Epidemiology of obesity
For thousands of years obesity was rarely seen. It was not until the 20th century that it became common, so much so that in 1997 the World Health Organization (WHO) formally recognized obesity as a global epidemic. As of 2005 the WHO estimates that at least 400 million adults (9.8%) are obese, with higher rates among women than men.
As of 2008, The World Health Organization claimed that 1.5 billion adults, 20 and older, were overweight and of these over 200 million men and nearly 300 million women were obese. The rate of obesity also increases with age at least up to 50 or 60 years old.
The top five countries with the highest obesity rates are as followed:
Once considered a problem only of high-income countries, obesity rates are rising worldwide. These increases have been felt most dramatically in urban settings. The only remaining region of the world where obesity is not common is sub-Saharan Africa.
Obesity rates in Western Africa are estimated to be 10%. Rates of obesity among women are three times those found in men. In urban West Africa rates of obesity have more than doubled in the last 15 years.
The peasants in Egypt believe that fatness is proper as the “envelope for conception;” therefore, there is enough room to bear and give warmth to the child.
China is currently facing challenges of overnutrition. This is believed to be primarily due to the rapid declines in physical activity and changing dietary habits which have occurred between the 1980s and the 2000s. The decline in physical activity is attributed to increasing technology in the workplace and changing leisure activities.
In 1989 65% of Chinese had jobs that required heavy labor. This decreased to 51% in the year 2000. Combined with this has been a change to a diet higher in meat and oil, and an increase in overall available calories. Available calories per person increased from 2,330 kilocalories (9,700 kJ) per day in 1980 to 2,940 kilocalories (12,300 kJ) per day in 2002. Rates of overweight and obese adults increased 12.9% in 1991 to 27.3% in 2004.
Overall rates of obesity are below 5% in China as a whole but are greater than 20% in some cities.
Obesity has reached epidemic proportions in India in the 21st century, with morbid obesity affecting 5% of the country's population. Urbanization and modernization has been associated with obesity. In Northern India obesity was most prevalent in urban populations (male = 5.5%, female = 12.6%), followed by the urban slums (male = 1.9%, female = 7.2%). Obesity rates were the lowest in rural populations (male = 1.6%, female = 3.8%).
Socioeconomic class also had an effect on the rate of obesity. Women of high socioeconomic class had rates of 10.4% as opposed to 0.9% in women of low socioeconomic class. With people moving into urban centers and wealth increasing, concerns about an obesity epidemic in India are growing.
In Iran the prevalence of obesity was 26.3% in 2008. Prevalence of obesity was more among women (39.5%) than men (14.5%).
Using the WHO criteria Japan has the lowest rate of obesity among the OECD member countries at 3.2%. However, as Asian populations are particularly susceptible to the health risks of excess adipose tissue the Japanese have redefined obesity as any BMI greater than 25. Using this cut off value the prevalence of obesity in Japan would be 20%, a threefold increase from 1962 to 2002. A 2008 report stated that 28.6% of men and 20.6% of women in Japan were considered to be obese.
Changing lifestyles, owing to urbanisation, as well as diet issues are the main reasons for obesity in Pakistan. According to a recent study, approximately one out of four Pakistani adults (or 22.2% of individuals) are classified as obese.
In 2002, 15% of children range from 6 to 12 years of age were overweight, by gender, 15.5% of male and 14.4% of female were overweight. In the same age range, 12％ of children were obese, by gender, 14.7％ of male and 9.1％ of female were categorized as obese. In 2005, 14.9% children range from 6 to 12 years of age were overweight, where by gender, 15.85% of male and 14.02% of female were overweight. 10.3% were categorized as obese, where by gender, 10.92% of male and 9.73% were categorized as obese.
Base on these reports done, the trends were inconclusive, although with more than 10% of the age group being obese, obesity does appear to be a problem.
Between the 1970s and the 2000s, rates of obesity in most European countries have increased. During the 1990s and 2000s, the 27 countries making up the EU reported rates of obesity from 10–27% in men and from 10–38% in women.
Most recent statistics  show that, among the 19 EU Member States for which data are available, the proportion of obese people in the adult population varied in 2008/9 between 8,0% (Romania) and 23,9% (UK) for women and between 7,6% (Romania) and 24,7% (Malta) for men.
