Background: Evidence suggests that underweight is associated with health consequences and has a higher prevalence among adults with learning disabilities compared to the general population. This research aimed to explore the perceptions of support staff of underweight in the adults with learning disabilities they support.

Method: Eleven support staff from residential learning disabilities services were interviewed. Interpretative phenomenological analysis was used to interpret the data.

Results: Three superordinate themes emerged that suggested a sense of uncertainty about supporting underweight residents, including that participants were holding conflicting ideas about underweight and were unsure about the causes and consequences of underweight. Participants perceived underweight in adults with learning disabilities as different from underweight in the general population, including that residents did not understand underweight. All participants described challenges associated with supporting underweight residents, including judgements that they might face and difficulties in encouraging underweight residents to eat. They also identified helpful strategies, including investigating underweight and trying different strategies to find one that was effective for the individual resident, and working as a team.

Conclusions: Overall, participants appeared to experience supporting underweight residents as complex and challenging, and fundamentally different from underweight in the general population. This is suggestive of an ‘us’ and ‘them’ approach, with participants’ understanding of causes of residents’ underweight possibly influencing how they responded to it. The challenges and judgements that participants described facing around supporting underweight residents can be seen in the context of underweight appearing to be overshadowed by overweight, in services and in society. Uncertainty and lack of confidence around underweight could be addressed through the development of national practice guidelines for supporting underweight residents, alongside staff training about underweight to promote awareness of it. Further research exploring the perspectives of adults with learning disabilities and of other professionals could helpfully inform such interventions.