An epidemic of obesity has swept the Western world. It started in the USA in the late 1970s. There is strong evidence that the primary cause is that we live in an obesogenic environment. The most important factor in this regard is the consumption of ultra-processed foods (UPFs). These foods often lead to an excessive energy intake. In addition, a diet rich in UPFs has a relatively low cost. Other important factors that contribute to the obesity epidemic probably include large portion sizes and a sedentary lifestyle. This chapter explores different strategies that may help lower the prevalence of obesity. The most common strategy is based on using education, advice, and encouragement (EAE) so as to persuade people to adopt a healthier diet. EAE has been used in large numbers of health promotion interventions since the 1970s. In addition, huge amounts of EAE have been delivered to the population in other forms such as food guides. The goal has been to lower the risk of developing chronic diseases of lifestyle (CDL) including obesity. In general, EAE has achieved only modest success. An alternative strategy is based on policies carried out by governments and is referred to here as action policies. Policies of this type have a strong track record of success over the past 200 years. For that reason there is a strong rationale for employing action policies in order to counter the obesogenic environment. Several action policies are proposed including broadly based policies directed to children and adolescents and that include schools and the wider community; using taxes and subsidies as tools to encourage people to eat a healthier diet; and imposing bans on food adverts that promote the purchase of unhealthy foods.