Perception of weight status in Australian adolescents

 This thesis examined Australian adolescents’ perception of their weight and the association of weight perception with weight related behaviours. Overall, this thesis indicated that many adolescents misperceive their weight status and that this is related to gender specific body ideals. Accurate perception of weight did not promote positive health behaviours.

A framework for evaluating the impact of obesity prevention strategies on socioeconomic inequalities in weight.

We developed a theoretical framework to organize obesity prevention interventions by their likely impact on the socioeconomic gradient of weight. The degree to which an intervention involves individual agency versus structural change influences socioeconomic inequalities in weight. Agentic interventions, such as standalone social marketing, increase socioeconomic inequalities. Structural interventions, such as food procurement policies and restrictions on unhealthy foods in schools, show equal or greater benefit for lower socioeconomic groups. Many obesity prevention interventions belong to the agento-structural types of interventions, and account for the environment in which health behaviors occur, but they require a level of individual agency for behavioral change, including workplace design to encourage exercise and fiscal regulation of unhealthy foods or beverages. Obesity prevention interventions differ in their effectiveness across socioeconomic groups. Limiting further increases in socioeconomic inequalities in obesity requires implementation of structural interventions. Further empirical evaluation, especially of agento-structural type interventions, remains crucial.

Effect of changes to the school food environment on eating behaviours and/or body weight in children: a systematic review

Previous school obesity-prevention reviews have included multi-component interventions. Here, we aimed to review the evidence for the effect of isolated food environment interventions on both eating behaviours (including food purchasing) and/or body weight. Five electronic databases were searched (last updated 30 November 2013). Of the 1,002 unique papers identified, 55 reported on school food environment changes, based on a review of titles and abstracts. Thirty-seven further papers were excluded, for not meeting the inclusion criteria. The final selection consisted of 18 papers (14 United States, 4 United Kingdom). Two studies had a body mass index (BMI) outcome, 14 assessed purchasing or eating behaviours and two studies assessed both weight and behaviour. Seventeen of 18 papers reported a positive outcome on either BMI (or change in BMI) or the healthfulness of food sold or consumed. Two studies were rated as strong quality and 11 as weak. Only three studies included a control group. A school environment supportive of healthy eating is essential to combat heavy marketing of unhealthy food. Modification of the school food environment (including high-level policy changes at state or national level) can have a positive impact on eating behaviours. A need exists, however, for further high-quality studies.

Three year follow-up of an early childhood intervention: what about physical activity and weight status?

Fundamental movement skills are a correlate of physical activity and weight status. Children who participated in a preschool intervention had greater movement skill proficiency and improved anthropometric measures (waist circumference and BMI z scores) post intervention. Three years later, intervention girls had retained their object control skill advantage. The study purpose was to assess whether at three year follow up a) intervention children were more physically active than controls and b) the intervention effect on anthropometrics was still present.

Identification of unprecedented anticancer properties of high molecular weight biomacromolecular complex containing bovine lactoferrin (HMW-bLf)

With the successful clinical trials, multifunctional glycoprotein bovine lactoferrin is gaining attention as a safe nutraceutical and biologic drug targeting cancer, chronic-inflammatory, viral and microbial diseases. Interestingly, recent findings that human lactoferrin oligomerizes under simulated physiological conditions signify the possible role of oligomerization in the multifunctional activities of lactoferrin molecule during infections and in disease targeting signaling pathways. Here we report the purification and physicochemical characterization of high molecular weight biomacromolecular complex containing bovine lactoferrin (≥250 kDa), from bovine colostrum, a naturally enriched source of lactoferrin. It showed structural similarities to native monomeric iron free (Apo) lactoferrin (∼78-80 kDa), retained anti-bovine lactoferrin antibody specific binding and displayed potential receptor binding properties when tested for cellular internalization. It further displayed higher thermal stability and better resistance to gut enzyme digestion than native bLf monomer. High molecular weight bovine lactoferrin was functionally bioactive and inhibited significantly the cell proliferation (p<0.01) of human breast and colon carcinoma derived cells. It induced significantly higher cancer cell death (apoptosis) and cytotoxicity in a dose-dependent manner in cancer cells than the normal intestinal cells. Upon cellular internalization, it led to the up-regulation of caspase-3 expression and degradation of actin. In order to identify the cutting edge future potential of this bio-macromolecule in medicine over the monomer, its in-depth structural and functional properties need to be investigated further.

Association of early childhood abdominal circumference and weight gain with blood pressure at 36 months of age: secondary analysis of data from a prospective cohort study

To assess whether changes in measures of fat distribution and body size during early life are associated with blood pressure at 36 months of age.

The influence of psychological factors on post-partum weight retention at 9 months

Design Therefore, the aim of this study was to explore the relationship between post-partum psychological distress and PWR at 9 months, after controlling for maternal weight factors, sleep quality, sociocontextual influences, and maternal behaviours. Method Pregnant women (N = 126) completed a series of questionnaires at multiple time points from early pregnancy until 9 months post-partum.

The effect of gender and age on the association between weight status and health-related quality of life in Australian adolescents

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.

