The World Health Organization (WHO) now describes the prevalence of obesity as an epidemic. (Obesity is defined by percentage of body fat. Women with more than 32 per cent of their weight from fat and men with more than 25 per cent are deemed obese.) People all over the world are getting fatter than ever. Once considered a problem only in high-income countries, obesity is dramatically on the rise in low- and middle-income countries. In recent years, there has been a growing recognition of an emerging epidemic of obesity in the developing societies. In fact, the rate of increase in obesity prevalence in developing countries can often exceed that in the industrialised world. Indeed, the yearly rate of increase in overweight and obesity in regions of Asia, Africa and South America is two- to five-fold that seen in the United States.

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. Once considered a problem only of high-income countries, obesity rates are rising worldwide. These increases have been felt most dramatically in urban settings.

Obesity has reached epidemic proportions in India in the 21st century, 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. 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.

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.