Genes, behavior and environment, all contribute to the development of obesity. According to the World Health Organization, the escalating international epidemic of obesity is now the most significant contributor to ill health, chronic diseases and substantial rise in death rate(1)..
Obesity accounts for 5-7% of national health expenditure in the US(2) and now outranks both smoking and drinking in its deleterious effects on health and health costs(3). Prevalence levels in the UK are just little behind (4) . The pediatric picture is just as gloomy with a 2-2.8-fold increase over a 10-year period in childhood obesity (5).
Obesity is a major risk factor for cardiovascular diseases, pulmonary diseases (such as sleep apnoea), metabolic diseases (e.g. diabetes and dyslipidaemia), osteoarticular diseases, for several of the commonest forms of cancer (6) and for serious psychiatric illness. Furthermore, childhood obesity is associated with early onset type 2 diabetes (7) and with an increased mortality risk for coronary heart disease in adulthood (8).
Heritability estimates for obesity are high (typically >0.70), comparing well with other complex, polygenic diseases such as schizophrenia (0.81) (9)and autism (0.90) (10), and are significantly higher than for other complex traits such as hypertension (0.29)(11) and depression (0.50) (12). In addition, the use of quantitative obesity sub-phenotypes that can be accurately measured has resulted in significant measures of heritability for skinfold thickness (13-14), waist circumference (16)and total and regional fat distribution(17).
If the escalating population prevalence of obesity and its serious implications for public health wider search for the genes involved in increasing a person’s risk of becoming overweight when exposed to an “obesogenic environment” of high-calorie food and inactivity which is known to affect some people more than others.
We’ve known for a long time that changes to our genes can increase our risk of obesity. For example, the gene FTO has been unequivocally associated with BMI, obesity and other obesity-related traits,” says Dr Eleanor Wheeler, from the Wellcome Trust Sanger Institute.
“In our study of severely obese children, we have found that apart from FTO gene, differences in or near two of the newly associated genes seem to have a comparable or greater effect on obesity: PRKCH and RMST.”
Genes are for childhood and adult obesity. different Rare genetic changes in one of the newly associated genes, LEPR, are known to cause a severe form of early onset obesity. The team recognized a more common variant in this gene, found in 6 per cent of the population, that can increase a person’s risk of obesity.
Some of the children in this study had an increased number of structural variations of their DNA that delete G-protein coupled receptors, important receptors in the regulation of weight. These receptors when analyzed are key targets for current drug development and may have potential therapeutic implications for obesity.
Some children will be obese because they have severe mutations, but our research indicates that some may have a combination of severe mutations and milder acting variants that in combination contribute to their obesity,” says Professor Sadaf Farooqi, from Cambridge’s Department of Clinical Biochemistry. This text is supplied by the Wellcome Trust.
Childhood obesity is often the result of the combination offered by interaction ï¿½between many genetic and environmental factors. Polymorphisms in various genes controlling appetite and metabolism predispose individuals to obesity when sufficient calories are present. Over 200 genes affect weight by determining activity level, food preferences, body type, and metabolism. Having two copies of the allele called FTO increases the likelihood of both obesity and diabetes .As such, obesity is a major feature of a number of rare genetic conditions that often present in childhood like Prader-Willi syndrome ,Bardet-Biedl syndrome, MOMO syndrome, Leptin receptor mutations, Congenital leptin deficiency and Melanocortin receptor mutations
In children with early-onset severe obesity (defined by an onset before ten years of age and body mass index over three standard deviations above normal), 7% harbor a single locus mutation.  One study found that 80% of the offspring of two obese parents were obese in contrast to less than 10% of the offspring of two parents who were of normal weight.  The percentage of obesity that can be attributed to genetics varies from 6% to 85% depending on the population examined. 
University college London stated that researchers findings suggest there are hundreds of other genetic variants influencing body weight that are yet to be discovered." reference of the journal can be found in references sections
Apart from genetic factor main role is also played by environment behavior. About 55 million school-aged children are enrolled in schools across the United States, and many eat and drink meals and snacks there. Yet, more than half of U.S. middle and high schools still offer sugary drinks and less healthy foods for purchase. There is prevalent dvertising of less healthy foods, while advertising for healthier foods is almost nonexistent in comparison. There is also Variation in licensure regulations among child care centers. More than 12 million children regularly spend time in child care arrangements outside the home. However, not all states use licensing regulations to ensure that child care facilities encourage more healthful eating and physical activity.
Lack of daily, quality physical activity in all schools. Most adolescents fall short of the 2008 Physical Activity Guidelines for Americans recommendation of at least 60 minutes of aerobic physical activity each day, as only 18% of students in grades 9-12 met this recommendation in 2007. No safe and appealing place, in many communities, to play or be active. Lack of breastfeeding support. Breastfeeding is a protective factor against childhood overweight and obesity. [28-29] However, in the United States, while 75% of mothers start out breastfeeding, only 13% of babies are exclusively breastfed at the end of 6 months. Television and media advertising unhealthy food , sugary drinks is also a major contributor to obesity . Children 8-18 years of age spend an average of 7.5 hours a day using entertainment media, including TV, computers, video games, cell phones, and movies. Of those 7.5 hours, about 4.5 hours is dedicated to viewing TV. Eighty-three percent of children from 6 months to less than 6 years of age view TV or videos about 1 hour and 57 minutes a day.
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