Obesity has reached pandemic proportions in the world. Who is to blame for this: the person or the State (or both?). An increase in diseases associated with excess weight is also worldwide reported, such as Diabetes, Hypertension and some types of cancers. Therefore, the economic impacts of these comorbidities are an important issue to be discussed by States and citizens. Although the World Health Organization (WHO) has set and classified obesity as a disease more than 30 years ago, the American Medical Society was until recently (2010) not so sure about this definition. This article discusses the relevance of the implementation of public health policies for prevention and control of obesity, along with the possible ethical limitations to these actions, considering the autonomy of individuals regarding their health.