Introduction: It is important to be aware of the ethical pitfalls in programmes to prevent overweight and obesity, such as stigmatization, blaming the victim and reinforcement of health inequalities. In this article, we present an ethical framework for facilitating a structured analysis to the extent to which a programme prevents overweight or obesity is ethically acceptable. Methods: First, we made an inventory of ethical issues in programmes to prevent overweight and obesity. Secondly, we studied the available ethical frameworks that address the area of public health. Finally, we designed an ethical framework for the prevention of overweight and obesity, which was tested in two international workshops. Results: At the heart of the framework is a list of eight questions on the morally relevant features of a programme: its effects on physical health, psychosocial well-being, informed choice, cultural values, equality, privacy, responsibility and liberty. Answering these questions provides a map of the potential ethical pitfalls of a specific programme. This mapping should be followed by a structured discussion of the arguments and their importance, and the decision whether, and if so under what conditions, the programme should be implemented. Conclusion: Considering the ethical aspects of the programmes to prevent obesity or overweight is extremely important in the face of the urgent and extensive health problem of overweight and obesity. Our framework is a practical tool for systematic ethical evaluation. It is applicable to a broad range of programmes in different stages of development and implementation.