as depression or anxiety disorders.  


Obesity in children

In Germany, 18% of those starting school are already too fat. By puberty, this number increases to 28%, according to studies, Boys have a higher risk of becoming overweight than girls.


In order to reduce the risk of children becoming overweight or even obese, care should be taken early on to ensure that they are guaranteed a balanced diet and enough exercise. 

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