Dusting off the epidemiological triad: could it work with obesity

The search for effective ways of dealing with obesity has centred on biological research and clinical management. However, obesity needs to be conceptualized more broadly if the modern pandemic is to be arrested. The epidemiological triad (hosts, agent/vectors and environments) has served us well in dealing with epidemics in the past, and may be worth re-evaluating to this end. Education, behaviour change and clinical practices deal predominantly with the host, although multidisciplinary practices such as shared-care might also be expected to impact on other corners of the triad. Technology deals best with the agent of obesity (energy imbalance) and it's vectors (excessive energy intake and/or inadequate energy expenditure), and policy and social change are needed to cope with the environment. The value of a broad model like this, rather than specific isolated approaches, is that the key players such as legislators, health professionals, governments and industry can see their roles in attenuating and eventually reversing the epidemic. It also highlights the need to intervene at all levels in obesity control and reduces the relevance of arguments about nature vs. nurture.


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Snowballing obesity: Australians will get run over if they just sit there.

* Overweight and obesity are very common in Australian adults (56%) and children (27%). * Rates of overweight and obesity are snowballing and will place greater burdens on health services for the treatment and care of chronic diseases. * Prevention is urgently required from health, social and economic perspectives, but the response to date has been inadequate.
* A long-term, sustained action plan starting with a focus on young people is needed. This should particularly address the “obesogenic” environments causing the epidemic. * Although whole-of-government action is required, support from and involvement by parents, carers, community leaders, healthcare professionals, teachers, childcare workers, urban planners, recreation managers, food manufacturers, employers, advertisers, and communicators is essential. *  The health sector should take the lead, but success will only come from concerted and integrated action across the whole of society. * There are now signs of political commitment to addressing overweight and obesity. Doctors should get behind this and help mobilise community support.

Diet, nutrition and the prevention of excess weight gain and obesity

Objective: To review the evidence on the diet and nutrition causes of obesity and to recommend strategies to reduce obesity prevalence.
Design: The evidence for potential aetiological factors and strategies to reduce obesity prevalence was reviewed, and recommendations for public health action, population nutrition goals and further research were made.
Results: Protective factors against obesity were considered to be: regular physical activity (convincing); a high intake of dietary non-starch polysaccharides (NSP)/fibre (convincing); supportive home and school environments for children (probable); and breastfeeding (probable). Risk factors for obesity were considered to be sedentary lifestyles (convincing); a high intake of energy-dense, micronutrient-poor foods (convincing); heavy marketing of energy-dense foods and fast food outlets (probable); sugar-sweetened soft drinks and fruit juices (probable); adverse social and economic conditions—developed countries, especially in women (probable).
A broad range of strategies were recommended to reduce obesity prevalence including: influencing the food supply to make healthy choices easier; reducing the marketing of energy dense foods and beverages to children; influencing urban environments and transport systems to promote physical activity; developing community-wide programmes in multiple settings; increased communications about healthy eating and physical activity; and improved health services to promote breastfeeding and manage currently overweight or obese people.
Conclusions: The increasing prevalence of obesity is a major health threat in both low- and high income countries. Comprehensive programmes will be needed to turn the epidemic around.

Socioeconomic status and weight change in adults: a review

In developed countries, obesity is inversely associated with socioeconomic status (SES) among women, and less consistently among men; whereas, in developing countries, the association is direct. However, the relationship of SES to weight change over time is unknown. This relationship was the focus of the present literature review. It was hypothesized that, compared with persons of higher SES, persons of low SES would show greater weight gain or risk of weight gain over time. A search of electronic databases identified 34 relevant articles from developed countries reporting on studies that assessed the relationship of various measures of SES with weight change over time in adults (there were too few papers from developing countries (n=1) to include). Results of the methodologically strongest studies (those which obtained objectively measured adiposity data and used a follow-up period of 4 years or more) showed that, among non-black samples, there were relatively consistent inverse associations between occupation and weight gain for men and women. When SES was assessed using education, evidence was slightly less consistent, but still provided some support for the hypothesized relationship. However, when income was used as the indicator of SES, findings were inconsistent, although there were fewer studies available. There was little support for a relationship between SES and weight gain for black samples. In the context of the worldwide epidemic of obesity, these findings suggest that in developed countries, weight gain prevention efforts might best be focused on those who are most socioeconomically disadvantaged, particularly those in lower status occupations.

