Central obesity as a precursor to the metabolic syndrome in the AusDiab study and Mauritius

Evidence from epidemiologic studies that central obesity precedes future metabolic change and does not occur concurrently with the appearance of the blood pressure, glucose, and lipid abnormalities that characterize the metabolic syndrome (MetS) has been lacking. Longitudinal surveys were conducted in Mauritius in 1987, 1992, and 1998, and in Australia in 2000 and 2005 (AusDiab). This analysis included men and women (aged 25 years) in three cohorts: AusDiab 2000–2005 (n = 5,039), Mauritius 1987–1992 (n = 2,849), and Mauritius 1987–1998 (n = 1,999). MetS components included waist circumference, systolic blood pressure, fasting and 2-h postload plasma glucose, high-density lipoprotein (HDL) cholesterol, triglycerides, and homeostasis model assessment of insulin sensitivity (HOMA-S) (representing insulin sensitivity). Linear regression was used to determine which baseline components predicted deterioration in other MetS components over 5 years in AusDiab and 5 and 11 years in Mauritius, adjusted for age, sex, and ethnic group. Baseline waist circumference predicted deterioration (P < 0.01) in four of the other six MetS variables tested in AusDiab, five of six in Mauritius 1987–1992, and four of six in Mauritius 1987–1998. In contrast, an increase in waist circumference between baseline and follow-up was only predicted by insulin sensitivity (HOMA-S) at baseline, and only in one of the three cohorts. These results suggest that central obesity plays a central role in the development of the MetS and appears to precede the appearance of the other MetS components.

Overweight, obesity and metabolic syndrome in rural south-eastern Australia

Aims & rationale/Objectives : To measure the prevalence of overweight, obesity and the metabolic syndrome in rural Australia.</p>

Methods :Two cross-sectional population surveys of chronic disease risk factors were carried out in rural Victoria (Corangamite Shire) and South Australia (Limestone Coast) in 2004-05. For both surveys, a stratified random sample of the population aged 25 to 74 years was drawn from the electoral roll. The surveys comprised a self-administered questionnaire, physical measurements and laboratory tests.</p>

Principal findings : A total of 841 individuals had complete questionnaire, health check and measured MetS data. The prevalence of overweight and obesity was 75% in males and 64.7% in females defined by BMI. Using waist circumference, the prevalence of overweight and obesity was higher in females (72.9%) than in males (63.2%). The overall prevalence of obesity of was 30.1% when defined by BMI, but 44.8% when defined by waist circumference. The prevalence of metabolic syndrome according to NCEP ATP III 2005 criteria was 29.0% in males and 28.5% in females. According to IDF criteria, the prevalence for males and females were 30.5% and 36.3%, respectively. The prevalence of metabolic syndrome and central (abdominal) obesity, hyperglycaemia, hypertension, and hypertriglyceridaemia increased with age.

Discussion : The prevalence of overweight and obesity, in particular central obesity, in rural Australia is very high as is the prevalence of metabolic syndrome.

Implications : Urgent population wide action is required to turn this trend around and regular monitoring of the trends in response to such action is essential.

The influence of hip circumference on the relationship between abdominal obesity and mortality

Background Higher waist circumference and lower hip circumference are both associated with increased cardiovascular disease (CVD) risk, despite being directly correlated. The real effects of visceral obesity may therefore be underestimated when hip circumference is not fully taken into account. We hypothesized that adding waist and hip circumference to traditional risk factors would significantly improve CVD risk prediction.

Methods In a population-based survey among South Asian and African Mauritians (n = 7978), 1241 deaths occurred during 15 years of follow-up. In a model that included variables used in previous CVD risk calculations (a Framingham-type model), the association between waist circumference and mortality was examined before and after adjustment for hip circumference. The percentage with an increase in estimated 10-year cumulative mortality of >25% and a decrease of >20% after waist and hip circumference were added to the model was calculated.

Results Waist circumference was strongly related to mortality only after adjustment for hip circumference and vice versa. Adding waist and hip circumference to a Framingham-type model increased estimated 10-year cumulative CVD mortality by >25% for 23.7% of those who died and 15.7% of those censored. Cumulative mortality decreased by >20% for 4.5% of those who died and 14.8% of those censored.

Conclusions The effect of central obesity on mortality risk is seriously underestimated without adjustment for hip circumference. Adding waist and hip circumference to a Framingham-type model for CVD mortality substantially increased predictive power. Both may be important inclusions in CVD risk prediction models.

