Epidemiology of obesity

In the last two decades obesity has reached epidemic proportions. World Health Organization estimates that globally more than 1 billion adults are overweight (BMI>25 kg/m²) and at least 300 million are obese (BMI>30 kg/m²). Obesity occurs when a misbalance between caloric intake and expenditure takes place. The rapid rise in excess weight in the population is therefore being driven by increased total energy intake, sedentary lifestyle or both. Increased consumption of more energy-dense, nutrient-poor foods with high content of sugar and saturated fats, combined with reduced physical activity, have led to obesity rates that have risen three-fold or more since 1980 in some areas of North America, the United Kingdom, Eastern Europe, the Middle East, the Pacific Islands, Australasia and China. This change in the obesity pattern across the geographical, ethnic, age and gender groups suggests that persistent environmental and/or behavioral changes underlie the epidemic. The most vulnerable populations are children, women and ethnic minorities. The impact of the obesity both on the individual health and the society is profound. This chapter introduces the obesity epidemic.