'You just eyeball it': Parent and nursery staff perceptions and influences on child portion size: A reflexive thematic analysis.

Background: Childhood obesity is one of the most serious public health epidemics of the 21st century. Observational studies report that increases in portion size (PS) have occurred in parallel with levels of obesity. Increased PSs of high-energy-dense foods can promote overeating, and without compensatory behaviours, can contribute to childhood obesity. Caregivers make decisions about PSs for children in the home and nursery environment, thus are gatekeepers to child food intake. Understanding caregiver PS decisions can aid in the best practice of PS provision to young children. The aim of this study was to explore parent and nursery staff influences on child PS selection and their suggestions for useful tools/strategies in PS decisions. Methods: A qualitative design was employed using focus group discussions (FGDs) with parents and nursery staff of children aged 3-5 years. FGDs were employed given their ability to generate rich data, as well as permit the exploration of collective perceptions, attitudes, behaviours and experiences. Data were analysed using an inductive, semantic approach to reflexive thematic analysis. Results: Four FGDs were conducted: two with parents ( n  = 13), two with nursery staff ( n  = 17). Four overarching themes were derived: (i) awareness of PS guidelines; (ii) control over PS; (iii) social influences on children's eating behaviours; (iv) child-specific, social and external factors influencing parent and nursery staff PS decisions. Additionally, participants discussed tools/strategies they believe would be useful in PS decisions. Conclusion: Data from the themes suggest that caregiver control, social, child-specific and external factors are more influential than PS guidelines in both parent and nursery staff PS decisions for young children aged 3-5 years. These findings can inform future childhood obesity prevention initiatives focussed on improving parent and nursery staff provision/use of age-appropriate PSs.