Written by Jenny Clark
April 22, 2011
Childhood obesity is rapidly becoming a global issue. It has been estimated that over 42 million children under the age of 5 were overweight in 2010, with nearly 35 million of those children living in developing countries (WHO, 2010). In the US, the amount of children who are classified as obese has more than tripled in the past 30 years ( CDC, 2010). The percentage of obese children between the ages of 6-11 years increased from 6.5% in 1980 to 19.6% in 2008. Adolescents with obesity (ages 12-19) also increased from 5.0% in 1980 to 18.1% in 2008. The World Health Organization defines obesity as “abnormal or excessive fat that presents a risk to health” (WHO, 2011). They measure obesity using the Body Mass Index (BMI) which uses a person’s height and weight as variables to determine their risk of a disease. A BMI greater than 25 is considered overweight and a BMI greater than 30 is considered obese.
With children, obesity is also measured using BMI, but age and sex are also factored in since their bodies are still growing (Obesity Action Coalition, 2010). Therefore, instead of measuring obesity as a BMI higher than a specific number, it is calculated in BMI-for-age percentile which indicates where the child’s weight is in comparison to other children of the same age and sex. If a child’s BMI-for-age-percentile is greater than 85%, the child is considered overweight. If a child’s BMI-for-age percentile is greater than 95%, the child is considered obese.
Being overweight during childhood has brought up many concerns due to the many health risks associated with excess fat tissue. Childhood obesity has been associated with insulin resistance, high cholesterol, high blood pressure, asthma, sleep disorders, hardening of the arteries, and mental health problems during young adulthood (Steinberger & Daniels, 2003; Paxon, 2006). It is estimated that the health-costs associated with childhood obesity rose from $35 million in 1980 to $127 million in 1998. This cost is relatively small compared the estimated $51.5 to $78.5 billion spent on hospital costs in 1998 for adult obesity. However, prices are expected to rise as more children become obese.
What causes obesity is not entirely understood. Many scientists agree that the increase in caloric intake with the reduction in energy expenditure is the underlining reason for the childhood obesity epidemic. Yet, even babies who are not able to eat high-calorie foods and cannot participate in physical activity increased in obesity as much as 73% since 1980 (Begley,2009). Therefore, new studies have been conducted to determine all the factors of obesity. Many scientists are finding numerous possible factors including parental influences, social influences, media and advertising, and genetics (Federal Trade Commission, 2008).
The parenting techniques used by parents are also thought to influence the likelihood of their children becoming overweight or obese. One factor that has been considered is the length of time in which a child is breastfed. Harder, et al. (2005) conducted a meta-analysis of studies on duration of breastfeeding and the risk of being overweight later in life. From the studies, they found that for each extra month that a child is breastfed, their risk of being overweight decrease by 4%. This trend continued up until the baby reached 9 months old. Researchers hypothesize that this effect happens because extra sugars and fats are added into bottle formula, whereas breast milk is full of natural nutrients and fats (ASPE, 2011). Also, the foods that the parents provide in the household are thought to encourage unhealthy eating habits if the foods are low in nutritional quality. In a study conducted by Whitaker, et al. (1997), adolescents with at least one obese parent had a 79% chance of being obese during adulthood compared to the 8% chance for children without an obese parent. Researchers believe that this occurs because a child of the obese parent adopts the unhealthy habits that the obese parent demonstrates and the child is more likely to be offered food of low-nutritional quality (ASPE, 2011).
Many social influences have also been thought to contribute to the rise in childhood obesity in the past few decades. Some of these influences include the increase in the number of restaurants and fast-food restaurants around the world, the increase in processed foods, the price differences in fresh foods in comparison to processed foods, the increase in portion sizes, and the types of foods that have become socially acceptable to eat (French, et al., 2001; Maibach, 2007; ASPE, 2011). In addition, the easier access to cars and other forms of mechanical transportation has greatly reduced the amount of walking and physical exercise required for people to offset their current daily caloric intake, likely contributing to the obesity epidemic. Socio-economic status has also been shown to influence a child’s risk of becoming overweight or obese in many parts of the world (Drenowatz, et al., 2010; Sodjinou, et al., 2008). Lower socio-economic status has been linked to an increase likelihood of poor nutrition, sedimentary activity, and poor food habits (Groholt, et al.,2008). All the hypothesized social influences contribute to the increase in caloric intake and the reduction in physical activity, which are thought to be the underlining cause of the obesity epidemic.
As mentioned earlier, advertising to children has a significant effect in what children want to eat and how little they participate in physical activity. In 2006 alone, food, beverage, and fast-food restaurants spent nearly $1.6 billion on advertisements to generate almost 136 billion food ads, with children being their main targeted audience. With all these ads directed at children, it is estimated that each child in the US receives an average of 65 messages of advertisement each day from television alone (Batadam & Wootan, 2007). In addition, Hasting, et al. (2003) found that advertisements have a distinct effect on the food children choose to eat, thus affecting the amount of high-calorie and low-nutritional quality food intake of the children that frequently see the advertisements. At the same time, using media has been shown to increase sedimentary activities and reduce the amount of participation in physical activity by children (Boyce, 2006; Jago, et al., 2005). Together, the increase of caloric intake and the decrease in physical activity resulting from media has negatively influenced how children interpret healthy living, which has thus contributed to the increasing amount of overweight and obese children.
