BACKGROUND:Small-scale evaluations suggest that the provision of feedback to parents about their child’s weight status may improve recognition of overweight, but the effects on lifestyle behaviour are unclear and there are concerns that informing parents that their child is overweight may have harmful effects. The aims of this study were to describe the benefits and harms of providing weight feedback to parents as part of a national school-based weight-screening programme in England.METHODS:We conducted a pre-post survey of 1,844 parents of children aged 4-5 and 10-11 years who received weight feedback as part of the 2010-2011 National Child Measurement Programme. Questionnaires assessed general knowledge about the health risks associated with child overweight, parental recognition of overweight and the associated health risks in their child, child lifestyle behaviour, child self-esteem and weight-related teasing, parental experience of the feedback, and parental help-seeking behaviour. Differences in the pre-post proportions of parents reporting each outcome were assessed using a McNemar’s test.RESULTS:General knowledge about child overweight as a health issue was high at baseline and increased further after weight feedback. After feedback, the proportion of parents that correctly recognised their child was overweight increased from 21.9% to 37.7%, and more than a third of parents of overweight children sought further information regarding their child’s weight. However, parent-reported changes in lifestyle behaviours among children were minimal, and limited to increases in physical activity in the obese children only. There was some suggestion that weight feedback had a greater impact upon changing parental recognition of the health risks associated with child overweight in non-white ethnic groups.CONCLUSIONS:In this population-based sample of parents of children participating in the National Child Measurement Programme, provision of weight feedback increased recognition of child overweight and encouraged some parents to seek help, without causing obvious unfavourable effects. The impact of weight feedback on behaviour change was limited; suggesting that further work is needed to identify ways to more effectively communicate health information to parents and to identify what information and support may encourage parents in making and maintaining lifestyle changes for their child.