How to influence the obesity landscape using health policies.

There is widespread acceptance that a significant and sustained impact on the growing global obesity burden requires implementation of a range of health policies to influence the obesity landscape. This acceptance is underpinned by the understanding that the obesity landscape is a complex interaction between the many factors that influence an individual's dietary intake and physical activity levels. Over the past decade we have seen increasing convergence in national and international recommendations on how to best improve this obesity landscape. In the past few years this has led to a noticeable increase in the implementation of these recommended national, state and local government policies. Here, we argue that to maximise the impact of population-level policies intended to improve diet and activity environments we need to see progress in a number of key areas, namely: broadening the range of environments that can be empowered to implement policy; improving our understanding of how best to combine multiple policies and interventions; and improving our understanding of the equity impact of these policies. We also argue that a key goal moving forward should be better capture and communication of the existing activities in order to more rapidly spread the uptake of these policies globally and at scale.

Trends in child and adolescent obesity prevalence in economically advanced countries according to socioeconomic position: a systematic review.

Recent obesity trends in children and adolescents suggest a plateau. However, it is unclear whether such trends have been experienced across socioeconomic groups. We analysed whether recent trends in child and adolescent overweight and obesity differ by socioeconomic position (SEP) across economically advanced countries. Eligible studies reported overweight and obesity prevalence in children and/or adolescents (2-18 years), for at least two time points since 1990, stratified by SEP. Socioeconomic differences in trends in child and adolescent overweight and obesity over time were analysed. Differences in trends between SEP groups were observed across a majority of studies. Over half the studies indicated increasing prevalence among low SEP children and adolescents compared to a third of studies among children and adolescents with a high SEP. Around half the studies indicated widening socioeconomic inequalities in overweight and obesity. Since 2000 a majority of studies demonstrated no change or a decrease in prevalence among both high and low SEP groups. However around 40% of studies indicated widening of socioeconomic inequalities post-2000. While our study provides grounds for optimism, socioeconomic inequalities in overweight and obesity continue to widen. These findings highlight the need for greater consideration of different population groups when implementing obesity interventions.

A systematic review of the effectiveness of whole-of-community interventions by socioeconomic position.

Whole-of-community (WOC) interventions have led to modest reductions in population weight gain. Whether they exhibit differential effectiveness by socioeconomic position (SEP) remains unknown. We aimed to summarize evidence of differential effectiveness of WOC interventions by SEP. Electronic databases and grey literature were searched to identify studies that evaluated the effectiveness of a WOC intervention on behavioural change measures, energy balance behaviours and/or anthropometric outcomes according to any measure of SEP. Interventions were assessed for the following characteristics: structural changes to the environment, number of settings the intervention acted in, presence of community engagement and whether equity was considered in its design. Ten studies were included. Nine reported a greater or equal effect among low SEP groups compared with high SEP groups. These studies commonly featured interventions that incorporated structural changes to the environment, acted across more than three settings and/or employed community engagement. Conclusions did not change when excluding low-quality studies (n = 4). WOC interventions represent an effective and equitable approach for the reduction of population weight. Structural components, a larger number of settings and community engagement were common in equitable WOC interventions and should be considered in the design of future WOC interventions.

Age-specific changes in BMI and BMI distribution among Australian adults using cross-sectional surveys from 1980 to 2008.

BACKGROUND: Research efforts have focused mainly on trends in obesity among populations, or changes in mean body mass index (BMI), without consideration of changes in BMI across the BMI spectrum. Examination of age-specific changes in BMI distribution may reveal patterns that are relevant to targeting of interventions. METHODS: Using a synthetic cohort approach (which matches members of cross-sectional surveys by birth year) we estimated population representative annual BMI change across two time periods (1980 to 1989 and 1995 to 2008) by age, sex, socioeconomic position and quantiles of BMI. Our study population was a total of 27349 participants from four nationally representative Australian health surveys; Risk Factor Prevalence Study surveys (1980 and 1989), the 1995 National Nutrition Survey and the 2007/8 National Health Survey. RESULTS: We found greater mean BMI increases in younger people, in those already overweight and in those with lower education. For men, age-specific mean annual BMI change was very similar in the 1980s and the early 2000s (P=0.39), but there was a recent slowing down of annual BMI gain for older women in the 2000s compared with their same-age counterparts in the 1980s (P<0.05). BMI change was not uniform across the BMI distribution, with different patterns by age and sex in different periods. Young adults had much greater BMI gain at higher BMI quantiles, thus adding to the increased right skew in BMI, whereas BMI gain for older populations was more even across the BMI distribution. CONCLUSIONS: The synthetic cohort technique provided useful information from serial cross-sectional survey data. The quantification of annual BMI change has contributed to an understanding of the epidemiology of obesity progression and identified key target groups for policy attention-young adults, those who are already overweight and those of lower socioeconomic status.