Globalisation, food and health in Pacific Island countries

Pacific Island countries (PICs) are experiencing an epidemic of obesity and consequent chronic diseases. Despite investment in the development of National Plans of Action for Nutrition (NPANs) and interventions to promote healthy eating and physical activity, nutritional status appears to show little improvement. This paper presents a synthesis of the findings from two research papers that were prepared for a 2003 food safety and quality meeting in Nadi, Fiji. The findings indicate that although lifestyle behaviours might be the immediate cause of dietary imbalances, greater attention should focus on omnipresent influences of globalisation as a critical element of the nutrition transition in the Pacific. In particular, those aspects of globalisation mediated through the World Trade Organization (WTO) Agreements that are placing pressures on food security and fostering increased dependence on imported food of poor nutritional quality. Rapid, significant and sustainable improvements in public health in PICs require interventions that can tackle these underlying contributors to ill health. There are opportunities to explore the use of food regulatory approaches to influence the composition, availability and accessibility of food products. Within the context of the WTO Agreements the legitimacy of food regulatory approaches will depend upon the case to demonstrate the relationship between the intervention and the protection of food security and public health nutrition. The challenges in realising these opportunities are: 1) to have the capacity to construct a case, 2) meet the technical and financial demands to administer and enforce regulatory approaches, and 3) to take advantage of opportunities available and to be able to fully participate in the international policy-making process.

Overweight and obesity in Australia: the 1999-2000 Australian Diabetes, Obesity and Lifestyle Study (AusDiab)

Objective:
To measure the prevalence of obesity in Australian adults and to examine the associations of obesity with socioeconomic and lifestyle factors.

Design:
AusDiab, a cross-sectional study conducted between May 1999 and December 2000, involved participants from 42 randomly selected districts throughout Australia.

Participants:
Of 20 347 eligible people aged > 25 years who completed a household interview, 11 247 attended the physical examination at local survey sites (response rate, 55%).

Main outcome measures:
Overweight and obesity defined by body mass index (BMI; kg/m2) and waist circumference (cm); sociodemographic factors (including smoking, physical activity and television viewing time).

Results:
The prevalence of overweight and obesity (BMI > 25.0 kg/m2; waist circumference > 80.0 cm [women] or > 94.0 cm [men]) in both sexes was almost 60%, defined by either BMI or waist circumference. The prevalence of obesity was 2.5 times higher than in 1980. Using waist circumference, the prevalence of obesity was higher in women than men (34.1% v 26.8%; P < 0.01). Lower educational status, higher television viewing time and lower physical activity time were each strongly associated with obesity, with television viewing time showing a stronger relationship than physical activity time.

Conclusions:
The prevalence of obesity in Australia has more than doubled in the past 20 years. Strong positive associations between obesity and each of television viewing time and lower physical activity time confirm the influence of sedentary lifestyles on obesity, and underline the potential benefits of reducing sedentary behaviour, as well as increasing physical activity, to curb the obesity epidemic.

Obesity prevention and public health

More than 22 million children under five are now obese or overweight. Globally, an estimated 10% of school-aged children, between five and 17 years old, are overweight or obese, and the situation is getting worse. Although recognised clinically for some time as an important condition that increases risk of ill-health in affected individuals, it is only recently, that obesity has been recognised as a population-wide problem that requires preventive action. Obesity is a major contributor to diseases and disability, the associated health costs are enormous, obesity has already reached epidemic proportions in many countries, and incidence is continuing to increase in children and adults. Disturbingly the epidemic is not confined to developed countries, with many developing countries and those in transition affected. While recognised as a major population health problem, our understanding of the causes of the epidemic is poor, there has been relatively little population-based research that has focused on the prevention of unhealthy weight gain, and as a consequence knowledge regarding how and where best to intervene is limited. This book draws together the existing literature and expertise and with a view to helping set the agenda for public health action. The book is divided into three sections. Part 1 provides an overview of the context of the problem. It examines the epidemiology of obesity, the role of behavioural factors, socio-cultural factors and environmental factors in the obesity epidemic. Part 2 reviews interventions across a range of key settings and in different population groups - drawing on existing research that has aimed to increase physical activity, promote healthy eating and prevent obesity at a population level. Given how little research there is that has specifically examined the effectiveness of interventions aimed at preventing obesity per se, Part 3 explores potential opportunities to prevent obesity

'I know I'm doing a good job': canonical and autobiographical narratives of teenage mothers

Teenage pregnancy is typically presented as a problem to be solved, if not as an epidemic in need of urgent intervention. This paper reports on Australian research that examined the phenomenon of teenage motherhood from the perspective of the young women themselves. The theoretical frame of narrative was adopted in order to understand both the way in which the young mothers were making sense of their own lives, and the way in which they interpreted the canonical narrative of teenage motherhood. Interviews with 20 young mothers demonstrated both their awareness of the canonical narrative, in which they are judged and condemned, and their contrasting autobiographical narratives, in which they are represented as good mothers who are capable of learning the skills of motherhood. Although the women refused to emphasise the disadvantages of teenage motherhood, they acknowledged difficulties. Throughout their autobiographical accounts, a 'consoling plot' was evident. Young women may be supported in their endeavour to emplot their lives to their own benefit by family narratives of teenage motherhood.

