Exercise as it relates to Disease/Childhood Obesity: How television is causing a fat epidemic among kids

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This Wikibooks page is an analysis of the research article "Association of obesity with physical activity, television programs and other forms of video viewing among children in Mexico City" by B HernaÂndez, et al. (1999)[1]

What is the background of this research?[edit]


In the past 30 years the prevalence of childhood obesity has risen significantly and become a major worldwide issue.[2] Obesity is defined as an excessive amount of adipose tissue that may lead to serious health complications.[3][4] Obesity in children is commonly measured using body mass index (BMI) results compared with a ‘BMI for age’ chart.[5] In 2010 an estimated 43 million children worldwide were overweight or obese, many of these aged under 5.[6] The World Health Organization estimates that approximately 1 in 3 European children aged 6-9 are overweight or obese.[3][5] Childhood obesity leads to obesity later in life with almost half of all overweight adults being overweight as children.[7] The disease is largely caused by an energy imbalance – more energy consumed than energy expended.[2][4] With the rise in technology, physical activity levels in children are rapidly decreasing.[7][8][9] This, along with an increase in parental obesity, poor diet and genetic and environmental factors, is leading to childhood obesity.[2]

Comorbidities of childhood obesity[2][4][edit]

Cardiiovascular Pyschological Endocrine Respiratory Musculoskeletal Gastrointestinal
Dislipidemia Depression Type 2 diabetes Asthma Slipped capital femoral epiphysis Fatty liver disease
Hypertension Eating disorders Precocious puberty Sleep apnea Blount's disease Steatohepatitis
Chronic inflammation Low self esteem Hypogonadism (males) Exercise intolerance Forearm fractures Gallstones
Endothelial dysfuntion Anxiety Polycystic ovary syndrome (females)

About the article[edit]

The article looks at the link between childhood obesity and television viewing time in particular.[1] The direct link between television and other screen based activities and fatness, is due to an increase in sedentary behaviour. The study was undertaken to evaluate the association between television and childhood obesity and to find evidence so interventions can be implemented.[1]

Where is the research from?[edit]

The study was conducted through the National Institute of Public Health, Mexico. Each of the authors are from recognized health institutions and universities in Mexico and USA.[1] The article was published in the International Journal of Obesity, a leading journal in the field.[10] The study was undertaken in Mexico City, at seven schools, three public and four private, with 712 children aged 9–16.[1]

What kind of study was it?[edit]

The research was conducted via a cross-sectional study.[1] This type of observational study involves capturing and measuring a number of variables in a specific population group, at a certain point in time. Cross-sectional studies are commonly used in the medical industry and often look at disease states.[11]

What did the research involve?[edit]

The study involved many variables. Firstly, the children completed a questionnaire on time spent participating in physical activity, and another on television viewing and other screen based activities. All children’s height and weight was recorded and BMI calculated.[1] Triceps skinfolds were measured 3 times and the average was collected. Subjects were also asked about their diet. Total energy intake and the percentage of energy obtained from fat was estimated and assessed.[1] Another survey was completed, asking children about how frequently they consume snacks while watching television: never, sometimes, frequently or always.[1] Further questions included children’s perception of parents’ weight status, parental education level and menarcheal status for females.[1]


Results may not be reliable or valid, as a large part of the research was completed via questionnaires answered by the children. Results may be either under or overestimated. Subjects may try to please the tester by answering what they think is ‘correct’, not what is true. Also the children’s perception of time may be inaccurate as they may struggle to estimate how many hours were spent on an activity. This method was used due to the number of participants and the specific variables.[1] To obtain more accurate results the study would need to be more invasive, which would be difficult in the circumstances. It is hard to pinpoint exactly the cause of obesity as the validity of many measurements is poor.

What were the basic results?[edit]

Out of the 712 children, only 461 gave complete information for all variables.[1] These results were used. The results showed that obesity risk decreased by 10% for every hour per day of moderate-to-vigorous exercise.[1] Inversely there was a 12% greater risk for each hour per day of television viewing. From BMI calculations, 24% of participants were classified as obese.[1] The average TV/video viewing time was 4.1 hours per day and the average time spent doing moderate-to-vigorous physical activity was 1.8 hours per day.[1] There was a high correlation between parental and childhood obesity.[1] Children from middle-income schools were at greater risk of obesity compared to lower-income. There were no significant links between childhood obesity and mother’s education level, perception of parental body size or menarche status.[1] Results were put into various tables providing percentages, ratios, averages and standard deviations from each of the components of the procedure.[1]

What conclusions can we take from this research?[edit]

Overall, both physical activity and television viewing levels are directly associated with childhood obesity.[1][8] Advertising during television programs may impact the correlation between obesity and TV watching, as unhealthy foods are commonly advertised and targeted at children.[4][12] The cause of the problem stems from increasing levels of sedentary behavior and specifically both parenting style and genetic influences.[4][8] It is necessary to identify factors relating to childhood obesity to implement appropriate and effective interventions to prevent the issue as early as possible.[4][8] Parents are as much to blame as any other factor causing the childhood obesity epidemic.[2][4][8][9]

Practical advice[edit]

Children are eating too much energy dense food and not getting enough exercise. School based interventions such as increasing physical education time and the number of healthy food options in canteens, will help to lower rates of childhood obesity.[13] Active transport can also combat this issue. Parents should encourage their children to walk to school and pack healthy lunches to instill good habits from a young age. Reducing TV viewing and increasing physical activity in an enjoyable way will assist to reverse the prevalence of obesity in children.

