The causes of excessive weight are manifold. The main causes are lifestyle (diet and exercise), heredity and socio-cultural factors. However, some diseases such as hypothyroidism and disorders of the cortisone (Cushing's syndrome), as well as some drugs such as hormones, antidepressants and corticosteroids may increase the weight.
The continuous increase in obesity can not be justified by genetic predisposition alone. It can be assumed that the hereditary systems of the Central Europeans have hardly changed in the last 100 years. Nevertheless, the problem is increasing rapidly. The reason for this is increasing calorie intake while decreasing physical activity.
It is too much, too fat and too sweet eaten and too many calorie-containing drinks (alcohol, soft drinks) are consumed. On the other hand, due to sedentary lifestyle, too little energy is consumed by body work. This leads to a positive energy balance. The excess energy is stored as a fat reserve, which is reflected in increasing body weight. The energy converted to our body is measured in kilocalories (kcal) or kilojoules (kJ) and consists of three components:
Basal metabolism (resting sales):
This is the energy required to maintain all vital metabolic processes and bodily functions at rest. The basal metabolic rate is hereditary to a certain extent and accounts for 50 to 70 percent of the total energy consumption. It depends on age, gender and especially muscle mass. More muscles lead - in contrast to sluggish adipose tissue - to increased resting.
By this one understands the energy, which is necessary for the utilization of the food. This proportion of energy accounts for about 8 percent of the total energy expenditure. So if you eat less, this energy consumption will decrease. While the body needs a lot of energy for carbohydrate utilization, it converts dietary fats into body fat with very little energy expenditure. This is also part of the problem of a high-fat diet.
This is the energy spent on the movement, the physical activities. It accounts for 20 to 40 percent of total energy consumption and is best influenced. Through exercise and sport, the work turnover can be increased, ie how high this proportion is, is all alone in our hands.
Sociocultural backgrounds have an important influence on the eating habits: what and how is eaten, taste preferences, portion size, speed of eating, etc. A representative survey in Germany shows that in the East of the Federal Republic much more hunger, hunger, food in society and alcohol are mentioned as a nutritional problem than in the west. On the other hand food comes from boredom and in stress more often in the west than in the east.
From the 3rd and 4th Swiss Nutrition Report it is also quite clear that there are nutritional differences between German-speaking Switzerland and French-speaking Switzerland. Such differences within a country can hardly be explained by the food supply, but rather by the prevailing food culture.
Genetics as a reason for obesity?
Scientific studies with twins and family studies show that hereditary factors are responsible for weight gain. Estimates of the hereditary share of obesity vary greatly (30 to 70 percent). Today, it is assumed that 30 to 40 percent of the obese are predisposed. The basal metabolic rate, which accounts for 50 to 70 percent of total energy use, is hereditary to some extent.
Food utilization plays a role
There are the good feed recyclers who handle their energy budget very economically. Not only do they burn fewer calories while doing nothing, they are also particularly good at putting on fat reserves. Poor feeders, on the other hand, burn up to 400 kilocalories a day, mostly as heat.
Set Point Theory
The set-point theory assumes that every person has an individual number of fat cells that remain constant at an adult age. The set-point, also called equilibrium point, indicates that everyone has an endogenous weight goal that the body strives for and defends. In addition to the number, it also seems to depend heavily on the volume (filling state) of the existing fat cells. The establishment of the individual set point should involve genetic traits, age, gender, body size, eating habits and physical activity.
Conclusion: Obesity is not inherited
Whatever role genes play, the factors affecting nutrition and exercise are decisive for the effects of genetic engineering. Not overweight is inherited, but the predisposition to it. Those who have inherited an economic metabolism can - unfairly or not - keep their energy balance in balance only through more exercise and less calorie intake.