At the beginning of the 21st Century, obesity has become the leading metabolic disease in the World. So much so, that the World Health Organisation refers to obesity as the global epidemic. In fact, obesity is a common disease affecting not only affluent societies but also developing countries. Currently 300 million people can be considered as obese and, due to the rising trend in obesity prevalence, this figure could double by year 2025 if no action is taken against this threat. In terms of health impairment, the importance of obesity lies in the fact that, besides being a disease in itself, it is a risk for many other diseases, mainly from the metabolic and cardiovascular area. Among these, type 2 diabetes, dyslipemia, hyperuricemia, arterial hypertension and cardiovascular disease are the most frequent. Also, respiratory diseases such as obesity hypoventilation syndrome and obstructive sleep apnoea syndrome are strongly associated with obesity.