Public Health England's (PHE) Behavioural Insights Team are leading and fully funding a randomised controlled research trial in collaboration with Derby City Council's Public Health Team and the Health and Social Care Research Centre at Derby University to test an intervention designed to help families provide healthier packed lunches for Primary School aged children.

Children in Derby gain more weight during primary school than the national average. For 4-5 year olds, Derby is in the best performing quartile of English councils, with 20% having excess weight. However, by the age of 10-11 Derby drops to the second lowest quartile, with 35% of children having excess weight . In order to reduce childhood obesity in Derby, primary schools are a key area to focus on. Furthermore, it is a priority to focus on children living in deprived areas, as there is a strong relationship between deprivation and childhood obesity.

Research shows that packed lunches are higher in sugar, salt and saturated fat than school meals. , Furthermore, the nutritional gap between packed lunches and school meals has widened since the introduction of the food-based standards for school meals in 2006. A cross sectional survey, assessing packed lunches of 1,294 children in 87 primary schools, found only 1% met the standards for school meals in England, with 82% containing restricted snacks, i.e., crisps or confectionary, and 61% including sugar sweetened drinks. Therefore, significantly improving the quality of packed lunches could be an important step to reducing childhood obesity rates in Derby.

Previous research has highlighted that improving the quality of packed lunches can be challenging. For example, a UK-wide randomised controlled trial found that a "SMART lunch box" intervention had a positive impact on certain food groups but failed to reduce the overall calories in lunchboxes. The intervention, which included an extensive set of approaches, e.g., lunch bags, food boxes, wall charts, food games and stickers, increased vegetables packed by 11% and decreased savoury snacks packed by 14%, but failed to reduce confectionary and sweetened drinks . Other interventions, using educational videos and incentives aimed at children, had similar small, yet positive effects over a 12-month period . However, research has shown that relatively small, sustained behavioural changes can have a big cumulative impact: reducing calorie consumption by just 30-100 calories a day would have a considerable effect on obesity levels . The small effects of previous studies also highlight the importance of robustly evaluating any approach that is introduced.

In order to reduce childhood obesity in Derby, primary schools are a key area to focus on. Research shows that packed lunches are higher in sugar, salt and saturated fat than school meals, and a survey found only 1% of packed lunches met the standards for school meals in England . Therefore, significantly improving the quality of packed lunches could be an important step to reducing childhood obesity rates in Derby.

This trial is designed to test whether a multiple component intervention, focused on parents and developed with an understanding of the drivers behind behaviour, can increase the healthiness of packed lunches brought into school by reducing the presence of unhealthy items.

Inclusion Criteria:

• All primary schools in Derby City
• Children in Years 3-6

Exclusion Criteria:

- Children in Years 1 - 2 due to universal provision of free school meals.

Parents and pupils will not be informed that their school is taking part in this research or that anonymous photographs will be taken of the contents of the lunch boxes brought into school by children in years 3 - 6.

Written consent was obtained from the Head Teacher in all participating schools.

Providing parents with information about the study is likely to change their behaviour and it will not be possible to assess whether the intervention itself has had an effect.