**3. The global epidemic of obesity**

The prevalence of obesity is escalating in most part of the world, affecting men, as well as women and children. Furthermore, obesity is presently no longer just a concern or a problem for developed countries, since it since long has become a growing problem in most developing countries, as well.

## **3.1. The prevalence of excessive weight gain**

One should emphasize that it may often be hard to draw a direct comparison of the prevalence of adiposity between different countries, due to differing or inconsistent classifications used for the assessment of the disease. This problem could be "rectified" adopting the WHO-developed, standardized assessment/classification of obesity in harmonizing surveys in the future. Analysing a large body of available data, the worldwide prevalence of obesity has shown to range from some 5% in China, Japan and a few African countries to levels rising to some 75% of the adult population in urban Samoa. These data speak for themselves and indicate a varying prevalence of obesity within different countries/parts of the world. Furthermore, obesity levels vary, depending on ethnic origin. In the USA, and particularly amongst women, there are marked differences in the prevalence of obesity, when scrutinizing populations of different ethnic origins. However, a growing prevalence of obesity amongst children is also a major concern worldwide. However, a certain discrepancy in the "acknowledged" agreement in defining obesity in both children and adolescents has introduced difficulties in estimating "true" prevalence data [3].

The International Obesity Task Force (IOTF) has launched a novel approach to estimate overweight and obesity amongst children. The intention here is to make it consistent with the definition of adult adiposity (http://bmj.com/cgi/content/abridged/320/7244/1240). Nevertheless, by using the existing WHO standards, collected information from some 80 developing countries, as well as a plethora of industrialized countries/areas around the world, an expert panel has suggested that some 22 million children under 5 years of age, were in fact overweight worldwide, already some 20 years ago. And, there also exists clear evidence that this problem is increasing; within the USA, the percentage of overweight children (aged 5–15 years of age) has more than doubled over the past 30 years, from some 15% to a stunning 30% [4].
