An epidemic of obesity emerged in the USA in 1976–1980. The epidemic then spread to many other Westernized nations. Many interventions have been carried out with the goal of lowering the prevalence of obesity. These have mostly taken the form of various types of health promotion (i.e., providing people with education, advice, and encouragement). These actions have achieved, at most, only limited success. A strategy with a better chance of success starts with the recognition that the fundamental cause of obesity is that we live in an obesogenic environment. It is therefore necessary to change the environment so that it fosters a generally healthy lifestyle, thereby leading to enhanced health for the population, including improved weight control. A major goal is to increase the intake of healthy foods (especially fruit, vegetables, and whole grains), while decreasing intake of unhealthy foods (especially ultra-processed foods such as sugar). This will require major changes of many government policies. Some of the required policies are as follows. Schools should implement policies that create a healthy environment for children. For example, they should adopt a policy that only foods of high nutritional quality are sold in vending machines or given to students within school meals. Policies need to go well beyond the school setting; a broad strategy is needed that creates a healthy environment for children. Another important policy is the manipulation of food prices in order to shift the diet toward healthy foods. This requires using subsidies to lower the price of healthy foods, while adding a tax to less healthy foods to increase the price. This policy has been implemented in many cities and countries in the form of a tax on sugar-sweetened beverages (SSBs). The advertising of unhealthy foods (including fast-food restaurants) should be banned, especially where children and adolescents are the major target. Such a ban could be extended to a complete ban on all advertising for unhealthy foods, including that directed at adults. The proposed policy measures are likely to be strongly opposed by food corporations.