What is obesity?
Obesity is an increase in body fat beyond normal levels. The Body Mass Index (BMI) is used for the medical assessment of weight. The BMI is calculated as the quotient of the body weight [kg] and the body height to the square [m²].
weight = 87 kg, size = 1,69 m
BMI = 87 kg / (1.69m x 1.69m) = 87 / 2.86 m² = 30, 4 kg/m²
Based on the BMI, the WHO classifies overweight as follows:
- Normal weight: BMI 18.5 - 24.9
- Overweight: BMI ≥ 25.0 and pre-obesity: BMI 25 - 29.9 kg/m²
- Obesity grade 1: BMI 30 - 34.9 kg/m²
- Obesity grade 2: BMI 35 - 39.9 kg/m²
- Obesity grade 3: BMI ≥ 40 kg/m²
Studies show that an increasing BMI is associated with a reduction in life expectancy.
However, the health risk is not only determined by the extent of obesity, but also by the distribution of body fat. For example, a waist circumference of ≥ 88 cm in women and ≥ 102 cm in men significantly increases the risk of metabolic and cardiovascular complications. Less problematic is the fat distribution type mostly common in females with fat deposits mainly on the hips and thighs (so-called pear shape).
The percentage distribution of fat and muscles should also be taken into account. A very muscular person with a low body fat percentage can be hidden behind a high BMI.
What are the underlying causes of overweight and obesity?
The basic rule is: Overweight occurs when the energy input is chronically higher than the body's energy requirements (positive energy balance). Various factors affect the energy balance:
- An essential factor in the development of obesity is the modern lifestyle with little exercise (sedentary occupations at work and leisure time) and malnutrition. Low physical activity results in low energy consumption. And when many fat- and sugar-rich foods (including drinks) are consumed, there is a great danger of becoming overweight.
- But family predisposition also plays a role in the development of obesity. The so-called basal metabolic rate, i.e. the number of calories burned in complete rest, seems to be genetically determined. This means that people can eat different amounts without becoming obese.
- Besides, the psyche can be an important factor. Stress, frustration, anxiety, boredom, etc. can trigger cravings and lead to obesity. Stress also increases the level of cortisol in the blood, which also promotes weight gain and obesity.
- Eating disorders such as bulimia, binge eating disorder, night eating disorder can also trigger overweight and obesity.
- In very rare cases (approx. 3-5 %), obesity is caused by organic causes and endocrine diseases (e.g. hypothyroidism, Cushing's syndrome).- Obesity can also be promoted by drugs such as some antidepressants, neuroleptics, antidiabetics, glucocorticoids and beta blockers.
- In addition, a number of other causes of obesity are possible, e.g. immobilization, pregnancy, surgery in the hypothalamus region, quitting nicotine.
Conservative treatment of obesity
Overweight should be treated at a BMI of 30 or more or a BMI between 25 and 29.9 with simultaneous presence of:
- overweight-related accompanying diseases (e.g. high blood pressure, type 2 diabetes) OR
- an abdominal fat distribution pattern OR
- diseases worsened by obesity, OR
- a high level of suffering
Even a moderate weight loss of less than 10% means an improvement in many accompanying diseases and complications of obesity.
The treatment of obesity should be based on the three pillars of nutritional, physical and behavioral therapy.
Nutritional therapy for obesity
In comparison to the previous diet, obesity patients should consume 500 to 1000 kcal less per day. It makes sense to prefer foods with a low energy density, i.e. low fat and sugar content, but high water and fiber content. The satiety of obese patients can be maintained by increasing the intake of fruit and vegetables. In the long term, a balanced mixed diet according to the guidelines of the German Nutrition Society (DGE) is recommended.
Extremely one-sided diets (e.g. total fasting) involve a high medical risk and do not result in long-term success. For persons with obesity, a formula diet (under medical supervision) may be appropriate for initial (i.e. temporary) weight reduction. The possible weight loss is, however, only permanent if behavioral and exercise therapy takes place at the same time and for a longer time afterwards.
Exercise therapy for obesity
The increase in energy consumption achieved through physical activity contributes to weight reduction and - even more - weight maintenance. This is because the increase in muscular mass also increases the basal metabolic rate. A good start for a person suffering from obesity is a sports activity of 30 to 50 minutes on three to five days a week. In addition to structured exercise programs, increased exercise in everyday life also promotes weight stabilization. A simple but regular walk can have a positive effect.
Behavioral therapy for obesity
Behavioral therapy makes sense especially with regard to long-term weight reduction and stabilization. Usually in weekly sessions lasting several months, methods of self-observation of nutritional and exercise behaviour (e.g. by means of a diary), a flexible (instead of rigid) behavioral control, a different way of dealing with stress, pressure and frustration as well as relapse management are developed.
Drug therapy for obesity
If this basic treatment does not lead to a weight reduction of the obesity patient of at least 5% after three to six months, further efforts in the area of diet and exercise can be supported by certain medications.
According to the recommendations of the interdisciplinary guideline on "Prevention and Treatment of Obesity" (published by: German Obesity Society, German Society for Nutrition, German Diabetes Society, German Society for Nutritional Medicine), the drug Orlistat can be used for this purpose. The drug inhibits the digestion of fat by blocking digestive enzymes, the so-called lipases. Orlistat may be prescribed by a physician to patients with a BMI of at least 28 and may only be used to complement obesity therapy with the basic programme described.
As the aim of the therapy is to change the patient's lifestyle, it may be appropriate for doctors, nutritionists, physiotherapists and behavioral therapists to provide care for obese patients for years or even a lifetime.
Surgical therapy of obesity
The requirements for surgical obesity therapy are defined in the medical guidelines of the respective professional associations. If the conventional (non-surgical) treatment has not been successful for at least 24 months, surgery can be recommended. In Germany, the following indications apply to obesity patients:
- Grade 3 obesity (BMI ≥ 40) or
- Grade 2 obesity (BMI ≥ 35) with other serious diseases (e.g. diabetes mellitus type 2)
In Switzerland, patients with a BMI of 35 or more may undergo bariatric surgery. The surgery should be preceded by two years of basic therapy, according to the guidelines of the SMOB (Swiss Society for the Study of morbid obesity and metabolic disorders). Patients with a BMI of 50 or more should undergo 12 months of non-surgical therapy prior to surgery.
Contraindications to surgery as obesity treatment are addiction to drugs and alcohol, consuming and immunodeficient diseases, bulimia nervosa as well as possible psychoses and personality disorders.
Depending on the mechanism by which weight loss is achieved, two groups of bariatric surgery procedures can be distinguished:
- bariatric surgery methods with the main goal of restriction, i.e. the quantitative restriction of the intake of solid food (e.g. gastric balloon, band gastroplasty, sleeve gastrectomy). Put simply, the stomach volume is significantly reduced.
- bariatric surgery methods with the goal of malabsorption, i.e. reduced absorption of nutrients (e.g. gastric bypass or biliopancreatic diversion (BPD) according to Scopinaro).
In 1 to 2% of obesity patients, perioperative complications occur (especially wound healing disorders, thromboses, pulmonary embolisms). Perioperative mortality is less than 1%. Long-term follow-up care for obesity patients is essential to counteract possible late complications. This is done through lifelong care by the obesity center or the interdisciplinary team of doctors and therapists of the clinic treating them.
The goal is to ensure the well-being of the patients and a long-term therapeutic success. This includes an ideal supply of nutrients and vitamins to rule out deficiency syndromes. Above all, weight should be stabilised permanently and relapses into previous habits that promote obesity should be prevented. Specialised physicians and obesity patients work hand in hand.