Trends in body mass index according to educational attainment for urban Australian adults between 1980 and 2007.

BACKGROUND: We have previously demonstrated that between the years 1980 and 2000, the mean body mass index (BMI) of the urban Australian population increased, with greater increases observed with increasing BMI. The current study aimed to quantify trends over time in BMI according to level of education between 1980 and 2007. METHODS: We compared data from the 1980, 1983 and 1989 National Heart Foundation Risk Factor Prevalence Studies, 1995 National Nutrition Survey, 2000 Australian Diabetes, Obesity and Lifestyle Study and the 2007 National Health Survey. For survey comparability, analyses were restricted to urban Australian residents aged 25-64 years. BMI was calculated from measured height and weight. The education variable was dichotomised at completion of secondary school. Four age-standardised BMI indicators were compared over time by sex and education: mean BMI, mean BMI of the top 5% of the BMI distribution, prevalence of obesity (BMI⩾30 kg m(-)(2)), prevalence of class II(+) obesity (BMI⩾35 kg m(-)(2)). RESULTS: Between 1980 and 2007, the mean BMI among men increased by 2.5 and 1.7 kg m(-)(2) for those with low and high education levels, respectively, corresponding to increases in obesity prevalence of 20 (from 12-32%) and 11 (10-21%) %-points. Among women, mean BMI increased by 2.9 and 2.4 kg m(-)(2) for those with low and high education levels, respectively, corresponding to increases in obesity prevalence of 16 (12-28%) and 12 (7-19%) %-points. The prevalence of class II(+) obesity among men increased by 9 (1-10%) and 4 (1-5%) %-points for those with low and high education levels, and among women increased by 8 (4-12%) and 4 (2-6%) %-points. Absolute and relative differences between education groups generally increased over time. CONCLUSIONS: Educational differences in BMI have persisted among urban Australian adults since 1980 without improvement. Obesity prevention policies will need to be effective in those with greatest socio-economic disadvantage if we are to equitably and effectively address the population burden of obesity and its corollaries.

The effect of educational status on the relationship between obesity and risk of type 2 diabetes.

OBJECTIVE: Obesity trends are likely to increase social disparities in diabetes. The magnitude of this effect depends on the strength of the relationship between obesity and diabetes across categories of disadvantage. This study aims to test the hypothesis that education level moderates the association between obesity and fasting plasma glucose (FPG), 2-h plasma glucose (2hPG), HbA1c level, and diabetes prevalence. METHODS: We used the baseline data from the Australian Obesity, Diabetes, and Lifestyle study in 2000 (n = 8646). We performed multiple linear regression analysis adjusted for confounding factors and stratified by education level. Body mass index (BMI) and waist circumference (WC) were positively associated with FPG, 2hPG, HbA1c and prevalence of diabetes. RESULTS: No moderating effect of education on these relationships was observed in the total population. In never smokers free of diagnosed diabetes at baseline the association of WC with 2hPG and HbA1c and of BMI with HbA1c was stronger in those with a lower level of education. CONCLUSIONS: Overall, these results suggest that the association between obesity and diabetes risk is independent of educational status. However, inconsistent results suggest that further analyses of an adequately powered longitudinal study of never smokers free of diabetes would be useful to further explore this hypothesis.

The effect of obesity prevention interventions according to socioeconomic position: a systematic review.

Obesity prevention is a major public health priority. It is important that all groups benefit from measures to prevent obesity, but we know little about the differential effectiveness of such interventions within particular population subgroups. This review aimed to identify interventions for obesity prevention that evaluated a change in adiposity according to socioeconomic position (SEP) and to determine the effectiveness of these interventions across different socioeconomic groups. A systematic search of published and grey literature was conducted. Studies that described an obesity prevention intervention and reported anthropometric outcomes according to a measure of SEP were included. Evidence was synthesized using narrative analysis. A total of 14 studies were analysed, representing a range of study designs and settings. All studies were from developed countries, with eight conducted among children. Three studies were shown to have no effect on anthropometric outcomes and were not further analysed. Interventions shown to be ineffective in lower SEP participants were primarily based on information provision directed at individual behaviour change. Studies that were shown to be effective in lower SEP participants primarily included community-based strategies or policies aimed at structural changes to the environment. Interventions targeting individual-level behaviour change may be less successful in lower SEP populations. It is essential that our efforts to prevent obesity do not leave behind the most disadvantaged members of society.

A systematic review of the impact of weight loss on cancer incidence and mortality.

