Informing a roadmap for cross-sectoral collaboration on portion size management as a national strategy to improve population nutrition - a Delphi study.

This study informs the agenda of a cross-sectoral, coordinated movement to tackle obesity through a combination of changing social norms, individual behaviours and industry practices around portion size. Although cross-sectoral collaboration for non-communicable disease prevention is encouraged by different organizations, strategic efforts to define a common agenda on portion size have been limited thus far. This research highlights important strategies in portion size interventions and steps needed for the success of such a movement, as part of a wider effort across sectors and stakeholders to halt and reverse obesity rates in the USA.