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Objectives: To examine the relationships between physical activity, sedentary behaviour and body mass index (BMI) among a sample of Australian adolescents., Methods: Anthropometric, demographic and behavioural data were collected from students (n=3040 mean age 14.6, 44% female) from 12 secondary schools in South West Victoria, Australia (response rate=48.6%). The appropriate descriptive, univariate and regression analysis were used to examine the strength of the associations between physical activity, sedentary behaviour and odds of overweight or obese and the effect of interaction between physical activity and sedentary behaviour on odds of overweight and obese., Results: Males were more likely to be active during the school day than females and had higher median hours of screen time per school day. Physical activity during the school day was associated with higher standardized BMI (BMI-z) among males. Higher levels of activity after school were associated with lower BMI-z for males and females. For both males and females the odds of overweight or obese were higher among the least active. An interaction was observed for females whereby the prevalence of overweight and obesity among the most physically active was lowest for the least sedentary and highest for the most sedentary., Conclusions: The relationships between physical activity, sedentary behaviour and BMI-z were complex. Interventions to reduce BMI through increasing physical activity or decreasing sedentary behaviour need to consider the complex inter-relationships between these variables and moderating factors such as age, sex and socio economic status in their design and interpretation., (Copyright © 2011 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Efforts to combat childhood obesity in Australia are hampered by the lack of quality epidemiological data to routinely monitor the prevalence and distribution of the condition. This paper summarises the literature on issues relevant to childhood obesity monitoring and makes recommendations for implementing a school-based childhood obesity monitoring program in Australia. The primary purpose of such a program would be to collect population-level health data to inform both policy and the development and evaluation of community-based obesity prevention interventions. Recommendations are made for the types of data to be collected, data collection procedures and program management and evaluation. Data from an obesity monitoring program are crucial for directing and informing policies, practices and services, identifying subgroups at greatest risk of obesity and evaluating progress towards meeting obesity-related targets. Such data would also increase the community awareness necessary to foster change. [ABSTRACT FROM AUTHOR]

This study examined the association of weight perception and weight satisfaction with body change intentions and weight-related behaviours in 928 overweight adolescents (aged 11–18 years, 44% female). Accurate perception of weight was associated with trying to lose weight and inaccurate perception was associated with trying to gain muscle. Weight dissatisfaction was associated with trying to lose weight and gain muscle. Accurate weight perception and weight dissatisfaction were not associated with healthy weight-related behaviours. Awareness of overweight and body dissatisfaction may be detrimental to the adoption of healthy weight-control behaviours. Interventions with overweight adolescents should encourage body satisfaction, rather than promoting awareness of overweight. [ABSTRACT FROM AUTHOR]

Background: Evidence suggests an inverse relationship between excess weight and health-related quality of life (HRQoL) in children and adolescents, however little is known about whether this association is moderated by variables such as gender and age. This study aimed to investigate these relationships. Methods: Participants were secondary school students (818 females, 52% and 765 males, 48%) from 23 secondary schools in Victoria, Australia. Age ranged from 11.0 to 19.6 years (mean age 14.5 years). The adolescent version of the Assessment of Quality of Life (AQoL) Instrument (AQoL-6D) which is a self-reported measure of adolescent quality of life was administered and anthropometric measures (height and weight) were taken. Assessment of weight status was categorized using the Body Mass Index (BMI). Results: HRQoL was associated with gender and age, but not weight status or socio-economic status; with males and younger adolescents having higher HRQoL scores than their female and older adolescent counterparts (both p < 0.05). There was also a significant interaction of weight status by gender whereby overweight females had poorer HRQoL (-.06 units) relative to healthy weight females (p < 0.05). Conclusions: This study contributes to the evidence base around factors associated with adolescent HRQoL and reveals that gender and age are important correlates of HRQoL in an Australian adolescent population. This knowledge is critical to inform the design of health promotion initiatives so they can be tailored to be gender- and age-specific. [ABSTRACT FROM AUTHOR]

Aim To determine which measurement of adiposity - standardised body mass index ( BMI-z), waist circumference or body fat percentage - is most closely correlated with adolescents' weight perception and whether this differs by gender. Methods Weight and height (used to calculate BMI-z), waist circumference and body fat percentage were measured in 2278 adolescents aged between 12 and 16 and compared with self-reported weight status. Results The distribution of subjects across the three weight categories (underweight, healthy weight and overweight) differed significantly between BMI-z, waist circumference and body fat percentage (p < 0.001). BMI-z was most closely aligned with perceived weight status in boys and girls, and waist circumference was also a good correlate of weight perception in boys. Boys were more likely than girls to underestimate their weight when it was defined by BMI-z; however, girls were equally likely to underestimate their weight when it was defined by waist circumference. The majority of adolescents underestimated their weight status when it was defined by BF%. Conclusion BMI-z is the closest correlate of self-perceived weight status. In the absence of internationally accepted reference values for waist circumference, BMI-z is the most appropriate measure to verify weight perception. [ABSTRACT FROM AUTHOR]

Objectives: A number of cross-sectional and prospective studies have now been published demonstrating inverse relationships between diet quality and the common mental disorders in adults. However, there are no existing prospective studies of this association in adolescents, the onset period of most disorders, limiting inferences regarding possible causal relationships. Methods: In this study, 3040 Australian adolescents, aged 11-18 years at baseline, were measured in 2005-6 and 2007-8. Information on diet and mental health was collected by self-report and anthropometric data by trained researchers. Results: There were cross-sectional, dose response relationships identified between measures of both healthy (positive) and unhealthy (inverse) diets and scores on the emotional subscale of the Pediatric Quality of Life Inventory (PedsQL), where higher scores mean better mental health, before and after adjustments for age, gender, socio-economic status, dieting behaviours, body mass index and physical activity. Higher healthy diet scores at baseline also predicted higher PedsQL scores at follow-up, while higher unhealthy diet scores at baseline predicted lower PedsQL scores at follow-up. Improvements in diet quality were mirrored by improvements in mental health over the follow-up period, while deteriorating diet quality was associated with poorer psychological functioning. Finally, results did not support the reverse causality hypothesis. Conclusion: This study highlights the importance of diet in adolescence and its potential role in modifying mental health over the life course. Given that the majority of common mental health problems first manifest in adolescence, intervention studies are now required to test the effectiveness of preventing the common mental disorders through dietary modification. [ABSTRACT FROM AUTHOR]