Further information/resources[edit]


  1. a b c d e f g h i j k l m n o p q r s Hernández, B., Gortmaker, S., Colditz, G., Peterson, K., Laird, N. and Parra-Cabrera, S. (1999). Association of obesity with physical activity, television programs and other forms of video viewing among children in Mexico City. International Journal of Obesity, [online] 23(8), pp.845-854. Available at: https://www.researchgate.net/profile/Graham_Colditz/publication/12809005_Hernandez_B_Gortmaker_SL_Colditz_GA_Peterson_KE_Laird_NM_Parra-Cabrera_S_Association_of_obesity_with_physical_activity_television_programs_and_other_forms_of_video_viewing_among_children_in_Mexico_Cit/links/541aaf6d0cf2218008bfd8b6/Hernandez-B-Gortmaker-SL-Colditz-GA-Peterson-KE-Laird-NM-Parra-Cabrera-S-Association-of-obesity-with-physical-activity-television-programs-and-other-forms-of-video-viewing-among-children-in-Mexi.pdf.
  2. a b c d e Ebbeling, C., Pawlak, D. and Ludwig, D. (2002). Childhood obesity: public-health crisis, common sense cure. The Lancet, [online] 360(9331), pp.473-482. Available at: http://corcom130-sp10-advertising.wikispaces.umb.edu/file/view/Childhood%20obesity.pdf/132419279/Childhood%20obesity.pdf.
  3. a b Who.int. (2017). WHO | What is overweight and obesity?. [online] Available at: http://www.who.int/dietphysicalactivity/childhood_what/en/.
  4. a b c d e f g Bhadoria, A., Sahoo, K., Sahoo, B., Choudhury, A., Sufi, N. and Kumar, R. (2015). Childhood obesity: Causes and consequences. Journal of Family Medicine and Primary Care, [online] 4(2), p.187. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4408699/.
  5. a b Eufic.org. (2017). Childhood Obesity Questions and Answers: (EUFIC). [online] Available at: http://www.eufic.org/en/healthy-living/article/childhood-obesity-questions-and-answers?gclid=CjwKCAjwo4jOBRBmEiwABWNaMbPgNcVDBzZk8wPPsBRqT06dLo3KdegI8TtRiNQZGKfb7W8rwOjB4xoCrQwQAvD_BwE.
  6. de Onis, M., Blossner, M. and Borghi, E. (2010). Global prevalence and trends of overweight and obesity among preschool children. American Journal of Clinical Nutrition, [online] 92(5), pp.1257-1264. Available at: http://ajcn.nutrition.org/content/92/5/1257.full.pdf+html?ijkey=C5xJj.Ubdr68.&keytype=ref&siteid=ajcn.
  7. a b Biro, F. and Wien, M. (2010). Childhood obesity and adult morbidities. American Journal of Clinical Nutrition, [online] 91(5), pp.1499S-1505S. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2854915/.
  8. a b c d e Dehghan, M., Akhtar-Danesh, N. and Merchant, A. (2005). Childhood obesity, prevalence and prevention. Nutrition Journal, [online] 4(1). Available at: https://nutritionj.biomedcentral.com/articles/10.1186/1475-2891-4-24.
  9. a b Deckelbaum, R. and Williams, C. (2001). Childhood Obesity: The Health Issue. Obesity Research, [online] 9(S11), pp.239S-243S. Available at: http://onlinelibrary.wiley.com/doi/10.1038/oby.2001.125/full.
  10. Nature.com. (2017). International Journal of Obesity. [online] Available at: http://www.nature.com/ijo/index.html.
  11. Health Knowledge. (2017). Introduction to study designs - cross-sectional studies. [online] Available at: https://www.healthknowledge.org.uk/e-learning/epidemiology/practitioners/introduction-study-design-css.
  12. Veerman, J., Van Beeck, E., Barendregt, J. and Mackenbach, J. (2009). By how much would limiting TV food advertising reduce childhood obesity?. The European Journal of Public Health, [online] 19(4), pp.365-369. Available at: https://academic.oup.com/eurpub/article/doi/10.1093/eurpub/ckp039/493457/By-how-much-would-limiting-TV-food-advertising.
  13. Karnik, S. and Kanekar, A. (2012). Childhood Obesity: A Global Public Health Crisis. International Journal of Preventive Medicine, [online] 3(1), pp.1-7. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3278864/.