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ZFBC BMI & Patient Information


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ZFBC BMI – Rechner


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Total Daily Energy Expenditure






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Workout Day Calories

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Weight Class

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In a severe form, overweight is referred to by the medical term obesity. The disease obesity is defined by the increase of body fat. Thus, obesity also reaches the status of a disease. The body mass index (BMI) serves as a measure for the classification of different overweight classes. The higher the BMI, the greater the risk for medical conditions closely related to obesity, concomitant diseases or secondary diseases.

Particularly in the developed industrial nations of Western Europe and the USA, morbid obesity is increasing at an above-average rate. For Switzerland, about 41 percent of the population is considered overweight, ten percent even obese.

If one is guided by the World Health Organization (WHO) definition of obesity, this means a body mass index of over 30kg/m², whereby the BMI is only to be understood as a rough guide. The BMI serves as a classification into the different degrees of obesity, whereby the body weight is divided by the body height squared.

Weight classification BMI (kg/m2)
Underweight <18,5
Normal weight 18,5-24,9
Overweight 25,0-29,9
Obesity grade I 30,0-34,9
Obesity grade II 35,0-39,9
Obesity grade III ≥40

If one follows this classification, then obesity begins at a BMI of 25 kg/m².

As obesity increases, so does the risk of many other diseases and ultimately the risk of premature death. The individual risk cannot be estimated on the basis of BMI alone, but must always be defined for the individual case.

The age and the exact determination of the body fat percentage play an important role. Accordingly, a very personal diagnosis and treatment is always advisable. The Center for Bariatric Surgery (ZFBC) also follows this basic approach in the unity of consultation, treatment, care and follow-up.


The causes of morbid obesity can vary greatly from individual to individual. Hier haben wir einige exemplarische Ursachen aufgeführt. In individual cases, a mixture of different causes of the disease may also be possible. This is clarified in each case in the individual diagnosis and consultation.


A common cause of severe obesity is ones lifestyle. The almost unlimited availability of food and luxury foods, increasing lack of exercise in everyday life and at work, and generally changed lifestyles promote the development of overweight to obesity in its various degrees.

Hormonal imbalances

In some, although rare, cases, the development of obesity is caused by hormonal imbalances. Even though this is much rarer, such diseases of the endocrine systems must therefore be ruled out. Examples of hormonal disorders associated with the development of morbid obesity are hypothyroidism or the excessive secretion of cortisol as an adrenocortical hormone, as observed for example in Cushing’s syndrome.

Genes, hereditary factors

Although research on this subject is far from complete, hereditary factors may also be responsible for morbid obesity. This has been proven beyond doubt. Inherited genes play an important role in this process, although morbid obesity can hardly be attributed to hereditary factors alone. A disturbance of the body’s regulatory system seems to be present in almost all overweight people.


Pathological overweight can lead to various concomitant diseases or promote their development. Such concomitant diseases further limit the quality of life of patients affected by morbid obesity. We have listed some of these concomitant diseases here as examples:

  • Lipid metabolism disorders (e.g. high cholesterol)
  • Blood sugar disease (type 2 diabetes mellitus)
  • Hypertension
  • Cardiovascular diseases (e.g. heart attack and stroke)
  • Breathing disorders during sleep (sleep apnea syndrome)
  • Gallstones
  • Infertility (especially in women, accompanied by menstrual disorders and increased body hair).
  • Wear and tear of joints (knee joints, hip joints, ankle joints, back pain)
  • Cancer
  • Mental disorders and impairments such as depression

Both morbid obesity and possible comorbidities are serious conditions, each requiring medical treatment. The treatment of morbid obesity can often be the first step in the further treatment of concomitant diseases.

In most cases, such diseases are treated directly by the medical disciplines. Even if this seems to make sense in individual cases, often only the symptoms are worked on, but rarely the actual cause, which can lie in pathological overweight.

Successful therapy of obesity is in many cases the key to sustainable treatment of concomitant diseases. However, permanent weight loss is difficult to achieve conservatively. A great deal of perseverance and a high level of motivation are required from both the doctor and the patient. Often, even this does not result in any improvement or only a slight improvement in the overall situation. Therefore, in addition to conservative methods, the range of services offered by the ZfbC also includes surgical intervention, which must be discussed and clarified in each individual case. In most cases, it is a whole system of medical services that are individually determined and medically supervised. This includes initial counseling as well as ongoing care, surgical interventions, psychological support and ongoing aftercare.

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