Background : Nutritional warnings are used as a public health strategy to prevent increases in obesity prevalence. Peru approved in 2013 and implemented in 2019 a Law requiring nutritional warnings on the marketing and packaging of processed foods high in sugar, sodium, saturated fat, and containing trans-fat. The complexity behind the implementation of this set of policies over six years provide unique learnings, essential to inform the obesity prevention context, especially when facing strong opposition from powerful stakeholders such as the food industry. Aims : Describe milestones and key stakeholders’ roles and stances during the nutritional warnings policy design in Peru; and identify and analyze the main drivers of policy change that explain its approval. Methodology : In 2021, interviews were conducted with 25 key informants, advocates and opponents of the policy, closely involved in its design. Interviews were analyzed using the Kaleidoscope Model as a theoretical framework. Relevant policy documents and news were also analyzed. Results : Milestones for this policy were the approval of the Law, Regulation, and Manual. Policy supporters were mainly from the Congress, civil society organizations, and Health Ministers; whereas opponents came from other parties in the Congress, ministries linked to the economic sector, the food industry, and media. Across the years, warning’s evolved from a single text, to traffic lights, to the approved black octagons. Main challenges included the strong opposition of powerful stakeholders; the lack of agreement for defining the appropriate evidence for nutritional warning parameters and design; and the political instability of the country. Based on the Kaleidoscope Model, the policy successfully targeted a relevant problem (unhealthy eating decisions) and had powerful advocates who effectively used focusing events to reposition the warnings in the policy agenda across the years. Negotiations weakened the policy but led to its approval. Importantly, government veto players were mostly in favor of the policy, which enabled its final approval despite the strong opposition. Conclusions : Despite the strong opposition faced and technical and political difficulties to define the best parameters and warnings’ design, Peru’s nutritional warnings policy was approved. Lessons learned are essential to inform similar and related prevention policies in Peru and elsewhere.

The authors have declared no competing interest.

Funding was provided by Bloomberg Philanthropies (grant numbers 46129 and 2019-71181). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The protocol was approved by the Comite Institucional de Etica en Investigacion (Institutional Research Ethics Committee) at Universidad Peruana Cayetano Heredia (UPCH), in Lima, Peru. The UPCH ethics committee is register at the Office for Human Research Protections (IRB00001014) and has Federalwide Assurance: FWA00000525.

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Data cannot be publicly shared because it contains potentially identifying information. Since we interviewed key stakeholders with specific and potentially unique knowledge about the nutritional warnings policy in Peru, the information they provided could ease their identification. Data requests could be sent to the corresponding author and they could be accessed on reasonable request