WHAT CAUSES OBESITY
Obesity is a complex and multifactorial disease, resulting from unbalance between ingested number of calories and energy expenditure for a given period of time.. Nonetheless, it is clear that obesity does not result from a simple overload of food or sustained lack of physical activity, as there are several factors that can influence the obtainment or maintenance of a surplus energy balance leading to a weight increase, which once established, tends to be maintained due to several mechanisms.
The rapid increase in the prevalence of obesity in the population (mainly in developed countries) is a short period of time makes one think that the determining genetic factors are not really of much significance; thus, factors that determine a change in dietary habits of the individual appear to be more significant (for instance, reduced physical activity) and changes in the quantity and amount of the daily diet (with increased intake of high-fat foods and calorie density).
Basically, obesity and overweight can be classified according to the triggering causes. Generally, there are several non-exclusive causes that interrelate to make a certain individual overweight or obese. Further along this document, each group will be discussed separately.