Obesity is increasing at an alarming rate throughout the world. Today it is estimated that there are more than 300 million obese people world-wide (1). Obesity is a condition of excess body fat often associated with a large number of debilitating and life-threatening disorders (2). It is still a matter of debate as to how to define obesity in young people(3). Weight exceeding 125% of the median weight for height is obesity. Overweight persons have a body-fat proportion intermediate between normal and obese (4). Weight tables, measurement of skin fold thickness and Body Mass Index (5).
Importance of childhood obesity
Eighty percent of overweigh 10-14 year old adolescents are at risk of becoming overweight adults compared to 25% of overweight preschool children (< 5 years old) and 50% of 6-9 year old overweight children (15). Obesity in childhood and adolescence has been related to an increase in mortality in adulthood on follow up. Hoffman et al observed almost twice the risk of death in adolescents (> 18 year olds) with BMI > 25 kg/m2(compared to subjects with BMI <25kg/m2) during 20 year follow up (16).
Epidemiology and global scenario of childhood obesity
Obesity has reached epidemic proportions in the developed part of the world with as many as 30-40% of adults being already obese and the incidence in children and adolescent is rising (17). World health organization has declared obesity as one of the most neglected diseases of significant public health importance. The 2002 World Health Report lists overweight as the fifth most serious risk factor for both developed countries and low mortality developing countries(18). According to the report of International Obesity Task Force (IOTF), in the year 2000 about 10% (a total of 155 million) of the young people aged 5-17 years globally were overweight; among whom 2-3% (30-45 million) were obese, a further 22 million younger children are also affected according to previous IOTF global estimates based on WHO data for under fives (18,19).
Tendencies and projections
It is predicted that the levels of obesity will continue to rise unless action is taken now. WHO has warned “the growth in the number of severely overweight adults to double that of underweight during 1995-2025” (WHO 1998) (29). From existing data it has been projected that by the year 2030 levels of obesity could be as high as 50-80% in the USA, between 30-40% in Australia, England and Mauritius and over 20% in some developing countries (30).
Key patterns associated with obesity
Factors, including age, gender and socio-economic status have been linked to obesity Clear gender difference is seen in most countries with more women than men being obese (22). Patterns have also emerged across socio-economic groups. In developed countries levels of obesity are higher in the lower socio-economic groups. In developing countries this relationship is reversed (31). The transition from a rural to an urban lifestyle is associated with increased levels of obesity which has been linked with dramatic changes in lifestyles (e.g. increased consumption of high energy dense foods and decrease in physical activity)
Cause of Obesity
Although the mechanism of obesity development is not fully understood, it is confirmed that obesity occurs when energy intake exceeds energy expenditure. Childhood obesity can be brought on by a range of factors which often act in combination (32,33).
Social and environmental factors
Changes in environmental and social factors are likely the main explanation for doubling of severe childhood obesity over the last 30 years. Obesity is encouraged by such “obesogenic environmental conditions that promote overeating”. “Passive over consumption” due to changes taking place in food marketing, consumer behavior (e.g., increases in consumption of food and beverages) and targeted marketing of high calorie dense foods with low nutrients (34). Consumers respond positively to changes in their environment. Numerous environmental factors that facilitate or limit physical activities have been identified Urban housing design and land use influence the physical activity of the residents of that area. Studies have shown that increasing access to physical activity in an organized, structured and supervised manner is effectively beneficial for youth (35).
Over the last decades, food has become more affordable to larger numbers of people as the price of food has decreased substantially relative to income and the concept of ‘food’ has changed from a means of nourishment to a marker of lifestyle and a source of pleasure. Clearly, increases in physical activity are not likely to offset an energy rich, poor nutritive diet. It takes between 1-2 hours of extremely vigorous activity to counteract a single large-sized (i.e., >=780 kcal) children′s meal at a fast food restaurant. Frequent consumption of such a diet can hardly be counteracted by the average child or adult (35).