The main cause is given by the genetic patrimony transmitted by the parents that determines the number of cells that store the fats, the adipocytes, the type of metabolism and the alimentary behavior.
There are also countless “environmental” factors that promote the onset of obesity: the intake of certain drugs; ethnic and socio-cultural factors that affect the eating habits of the entire community; nutritional and dietary factors; psychological factors; sedentariness; diseases and endocrine dysfunctions such as thyroid.
When the excess of fat mass exceeds 17% of the body weight in men and 25% in women, obesity is referred to as a real disease. A distinction is also made between men and women on the basis of the type of distribution of adipose mass.
There is an obesity called android, more frequent in male individuals, characterized by a distribution of fat at abdominal level (type apple) with increased risk of cardiovascular disease because the fat accumulates around the viscera and vessels and an obesity called ginoid, more typical for the female sex, with a distribution of fat at the level of the buttocks and thighs (type pear).