Objectives: Snacks contribute to overconsumption of energy-dense foods and thence obesity. Previous studies in this area are limited by self-reported data and small samples. In a large population-based cohort of parent–child dyads, we investigated how modification of pre-packaged snack food, i.e. (a) item quantity and variety, and (b) dishware (boxed container) size affected intake. Methods: Design: Randomized trial nested within the cross-sectional Child Health CheckPoint of the Longitudinal Study of Australian Children, clustered by day of visit. Sample: 1299 11–12 year olds, 1274 parents. Exposure: 2 × 2 manipulation of snack box container size and item quantity/variety: (1) small box, few items, (2) large box, few items, (3) small box, more items, (4) large box, more items. Procedure: Participants received a snack box during a 15 min break within their 3.5 h visit; any snacks remaining were weighed. Outcomes: Consumed quantity (grams) and energy intake (kilojoules). Analyses: Unadjusted linear regression. Results: Children who were offered a greater quantity and variety of snack items consumed considerably more energy and a slightly higher food mass (main effect for energy intake: 349 kJ, 95% CI 282–416, standardized mean difference (effect size) 0.66; main effect for mass: 10 g, 95% CI 3–17, effect size 0.17). In contrast, manipulating box size had little effect on child consumption, and neither box size nor quantity/variety of items consistently affected adults’ consumption. Conclusion: In children, reducing the number and variety of snack food items available may be a more fruitful intervention than focusing on container or dishware size. Effects observed among adults were small, although we could not exclude social desirability bias in adults aware of observation.

Additional Metadata
Persistent URL dx.doi.org/10.1038/s41366-019-0407-z, hdl.handle.net/1765/118387
Journal International Journal of Obesity
Kerr, J.A, Jansen, P.W, Mensah, F.K.F, Gibbons, K. (Kay), Olds, T.S. (Tim S.), Carlin, J.B, … Wake, M. (2019). Child and adult snack food intake in response to manipulated pre-packaged snack item quantity/variety and snack box size: a population-based randomized trial. International Journal of Obesity. doi:10.1038/s41366-019-0407-z