The prevalence of obesity is increasing at an alarming rate in many parts of the world. About 2 billion people are overweight and one third of them obese. The plight of the most affected populations, like those in high-income countries in North America, Australasia and Europe, has been well publicized. However, the more recent increases in population obesity in low-and middle-income countries that are now increasingly being observed have been less recognized. Based on the existing prevalence and trend data and the epidemiological evidence linking obesity with a range of physical and psychosocial health conditions, it is reasonable to describe obesity as a public health crisis that severely impairs the health and quality of life of people and adds considerably to national health-care budgets. Intersectoral action to manage and prevent obesity is urgently required to reverse current trends.