The newest theory in obesity research involves looking at different genes that might be associated with a person’s ability to use dietary fats as fuel, the ability to store body fat, or the poor regulation of appetite that may cause a person to become obese even without the excess caloric intake and physical inactivity (CDC, 2011). These genes have been referred to as “energy-thrifty genes” because it is thought that they make people’s bodies unable to adapt to our society’s abundant food supply, which our ancestors did not have access to all year round. Currently, there have been three genes whose presence in the body have been found that correlate with obesity: FTO, MC4R, and PCSK1 (Hofker & Wijmenga, 2009). FTO and MC4R have been shown to correlate to BMI in obese individuals. PCSK1, along with MC4R, has been shown to be linked with severe or syndromic forms of obesity in mice and humans. However, the links between each of the genes are not fully understood and are still being researched. In addition, many more genes are being researched to determine whether there are more genes correlated to obesity. Nevertheless, future findings in obesity genetics will provide a better understanding of treatment and prevention methods for obese children and obese adults.
In conclusion, many factors have contributed to the childhood obesity epidemic that many developing countries are currently facing. In order to prevent childhood obesity from continuing to rise, more attention should be put towards changing these factors and educating children how to live healthily and develop healthy eating habits early in life.
References:
ASPE (2011). Childhood Obesity. U.S. Department of Health & Human Services: Assistant Secretary for Planning and Evaluation. [web] http://aspe.hhs.gov/health/reports/child_obesity/#_ftn93. Viewed on March 9, 2010.
Begley, S. Born to be big. Newsweek, 154, 12, p56-62.
Boyce, T. (2007). The media and obesity. The International Association of the Study of Obesity. Obesity Reviews 8, 1, 201-205.
CDC (2010). Childhood Obesity. National Center for Chronic Disease Prevention and Health Promotion, Division of Adolescent and School Health. [Web] http://www.cdc.gov/healthyyouth/obesity/. Viewed on March 9, 2011.
CDC (2011). Genomics and Health: Obesity and Genomics. Office of Surveillance, Epidemiology, and Laboratory Services, Public Health Genomics. [web] http://www.cdc.gov/genomics/resources/diseases/obesity/obesedit.htm. Viewed on March 9, 2010.
Drenwatz, C., Eisenmann, J.C., Pfeiffer, K. A., Welk, G., Heelan, K., Gentile, D. and Walsh, D. (2010). Influence of socio-economic status on habitual physical activity and sedentary behavior in 8- to 11-year old children. BMC Public Health, 10, 214.
Harder, T., Bermann, R., Kallischnigg, G., and Plagemann, A. (2005). Duration of breastfeeding and risk of overweight: a meta-analysis. American Journal of Epidemiology, 162, (5), 397-403
Hastings, G., Stead, M., McDermott, L., Forsyth, A., MacKintosh, A. M., Rayner, M., Godfrey, C., Caraher, M., and Angus, K. Review of research on the effects of food promotion to children: final report. Food Standards Agency. Downloaded at http://www.food.gov.uk/multimedia/pdfs/foodpromotiontochildren1.pdf
Groholt, E.K, Stigum, H., Nordhagen, R. Overweight and obesity among adolescents in Norway: cultural and socio-economic differences. Journal of Public Health, 30 (3): 258-265.
Hofker, M. and Wijmenga, C. A supersized list of obesity genes. Nature Genetics, 41 (2): 139-140.
Jago, R., Baranowski, T., Baranowski, J. C., Thompson, D. and Greaves, K.A. (2005). BMI from 3-6 of age is predicted by television viewing and physical activity, not diet. International Journal of Obesity, 29: 557-564.
Obesity Action Coalition (2010). All About Obesity. Obesity Action Coalition. [web] http://www.obesityaction.org/aboutobesity/childhoodobesity/childhood.php. Viewed on March 9, 2011.
Paxon, C. (2006). Childhood Obesity: The Future of Children. The Future of Children Journal, 16, 1, spring.
Sodjinou, R., Agueh, V., Fayomi, B, and Delisle, H. (2008). Obesity and cardio-metabolic risk factors in urban adults of Benin: Relationship with socio-economic status, urbanisation, and lifestyle patterns. BMC Public Health, 8,84.
Steinberger, J. and Daniels, S. R. Obesity, Insulin Resistance, Diabetes, and Cardiovascular Risk in Children: An American Heart Association Scientific Statement From the Atherosclerosis, Hypertension, and Obesity in the Young Committee (Council on Cardiovascular Disease in the Young) and the Diabetes Committee (Council on Nutrition, Physical Activity, and Metabolism). (2003). The American Heat Association Circulation, 107, 1448-1453.
Whitaker, R. C., Wright, J. A., Pepe, M.S., Seidel, K. D., and Dietz, W. H. Predicting obesity in young adulthood from childhood and parental obesity. The New England Journal of Medicine, 337 (13): 869-873.
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