In the UK the rate of obesity has increased about fourfold over the last 30 years, reaching levels of 22-24% in 2008/9. The United Kingdom now has one of the highest rates of obesity in Europe.
|Year||Percent males obese||Percent females obese|
The number of Canadians who are obese has risen dramatically in recent years. In 2004, direct measurements of height and weight found 23.1% of Canadians older than 18 had a BMI greater than 30. When broken down into degrees of obesity, 15.2% were class I (BMI 30–34.9), 5.1% were class II (BMI 35–39.9), and 2.7%, class III (BMI > 40). This is in contrast to self-reported data the previous year of 15.2% and in 1978/1979 of 13.8%. The greatest increases occurred among the more severe degrees of obesity; class III obesity increased from 0.9% to 2.7% from 1978/1979 to 2004. Obesity in Canada varies by ethnicity; people of Aboriginal origin have a significantly higher rate of obesity (37.6%) than the national average.
In children obesity has substantially increased between 1989 and 2004 with rates in boys increasing from 2% to 10% and rates among girls increasing from 2% to 9%.
Mexico has the highest rate of obesity among OECD members.
The United States has the second highest obesity rates in the developed world. This is a long-standing phenomenon: already by 1962, 45% of adult Americans were overweight, and 13% of adult Americans were obese; these numbers were already higher than obesity rates observed in most developed countries as late as 2001-02. From 1980 to 2002, obesity rates have doubled, reaching the current rate of 33% of the adult population.
As of 2007, 33% of men and 36% of women are obese. Rates of obesity vary between social groups, with minorities and low-income individuals more likely to be overweight. The rates are as high as 50% among African American women.
Geography is a major factor. The American South has been described alternatively as "Stroke belt", "Obesity belt", or "Diabetes belt", to reflect the fact that all residents of the region have high incidences of these three conditions, compared to people of the same race/ethnicity elsewhere in the country. The lowest obesity rates of major racial/ethnic groups across 50 states are thought to be among non-Hispanic white residents of Colorado and Hawaii, at around 16%. However, these numbers are based on self-reported height and weight data and likely to be underestimated (the bias is so large that, for example, estimates of obesity that rely on self-reported data arrive at the rate of 22% among non-Hispanic white females, whereas studies that involve direct measurement show that the rate is closer to 34%.) 
The prevalence of class III obesity (BMI ≥40) has increased the most dramatically, from 1.3% in the late 1970s, to 2.9% in 1988-94, to 4.7% in 2000, to 5.7% in 2008. Among African American women, its prevalence is estimated to be as high as 14%.
The overall rate of obesity began to plateau in the '00s, but severe obesity and obesity in children continued to rise. In January 2010, a study published in the Journal of the American Medical Association found that the obesity rate for American women has remained constant over the last decade, with only small rises amongst men and children.
Obesity is one of the leading health issues in US society, resulting in about 300,000 excess deaths per year in the United States. About 65 percent of Americans are now considered either overweight or obese. However, using a different methodology and incorporating new data, researches at the Centers for Disease Control and Prevention reduced the estimate to 26,000 excess deaths per year  According to National Health and Nutrition Examination Study collected between 1970s and 2004, overweight and obesity prevalence have increased steadily among all groups of Americans over the past three decades.
Oceania and the Pacific
According to self-reported and measured results of the 2007-2008 National Health Survey, 61% of Australians were overweight (above a 25 BMI), with 24% falling into the "obese" category (above a 30 BMI). Men were more likely to be overweight (67.7%) and obese (25.5%) than women (30.9% and 23.4% respectively).
Obesity in New Zealand has become an important national health concern in recent years, with high numbers of people afflicted in every age and ethnic group. In 2011/12, 28.4% of New Zealand adults were obese, a number only surpassed in the Anglosphere by the United States.
Many of the island nations of the South Pacific have very high rates of obesity. Nauru has the highest rates of obesity in the world (94.5%) followed by Samoa, the Federated States of Micronesia, and the American Samoa. Being big has traditionally been associated with health, beauty, and status and many of these beliefs remain prevalent today.
- "www.iotf.org" (PDF). IOTF. Retrieved Jan 29, 2008.
- Anon (2005). OECD Factbook: Economic, Environmental and Social Statistics. Organization for Economic Co-operation and Development. ISBN 92-64-01869-7.
- Haslam D (March 2007). "Obesity: a medical history". Obes Rev. 8 Suppl 1: 31–6. doi:10.1111/j.1467-789X.2007.00314.x. PMID 17316298.
- Caballero B (2007). "The global epidemic of obesity: An overview". Epidemiol Rev 29: 1–5. doi:10.1093/epirev/mxm012. PMID 17569676.
