In recent years policy makers and public health professionals have described obesity and its associated diseases as a major global public health problem. Bioethicists have tried to address the normative implications of proposed public health interventions by developing guidelines or proposing ethical principles that ethically grounded health policy responses should take into consideration. We are reviewing here relevant literature and conclude that while there are clearly health implications resulting from the increasing number of seriously obese people across the globe, there (...) appear to be legitimate questions about the scope of the problem as well as questions about whether particular demonstrable correlations are indicative of causations. These empirical questions require further clinical and epidemiological research. We then review currently discussed public health ethics guidance documents and proposals. Suffering from the same conceptual problems that are known features of principle-based bioethics, insofar as their capacity to ground ethically justifiable policies is concerned, they are unsuitable for actual policy development. Even if the empirical questions were resolved, health policy makers could not rely on currently existing prominent public health ethics guidance documents to develop ethically defensible policies. Further empirical and ethics research is necessary to develop ethically defensible public health policies targeting obesity. (shrink)