Obesity (adiposity)

Obesity (adiposity)
International Classification (ICD) E66.-
Symptoms Weight gain, abnormal fat accumulation, Limited physical performance, Hyperhidrosis, Heartburn, Sleep apnea, Increased risk of secondary diseases
Possible causes genetic disposition, psychosocial factors, Physical inactivity, over-energy, Medication, Metabolic diseases, Sleep deprivation
Possible risk factors Physical inactivity, over-energy, psychological disorders, psychological stress, radical changes in one's life
Possible therapies Nutritional therapy, Behavior modification, Exercise Therapy, surgical procedure, Medication
disease.indicated_substances Orlistat
(iStock / Liudmila Chernetska)


Obesity is a chronic, treatable condition in which body fat increases beyond normal levels. The word is derived from the Latin "adeps" (fat). The disease affects numerous bodily functions and increases the risk of disease and death. The body mass index (BMI) is often used for weight classification. The body mass index (BMI) is formed from the quotient of weight and height squared (kg/m2). A BMI of 30 kg/m2 or more is considered obesity. So-called extreme obesity is present from a BMI of 40 kg/m2.


The body mass index

Since the exact measurement of body fat is often difficult, the BMI is often used for obesity classification. However, BMI does not provide any information about a person's body fat percentage.



Risk of concomitant diseases


< 18,5


Normal weight

18,5 - 24,9



≥ 25


25 - 29,9

somewhat increased

Obesity grade I

30 - 34,9


Obesity grade II

35 - 39,9


Obesity grade III

≥ 40

very high


In Austria, about one third (34.5%) of people are currently overweight and 16.6% of the population is affected by obesity. In Germany, the figures are somewhat higher. Here, about half of the population is affected by overweight and about a quarter of adults are obese (24%). The incidence of obesity generally increases with age, with two-thirds of those affected not developing obesity until adulthood. However, in recent years, an increase in obesity has been observed in young adults and also in women of childbearing age. Obesity is less common overall in individuals with high socioeconomic status.


In obesity, the body gets a surplus of energy in the form of food, while at the same time too little energy is consumed in the form of exercise. This surplus usually exists for a long period of time and is stored in the fat cells of the body. Genes, hormones, lifestyle, psychological factors and also the environment play a role in the development of the disease. The increase in the incidence of obesity is currently attributed primarily to fattening environmental factors. These are characterized by overeating, a lack of exercise, and the consumption of highly processed foods.

The following are possible causes of obesity:

  • genetic causes

  • familial disposition

  • high food availability

  • lack of sleep

  • stress

  • depression

  • low social status

  • Eating disorders (e.g. binge eating disorder)

  • Metabolic disorders (e.g., hypothyroidism, Cushing's syndrome)

  • Medication (e.g., antidepressants, neuroleptics, beta-blockers)

  • Other causes (e.g. immobilization, pregnancy, smoking cessation)

The western diet

The modern diet in industrialized nations, compared to the diet of our ancestors, has an energy density that is about 2 to 3 times higher. This is the result of a higher density of "fast food" products and highly processed foods with a lot of fat and sugar. The fiber content of these products, on the other hand, is usually low. Since the feeling of satiety also depends on the distension of the stomach, the feeling of satiety is triggered later when such energy-dense foods are eaten. This circumstance favors increased calorie intake. In recent years, the average portion sizes of fast food products have also increased, as a result of which people often consume a larger amount of food. Children, adolescents and young adults nowadays also consume high-sugar soft or energy drinks more often, which can greatly increase the risk of obesity if consumed regularly.

Fixed or regular mealtimes also prevent obesity. However, many people nowadays eat on occasion or even spontaneously (so-called snacking), which makes it more difficult to control energy intake. Often, spontaneous eating also tends to involve fast food or so-called "convenience" products.

The influence of daily life

Many factors of daily life influence the occurrence of obesity. For example, desk jobs and long commutes to work can make access to physical activity more difficult. In addition, in urban areas, there are often few opportunities for running, cycling, or even other sports. Education, educational level, and housing also influence the risk for obesity. In general, obesity occurs less frequently in people with academic education and high household income than in people with low socioeconomic status.


