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Background: To determine the effects of participation in Curtin University's Activity, Food and Attitudes Program (CAFAP), a community-based, family-centered behavioural intervention, on the physical activity, sedentary time, and healthy eating behaviours of overweight and obese adolescents., Methods: In this waitlist controlled clinical trial in Western Australia, adolescents (n = 69, 71% female, mean age 14.1 (SD 1.6) years) and parents completed an 8-week intervention followed by 12 months of telephone and text message support. Assessments were completed at baseline, before beginning the intervention, immediately following the intervention, and at 3-, 6-, and 12- months follow-up. The primary outcomes were physical activity and sedentary time assessed by accelerometers and servings of fruit, vegetables and junk food assessed by 3-day food records., Results: During the intensive 8-week intervention sedentary time decreased by -5.1 min/day/month (95% CI: -11.0, 0.8) which was significantly greater than the rate of change during the waitlist period (p = .014). Moderate physical activity increased by 1.8 min/day/month (95% CI: -0.04, 3.6) during the intervention period, which was significantly greater than the rate of change during the waitlist period (p = .041). Fruit consumption increased during the intervention period (monthly incidence rate ratio (IRR) 1.3, 95% CI: 1.10, 1.56) and junk food consumption decreased (monthly IRR 0.8, 95% CI: 0.74, 0.94) and these changes were different to those seen during the waitlist period (p = .004 and p = .020 respectively)., Conclusions: Participating in CAFAP appeared to have a positive influence on the physical activity, sedentary and healthy eating behaviours of overweight and obese adolescents and many of these changes were maintained for one year following the intensive intervention., Trial Registration: Australia and New Zealand Clinical Trials Registry ACTRN12611001187932.

Objective: To determine whether sleep timing behaviour is associated with energy intake and diet quality in children and adolescents., Design: Cross-sectional analysis of nationally representative survey data., Sample: A total of 2200 participants of the 2007 Australian National Children's Nutrition and Physical Activity Survey aged 9-16 years with 2 days of food intake data, 4 days of use of time data and complete anthropometry. Participants were grouped into one of four sleep-wake behaviour categories: early bed-early rise (EE); early bed-late rise (EL); late bed-early rise (LE) and late bed-late rise (LL). The four categories were compared for body mass index (BMI) z-score, energy intake and diet quality assessed using the Dietary Guideline Index for Children and Adolescents. Analyses were adjusted for survey design, sociodemographic characteristics, sleep duration and physical activity level (PAL)., Results: In adjusted multivariate regression models with sleep timing behaviour group as the independent variable, the 'LL' category compared with the 'EE' category had a higher BMI z-score (β=0.20, 95% confidence interval (CI) 0.06 to 0.34, P=0.007), and lower diet quality (β=-4.0, 95% CI -5.7 to -2.3, P<0.001). Children and adolescents who went to bed late also had a higher intake of extra foods (that is, energy-dense, nutrient-poor foods) while those whom went to bed early consumed more fruit and vegetables. Energy intake was associated with sleep duration (β=-4.5 kJ, 95% CI -6.7 to -2.4, P<0.001), but not sleep timing behaviour., Conclusion: Late bedtimes and late wake up times are associated with poorer diet quality, independent of sleep duration, PAL and child and sociodemographic characteristics.

Background: Both reduced moderate-to-vigorous physical activity (MVPA) and increased screen time have been implicated in the aetiology of childhood overweight/obesity. This study aimed to determine which behaviour had the stronger association with overweight/obesity., Method: 2200 randomly selected 9- to 16-year-old Australians provided four 24-h use-of-time recalls. Participants were classified into weight status categories and as high or low physical active, and high or low screen time according to Australian guidelines (≥60 min MVPA; ≤120 min recreational screen time daily). Multivariate logistic regression was used to calculate the odds ratios (OR) for overweight/obesity for each screen time and MVPA category., Results: Increased likelihood of overweight or obese was often associated with high screen time (ORs, 2.13-2.55 for boys and 1.47-1.72 for girls), but only sometimes and less strongly associated with low MVPA (ORs, 0.49-2.55 for boys and 1.06-1.47 for girls). Analyses conducted for combined screen time and MVPA categories showed screen time to be a stronger indicator of weight status than physical activity, especially in boys., Conclusion: Overweight and obesity were more strongly associated with screen time than physical activity. Screen time may be an important target for interventions aimed at reducing childhood overweight and obesity., (© 2012 The Author(s)/Acta Paediatrica © 2012 Foundation Acta Paediatrica.)

Background: Obese adolescents achieve less moderate to vigorous physical activity (MVPA) than normal-weight adolescents, but the nature and extent of the deficit is unclear. This study aimed to describe differences in MVPA across weight status categories by domain of activity (sport, play, and active transport) and specific activity-sets (e.g. team sports, playground games, and chores) using minutes of activity, estimated intensity, and estimated energy expenditure as metrics of MVPA., Method: Anthropometric, use-of-time, and pedometer data were collected on a random sample of 2,200 Australian children aged 9-16 years. Minutes of activity, intensity metabolic equivalents of tasks (METs), and energy expenditure (MET.min) within each domain were estimated using an energy cost compendium., Results: Obese adolescents reported 174 MET.min/d lower MVPA energy expenditure than normal-weight peers (p < .0001), more than accounting for the entire difference in total daily energy expenditure (154 MET.min/d). Of this difference, 121 MET.min/d was associated with lower sports participation (p < .0001) and 45 MET.min/d with less free play (p = .03). There were no differences in minutes of active transport or in reported activity intensity across weight status categories in sport, free play, or active transport. The differences in MVPA participation between obese and normal-weight adolescents were largely because of different levels of participation in team sports, cycling, partner sports (boys), and dancing (girls)., Conclusion: More than two-thirds of the difference in energy expenditure between obese and normal-weight Australian adolescents was because of lower participation in sport. Strategies for engaging obese adolescents in sport may help to redress deficits in energy expenditure., (Copyright © 2011 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.)