The effect of obesity on polycystic ovary syndrome : a systematic review and meta-analysis

While many women with polycystic ovary syndrome (PCOS) are overweight, obese or centrally obese, the effect of excess weight on the outcomes of PCOS is inconsistent. The review aimed to assess the effects of overweight, obesity and central obesity on the reproductive, metabolic and psychological features of PCOS. MEDLINE, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials (CENTRAL) and PSYCINFO were searched for studies reporting outcomes according to body mass index categories or body fat distribution. Data were presented as mean difference or risk ratio (95% confidence interval). This review included 30 eligible studies. Overweight or obese women with PCOS had decreased sex hormone-binding globulin (SHBG), increased total testosterone, free androgen index, hirsutism, fasting glucose, fasting insulin, homeostatic model assessment-insulin resistance index and worsened lipid profile. Obesity significantly worsened all metabolic and reproductive outcomes measured except for hirsutism when compared to normal weight women with PCOS. Overweight women had no differences in total testosterone, hirsutism, total-cholesterol and low-density lipoprotein-cholesterol compared to normal weight women and no differences in SHBG and total testosterone compared to obese women. Central obesity was associated with higher fasting insulin levels. These results suggest that prevention and treatment of obesity is important for the management of PCOS.

The effect of physical activity on psychological distress, cortisol and obesity: results of the farming fit intervention program

Background:
Rural and regional Australians have a higher likelihood of mental illness throughout their lifetime than people living in major cities, although the underlying reasons are not yet well defined. Additionally, rural populations experience more lifestyle associated co-morbidities including obesity, diabetes and cardiovascular disease. Research conducted by the National Centre for Farmer Health between 2004 and 2009 revealed a positive correlation between obesity and psychological distress among the farming community. Chronic stress is known to overstimulate the regulation of the hypothalamic-pituitary-adrenal (HPA) axis and cortisol secretion which are associated with abdominal adiposity. Increasing physical activity may normalise cortisol secretion and thereby positively impact both physical and mental health. This paper assesses the effects of increasing physical activity on obesity, health behaviors and mental health in Victorian farming men and women.

Methods:
Farming Fit was a six month quasi-experimental (convenience sample) longitudinal design control-intervention study. Overweight or obese (BMI ?25?kg/m2) farm men (n?=?43) and women (n?=?29) were recruited with demographic, health behaviors, anthropometric, blood pressure and biochemistry data collected at baseline and at a six months. Salivary cortisol and depression anxiety stress scale results were collected at baseline, three and six months. The intervention group (n?=?37) received a personalized exercise program and regular phone coaching to promote physical activity.

Results:
The intervention group showed significant reductions in body weight and waist circumference. Results indicated that following the six month exercise program, the intervention group were 2.64???0.65?kg lighter (p?<?0.001), had reduced waist circumference by 2.01???0.86?cm (p?=?0.02) and BMI by 0.97???0.22?kg/m2 (p?<?0.001) relative to the control group.

Conclusion:
Increasing physical activity altered measures of obesity in farm men and women but did not affect mental health measures or cortisol secretion levels.

The impact of interventions to prevent obesity or improve obesity related behaviours in children (0-5 years) from socioeconomically disadvantaged and/or indigenous families: a systematic review

Background
Children from disadvantaged families including those from low socioeconomic backgrounds and Indigenous families have higher rates of obesity, making early intervention a priority. The aim of this study was to systematically review the literature to examine the effectiveness of interventions to prevent obesity or improve obesity related behaviours in children 0-5 years from socioeconomically disadvantaged or Indigenous families.

Methods
Searches of major electronic databases identified articles published from 1993–2013 targeting feeding practices, anthropometric, diet, activity or sedentary behaviour outcomes. This was supplemented with snowballing from existing reviews and primary studies. Data extraction was undertaken by one author and cross checked by another. Quality assessments included both internal and external validity.

Results
Thirty-two studies were identified, with only two (both low quality) in Indigenous groups. Fourteen studies had a primary aim to prevent obesity. Mean differences between intervention and control groups ranged from -0.29 kg/m2 to -0.54 kg/m2 for body mass index (BMI) and -2.9 to -25.6% for the prevalence of overweight/obesity. Interventions initiated in infancy (under two years) had a positive impact on obesity related behaviours (e.g. diet quality) but few measured the longer-term impact on healthy weight gain. Findings amongst pre-schoolers (3–5 years) were mixed, with the more successful interventions requiring high levels of parental engagement, use of behaviour change techniques, a focus on skill building and links to community resources. Less than 10% of studies were high quality. Future studies should focus on improving study quality, including follow-up of longer-term anthropometric outcomes, assessments of cost effectiveness, acceptability in target populations and potential for implementation in routine service delivery.

