BACKGROUND: Presidents with no possibility of re-election overvalue far-future rewards and succumb to terminal logic behavior (TLB), responding to end-of-tenure legacy concerns despite political context. Government authorities perceiving the outgoing government is losing power at the end of term behave under the logic of strategic defection (SD), dissociating from the outgoing government once it is perceived powerless. In countries where re-election is impossible and government turnover and inconstant political parties are concerns, governmental officials at all levels may show TLB and SD during transitions that affect policy sustainability. OBJECTIVES: This study aimed to understand the context during presidential transitions that makes TLB and SD relevant, whether TLB and SD affect sustainability of food and nutrition security policy (FNSP), and the tactics for navigating transitions that favor sustainability. METHODS: A case-study design was used with semi-structured qualitative interviews and document review of news articles in Guatemala. Purposeful criteria and snowball sampling were used to recruit 52 policy actors implementing an FNSP across 2 transitions; 252 news articles from the referenced period covering topics on policy programmatic areas were purposefully sampled. Interviews were analyzed using coding and thematic analyses. News articles were analyzed using a priori thematic coding for verifying themes in interviews and data triangulation. RESULTS: Governmental officials were replaced by others during transitions; political parties were perceived as inconstant. TLB and SD occurred at all levels and had consequences for sustainability of FNSP: implementation slow-down, dysfunctional collaboration, inefficient use of resources, benefits not reaching targeted groups, and loss of momentum. These occurred through individual, institutional, and political mechanisms. Civil society, international organizations, and government adopted tactics for maximizing sustainability. CONCLUSIONS: Understanding governmental officials' experiences and the extent to which TLB and SD occur and affect sustainability could be advantageous to develop compensatory actions for reaching long-term FNSP goals.