Nutrition surveys or surveillance : one-night stands or a long-term commitment?

Many disparate groups in Australia now concur about the need for continuous food and nutrition monitoring.

Beliefs about the causes of weight change in the Australian population

OBJECTIVE: To describe self-reported weight change and beliefs about the causes of weight change and to examine whether these vary by sex and weight status.
DESIGN: This cross-sectional population study examined data from the 1995 Australian National Health and Nutrition Surveys.
SUBJECTS: A total of 10 624 randomly-selected adults provided data.
MEASURES: Objectively measured height and weight, perceptions of current weight status, self-reported weight change over the past year, and reasons for weight change.
RESULTS: Thirty-five percent of participants reported a weight gain in the last 12 months, with females, and those already overweight more likely to report a recent increase in weight. Approximately one in five participants reported a recent weight loss. Those who had recently gained weight were more likely to perceive themselves as overweight regardless of actual weight status. Commonly reported reasons for weight gain included a change in physical activity level (52% males and 35% females) and a change in the amount of food/drink consumed (30% males, 27% females). Similar reasons were given for weight loss.
CONCLUSIONS: Findings of widespread reported weight gain, particularly among those already overweight, suggest Australia's obesity epidemic may be worsening. Strategies are urgently required to better inform individuals about the factors impacting on their weight in order to prevent further weight gain.

Which aspects of socioeconomic status are related to obesity among men and women?

OBJECTIVE: This study aimed to investigate the relationships between body weight and fat distribution, and four empirically derived domains of socioeconomic status: employment, housing, migration status and family unit.

DESIGN: A population-based study was used.

PARTICIPANTS: A total of 8667 randomly-selected adults (4167 men; 4500 women) who participated in the 1995 Australian National Health and Nutrition Surveys provided data on a range of health factors including objective height, weight and body fat distribution, and a range of sociodemographic indicators.

RESULTS: Results demonstrated associations for women, after controlling for age, between the employment domain, and body mass index and waist-to-hip ratio. Low status employed women were 1.4 times as likely to be overweight as high status employed women. There were less consistent relationships observed among these factors for men. Relationships between family unit and indicators of body weight and body fat distribution were observed for both men and women, with those who were married, particularly men (OR=1.6, 95% CI 1.4-2.0), at higher risk of overweight. The migration and housing socioeconomic status domains were not consistently associated with body mass index or waist-to-hip ratio.

CONCLUSIONS: These findings indicate that different components of socioeconomic status may be important in predicting obesity, and thus should be examined separately. Future research would benefit from investigating the underlying mechanisms governing the relationships between socioeconomic status domains further, particularly those related to employment and family unit and obesity

Social factors and obesity: an investigation of the role of health behaviours

OBJECTIVES: This study evaluated a behavioural model of the relation between social factors and obesity, in which differences in body mass index (BMI) across sociodemographic groups were hypothesized to be attributable to social group differences in health behaviours affecting energy expenditure (physical activity, diet and alcohol consumption and weight control).

METHODS: A total of 8667 adults who participated in the 1995 Australian National Health and Nutrition Surveys provided data on a range of health factors including objectively measured height and weight, health behaviours, and social factors including family status, employment status, housing situation and migration status.

RESULTS: Social factors remained significant predictors of BMI after controlling for all health behaviours. Neither social factors alone, nor health behaviours alone, adequately explained the variance in BMI. Gender-specific interactions were found between social factors and individual health behaviours.

CONCLUSIONS: These results suggest that social factors moderate the relation between BMI and weight-related behaviours, and that the mechanisms underlying sociodemographic group differences in obesity may vary among men and women. Additional factors are likely to act in conjunction with current health behaviours to explain variation in obesity prevalence across sociodemographic groups.

Challenges in translating scientific evidence into mandatory food fortification policy: an antipodean case study of the folate- neural tube defect relationship

Objective: To identify challenges in translating scientific evidence of a  nutrient and health relationship into mandatory food fortification policy.
Design: A case study approach was used in which available evidence  associated with the folate–neural tube defect relationship was reviewed against the Australia New Zealand Food Regulation Ministerial Council's Policy Guideline for mandatory food fortification. Results: Three particular challenges were identified. The first is knowing when and how to act in the face of scientific uncertainty. The second is knowing how to address the special needs of at-risk individuals without compromising the health and safety of the population as a whole. The third is to ensure that a policy is sufficiently monitored and evaluated. Conclusions: Despite the availability of compelling evidence of a relationship between a particular nutrient and a health outcome, a definitive policy response may not be apparent.  Judgement and interpretation inevitably play significant roles in influencing whether and how authorities translate scientific evidence into mandatory food fortification policy. In relation to the case study, it would be prudent to undertake a risk–benefit analysis of policy alternatives and to implement nutrition education activities to promote folic acid supplement use among the target group. Should mandatory folate fortification be implemented,  comprehensive monitoring and evaluation of this policy will be essential to know that it is implemented as planned and does more good than harm. In relation to mandatory food fortification policy-making around the world,  ongoing national nutrition surveys are required to complement national policy guidelines.