Conclusion
There is an urgent need for further research on effective obesity prevention interventions for Indigenous children. The findings from the growing body of intervention research focusing on obesity prevention amongst young children from socioeconomically disadvantaged families suggest intervention effects are modest but promising. Further high quality studies with longer term follow up are required.

The measurement of GLUT4 translocation in 3T3-L1 adipocytes

Type 2 diabetes (T2D) is one of the fastest growing threats to human health in westernised and developing countries and is associated with central obesity, atherosclerosis, dyslipidaemia, hyperinsulinaemia and  hypertension. Insulin resistance, defined as a diminished response to ordinary levels of circulating insulin in one or more peripheral tissues, is an integral feature of T2D pathophysiology. This includes an impairment of insulin to inhibit hepatic glucose output and to stimulate glucose disposal into muscle and fat. While insulin is responsible for a number of specific biological responses, stimulation of glucose transport is critical for the maintenance of glucose homeostasis. The primary mechanism for insulin stimulation of glucose uptake into muscle and fat is the translocation of glucose transporter 4 (GLUT4) to the cell surface from intracellular storage vesicles within the cell. A major advantage in focussing on insulin regulation of glucose transport is that this represents the endpoint of multiple upstream signalling pathways. This chapter describes the measurement of GLUT4 translocation in cultured cells and its potential application for both  mechanistic and therapeutic studies.

The metabolic syndrome in Australia : prevalence using four definitions

Objective : To compare the prevalence of the Metabolic Syndrome (MetS) defined by four definitions and to determine which definition best identifies those at high cardiovascular disease (CVD) risk and with insulin resistance.

Methods : AusDiab is a population-based survey of 11,247 Australians. Participants had anthropometry, blood pressure, and fasting biochemistry. Ten-year CVD risk was calculated.

Results : The prevalence of the MetS using the ATPIII, WHO, IDF, and EGIR definitions was 22.1% (95%Cl: 18.8, 25.4), 21.7% (19.0, 24.3), 30.7% (27.1, 34.3), and 13.4% (11.8, 14.9), respectively. Comparing those with to those without the MetS, the odds ratios (95%CI) for having a 10 year CVD risk ≥15% were 6.6 (5.4, 8.2), 5.5 (4.7, 6.5), 5.6 (4.8, 6.6), and 3.5 (3.0, 4.1), for the WHO, ATPIII, IDF, and EGIR definitions, respectively. The population attributable risk (PAR) of high CVD risk due to the MetS was highest for the IDF (23.4%). Insulin resistance was detected in 56.1, 69.7, 50.9, and 91.1% of those meeting the ATPIII, WHO, IDF, and EGIR definitions, respectively.

Conclusion : The WHO definition was associated with the greatest CVD risk, but is not practical for clinical use. The higher PAR due to the IDF definition, with only slightly lower CVD risk than WHO, and clinical utility of the IDF definition, indicates that it may be a useful tool for CVD prevention.

A cross-sectional study of the individual, social, and built environmental correlates of pedometer based physical activity among elementary school children

Background: Children who participate in regular physical activity obtain health benefits. Preliminary pedometerbased cut-points representing sufficient levels of physical activity among youth have been established; however limited evidence regarding correlates of achieving these cut-points exists. The purpose of this study was to identify correlates of pedometer-based cut-points among elementary school-aged children.
Method: A cross-section of children in grades 5-7 (10-12 years of age) were randomly selected from the most (n = 13) and least (n = 12) ‘walkable’ public elementary schools (Perth, Western Australia), stratified by socioeconomic status. Children (n = 1480; response rate = 56.6%) and parents (n = 1332; response rate = 88.8%) completed a survey, and steps were collected from children using pedometers. Pedometer data were categorized to reflect the sex-specific pedometer-based cut-points of ≥15000 steps/day for boys and ≥12000 steps/day for girls. Associations between socio-demographic characteristics, sedentary and active leisure-time behavior, independent mobility, active transportation and built environmental variables - collected from the child and parent surveys - and meeting pedometer-based cut-points were estimated (odds ratios: OR) using generalized estimating equations.
Results: Overall 927 children participated in all components of the study and provided complete data. On average, children took 11407 ± 3136 steps/day (boys: 12270 ± 3350 vs. girls: 10681 ± 2745 steps/day; p < 0.001) and 25.9% (boys: 19.1 vs. girls: 31.6%; p < 0.001) achieved the pedometer-based cut-points. After adjusting for all other variables and school clustering, meeting the pedometer-based cut-points was negatively associated (p < 0.05) with being male (OR = 0.42), parent self-reported number of different destinations in the neighborhood (OR 0.93), and a friend’s (OR 0.62) or relative’s (OR 0.44, boys only) house being at least a 10-minute walk from home. Achieving the pedometer-based cut-points was positively associated with participating in screen-time < 2 hours/day (OR 1.88), not being driven to school (OR 1.48), attending a school located in a high SES neighborhood (OR 1.33), the average number of steps among children within the respondent’s grade (for each 500 step/day increase: OR 1.29), and living further than a 10-minute walk from a relative’s house (OR 1.69, girls only).
Conclusions: Comprehensive multi-level interventions that reduce screen-time, encourage active travel to/from school and foster a physically active classroom culture might encourage more physical activity among children.

