Obesity is a major public health problem worldwide contributing to increased morbidity and mortality. There are several indices of obesity which include body mass index, waist-hip circumference ratio and skinfold thickness. The prevalence of obesity varies from 7% in France to 32.8% in Brazil. However, the comparison of obesity across different countries is difficult as there are different age structures of the population, measurement techniques are not the same and surveys may not be population-based. Trends in developed and developing countries suggest that the rates of obesity are increasing. This rising trend may be contributed by factors such as low levels of physical activity, high calorie intake and long hours of watching television. Cohort and cross-sectional studies have shown that obesity may be linked to an increased risk of coronary heart disease, hypertension, diabetes mellitus and gallstones. There is also a positive association between obesity and cancer. The mortality of obese adults, adolescents and children is higher than that of the general population. Multi-prolonged intervention strategies are needed to prevent obesity and its associated complications.