Degree Name

Doctor of Philosophy


Faculty of Education


In Australia, the prevalence of overweight and obesity has doubled among young people from the mid-1980s to the mid-1990s. Unfortunately, these rates have continued to increase, with recent data showing prevalence rates for obesity trebling from the 1985. Particularly pertinent for this study is the fact that in the state of New South Wales, adolescent boys aged 12 to 15 years have shown the greatest increase over this time period, compared with girls and younger boys. The increasing prevalence of adolescent overweight has been driven by key dietary, physical activity and sedentary behaviours. Using an Ecological Systems Model, these key behaviours are influenced by a range of individuals factors, as well as the settings in which adolescents spend most of their time (e.g. home and school), and the people with whom adolescents associate (e.g. family and peers). To prevent adolescent overweight and obesity, it is imperative that these factors are targeted in the development of obesity prevention interventions. To date, one of the most opportune settings for these interventions has been schools, with significant improvements reported in many outcomes, including body mass index (BMI). Despite this, there has been a dearth of evidence guided school-based obesity prevention interventions that target adolescent boys. This thesis reports on two studies that were part of The Fitness Improvement Lifestyle Awareness (FILA) Program. These were a Proof-of-Concept trial (POC trial) followed by a Pilot Randomised Controlled Trial (Pilot RCT). The aim of both studies was to assess the feasibility (screening, recruitment and retention of participants, and collection of useable measurement data), acceptability (implementation of sessions, participant attendance and enjoyment of sessions, and the promotion of the program among key staff and parents) and the potentially efficacy of a multifaceted secondary school-based obesity prevention program (The FILA Program). In both trials, The FILA Program was designed to prevent unhealthy weight gain, improve cardiorespiratory fitness, promote participation in habitual moderate to vigorous physical activity, reduce time spent in small screen recreation, increase fruit consumption and reduce sweetened beverage consumption among 12 to 13 year old boys. Social Cognitive Theory was the conceptual framework underpinning the design of both trials. The POC trial assessed the feasibility, acceptability and potential efficacy of The FILA Program among a single group of 16 Year 7 boys (mean age = 12.5 ± 0.3 years). Measurements were collected at baseline and follow-up (6 months), with the primary outcome being BMI, and waist circumference, percentage body fat, cardiorespiratory fitness, objectively measured physical activity and time spent in small screen recreation as secondary outcomes. Results confirmed that the POC trial was feasible (appropriate screening procedures), acceptable (implementation of The FILA Program; participant attendance and enjoyment of sessions; and staff satisfaction) and potentially efficacious. With a larger sample and a comparison group, the Pilot RCT endeavoured to more thoroughly test the potential efficacy of The FILA Program. The Pilot RCT was a 16 week, 2-arm parallel group trial, in which 33 Year 7 boys (mean age = 12.5 ± 0.4 years) participated. The boys were randomly assigned to an intervention (n = 16) or active comparison group (n = 17). The intervention consisted of one 60 minute curriculum session and two 20 minute lunchtime sessions per week, for 19 weeks. The active comparison group participated in a weekly 60 minute curriculum session. The primary outcome was BMI, with additional measurements of sweetened beverage and fruit consumption included as secondary outcomes. The timing of these measurements were the same as the POC trial (baseline and 6 month follow up). The Pilot RCT verified that The FILA Program was feasible, acceptable and potentially efficacious. Goals for screening and recruitment procedures, retention of participants, collection of useable data, implementation of and participant attendance at sessions and participant and staff satisfaction were attained. Potential efficacy findings reported a small to medium effect size for waist circumference, percentage body fat, cardiorespiratory fitness, weekday physical activity, time spent in small screen recreation on weekends and fruit consumption. These changes occurred with no adverse effect on participants’ physical, emotional and psychosocial functioning. Only small effect sizes were found for BMI, weekend physical activity, time spent in small screen recreation on weekdays and sweetened beverage consumption suggesting that The FILA Program was not as beneficial in modifying these outcomes. The study’s findings reinforce the potential that schools have in reducing the prevalence of adolescent overweight and obesity. Future implementations of The FILA Program will need to be tested in larger efficacy studies that are powered to detect statistically significant changes in outcomes, and enhance the understanding of Social Cognitive Theoretical constructs, by testing single or selected components.



Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.