November 3, 2025, 11:51 am | Read time: 8 minutes
Obesity has many names: corpulence or morbid overweight. They all have something in common: They describe a condition that can be not only hazardous to health but also life-threatening. FITBOOK explains the causes, risks, and treatment options.
What is Obesity?
Obesity is one of the most common chronic nutritional and metabolic diseases. About a quarter of men and women in Germany are considered severely overweight. The disease is characterized by an above-average increase in body fat percentage.
Obesity is diagnosed when there is significant overweight that is harmful to health. The chronic disease severely limits the quality of life of those affected and also poses a high risk for secondary diseases, such as osteoarthritis, diabetes, or cardiovascular diseases. The German Obesity Society defines obesity as “an increase in body fat beyond the normal level.” The fat percentage is considered too high when the Body Mass Index (BMI) is over 30.
Obesity in Childhood
About 15 percent of children and adolescents in Germany between the ages of three and 17 are overweight or obese. Approximately 6 percent are considered obese—meaning severely overweight with a risk of disease. Current health insurance data show that, especially since the COVID-19 pandemic, more children are overweight, and this trend has not yet reversed.1
The causes are varied: an unbalanced diet, too little exercise, high media consumption, family stress, or stress in general. Genetic factors and parental role models also play a part. In addition to physical consequences such as high blood pressure or joint problems, being overweight can also lead to social exclusion, bullying, and psychological stress. Early prevention and education are therefore all the more important—both in families and in daycare centers and schools.
Classification and Consequences of Obesity
The World Health Organization (WHO) distinguishes three degrees of severity and a preliminary stage (pre-obesity). These classifications help determine the extent of obesity and assess the risk of secondary diseases. This allows for the identification of appropriate treatments.
How to Recognize Obesity
With the Body Mass Index (BMI), it is possible to identify obesity and determine its stage. This is done by dividing one’s body weight by the square of their height in meters. For diagnosing obesity, a gastroscopy, cortisol level determination, or lab values can also be used.
Pre-obesity
A BMI of 25 to 29.9 is considered pre-obesity. This means that overweight is present and is a precursor to obesity.
The risk of comorbidities is slightly increased. Since overweight is already present, the likelihood of developing high blood pressure or type 2 diabetes is higher.
Obesity Grade 1
Grade 1 is defined by a BMI of 30 to 34.9.
Possible consequences include high blood pressure, cardiovascular diseases, insulin resistance, type 2 diabetes, and stroke.
Obesity Grade 2
This grade is characterized by a BMI between 35 and 39.9. The overweight is already significantly advanced, and the consequences can become noticeable in daily life.
Those affected often struggle with shortness of breath, back and joint pain, and fatigue. They are also limited in their mobility. In addition to the previously mentioned secondary diseases, lipid metabolism disorders, fatty liver, gout, and arteriosclerosis may occur. The risk of heart attacks, strokes, and diabetes is significantly increased. Severe psychological stress may accompany obesity.
Obesity Grade 3
This stage is considered the most severe form of obesity. With a BMI of 40 or more, it is also referred to as Adipositas permagna.
Reduced performance, joint problems, knee and back pain, and excessive sweating are just a few of the symptoms that can occur. Psychological symptoms, such as frustration, insecurity, or self-doubt due to excessive body weight, may also arise. Depression can also be a consequence.
Those affected often isolate themselves from their social environment or have difficulty managing daily life. People with Obesity Grade 3 have a significantly increased risk of developing type 2 diabetes, coronary heart disease, heart attack, and cancer.
Other Consequences
Depending on how advanced the obesity is, heart failure, sleep apnea, and digestive tract diseases can also result. Additionally, obesity can lead to metabolic and hormonal disorders, which can cause impotence in men or infertility in women. Skin diseases, such as fungal infections, may also occur.
Even if no secondary diseases have yet occurred in those affected, they often face limitations in daily life and social problems (exclusion, reduced quality of life).
Causes of Obesity
The causes of obesity can be varied. Genetic predispositions also play a role, as certain genes increase the risk of obesity.2 However, this is not the only determining factor. External influences can also contribute to the development of the disease:
- Lack of exercise
- Lifestyle (possibly influenced by parents)
- Constant availability of food
- Unbalanced diet
- Stress and lack of sleep
- Diets
- Cultural meanings (overweight as a beauty ideal in Africa)
- Depressive disorders
- Medications
- Family disposition (genetic predisposition)
- Quitting smoking or pregnancy
- Little to no education about healthy eating
Obesity usually results from excessive calorie intake. Unhealthy and high-fat foods provide more energy than the body can use, leading to an increase in fat tissue and weight gain. Those affected often eat secretly or hide the actual amount. They also have difficulty feeling physically full, making it hard to control their eating behavior. Binge eating, for example, could be a cause. These episodes can be used to cope with stress or to replace a lack of emotional support.
Moreover, societal developments make it particularly difficult to balance calorie intake and expenditure. Today, fewer people work in physically demanding jobs. Additionally, they often spend their leisure time sitting.
Symptoms
One of the most obvious symptoms of obesity is a significant increase in body weight and body fat percentage. Other symptoms may include breathing difficulties, joint pain, skin irritations, fatigue, or disordered eating behavior.
Who is Affected by Obesity?
According to data from the Robert Koch Institute, about 24 percent of all men and women in Germany are severely overweight3, including
- 17 percent with Obesity Grade 1
- 5 percent with Obesity Grade 2
- 2 percent with Obesity Grade 3
Differentiating Between Obesity and Overweight
While both terms are related, it is important to distinguish them correctly. Obesity focuses on a specific form of overweight (the body’s fat percentage has reached a critical point), whereas overweight refers only to excessive body weight relative to height.
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How Can Obesity Be Treated?
To successfully treat the disease, it is not enough to lower the BMI to a certain value. Treatment includes dietary changes, physical activity, and medical examinations. It is crucial to develop healthy eating habits with reduced calorie content and balanced, nutrient-rich meals. Long-term lifestyle changes, including healthy eating and physical activity, are important factors for losing weight.4
In some cases, medical treatment involving weight loss medications may be necessary. These are only considered if dietary changes and increased physical activity do not result in sufficient weight loss. People with Obesity Grade 2 or 3 may need surgical intervention, such as gastric reduction. Due to the associated complications or side effects, careful consideration is beneficial.
In addition to physical treatment, it is also important to provide psychological support to those affected. Behavioral therapy can help replace old thought and behavior patterns that contributed to obesity with newer, healthier ways of thinking.
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Prevention of Obesity
Obesity is a very serious disease that can have life-threatening consequences if left untreated. Therefore, it is essential to develop healthy eating habits and regular physical activities from a young age. It is important to not only understand the causes and risks but also actively take preventive measures. Timely diagnosis, healthy eating, and exercise can help reduce or completely treat the consequences of obesity.