Community-based natural resource management (CBNRM) has a promise to improve equitable and sustainable outcomes. However, with the growing problem of hunger and food insecurity in the global south, debate has emerged about the ability of CBNRM institutions to forge better link between forest sustainability and just food security. This paper analyses the questions of how local institutions within Nepalese community forestry mediate issues of justice and sustainability, and to what extent these CF institutions are responsive to the dual challenge of enhancing forest sustainability and food security. This study is based on a review of forest governance literature, policy documents, recent fieldworks in Lamjung and Kavre districts, while also drawing on the emerging international initiatives around linking forest to food security. Firstly, we find that there is the forest-food paradox. On the one hand, local institutions consider communal land to be crucial to the livelihoods of the poorest households. On the other hand, the current forest bureaucracy, policy and practice of forest governance continue to promote natural forest vegetation without paying attention to food crops. The legal definition of forest excludes agricultural crops, thus locking a large part of the country’s land as anti-food system. Secondly, we trace the roots of this paradox in the underlying institutional regimes of agriculture and forestry, identifying drivers to food insecurity. Using examples, we show that food security outcomes depend on how forest and agriculture are managed as unified systems. Finally, we establish that linking ‘just food security’ with forest management is likely to reinforce the social foundations of ecological sustainability. Based on this analysis, we conclude that Nepal’s community forestry institutions have the potential to further enhance food security outcomes by linking justice and sustainability agendas.