epidemiology and social impact of obesity;epidemiological surveys – shows the mean weight of increasing population;centers for disease control and prevention (CDC);behavioral risk factor surveillance system (BRFSS);European health examination survey (EHES) – introduces objective measures of height, weight, blood pressure and cholesterol;NHANES data – provides vivid comparisons between genders, ethnic and age groups;obesogenic factors – contributes to the rising prevalence of obesity;socio-economic status and educational status – inversely related to the prevalence of obesity;wide range of chronic diseases – gall-bladder disease, fatty liver, sleep apnoea and osteoarthriti