- World Health Organization (2000). Technical report series 894: Obesity: Preventing and managing the global epidemic. (PDF). Geneva: World Health Organization. ISBN 92-4-120894-5.
- "Obesity and overweight". World Health Organization.
- Peter G. Kopelman, Ian D. Caterson, Michael J. Stock, William H. Dietz (2005). Clinical obesity in adults and children: In Adults and Children. Blackwell Publishing. p. 493. ISBN 1-4051-1672-2.
- Haslam DW, James WP (October 2005). "Obesity". Lancet 366 (9492): 1197–209. doi:10.1016/S0140-6736(05)67483-1. PMID 16198769.
- Abubakari AR, Lauder W, Agyemang C, Jones M, Kirk A, Bhopal RS (July 2008). "Prevalence and time trends in obesity among adult West African populations: a meta-analysis". Obes Rev 9 (4): 297–311. doi:10.1111/j.1467-789X.2007.00462.x. PMID 18179616.
- Brown & Konner. An Anthropological Perspective on Obesity. Mayfield Publishing Company. ISBN 1-55934-723-6.
- "The double burden of malnutrition Case studies from six developing countries". Food and Agricultural Organization of the UN. Retrieved January 11, 2009.
- "www.fao.org". Food and Agricultural Organization of the UN.
- Popkin, Barry (August 22, 2007). "The World Is Fat". Scientific American. p. 94. ISSN 0036-8733. Retrieved 2008-07-24.
- "www.who.int" (PDF). WHO. Retrieved February 22, 2009.
- "India facing obesity epidemic: experts". The Hindu. 2007-10-12.
- Yadav K, Krishnan A (September 2008). "Changing patterns of diet, physical activity and obesity among urban, rural and slum populations in north India". Obes Rev 9 (5): 400–8. doi:10.1111/j.1467-789X.2008.00505.x. PMID 18627500.
- Praween Kumar Agrawal (2002-05-23). "Emerging obesity in northern Indian states: A serious threat for health" (PDF). IUSSP Conference, Bankik, 10 June–12-2002. Retrieved 2008-07-24.
- Rashidy-Pour A, Malek M, Eskandarian R, Ghorbani R (January 2009). "Obesity in the Iranian population". Obes Rev 10 (1): 2–6. doi:10.1111/j.1467-789X.2008.00536.x. PMID 19021868.
- Harden, Blaine, "Japanese Women Buck Obesity Trend", Washington Post, March 10, 2010.
- Anuurad E, Shiwaku K, Nogi A et al. (November 2003). "The new BMI criteria for asians by the regional office for the western pacific region of WHO are suitable for screening of overweight to prevent metabolic syndrome in elder Japanese workers". J Occup Health 45 (6): 335–43. doi:10.1539/joh.45.335. PMID 14676412.[dead link]
- Kanazawa M, Yoshiike N, Osaka T, Numba Y, Zimmet P, Inoue S (December 2002). "Criteria and classification of obesity in Japan and Asia-Oceania". Asia Pac J Clin Nutr. 11 Suppl 8: S732–S737. doi:10.1046/j.1440-6047.11.s8.19.x. PMID 12534701.
- Fukue, Natsuko, "TV gets fickle fans flocking to fads to shed fat", Japan Times, March 9, 2010, p. 3.
- "One in four adults is overweight or clinically obese". Gulf News. December 17, 2006.
- Streib, Lauren (2 August 2007). "World's Fattest Countries". Forbes.
- Committee for Health and Development Promotion for Children(兒童健康推展委員會) (April 4, 2007). "肥胖防治要從小紮根". Ministry of Health Promotion, Department of Health, Taiwan (R.O.C.).
- Tim Lobstein, Neville Rigby, Rachel Leach (2005-03-15). EU platform on diet, physical activity and health: International Obesity Task Force EU Platform Briefing Paper (PDF). International Obesity Task Force. Retrieved 2008-07-23.
- Eurostat - Statistics Explained: Overweight and obesity - BMI_statistics, see 'Source data for tables, figures and maps'
- Great Britain Parliament House of Commons Health Committee (May 2004). Obesity - Volume 1 - HCP 23-I, Third Report of session 2003-04. Report, together with formal minutes. London, UK: TSO (The Stationery Office). ISBN 0-215-01737-4. Retrieved 2007-12-17.
- Tjepkema M (2005-07-06). "Measured Obesity–Adult obesity in Canada: Measured height and weight". Nutrition: Findings from the Canadian Community Health Survey. Ottawa, Ontario: Statistics Canada.
