Lunchtime purchasing habits and physical activity in school children and their links to obesity

Abstract

The prevalence of childhood obesity has raised concerns, with factors such as declining physical activity (PA) levels and poor food habits being suggested as contributors. Previous studies relied on self-reported data from children, liable to potential bias and errors. To address these limitations, my research adopted validated methodological approaches to explore the impact of PA and the school food environment on children's BMI. My study accurately measured height and weight , calculating BMI percentiles. Accelerometers were employed to track PA changes from early Primary 2 to later Primary 7 stages. These measures allowed a more precise assessment of their influence on BMI and blood pressure (BP). Additionally, a novel approach of observing students' lunch purchasing behaviour directly over a year, without direct questioning, revealed insights into eating habits beyond schools. Four studies were undertaken. The first analysed various school lunch choices' association with BMI using data from the Health Behaviour in School-aged Children (HBSC) and the National Diet and Nutrition Survey (NDNS). None of the lunch types correlated with BMI in either dataset. The second study investigated the influence of food outlets around secondary schools on pupils' lunch choices, I found only the percentage of cafés and bakeries significantly affected food and drink buying patterns.

The third study explored the contribution of energy and fat intakes from various lunch sources to total intake and BMI. Though a weak relationship initially emerged, further analysis accounting for socioeconomic status and ethnicity, no association was found. Fast-food outlets accounted for 23% of energy intake. Lastly, the fourth study, part of the Scottish Lifestyle Organised Sport and Health (SLOSH) project, examined over six years changes in PA's association with BMI and (BP). No significant links were found between PA levels and either BMI percentile or blood pressure, despite an overall reduction in activity levels.