The symptoms of obesity are varied and depend, among other things, on the age of the person affected, concomitant diseases and the severity of the obesity. Typical conditions include dyspnea, frequent back pain, and varicose veins.

(iStock / towfiqu ahamed)

Complications of obesity

Obesity is considered an important risk factor for a variety of diseases. According to the WHO, obesity is responsible for about 44% of all cases of diabetes and about 23% of all cases of coronary heart disease worldwide. In addition, it is estimated that obesity is causative for about 7 - 41 % of all cancers. In Germany alone, obesity-associated diseases cause total annual costs of around 10 - 20 billion euros.

Diseases for which obesity is a significant risk factor:

  • Diseases of the musculoskeletal system (e.g., knee osteoarthritis)

  • Gallstones (cholecystolithiasis)

  • Fatty liver (steatosis hepatis)

  • Gout (hyperuricemia)

  • Increased blood fat levels (hyperlipidemia)

  • High blood pressure (hypertension)

  • Heart failure (cardiac insufficiency)

  • Neurodegenerative diseases (e.g. dementia)

Risk of comorbidities according to WHO:

Risk > 3-fold increased

Risk about 2 - 3-fold increased

Risk 1 - 2-fold increased

Diabetes (type 2 diabetes)

Coronary heart disease


Gallstone disease


Polycystic ovary syndrome

Elevated blood lipid levels

Knee joint osteoarthritis

Hip osteoarthritis

Insulin resistance


Back pain

Fatty liver

Reflux esophagitis


Sleep apnea syndrome


Problematic abdominal fat

Visceral fat in the abdomen is not simply present, but can be considered like an organ in its own right. It is metabolically active and produces hormones as well as other substances that promote inflammation throughout the body. In addition, these hormones weaken the immune system. Thus, the body is constantly fighting chronic inflammation, which promotes the onset of high blood pressure, diabetes, and heart disease, among other conditions. For example, adipokines are signal molecules that are increasingly produced in human adipose tissue and are involved in the development of type 2 diabetes mellitus or atherosclerosis.

From a BMI of ≥ 25 kg/m2, the waist circumference should therefore always be measured in those affected. This allows the visceral fat to be assessed. Waist circumferences of ≥ 88 cm in women and ≥ 102 cm in men indicate abdominal obesity with a significantly increased risk of developing obesity-associated diseases.

Stigma and discrimination.

Obesity has a variety of psychosocial implications. In recent years in particular, there has been an increased focus on the stigma and discrimination that often accompany the condition. In the Western world, obesity is usually viewed negatively, and studies in Germany have also shown that obese people are devalued. Many people assume that people develop obesity due to laziness, lack of discipline and weakness of will. This prejudice should be questioned, since from the current medical point of view many factors and also physical diseases can promote the occurrence of obesity.


The following diagnostic steps are necessary or recommended for an obesity evaluation:

Medical history

Onset and development of overweight

Possible influencing factors

Motivation of the person concerned for treatment

Family history

Nutritional history

Recording of physical activity

Physical examination

Height, weight, BMI

Circumference of the waist

Blood pressure with possible long-term blood pressure measurement

Determination of resting energy consumption

Laboratory diagnostics

Blood count, electrolytes, creatinine, transaminases

Lipid status

Blood glucose, possibly HbA1c value

Oral glucose load test

TSH basal (at initial examination)

Imaging procedures


Cardiac ultrasound

Upper abdominal ultrasound

In particular, the attending physician should also inquire about the patient's diet or physical activity. This is usually done with a free protocol, questionnaires or a pedometer. Differential diagnoses of obesity include bulimia nervosa or binge eating syndrome.

Treating physicians should always ask about other metabolic risk factors such as elevated blood lipid levels ( hyperlipidemia ), diabetes mellitus, and high blood pressure (hypertension) during the medical history.

Secondary obesity

In about 1 - 5 % of obesity sufferers, the overweight occurs in the course of secondary obesity. These should be ruled out prior to obesity treatment.