Plant pathogens causing vegetation dieback: a serious threat to the conservation of small mammals in Australia

The soil-borne plant pathogen Phytophthora cinnamomi occurs in most Australian states. It is pathogenic to many Australian species, particularly the Proteaceae, Fabaceae, Dillineaceae and Epacridaceae. In Western Australia, c. 2000 of the 9000 endemic plant species are directly affected by the disease. The epidemic of plant deaths caused by P. cinnamomi is recognised as one of 11 Key Threatening Processes to the Australian Environment, and is now also acknowledged as a potential threat fauna in a range of communities. The implications of landscape modification due to the effects of P. cinnamomi dieback prompted our research, designed to measure the distribution and abundance of small mammals in disease-affected ecosystems. This study was in the Jarrah (Eucalyptus marginata) forests in the Darling Range, Western Australia and measured the distribution and abundance of one small mammal species, the Mardo (Antechinus flavipes) by Elliott trapping in forests with (1) high, (2) mixed and (3) no evidence of Phytophthora dieback. Trap success was highest in sites with no effect of Phytophthora (7.3 animals per 100 trap nights), whereas the lowest trap success was recorded at the high impact sites (0.67 animals per 100 trap night). There was a significant difference in trap success of Mardos in Elliott trapping over 1800 trap nights (x²= 23.19, d.f = 5, p < 0.001). An examination of the distribution of individuals and sexes suggests that Phytophthora-affected sites act as sinks for Mardos, while source areas are healthy, unaffected Jarrah forest.

Estimating the changes in energy flux that characterize the rise in obesity prevalence

Background: The daily energy imbalance gap associated with the current population weight gain in the obesity epidemic is relatively small. However, the substantially higher body weights of populations that have accumulated over several years are associated with a substantially higher total energy expenditure (TEE) and total energy intake (TEI), or energy flux (EnFlux = TEE = TEI).
Objective: The objective was to develop an equation relating EnFlux to body weight in adults for estimating the rise in EnFlux associated with the obesity epidemic.
Design: Multicenter, cross-sectional data for TEE from doubly labeled water studies in 1399 adults aged 5.9 ± 18.8 y (mean ± SD) were analyzed in linear regression models with natural log (ln) weight as the dependent variable and ln EnFlux as the independent variable, adjusted for height, age, and sex. These equations were compared with those for children and applied to population trends in weight gain.
Results: ln EnFlux was positively related to ln weight (β = 0.71; 95% CI: 0.66, 0.76; R2 = 0.52), adjusted for height, age, and sex. This slope was significantly steeper than that previously described for children (β = 0.45; 95% CI: 0.38, 0.51).
Conclusions: This relation suggests that substantial increases in TEI have driven the increases in body weight over the past 3 decades. Adults have a higher proportional weight gain than children for the same proportional increase in energy intake, mostly because of a higher fat content of the weight being gained. The obesity epidemic will not be reversed without large reductions in energy intake, increases in physical activity, or both.

Economic Evaluation of a Primary Care Trial to Reduce Weight Gain in Overweight/Obese Children: The LEAP Trial

Background:- A common policy response to the childhood obesity epidemic is to recommend that primary care physicians screen for and offer counseling to the overweight/obese. As the literature suggests, this approach may be ineffective; it is important to document the opportunity costs incurred by brief primary care obesity interventions that ultimately may not alter body mass index (BMI) trajectory.

Methods:- Live, Eat and Play (LEAP) was a randomized controlled trial of a brief secondary prevention intervention delivered by family physicians in 2002-2003 that targeted overweight/ mildly obese children aged 5 to 9 years. Primary care utilization was prospectively audited via medical records, and parents reported family resource use by written questionnaire. Outcome measures were BMI (primary) and parent-reported physical activity and dietary habits (secondary) in intervention compared with control children.

Results:- The cost of LEAP per intervention family was AU $4094 greater than for control families, mainly due to increased family resources devoted to child physical activity. Total health sector costs were AU $873 per intervention family and AU $64 per control, a difference of AU $809 {P < .001). At 15 months, intervention children did not differ significantly in adjusted BMI or daily physical activity scores compared with the control group, but dietary habits had improved.

Conclusions:- This brief intervention resulted in higher costs to families and the health care sector, which could have been devoted to other uses that do create benefits to health and/or family well-being. This has implications for countries such as the United States, the United Kingdom, and Australia, whose current guidelines recommend routine surveillance and counseling for high child BMI in the primary care sector.