Background: Popular media, health experts and researchers talk about a paediatric 'obesity epidemic' with exponentially increasing rates of obesity and overweight. However, some recent reports suggest that prevalence may have plateaued. This study examined trends in the prevalence of Australian childhood overweight and obesity since 1985. Specifically, it aimed to determine whether there have been (a) overall increases in average body mass index (BMI), (b) differential patterns of change within age groups and (c) increases in BMI within each weight-status category., Method: Forty-one Australian studies of childhood weight status conducted between 1985 and 2008 were reviewed. The studies included data on 264 905 Australians aged 2-18 years, with raw data being available on 70 758 children (27%). Children were classified as overweight or obese based on BMI using the criteria of Cole et al. (BMJ, 2000). The prevalence estimates were adjusted for age and sex, and plotted against measurement year using Lowess plots and two-linear-segment models. Where raw data were available, BMI z-scores (UK 1990 standard) were plotted against measurement year for all children and children in various age groups. Lowess plots and two-linear-segment models were used to assess secular trends in BMI z-scores pre- and post-1996 within age, gender and weight-status categories., Results: There has been a plateau, or only slight increase, in the percentage of boys and girls classified as overweight or obese, with almost no change over the last 10 years. In boys and girls, prevalence rates have settled around 21-25% for overweight and obesity together, and 5-6% for obesity alone. Similar trends were found for BMI z-scores. These patterns were fairly consistent across the age span. Within each weight-status category, average BMI has not increased., Conclusions: Although levels of Australian paediatric overweight remain high, the prevalence of overweight and obesity seems to have flattened and has not followed the anticipated exponential trajectory.

Background/objectives: There are abundant data on secular trends in the body mass index (BMI) of children. However, BMI is an imperfect index of fatness, whereas skinfold thicknesses provide a more direct measure. This study aims to meta-analyse historical studies of triceps and subscapular skinfold thicknesses in young people aged 0-18 years in developed countries., Subjects/methods: A total of 154 studies conducted between 1951 and 2003 were analysed, covering 2390 reports at the age x sex x country level, and more than 458,547 young people from 30 developed countries. Percentage body fat (% BF) was estimated using the Slaughter equations. The distribution of fat on the body was indexed by the triceps/subscapular (T/S) ratio. The skewness of skinfold distributions was operationalized by the coefficient of variation and the mean-median difference., Results: There have been increases in triceps and subscapular skinfold thicknesses, at the rate of 0.4-0.5 mm per decade over the period 1951-2003. % BF has been increasing at the rate of 0.9% BF per decade. The distribution of fat on the body, as indexed by the triceps/subscapular (T/S) ratio, has become more central. There has been an increasing positive skew in the distribution of subcutaneous fat thickness in the population., Conclusions: These trends describe very unfavourable changes in the body composition of young people, foreshadowing a potential increase in the incidence of cardiovascular and metabolic disease.

Aims: This study quantifies the cross-sectional and longitudinal relationships between young people's fatness (BMI, skinfold thickness) and fitness (performance on tests of aerobic fitness)., Background: Over the last 20-30 years, young people have become fatter and less fit. It is likely that the decline in fitness is largely due to increases in fatness. There are strong mechanistic connections; within cohorts, variability in fatness accounts for about 20% of variability in running performance; there is a strong correlation between overweight prevalence and relative fitness across specific cohorts from different countries; and secular declines in fitness coincide temporally with increases in BMI., Methods: Australians aged 10-12 years tested in 1985 were matched for age, sex, BMI and triceps skinfold thickness with their counterparts tested in 1997 (n = 279 matched pairs), and 12-15 year-old tested in 1995-1996 were matched with their counterparts tested in 1999-2000 (n = 2,834 matched pairs). Performance differences on running tests in the matched datasets were compared with performance differences in the complete (unmatched) datasets., Results: Performance differences persisted even when young people were matched for fatness. Matching for fatness reduced overall performance differentials by 29-61%. Other factors such as reduced physical activity and subsequent training effect are likely to have contributed to the decline.

Objective: To investigate secular trends in waist girth and skinfold measures among Australian children from 1985 and 1997/2002, matched for body size., Subjects: A total of 2604 children (10-12 years old) measured in the 1985 Australian Health and Fitness Survey and in two later surveys of South Australian schoolchildren (1997/2002), were matched for age, stature, weight and body mass index (BMI). Measurements. The matched children were compared by ANOVA on waist and hip girths, waist-to-hip ratio (WHR) and abdominal and triceps skinfolds, taken by trained anthropometrists., Results: Between the survey periods, there were significant increases in waist girth, WHR, and the two skinfold measures, but more so for abdominal skinfold. The differences in abdominal skinfold, waist girth and WHR were greater for girls than boys., Conclusions: In Australian children matched for body size, there have been increases in measures of fatness and central adiposity over the last 20 years. This suggests that reported secular trends in BMI may be under-estimating the looming public health crisis.