The Body Mass Index: The Illusion of Control

The Body Mass Index: The Illusion of Control

Body mass index (BMI) is often seen as a benchmark for physical health, but for people struggling with anorexia, it can become an obsession. This fixation is not simply a matter of self-discipline or willpower; rather, the disease has taken complete control over sufferers. They live in a world where their self-esteem is directly linked to a number on the scale. However, this number reflects a distorted reality that is deeply rooted in the core of their perception.

What role does BMI play in anorexia nervosa?

For people with anorexia nervosa, the BMI is more than just a number. It becomes the ultimate measure of success and self-control. But in reality, it is the disease that keeps control. Sufferers follow extremely restrictive diets, subject themselves to excessive exercise and rebel against all forms of food intake, believing that this will give them power over their lives. But this supposed act of self-determination is actually a sign of loss of control.

The balancing act between health and self-perception becomes particularly difficult when BMI is seen as the sole measure of health. A healthy BMI does not necessarily guarantee good physical or mental health and does not take into account muscle mass, bone structure or individual physical differences. People who are considered “healthy” according to BMI guidelines may still suffer from anorexia, as the condition is not just a matter of weight, but also of mental health and self-perception.

What role does society play?

Society plays a decisive role in the perception of BMI and body image. Media and social networks often promote an unrealistic ideal image that puts pressure on individuals to conform to it. This can increase the risks of developing anorexia, especially in young people who are particularly vulnerable to self-image influences.

To combat anorexia effectively, a comprehensive view is needed that goes beyond BMI. Health professionals emphasize the importance of a holistic approach to health assessment that includes psychological well-being, physical health and individual life circumstances. Prevention and treatment of anorexia nervosa requires a deep understanding of the underlying mental health issues as well as the promotion of healthy, realistic body images.

Creating a healthy environment

Finding the balance between a healthy BMI and a positive self-perception requires education, awareness and support. It is important to create an environment where people of all body sizes and shapes are accepted and where health is understood as a broad spectrum that goes far beyond a number. By shifting the focus from strict BMI targets to a broad understanding of health and wellbeing, we can pave the way for a healthier and more inclusive society.

How is BMI calculated?

Body mass index (BMI) is calculated by dividing body weight in kilograms by the square of height in meters. The formula is

BMI = weight (in kg)/ (height in meters)²

Limit values for the BMI:

  1. Factors not taken into account: BMI does not take into account the distribution of muscle mass, fat, bone mass and water in the body. Two people can have the same BMI but a very different body composition. For example, an athletically built person with a lot of muscle mass could have the same BMI as someone with a higher body fat percentage.
  2. Age and gender differences: BMI does not take into account age-related changes in physique and fat percentage or gender-specific differences. Women biologically have a higher body fat percentage than men, which the BMI does not differentiate.


Why the BMI is only a guideline

The BMI serves as a rough guide for the ratio of body weight to height and can help to classify people into different weight categories in order to identify potential health risks. The World Health Organization (WHO) defines the categories as follows:

  • Underweight: BMI below 18.5
  • Normal weight: BMI 18.5 to 24.9
  • Overweight: BMI 25 to 29.9
  • Adiposity (obesity): BMI 30 and above


Despite its widespread use, BMI is only one of several indicators of health. It does not provide information about the distribution of body weight or a person’s state of health. For example, someone with a “normal” BMI may still have a high body fat percentage and associated health risks. Similarly, someone with a “high” BMI may be very healthy due to muscle mass.

A particularly low BMI should still be taken seriously as a potential indicator of health problems, even if it alone does not tell the full story about a person’s health. It is important to seek help to get a comprehensive assessment that goes beyond this single measurement and considers other aspects of health.

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