In 1995, the World Health Organisation launched a Global School Health Initiative to reduce health risks among young people. In the UK, the National Healthy School Programme (HSP) developed as part of a wider government commitment to promoting social inclusion. One of the key issues to be tackled by the programme is childhood obesity, for obesity is widely argued to be a public health problem for which a solution needs to be found. However, the assumption that obesity is necessarily problematic and that a higher body weight leads to health problems and social exclusion, is not without challenge. Critics of anti-obesity campaigns question the significance of weight per se and highlight the potential implications of discrediting not only fatness, but also the people who are seen as fat. This paper therefore explores the experiences of young people with obesity within the secondary school environment in relation to areas of concern prioritised by the HSP. The paper draws upon data from a qualitative research study involving 18 children and young people, between the ages of 10 and 17. Data were generated in focus group discussions and individual interview with participants of a community-based obesity intervention programme in South Yorkshire, UK. Data collection took place in 2005, and thematic analysis of the data was undertaken. Findings suggest that the issues prioritised in the HSP, particularly physical exercise and healthy eating, present challenges to young people with obesity and can reinforce their vulnerability to bullying in schools and contribute to their social exclusion. It concludes that social exclusion is a process experienced by, and pertinent to, children and young people, which has meaning for their experiences of, and during, childhood and youth. The whole-school approach of the HSP may fail to adequately address the experiences of marginalised and vulnerable groups of young people within schools, challenging and undermining the social inclusion agenda in which the programme is grounded and contributing to the construction of undesirable, fat, young bodies.