For thousands of years obesity was rarely seen.^[157] It was not until the 20th century that it became common, so much so that in 1997 the WHO formally recognized obesity as a global epidemic.^[75] As of 2005 the WHO estimates that at least 400 million adults (9.8%) are obese, with higher rates among women than men.^[1] The rate of obesity also increases with age at least up to 50 or 60 years old.^[9] Once considered a problem only of high-income countries, obesity rates are rising worldwide. These increases have been felt most dramatically in urban settings.^[1] The only remaining region of the world where obesity is not common is sub-Saharan Africa.

World obesity prevalence among males.55% ">^[156]

<5% 5–10% 10–15% 15–20% 20–25% 25–30% 30–35% 35–40% 40–45% 45–50% 50–55%
>55%