Background:
     
     Theories of the policy process are recommended as tools to help explain both policy stasis and change.
   

Methods:
     
     A systematic review of the application of such theoretical frameworks within the field of obesity prevention policy was conducted. A meta-synthesis was also undertaken to identify the key influences on policy decision-making.
   

Results:
     
     The review identified 17 studies of obesity prevention policy underpinned by political science theories. The majority of included studies were conducted in the United States (US), with significant heterogeneity in terms of policy level (e.g., national, state) studied, areas of focus, and methodologies used. Many of the included studies were methodologically limited, in regard to rigour and trustworthiness. Prominent themes identified included the role of groups and networks, political institutions, and political system characteristics, issue framing, the use of evidence, personal values and beliefs, prevailing political ideology, and timing.
   

Conclusions:
     
     The limited application of political science theories indicates a need for future theoretically based research into the complexity of policy-making and multiple influences on obesity prevention policy processes.