BMI and biological age

The body mass index (BMI)

The body mass index is also called the 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).

However, the following is important : The BMI only takes into account body weight and height. Age and gender are also included when assessing normal, under or overweight. The muscle mass or the fat percentage of the body are not measured and therefore not taken into account. In this way, only a first 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 the body weight is rather low, normal or high. In addition, the BMI cannot provide any information about the reasons for being underweight 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

Body Mass Index Biozoom Vitalitycheck

BMI in children and adolescents

In contrast to adults, the BMI does not say much in children and adolescents, as the body composition changes constantly and also depending on the gender. However, in order to still be able to determine a BMI in children, so-called reference values were calculated, which include both age and gender.

Problems of overweight and obesity

From a body mass index of 25, a person is considered overweight according to the guidelines of the World Health Organization, and from a BMI of 30 as obese.

A person becomes overweight or obese when he supplies his body with more energy than he uses during the day. Diet and exercise are two indicators that have a significant impact 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 diseases increases with increasing obesity and thus the likelihood of dying earlier than people with a normal weight is greater.


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


- Metabolic diseases such as type 2 diabetes or gout

- Diseases of the organs, particularly susceptible are liver, kidneys and gall bladder

- Infertility especially in men

- Disease of the musculoskeletal system, e.g. hip or kinetosis

- Diseases of the cardiovascular system, for example atrial fibrillation, strokes or high blood pressure


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


Overweight in children

In Germany, 18% of those starting school are already too fat. By puberty this number rises to 28%, and studies show that boys have a higher risk of becoming overweight than girls.


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

The biological age

Biological age is also called metabolic age and tells us what state our body is really in. To determine the biological age, you need the sum of the calendar age and the emotional and physical influences.


The biological age is related to the ability of the heart to adapt to different loads by varying the heartbeat. This adaptability decreases with age.


A healthy lifestyle helps people age more slowly compared to their age group, while an unhealthy lifestyle makes the aging process much faster. The current biological age is calculated based on the current adaptability of the heart combined with its eating behavior.

If the user does better than his peer group, he is considered biologically younger and vice versa.


A healthy diet, regular exercise and the ability to relax can slow down the biological aging process.