Assessing the case for mandatory folate fortification : policy-making in the face of scientific uncertainties

This paper presents the view that policymakers face scientific uncertainties in assessing the case for mandatory folate fortification as a policy response to epidemiological evidence of the relationship between folate and neural tube defects. Moreover, the resolution of these uncertainties is confounded by the under-resourced state of nutrition information systems in Australia and New Zealand. The uncertainties relate to potential risks and benefits associated with the intervention for the target group and the population in general. These risks and benefits reflect the mismatch between evidence and policy that arises when addressing a presumed genetic abnormality in at-risk individuals with an intervention that is population-wide in its scope. There is an urgent need to conduct ongoing national nutrition surveys and monitor and evaluate policy interventions to strengthen the capacity of nutrition information systems to inform decision-making for this current, and future, public health nutrition policy.

Factors influencing reported food intake

A study was conducted to investigate the possible influence of body size and composition, errors in portion size estimation, level of satisfaction with body size and degree of dietary restraint on the level of reported food intake obtained using both a food frequency questionnaire and weighed food record. The findings suggest that in dietary studies based on weighed food records, 'weight consciousness', as determined using a measure of dietary restraint, could be more important than influence of body size in determining the level of reported intake.

Cross-continental comparison of national food consumption survey methods—A narrative review

Food consumption surveys are performed in many countries. Comparison of results from those surveys across nations is difficult because of differences in methodological approaches. While consensus about the preferred methodology associated with national food consumption surveys is increasing, no inventory of methodological aspects across continents is available. The aims of the present review are (1) to develop a framework of key methodological elements related to national food consumption surveys, (2) to create an inventory of these properties of surveys performed in the continents North- America, South-America, Asia and Australasia, and (3) to discuss and compare these methodological properties cross-continentally. A literature search was performed using a fixed set of search terms in different databases. The inventory was completed with all accessible information from all retrieved publications and corresponding authors were requested to provide additional information where missing. Surveys from ten individual countries, originating from four continents are listed in the inventory. The results are presented according to six major aspects of food consumption surveys. The most common dietary intake assessment method used in food consumption surveys worldwide is the 24-HDR (24 h dietary recall), occasionally administered repeatedly, mostly using interview software. Only three countries have incorporated their national food consumption surveys into continuous national health and nutrition examination surveys.

Is the health burden associated with obesity changing?

Prioritization of obesity prevention and management policy is based on one's understanding of the health risks associated with increasing body weight. However, there is evidence that the magnitude of these health risks may be changing over time. Here, the authors analyze the theoretical drivers of these changes and then examine whether there is empirical evidence to support the theory. They conclude that, although the mortality risks associated with increasing body weight may be decreasing over time, the overall health burden appears likely to increase.

Investigating the media power of a population health monitoring survey: case study of the NSW Schools Physical Activity and Nutrition Survey (SPANS)

Objective
To examine the extent and nature of news coverage of a government-funded population monitoring survey of children and the potential implications of this coverage for public health advocacy.

Methods
Case study of the NSW Schools Physical Activity and Nutrition Survey (SPANS), a population monitoring survey of school-aged children's weight and weight-related behaviours, conducted in 1997, 2004 and 2010. Printed news items from all Australian newspapers between January 1997 and December 2011 mentioning the survey findings were identified from the Factiva database and a descriptive analysis of the content conducted.

Results
Overall, 144 news items were identified. The news angles focused mainly on physical activity/sedentary behaviour; overweight/obesity and nutrition; however these angles changed between 1997 and 2011, with angles focused on physical activity/sedentary behaviour increasing, compared with overweight/obesity and nutrition angles (p=0.001). Responsibility for obesity and weight-related behaviours was most frequently assigned to parents and food marketing, and the most common solutions were policy strategies and parental/child education and support.

Conclusions
Population health surveys are newsworthy and when coupled with strategic dissemination, media can contribute to communicating health issues and interpreting findings in ways that are relevant for consumers, policy makers and stakeholders.

Implications
This case study emphasises the news value of government-funded population surveys, while providing a cautionary note about media focus on individual studies rather than a larger body of research evidence.

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 27 349 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.