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. The rate of obesity also increases with age at least up to 50 or 60 years old. 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.
-in Australia
Obesity in Australia has been described as an "epidemic" with "increasing frequency." The Medical Journal of Australia found that obesity in Australia more than doubled in the two decades preceding 2003, and the unprecedented rise in obesity has been compared to the same health crisis in America.
Prevalence of obesity in the Australian population
Australian adults
In 2007, the World Health Organization (WHO) found that 67.4% of Australian adults are overweight, ranking 21st in the world, and third out of the major countries in the Anglosphere, behind the United States (ranked 9th) and New Zealand (ranked 17th). A 2005 WHO study found that just over 20% of Australian adults are obese, which is expected to rise to roughly 29% in 2010 if current trends continue.
In the 2005 National Health Survey, 53.6% of Australians reported being overweight (above a 25 BMI), with 18% falling into the "obese" category (above a 30 BMI). This is nearly double the reported number from 1995, when 30% of adults were overweight and 11% were obese. Such representations would be skewed downward as people tend to overestimate their height and under-report their weight, the two key criteria to determine a BMI reading. In the National Health Survey, obesity reports were fairly common across the board, with no major outliers. Victoria had the lowest incidence of obesity, at 17.0% of the population, with South Australia reporting the highest numbers at 19.6%.
Australian children

The percentage of overweight and obese children in Australia, despite heavy increases in the 1980s and the first half of the 1990s, have remained mostly steady for the past 10 years, with 23 to 24% of Australians under the age of 18 classified as overweight, and 5 to 6% of the same demographic classified as obese.
Increased media attention on childhood obesity, in 2007 and 2008 especially, caused many researchers to print findings that the rate of obesity for children has reached a plateau or that the claims are simply "exaggerated." The reports caused Dr. Rosanna Capolingua, President of the Australian Medical Association, to issue a statement admonishing people and media outlets for "trivialising" the issue.
in Canada-
Obesity in Canada concern with health officials stating that it is one of the leading causes of preventable deaths in Canada. According to Forbes, Canada ranks 35 on a 2007 list of fattest countries with a percentage of 61.1% of its citizens with an unhealthy weight.
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%.

Regional differences
A 2004 study called the Canadian Community Health Survey, found 23% of Canadians 18 and older were obese and 36% more were overweight (as determined by body mass index). In children and adolescents, 8% were obese and 18% overweight. Rates of obesity varied significantly between the province, from an obesity rate of 19% in British Columbia to a rate of 34% in Newfoundland and Labrador. The prevalence of obesity in the two most populated provinces, Ontario and Quebec, matched those of thirty US states, at a level equal to or greater than 25%. The study found people that live in cities (Census Metropolitan Areas) had significantly lower obesity rates in Nova Scotia, Ontario, Manitoba, Alberta and British Columbia. In Quebec the relationship approached significance (p=0.8), while in Newfoundland and Labrador, New Brunswick and Saskatchewan the rate of obesity did not vary significantly between CMAs and rural areas.
A 2005 report released by the Canadian government's Economics Division reported that "In 2004, approximately 6.8 million Canadian adults aged 20 to 64 were overweight, and an additional 4.5 million were obese. Roughly speaking, an adult male is considered overweight when his body weight exceeds the maximum desirable weight for his height, and obese when his body weight is 20% or more over this desirable weight. A similar guideline holds true for women, but at a threshold of 25% rather than 20%. Dramatic increases in overweight and obesity among Canadians over the past 30 years have been deemed to constitute an epidemic."
-in China
Obesity in China is a health concern with according toWHO, an overall rates of obesity at below 5% as a whole but greater than 20% in some cities. It is a dramatic change from when China was experiencing famines as a result from the Great Leap Forward. The rate of obesity in China has doubled in 10 years, according to a government report. The problem is mostly confined to the cities where fast food culture and globalisation has increased the problem in comparison to poorer rural areas. However, the very large populations within cities in China means that today one fifth of the approximate total of one billion overweight or obese people on the planet are Chinese.
Issues
Statistics from the Chinese Health Ministry have revealed that urban Chinese boys age 6 are 2.5 inches taller and 6.6 pounds heavier on average than Chinese city boys 30 years ago. A leading child-health researcher, Ji Chengye, has stated that, "China has entered the era of obesity. The speed of growth is shocking."[1]
Economic expansion and the increase in living standards as a result has seen food intake increase on average in the cities and the growth of automation and transport has seen less physical labor. Rapid motorization has drastically reduced levels of cycling and walking in China. A 2002 report has revealed a direct correspondence between ownership of motorized transport by households in China and increasing obesity related problems in children and adults.
The introduction of processed foods through globalisation in China and the problem of obesity is a recent phenomenon, as only 45 years ago the country faced starvation during the leadership of Mao Zedong.
However while malnutrition has been mostly ended in cities today, millions of rural poor, especially in rural western China are still a far cry from the problem facing the cities.
The problem is affecting the young generations although some sources indicate the problem is worse with those between 35 and 59 where more than half are now overweight in cities, a figure similar to that in industrialised countries. However, they state that the younger generations are increasingly at risk. Today, 8% of 10- to 12-year-olds in China's cities are considered obese and an additional 15% are overweight, according to Chinese Ministry of Education.
-European Union
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.
-in India
Obesity has reached epidemic proportions in India in the 21stcentury, with morbid obesity affecting 5% of the country's population. India is following a trend of other developing countries that are steadily becoming more obese. Unhealthy, processed food has become much more accessible following India's continued integration in global food markets. Indians are genetically susceptible to weight accumulation especially around the waist. While studying 22 different SNPs near to MC4R gene, scientists have identified a SNP (single nucleotide polymorphism) named rs12970134 to be mostly associated with waist circumference.
NFHS data
This is a list of the states of India ranked in order of percentage of people who are overweight or obese.
States Males (%) Males rank Females (%) Females rank
Punjab
30.3 1 37.5 1
Goa
20.8 3 27 3
Tamil Nadu
19.8 4 24.4 4
Andhra Pradesh
17.6 5 22.7 10
Kerala
24.3 2 34 2
Sikkim
17.3 6 21 8
Mizoram
16.9 7 20.3 17
Himachal Pradesh
16 8 19.5 12
Maharashtra
15.9 9 18.1 13
Gujarat
15.4 10 17.7 7
Haryana
14.4 11 17.6 6
Karnataka
14 12 17.3 9
Manipur
13.4 13 17.1 11
12.1 14 16 15
Uttarakhand
11.4 15 14.8 14
Arunachal Pradesh
10.6 16 12.5 19
Uttar Pradesh
9.9 17 12 18
Jammu and Kashmir
8.7 18 11.1 5
22
Rajasthan
8.4 20 9 20
Meghalaya
8.2 22 8.9 26
Orissa
6.9 23 8.6 25
Assam
6.7 24 7.8 21
Chattisgarh
6.5 25 7.6 27
West Bengal
6.1 26 7.1 16
Madhya Pradesh
5.4 27 6.7 23
Jharkhand
5.3 28 5.9 28
Tripura
5.2 29 5.3 24