Possible underlying diseases that can trigger obesity include:

  • hormonal changes

  • hypothyroidism (underactive thyroid gland )

  • Cushing's disease

  • benign tumors of the pancreas with insulin secretion

  • Central nervous changes

  • neoplasms or damage to the hypothalamus

In addition to diseases, drugs can also be involved in the development of obesity. These include, in particular, antidepressants (e.g., mirtazapine), neuroleptics (e.g., clozapine, olanzapine), hypnotics, antiepileptic drugs (e.g., gabapentin, valproic acid), steroids, antihistamines (e.g., ranitidine), oral antidiabetics, and insulin.


Nowadays, there is a wide range of therapeutic options to treat obesity, prevent secondary diseases and improve the overall quality of life.

The most important goals of obesity therapy are:

  • Prevention of secondary diseases

  • Maintenance of metabolic health

  • Treatment of existing underlying diseases

  • Destigmatization

  • Promotion of body awareness

  • Promotion of self-confidence

Treatment goals in obesity therapy are always individual and should always be agreed with the person affected. In the case of obesity without concomitant diseases, the goal is usually a weight reduction of 5-10% with subsequent weight stabilization. However, the amount of weight loss targeted also depends on the concomitant diseases of the affected person. For example, in patients with an existingdiabetes (diabetes mellitus type 2), a weight reduction of about 5 - 15 % is recommended. The subjective improvement of the quality of life always has a high priority in the treatment of obesity patients.

A combination of a moderately hypocaloric diet, exercise, and behavior modification is currently recommended as standard therapy for obesity. If these measures do not achieve a 5% to 10% weight reduction in 3 - 6 months, intensification of therapy - e.g., with a highly restrictive caloric intake in the form of a low-calorie diet - should be considered.

BMI and waist circumference as therapy indication

BMI alone is not sufficient as a criterion for indicating obesity treatment and must often be expanded to include waist circumference. In this context, waist circumference is suitable as a measure of the fat distribution pattern. Waist circumferences of ≥ 88 cm in women and ≥ 102 cm in men are associated with a significantly increased risk (relative risk 2-4) for metabolic and cardiovascular diseases.

Gesunde Kost (iStock /vaaseenaa)

Nutrition therapy

The goal of nutrition therapy is a negative energy balance. Patients should still experience a feeling of satiety through the calorie-reduced diet in order to be able to establish the form of therapy in daily life in the long term. Low-fat foods as well as plant foods with a high fiber content are to be preferred here. The composition of the macronutrients (fat, protein, carbohydrates) is not decisive.

A clever choice of foods - lower-energy foods, fruits and vegetables - can usually achieve energy savings of 500 to 800 kcal per day. In doing so, the amount of food can often be maintained, allowing sufferers to continue to have a good feeling of satiety.

Another simple measure is to limit fat intake. Here, instead of 80 - 130 g per day, 60 g of fat per day should be supplied. This concept is relatively easy to implement, as those affected only need to focus on the intake of one macronutrient. This measure often leads to a weight loss of 3 to 5 kg and it is particularly suitable for weight stabilization as well as for obesity primary prevention.

Behavior modification

Methods of learning and behavioral psychology are suitable for practicing healthy eating behavior and lifestyle. For example, triggers for food intake can be analyzed and identified. Unfavorable behavioral patterns related to food intake can also often be changed with professional psychological help. It is recommended to decouple food intake from external factors and to set rules for meals as well as for food shopping. Group interventions are also suitable for changing eating behavior and are often more successful than individual sessions.

Exercise therapy

Exercise has other positive effects on the body besides increasing energy expenditure. Every obesity sufferer should therefore be encouraged to increase regular exercise activity. Sport or physical activity also has the advantage of preserving muscle mass during dieting, which also improves the long-term results of weight loss.

Exercise can increase the body's calorie consumption. In addition, the appetite decreases through sports and stress regulation also works better. For many people, various sports are a stabilizing social event, and sports have a particularly positive effect on the cardiovascular system, which is often affected by obesity. Ideally, one should exercise at least three to five times a week for 30 minutes. Attention should also be paid to achievable goals, because it is better to exercise less regularly than to hold irregular intensive training.

The type of sport is secondary, although endurance sports are usually more beneficial than strength sports. Since obesity patients are often untrained, regular sports should be performed only after a medical examination. The load intensity can then be gradually increased, although overloading should be avoided at all costs due to the increased risk of injury in obesity.


Medications should always be seen as a support to a lifestyle change and should always be combined with it.