- Lau DC, Douketis JD, Morrison KM, Hramiak IM, Sharma AM, Ur E (April 2007). "2006 Canadian clinical practice guidelines on the management and prevention of obesity in adults and children summary". CMAJ 176 (8): S1–13. doi:10.1503/cmaj.061409. PMC 1839777. PMID 17420481.
- "Obesity and Overweight for Professionals: Data and Statistics: Adult Obesity Facts". Centers for Disease Control and Prevention. 2012-08-13. Retrieved 2012-11-05.
- Ogden CL, Carroll MD, Curtin LR, McDowell MA, Tabak CJ, Flegal KM (2006). "Prevalence of overweight and obesity in the United States, 1999–2004". JAMA 295 (13): 1549–55. doi:10.1001/jama.295.13.1549. PMID 16595758.
- Bessesen DH (June 2008). "Update on obesity". J. Clin. Endocrinol. Metab. 93 (6): 2027–34. doi:10.1210/jc.2008-0520. PMID 18539769.
- "International Obesity Task Force" (PDF). March 15, 2005. Retrieved 2008-09-19.
- Healy, Melissa (2011-03-08). "Diabetes belt: American South gets more health notoriety". Los Angeles Times.
- "Prevalence of obesity among adults, by black/white race or Hispanic ethnicity, census region, and sex --- Behavioral Risk Factor Surveillance System surveys, United States, 2006−2008".
- <Please add first missing authors to populate metadata.>. Economic Caused and Consequences of Obesity.
- Flegal, KM; Carroll, MD; Ogden, CL; Johnson, CL (2002). "Prevalence and Trends in Obesity Among US Adults, 1999-2000". JAMA: the Journal of the American Medical Association 288 (14): 1723–7. doi:10.1001/jama.288.14.1723. PMID 12365955.
- Flegal, KM; Carroll, MD; Ogden, CL; Curtin, LR (2010). "Prevalence and Trends in Obesity Among US Adults, 1999-2008". JAMA: the Journal of the American Medical Association 303 (3): 235–41. doi:10.1001/jama.2009.2014. PMID 20071471.
- Flegal, KM; Katherine M. Flegal, PhD; Margaret D. Carroll, MSPH; Cynthia L. Ogden, PhD; Lester R. Curtin, PhD (January 13, 2010). "Prevalence and Trends in Obesity Among US Adults, 1999–2008". Journal of the American Medical Association 303 (3): 235–241. doi:10.1001/jama.2009.2014. PMID 20071471.
- Allison, DB, Fontaine, KR, Manson, JR., Stevens, J, Vanitallie, TB (1999). "Annual deaths attributable to obesity in the United States". JAMA 282 (16): 1530–8. doi:10.1001/jama.282.16.1530. PMID 10546692.
- Flegal, KM, Carroll, MD, Odgen, CL et al. (2002). "Prevalence and trends in obesity among US adults, 1999–2000" (PDF). JAMA 288 (14): 1723–7. doi:10.1001/jama.288.14.1723. PMID 12365955.
- Flegal, Katherine M., et al., "Excess Deaths Associated with Underweight, Overweight, and Obesity," Journal of the American Medical Association 293, no. 15 (2005): 1861-67
- National Institutes of Health (1998). "Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: the evidence report" (PDF). Obese Res 6 (Suppl 2): 51S.
- Ogden, CL, Carroll, MD, Curtin, LR, McDowell, MA, Tabak, CJ, Flegal, KM (2006). "Prevalence of overweight and obesity in the United States, 1999–2004". JAMA 295 (13): 1549–1555. doi:10.1001/jama.295.13.1549. PMID 16595758.
- "Body section (Overweight and Obesity 2007-08)" (PDF). Retrieved 2012-03-19.
- "Obesity - Social Report 2008". Ministry of Social Development. June 1, 2008. Retrieved 2009-07-05.
- Ministry of Health (2012). The Health of New Zealand Adults 2011/12. Wellington: Ministry of Health.
- Lauren Streib (February 8, 2007). "World's Fattest Countries". Forbes. Retrieved 2009-02-12.
- "Obesity in the Pacific Too Big To Ignore" (PDF). Secretariat of the Pacific Community. WHO. 2002. Retrieved 2008-09-30.
- World Health Organisation Globa Database on Body Mass Index
- Ogden, Cynthia L. et al. (2013). Prevalence of obesity among adults: United States, 2011-2012. Hyattsville, Md.: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Health Statistics.