-Iran

In Iran, as of 2008, 26.3% of the population is obese. Obesity was more among women (39.5%) than men (14.5%).
-japan
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.
in New Zealand-
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. As of June 2008, 26.5% of New Zealanders are obese, a number only surpassed in the Anglosphere by the United States.
Prevalence of obesity in New Zealand's population
New Zealand's adults
Out of a total estimated population of 4.3 million in 2008, the Ministry of Health's studies show that roughly 1.13 million New Zealand adults are overweight (BMI between 25.0 and 29.9), with an extra 826,000 obese (BMI over 30.0). The 2008 figures, which represent samples from 2006 and 2007, show that 25% of New Zealand adults are obese, a slight increase from 2002 and 2003 (24%) but a wide rise from 1997 (19%). If current trends are to continue, the obesity rate will rise to 29% by 2011.
Obesity is more prevalent in New Zealand females from age 5 until the age of 34, at which time the males overtake the females in terms of percentage. After essentially coming in at a dead heat in the 55 to 64 bracket, female obesity becomes a higher risk for 65-74 year olds than it does for males, only to switch odds again after 75.
New Zealand's children
As of 2007, over 30 percent of children in New Zealand were classified as overweight. In the 2008 figures, 8.3% of children ages 5 to 14 in New Zealand were classified as obese. While more numerous than the same demographic in Australia (between 5 and 6%), the number of obese children actually declined from a record high of 9% set in 2002. Starting in 2006, the government has worked to cut high-fat foods and high-sugar drinks from school cafeterias, and also to curb advertising for junk food during daytime television hours; these moves are being credited with slowing the rate of obesity in New Zealand, especially among the young.
-Taiwan
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, the problem of overweight and obesity does appear to be a problem.
in the United States-
Obesity in the United States hasbeen increasingly cited as a major health issue in recent decades. While many industrialized countries have experienced similar increases, obesity rates in the United States are among the highest in the world with 64% of adults being overweight or obese, and 26% are obese.
Estimates of the number of obese American adults have been steadily expanding, from 19.4% in 1997, 24.5% in 2004 to 26.6% in 2007. Should current trends continue, 75% of adults in the United States are projected to be overweight and 41% obese by 2015.
The direct medical cost of obesity and indirect economic loss to obesity has been estimated to be as high as $51.64 billion and $99.2 billion in 1995, respectively; this rose to $61 billion and $117 billion in 2000. Researchers for the Centers for Disease Control and Prevention and RTI International estimate that in 2003, obesity-attributable medical expenditures reached $75 billion.
Prevalence
Obesity rates have increased dramatically for all population groups in the United States over the last several decades. Between 1986 and 2000, the prevalence of severe obesity (BMI ≥ 40 kg/m2) quadrupled from one in two hundred Americans to one in fifty. Extreme obesity (BMI ≥ 50 kg/m2) in adults increased by a factor of five, from one in two thousand to one in four hundred. There have been similar increases seen in children and adolescents, with the prevalence of overweight in pediatric age groups nearly tripling over the same period. Approximately nine million children over six years of age are considered obese. Several recent studies have shown that the rise in obesity in the US is slowing, possibly explained by saturation of health-oriented media or a biological limit on obesity.
By age group
Historically, obesity primarily afflicted adults, but this has changed in the last 2 decades. 15-25 percent of American children are now obese. Children who are obese are likely to be obese in adulthood and to develop obesity-related health problems.
Newborns
Some newborns may be born big but this is more often a problem with a medical disorder. Unlike adults, newborns do not develop obesity. The number one cause of big babies is diabetes but this is not considered to be an obese baby.
Children & Teens
It is estimated that close to 25% of children and teenagers are either overweight or obese. The percentage is higher in minorities like Pima Indians, Latinos, Asians and African Americans.[] This has been attributed in part to sedentary lifestyle and consumption of fast foods.
Elderly
Although obesity is reported in the elderly, the numbers are still significantly lower than the levels seen in the young adult population. It is speculated that socioeconomic factors may play a role in this age group when it comes to developing obesity.
Western 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.