Possible agents for the treatment of obesity are:

Active ingredient

Mechanism of action

Common side effects


Lipase inhibitor (inhibits fat absorption in the intestine)

flatulence, bloating, fatty stools

liraglutide, semaglutide

GLP-1 receptor agonists (inhibit appetite and slow gastric emptying)

Nausea, vomiting, diarrhea, constipation


Opioid antagonist/norpinephrine dopamine reuptake inhibitors ( release of anorexigenic hormones, inhibition of reward center)

Nausea, vomiting, dizziness, headache, constipation, insomnia, flushing, hypertension, dry mouth, fatigue

Bariatric surgery

In the case of bariatric surgery, patients must always be carefully informed about the risks and consequences of the operation, as the risk of surgery is greatly increased in the case of existing obesity.

The indication for surgery is usually only given for a BMI of over 40. With a BMI of over 35, surgery can be considered if concomitant diseases make rapid weight reduction necessary or all other attempts at therapy have failed.

In principle, these surgical interventions attempt to reduce the volume of the stomach. This results in a limited food intake, which in turn leads to weight reduction.

The various procedures include:

  • Gastric Banding: A silicone band is placed around the stomach and then filled with fluid as needed. This reduces the entrance to the stomach and allows only small amounts of food to be ingested.
  • Vertical gastroplasty: part of the stomach is separated by staple sutures and secured by a silicone band.
  • Gastric balloon: A balloon is inserted into the stomach and filled with more or less fluid as needed. This method is rarely used today.

However, for a permanent reduction in body weight, eating habits should also be changed and optimized. In addition, those affected usually continue to require intensive internal, nutritional and psychological care after surgery. Micronutrients such as vitamins and trace elements often need to be supplemented after bariatric surgery.


For many people with severe overweight, losing weight without professional help is almost impossible. The body registers a significant weight loss and then tends to return to the initial weight (so-called yoyo effect). This is based on evolutionary biological mechanisms. In early human history, severe weight loss was life-threatening and much more dangerous than weight gain or even obesity.

Obese people have a shorter life expectancy than people of normal weight. The younger the person, the greater the correlation between BMI and mortality risk. A BMI of 30 to 35 kg/m² shortens life by about two to four years on average. A BMI of 40 to 45 kg/m² even reduces people's life expectancy by eight to ten years. This shortened life expectancy is caused by obesity-associated secondary diseases. In older age, however, the correlation between BMI and mortality risk decreases significantly.

In most cases, permanent weight reduction can only be achieved through long-term treatment concepts with medical support. It is advisable not to fixate on a certain desired weight, but to lead a healthier life overall through a permanent change in lifestyle. This helps to lose excess weight slowly but permanently and in a healthy way. A high level of self-motivation on the part of patients is also useful here and greatly increases the success rate of obesity therapy.

A diet should therefore not be primarily goal-oriented, but should be seen as a lifelong and balanced change in diet. It is advisable to optimize it so that it is healthy and tastes good at the same time. Because only then it is permanently feasible. Optimally, this healthier diet should be combined with regular physical activity.


Even small phases of increased physical activity during the day can help prevent obesity.

To lose weight or maintain one's own weight, attention should be paid to a low-fat and high-fiber diet. Foods with a low energy density are particularly suitable for this purpose. These have fewer calories because they are rich in water and fiber. Snacks, fast food and sugary or alcoholic beverages should be avoided as far as possible.

Editorial principles

All information used for the content comes from verified sources (recognised institutions, experts, studies by renowned universities). We attach great importance to the qualification of the authors and the scientific background of the information. Thus, we ensure that our research is based on scientific findings.
Dr. med. univ. Moritz Wieser

Dr. med. univ. Moritz Wieser

Moritz Wieser graduated in human medicine in Vienna and is currently studying dentistry. He primarily writes articles on the most common diseases. He is particularly interested in the topics of ophthalmology, internal medicine and dentistry.

Thomas Hofko

Thomas Hofko

Thomas Hofko is in the last third of his bachelor's degree in pharmacy and is a writer on pharmaceutical topics. He is particularly interested in the fields of clinical pharmacy and phytopharmacy.

The content of this page is an automated and high-quality translation from DeepL. You can find the original content in German here.



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