Causes Of Obesity

In this article, we are going to talk about an important question about factors that may affect obesity. Many patients and many physicians have often questions that about it. I think it is good that we try to summarize and update this particular aspect.

What we know to start with is that obesity is a multifactorial disease. This implicates that it is influenced by many factors to start with the genetic ones.


We know that roughly 20% of maybe over 20% of the body mass index variability can be accounted for by genetic variations. One mutation or one polymorphism may become more or less important but it's roughly 20 to 30 percent. We know that obesity is partly heritable because we have found in many studies that there is a strong link between body mass index and other estimates of fat accumulation and family members. This has been studied in family studies, in dizygotic twins, in people living in different areas of the world. Each time the genetic aspect came into a consideration.


When we move from the genes to another aspect, which is important in that multifactorial aspect, is the environment. We know that more food is consumed when people are eating in company than when they do that alone. We also know that consumption of high amounts of fats is, of course, playing an important role.

A misconception people sometimes have is that the so called and labeled healthy fats, such as the monounsaturated fatty acids, there may be healthy and good for health. But calorie-wise, they are exactly the same as the bad saturated fat. And a very particular aspect to consider for the future certainly with the environment is the transfats that are very often used in commercial production of some foods. Transfat it has been clearly shown that there is a strong link between an accumulation of fat.

Medicinal Physiological and Psychological Aspects

Besides these initial factors, we also have medicinal physiological and psychological aspects that may play a role in the development of overweight and obesity.

Let's look at medicines. Certain medications may contribute to weight gain including corticosteroids and other hormones, antidepressants and specific neuroleptics, treatments for epilepsy, HIV, and glucose lowering agents that we prescribe for diabetes may definitely contribute to a weith gain.

We know, for instance, if we prescribe insulin or classical conventional glucose lowering agents that they may in the initial period of prescription lead to weight gain of a few kilos.

Psychological factors: lack of sleep, stress, depression, anxiety or also aspects we are very complex systems that may lead to overweight and obesity as well. In physiology, we know that a number of endocrine diseases such as hypothyroidism, growth hormone deficiency and Cushing's disease in excess of corticosteroids may contribute to obesity as well.

Other factors like fat metabolism, plasma lipoprotein levels, and oxidation reactions also contribute. Very recently we also know that the environment, endocrine disruptors may also accumulate within the body.

Endocrine disruptors are compounds that we find in the environment such as bisphenol, dioxins. All those these compounds have been banned for many years from industrialization processes. They accumulate in fat cells and the consequences can be seen for many years.

Brain Factor Of Obesity

The final aspect of the development of obesity is what happens in the brain. I would like to tell that to you because people should understand physiology because physiology is the background for the later link for therapy. If we understand very well physiology, then we might better understand why some medications and approaches help and why this is an overall very complex system.

For instance, if we understand how physiological hormones, transmitters, peptides that are released from the fat cell such as leptin from the stomach, such as grilling, such as hormones from the guts. How these products talk to the brain, where they are mediated by pathways within the brain through different receptors. This finally may lead either true full intake, less food intake, satiety and finally combustion. This brings them to energy expenditure, which has been covered separately.

What Is Obesity?

What obesity exactly is? We have weight, we have BMI, we have a waist and hip circumference, we have total fatness that you can measure. However, there is still an additional interesting aspect. Is that's the difference between fat cells?

Our body has atrophic and hyperplastic fat cells, but we also have brown and white fat. What's the difference? Well, brown fats that we usually see is present in animals that we see immediately after birds in humans, is mainly located around the neck, around the large blood vessels of the thoracic region.

Brown fat is very closely related to thermogenesis as you have learned - one of the mechanisms by which the body can produce heat. This generation of thermogenesis and this specific heat may account for 15% of energy expenditure in general.

The ability or the inability to utilize this brown fat thermogenesis may finally result in obesity because this brown adipose tissue of obese individuals is less responsive to stimulation. And one of these stimulatory mechanisms is called adaptation.

Research is being undertaken to try to convert these white adipose tissue into brown adipose tissue.

Let us make a clear difference between white and brown fat cells. White fat cells are responsible for energy storage, whereas the brown fat cells are more dedicated to heat production and so maybe helping in a weight loss process.

White fat cells are increasing by age. And with age, unfortunately, the brown fat cells are decreasing. That's the reason why researchers, by the way, try to find potential drugs that may help in the so-called browning of these.

The final and health linked aspect is that the brown adipose tissue (brown fat cells) are less associated with overweight and obesity complications what we more clearly observed with the large amounts of white adipose tissue.

You immediately understand that this physiological aspects that has been detected only after a few years is important for potential future new approaches of therapy.