Increasing proportions of Australians are overweight or obese, a problem shared by all developed and, increasingly, developing nations. Now as many people in the world are overweight as underweight. Increasing obesity is a serious public health as well as economic problem. Its associated greater risks of high blood pressure, heart disease, osteoarthritis, type 2 diabetes, some cancers and other health problems consume considerable proportions of healthcare budgets. Health inequalities often reflect social inequalities, but with overweight there is also a male-female difference in the relationship between overweight and socioeconomic status. Health promotion campaigns are underestimating the social determinants of health, and "risk fatigue" is affecting attitudes to complying with healthy lifestyle standards. Proposals to reverse the obesity trend, such as taxing or restricting the advertising of unhealthy foods, raise contentious issues of choice and regulation.