Obesity policy action framework and analysis grids for a comprehensive policy approach to reducing obesity

A comprehensive policy approach is needed to control the growing obesity epidemic. This paper proposes the Obesity Policy Action (OPA) framework, modified from the World Health Organization framework for the implementation of the Global Strategy on Diet, Physical Activity and Health, to provide specific guidance for governments to systematically identify areas for obesity policy action. The proposed framework incorporates three different public health approaches to addressing obesity: (i) 'upstream' policies influence either the broad social and economic conditions of society (e.g. taxation, education, social security) or the food and physical activity environments to make healthy eating and physical activity choices easier; (ii) 'midstream' policies are aimed at directly influencing population behaviours; and (iii) 'downstream' policies support health services and clinical interventions. A set of grids for analysing potential policies to support obesity prevention and management is presented. The general pattern that emerges from populating the analysis grids as they relate to the Australian context is that all sectors and levels of government, non-governmental organizations and private businesses have multiple opportunities to contribute to reducing obesity. The proposed framework and analysis grids provide a comprehensive approach to mapping the policy environment related to obesity, and a tool for identifying policy gaps, barriers and opportunities.

Sociocultural factors relating to Tongans' and Indigenous Fijians' patterns of eating, physical activity and body size

This paper reviews literature between 1974 and 2007 that addresses the impact of sociocultural factors on reported patterns of eating, physical activity (activity) and body size of Tongans and indigenous Fijians (Fijians) in their countries of origin. There have been changes in diet (more imported and fewer traditional foods), activity (reduced, especially in urban settings), residence (rural-urban shift) and body size (increased obesity and at a younger age). The prevalence of overweight/obesity in Tongans and Fijians has increased rapidly over the last two decades and remains among the highest in the world (>80% in Tonga; >40% in Fiji), with more females reported to be obese than males. The few studies that investigated sociocultural influences on patterns of eating, activity and/or body size in this population have examined the impact of hierarchical organisation, rank and status (sex, seniority), values (respect, care, co-operation) and/or role expectations. It is important to examine how sociocultural factors influence eating, activity and body size in order to i) establish factors that promote or protect against obesity, ii) inform culturally-appropriate interventions to promote healthy lifestyles and body size, and iii) halt the obesity epidemic, especially in cultural groups with a high prevalence of obesity. There is an urgent need for more systematic investigations of key sociocultural factors, whilst taking into account the complex interplay between sociocultural factors, behaviours and other influences (historical; socioeconomic; policy; external global influences; physical environment).

Preventing childhood obesity : the sentinel site for obesity prevention in Victoria, Australia

In spite of greater awareness of the need for action to reduce obesity, the evidence on sustainable community approaches to prevent childhood and adolescent obesity is surprisingly sparse. This paper describes the design and methodological components of the Sentinel Site for Obesity Prevention, a demonstration site in the Barwon-South West region of Victoria, Australia, that aims to build the programs, skills and evidence necessary to attenuate and eventually reverse the obesity epidemic in children and adolescents.

The Sentinel Site for Obesity Prevention is based on a partnership between the region's university (Deakin University) and its health, education and local government agencies. The three basic foundations of the Sentinel Site are: multi-strategy, multi-setting interventions; building community capacity; and undertaking program evaluations and population monitoring. Three intervention projects have been supported that cover different age groups (preschool: 2–5 years, primary school: 5–12 years, secondary school: 13–17 years), but that have many characteristics in common including: community participation and ownership of the project; an intervention duration of at least 3 years; and full evaluations with impact (behaviours) and outcome measures (anthropometry) compared with regionally representative comparison populations.

We recommend the Sentinel Site approach to others for successfully building evidence for childhood obesity prevention and stimulating action on reducing the epidemic.

Obesity prevention : the role of policies, laws and regulations

The commercial drivers of the obesity epidemic are so influential that obesity can be considered a robust sign of commercial success – consumers are buying more food, more cars and more energy-saving machines. It is unlikely that these powerful economic forces will change sufficiently in response to consumer desires to eat less and move more or corporate desires to be more socially responsible. When the free market creates substantial population detriments and health inequalities, government policies are needed to change the ground rules in favour of population benefits.
Concerted action is needed from governments in four broad areas: provide leadership to set the agenda and show the way; advocate for a multi-sector response and establish the mechanisms for all sectors to engage and enhance action; develop and implement policies (including laws and regulations) to create healthier food and activity environments, and; secure increased and continued funding to reduce obesogenic environments and promote healthy eating and physical activity.
Policies, laws and regulations are often needed to drive the environmental and social changes that, eventually, will have a sustainable impact on reducing obesity. An 'obesity impact assessment' on legislation such as public liability, urban planning, transport, food safety, agriculture, and trade may identify 'rules' which contribute to obesogenic environments. In other areas, such as marketing to children, school food, and taxes/levies, there may be opportunities for regulations to actively support obesity prevention. Legislation in other areas such as to reduce climate change may also contribute to obesity prevention ('stealth interventions'). A political willingness to use policy instruments to drive change will probably be an early hallmark of successful obesity prevention.