Epidemiology of obesity
Obesity has been observed throughout human history. Many early depictions of the human form in art and sculpture appear obese. However, it was not until the 20th century that obesity became common — so much so that, in 1997, the World Health Organization (WHO) formally recognized obesity as a global epidemic and estimated that the worldwide prevalence of obesity has nearly tripled since 1975. Obesity is defined as having a body mass index (BMI) greater than or equal to 30 kg/m2, and in June 2013 the American Medical Association classified it as a disease. In countries of the Organisation for Economic Co-operation and Development (OECD), one child out of five is overweight or obese. Once considered a problem only of high-income countries, obesity rates are rising worldwide. In 2014, the mean BMI in 128 countries was above the threshold for overweight. Globally, there are now more people who are obese than who are underweight, a trend observed in every region over the world except parts of sub-Saharan Africa and Asia. In 2013, an estimated 2.1 billion adults were overweight, as compared with 857 million in 1980. Of adults who are overweight, 31% are obese. Increases in obesity have been seen most in urban settings. Since body fat can be measured in several ways, statistics on the epidemiology of obesity vary between sources. While BMI is the most basic and commonly used indicator of obesity, other measures include waist circumference, waist-to-hip ratio, skinfold thicknesses, and bioelectrical impedance. The rate of obesity increases with age at least up to 50 or 60 years old. Sex- and gender-based differences also influence the prevalence of obesity. Globally there are more obese women than men, but the numbers differ depending on how obesity is measured. 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 doubled between the 1990s and 2000s. Egypt In Egypt, according to data from the 2016 Global Burden of Disease study, overweight and obesity (as measured by high BMI) was the country's leading risk factor driving the most death and disability combined. Asia China In the twenty first century, China faces challenges of obesity and chronic disease. 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 per day in 1980 to 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