Obesity is well recognized as a significant risk factor for certain cancers; however, a corresponding risk reduction with weight loss is not yet clearly defined. This review aims to examine the literature investigating the effect of all types of weight loss on cancer incidence and mortality, and to more clearly describe the relationship between these two factors. A literature search identified 34 publications reporting weight loss data in relation to cancer incidence or mortality. All except one were observational studies and the majority used self-reported weights and did not define intentionality of weight loss. 16/34 studies found a significant inverse association between weight loss and cancer incidence or mortality. The remainder returned null findings. The observed association was more consistently seen in studies that investigated the effect of intentional weight loss (5/6 studies) and the risk reduction was greatest for obesity-related cancers and in women. In conclusion, intentional weight loss does result in a decreased incidence of cancer, particularly female obesity-related cancers. However, there is a need for further evaluation of sustained intentional weight loss in the obese with less reliance on self-reported weight data and more focus on male populations.

The relationship between body mass index prior to old age and disability in old age.

OBJECTIVES: To analyse the relationship between body mass index (BMI) in middle-age and disability status in old-age using data from the Melbourne Collaborative Cohort Study (MCCS). METHODS: A total of 41 514 participants enroled in the MCCS between 1990-1994. Height and weight were measured at baseline and disability, defined as limitations to self-care activities of daily living (ADLs) and self-care plus mobility activities, was identified at follow-up (2003-2007). In all, 6300 participants were <65 years at baseline, 70 years at follow-up and not missing BMI at baseline or ADLs at follow-up. The association between BMI in six categories (BMI 18.5-22.5; 22.5-25; 25-27.5; 27.5-30; 30-35; 35+) and disability status was analysed using logistic regression. Models were stratified by sex, and sequentially adjusted for age, education, country of birth, then smoking, alcohol, fruit and vegetable intake, and physical activity. RESULTS: Adjusted odds ratios for composite self-care ADL and mobility limitations compared with BMI 18.5-22.5 kg m(-2) were 1.73 (95%CI 1.14-2.64) for BMI 30-35 kg m(-2) and 3.46 (1.78-6.73) for BMI 35+ kg m(-2) in males. In females, adjusted odds ratios were 1.29 (1.00-1.68) for BMI 22.5-25 kg m(-2), 1.74 (1.35-2.24) for BMI 25-27.5 kg m(-2), 2.58 (1.98-3.36) for BMI 27.5-30 kg m(-2), 2.74 (2.10-3.58) for BMI 30-35 kg m(-2) and 4.21 (3.12-5.88) for BMI 35+ kg m(-2). CONCLUSION: A graded relationship was observed between BMI and disability in males and females, across the continuum of BMI. These results highlight the importance of a healthy body weight at middle age in order to reduce the risk of disability in old age.

Screening for diabetes.

The prevalence of type 2 diabetes is rapidly increasing. A strong rationale exists for identifying asymptomatic individuals who are at high risk or are likely to have diabetes. Screening programs may provide a conduit through which diabetes intervention may be targeted towards those who might benefit most. Diabetes screening could lessen disease burden in two ways. Firstly, by identifying people with undiagnosed diabetes, the burden of diabetes complications could be lessened through appropriate management of the condition. Secondly, by indentifying people at high risk of developing diabetes, and entering these people into diabetes prevention programs, the number of people with diabetes could be reduced. Screening for diabetes should ideally involve a non-invasive risk assessment followed by blood testing for those found to be at high risk. It should be noted that conclusive randomised controlled trial data to support the long-term health and economic impact of screening programs is lacking. The answers surrounding who and how we should screen for diabetes and the associated long term benefits will continue to evolve as the evidence base builds. As the use of screening for diabetes builds in popularity, it is essential that health care systems are sufficiently equipped to effectively manage the newly identified high risk and prevalent cases of type 2 diabetes.

Increasing body weight and risk of limitations in activities of daily living: a systematic review and meta-analysis.

This study examined the relationship between normal weight, overweight and obesity class I and II+, and the risk of disability, which is defined as impairment in activities of daily living (ADL). Systematic searching of the literature identified eight cross-sectional studies and four longitudinal studies that were comparable for meta-analysis. An additional four cross-sectional studies and one longitudinal study were included for qualitative review. Results from the meta-analysis of cross-sectional studies revealed a graded increase in the risk of ADL limitations from overweight (1.04, 95% confidence interval [CI] 1.00-1.08), class I obesity (1.16, 95% CI 1.11-1.21) and class II+ obesity (1.76, 95% CI 1.28-2.41), relative to normal weight. Meta-analyses of longitudinal studies revealed a similar graded relationship; however, the magnitude of this relationship was slightly greater for all body mass index categories. Qualitative analysis of studies that met the inclusion criteria but were not compatible for meta-analysis supported the pooled results. No studies identified met all of the pre-defined quality criteria, and subgroup analysis was inhibited due to insufficient comparable studies. We conclude that increasing body weight increases the risk of disability in a graded manner, but also emphasize the need for additional studies using contemporary longitudinal cohorts with large numbers of obese class III individuals, a range of ages and with measured height and weight, and incident ADL questions.