Abstract: Two principles are needed to tackle obesity effectively: inequalities must be kept at the forefront of interventions and action on the social determinants of health must involve the whole of government. On the one hand, there is a rational approach to policy, laying out the problem, examining the causes, and planning interventions. On the other is the Realpolitik, which engages politicians and fits the evidence to preconceived policies. The key is to bring the rational and the Realpolitik to work together. Ministries of Health must learn to collaborate with their counterparts operating in other sectors, because these have significant impact on health and health inequities. Conversely, other ministries must recognize that they too have an impact on health. Government considers that it has both sectoral and whole-of-government issues, and health must become part of the latter. Health is a crucial marker of the population's well-being, which is influenced by social, economic, and political factors across society.