Sociocultural influences on strategies to lose weight, gain weight, and increase muscles among ten cultural groups

This study determined how sociocultural messages to change one's body are perceived by adolescents from different cultural groups. In total, 4904 adolescents, including Australian, Chilean, Chinese, Indo-Fijian, Indigenous Fijian, Greek, Malaysian, Chinese Malaysian, Tongans in New Zealand, and Tongans in Tonga, were surveyed about messages from family, peers, and the media to lose weight, gain weight, and increase muscles. Groups were best differentiated by family pressure to gain weight. Girls were more likely to receive the messages from multiple sociocultural sources whereas boys were more likely to receive the messages from the family. Some participants in a cultural group indicated higher, and others lower, levels of these sociocultural messages. These findings highlight the differences in sociocultural messages across cultural groups, but also that adolescents receive contrasting messages within a cultural group. These results demonstrate the difficulty in representing a particular message as being characteristic of each cultural group.

Screen media, parenting practices, and the family environment in Australia: a longitudinal study of young children’s media use, lifestyles, and outcomes for healthy weight

Few studies of media use and adiposity explore the influence of parenting on children’s lifestyle behaviors. Screen media access, bedroom television, lack of physical activity, and snacking on energy-dense foods have long been implicated in child overweight. This research used data from the first three waves of the Longitudinal Study of Australian Children to investigate, prospectively, the associations between parental practices in early to middle childhood and children’s behaviors and weight in late childhood. A path model was used to investigate whether consistent parentingpredicted setting of boundaries for access to and use of media, and was indirectly associated with children’s lifestyle behaviors that increase the likelihood of healthy weight maintenance. The findings demonstrated that children’s lifestyles pertinent to weight maintenance and media use cluster together and involve both old and newer screen media, but are also predicted by parenting practices and the family environment.

Great 'app-eal' but not there yet: a review of iPhone nutrition applications relevant to child weight management

Aims: There is increasing interest in the use of smartphone applications (apps) for delivering child obesity management interventions and supporting lifestyle behaviour change; however, there has been very little academic research on their development. Our aim is to review nutrition-related apps designed for children currently available in Australia for their usefulness in education or support behavioural interventions for child obesity. Methods: Apps available for download in iTunes Australia between 2 April and 3 June 2013 which were suitable for children >12 years were identified. Key words were chosen to identify apps applicable to children, focusing on nutrition. Results: A total of 27 apps were included. Most apps (24/27) were not based on evidence-informed recommendations. A third of apps were developed in the USA (n = 10; 37%) and were free (67%), nine apps required upfront payment, with a mean cost of $A2.80 (range $A0.99-$A7.49). The most common nutrition features were the promotion of energy balance (n = 12 apps) and guidance on appropriate portion size (n = 15). The most common behaviour change feature was goal setting (n = 15). The five apps that scored most highly against the characteristics reviewed were: Calorie Counter Pro by My Net Diary, Weight Watchers, Swap It Don't Stop It, Control My Weight by CalorieKing and Rate What I Ate-Photo Diet Tracker. Conclusions: Very few apps were identified that could be used in education or support behavioural interventions for child obesity. There is a need to harness this technology and evaluate the applicability and use within childhood obesity research interventions.

Healthy weight regulation and eating disorder prevention in high school students: a universal and targeted web-based intervention

Background: Given the rising rates of obesity in children and adolescents, developing evidence-based weight loss or weight maintenance interventions that can be widely disseminated, well implemented, and are highly scalable is a public health necessity. Such interventions should ensure that adolescents establish healthy weight regulation practices while also reducing eating disorder risk.

Objective: This study describes an online program, StayingFit, which has two tracks for universal and targeted delivery and was designed to enhance healthy living skills, encourage healthy weight regulation, and improve weight/shape concerns among high school adolescents.

Methods: Ninth grade students in two high schools in the San Francisco Bay area and in St Louis were invited to participate. Students who were overweight (body mass index [BMI] >85th percentile) were offered the weight management track of StayingFit; students who were normal weight were offered the healthy habits track. The 12-session program included a monitored discussion group and interactive self-monitoring logs. Measures completed pre- and post-intervention included self-report height and weight, used to calculate BMI percentile for age and sex and standardized BMI (zBMI), Youth Risk Behavior Survey (YRBS) nutrition data, the Weight Concerns Scale, and the Center for Epidemiological Studies Depression Scale.

Results: A total of 336 students provided informed consent and were included in the analyses. The racial breakdown of the sample was as follows: 46.7% (157/336) multiracial/other, 31.0% (104/336) Caucasian, 16.7% (56/336) African American, and 5.7% (19/336) did not specify; 43.5% (146/336) of students identified as Hispanic/Latino. BMI percentile and zBMI significantly decreased among students in the weight management track. BMI percentile and zBMI did not significantly change among students in the healthy habits track, demonstrating that these students maintained their weight. Weight/shape concerns significantly decreased among participants in both tracks who had elevated weight/shape concerns at baseline. Fruit and vegetable consumption increased for both tracks. Physical activity increased among participants in the weight management track, while soda consumption and television time decreased.

Conclusions: Results suggest that an Internet-based, universally delivered, targeted intervention may support healthy weight regulation, improve weight/shape concerns among participants with eating disorders risk, and increase physical activity in high school students. Tailored content and interactive features to encourage behavior change may lead to sustainable improvements in adolescent health.