The Melbourne Diabetes Prevention Study (MDPS) : study protocol for a randomized controlled trial

Background
Worldwide, type 2 diabetes (T2DM) prevalence has more than doubled over two decades. In Australia, diabetes is the second highest contributor to the burden of disease. Lifestyle modification programs comprising diet changes, weight loss and moderate physical activity, have been proven to reduce the incidence of T2DM in high risk individuals.

As part of the Council of Australia Governments, the State of Victoria committed to develop and support the diabetes prevention program ‘Life! Taking action on diabetes’ (Life!) which has direct lineage from effective clinical and implementation trials from Finland and Australia. The Melbourne Diabetes Prevention Study (MDPS) has been set up to evaluate the effectiveness and cost-effectiveness of a specific version of the Life! program.

Methods/design
We intend to recruit 796 participants for this open randomized clinical trial; 398 will be allocated to the intervention arm and 398 to the usual care arm. Several methods of recruitment will be used in order to maximize the number of participants. Individuals aged 50 to 75 years will be screened with a risk tool (AUSDRISK) to detect those at high risk of developing T2DM. Those with existing diabetes will be excluded. Intervention participants will undergo anthropometric and laboratory tests, and comprehensive surveys at baseline, following the fourth group session (approximately three months after the commencement of the intervention) and 12 months after commencement of the intervention, while control participants will undergo testing at baseline and 12 months only.

The intervention consists of an initial individual session followed by a series of five structured-group sessions. The first four group sessions will be carried out at two week intervals and the fifth session will occur eight months after the first group session. The intervention is based on the Health Action Process Approach (HAPA) model and sessions will empower and enable the participants to follow the five goals of the Life! program.

Discussion
This study will determine whether the effect of this intervention is larger than the effect of usual care in reducing central obesity and cardiovascular risk factors and thus the risk of developing diabetes and cardiovascular disease. Also it will evaluate how these two options compare economically.

Muscle p70S6K phosphorylation in response to soy and dairy rich meals in middle aged men with metabolic syndrome: a randomised crossover trial

The mammalian target of rapamycin (mTOR) pathway is the primary regulator of muscle protein synthesis. Metabolic syndrome (MetS) is characterized by central obesity and insulin resistance; little is known about how MetS affects the sensitivity of the mTOR pathway to feeding.

GM3 ganglioside and phosphatidylethanolamine-containing lipids are adipose tissue markers of insulin resistance in obese women

AimsThe association between central obesity and insulin resistance reflects the properties of visceral adipose tissue. Our aim was to gain further insight into this association by analysing the lipid composition of subcutaneous and omental adipose tissue in obese women with and without insulin resistance.MethodsSubcutaneous and omental adipose tissue and serum were obtained from 29 obese non-diabetic women, 13 of whom were hyperinsulinemic. Histology, and lipid and gene profiling were performed.ResultsIn omental adipose tissue of obese, insulin-resistant women, adipocyte hypertrophy and macrophage infiltration were accompanied by an increase in GM3 ganglioside and its synthesis enzyme ST3GAL5; in addition, phosphatidylethanolamine (PE) lipids were increased and their degradation enzyme, PEMT, decreased. ST3GAL5 was expressed predominantly in adipose stromovascular cells and PEMT in adipocytes. Insulin resistance was also associated with an increase in PE lipids in serum.InterpretationThe relevance of these findings to insulin resistance in humans is supported by published mouse studies in which adipocyte GM3 ganglioside, increased by the inflammatory cytokine tumour necrosis factor-α, impaired insulin action, and PEMT was required for adipocyte lipid storage. Thus, in visceral adipose tissue of obese humans, an increase in GM3 ganglioside secondary to inflammation may contribute to insulin resistance and a decrease in PEMT may be a compensatory response to adipocyte hypertrophy.International Journal of Obesity accepted article preview online, 26 October 2015. doi:10.1038/ijo.2015.223.

Behavioural determinants of the obesity epidemic

Obesity is a serious and growing public health problem affecting developed and developing countries. It is generally agreed that the causes of the current obesity epidemic are not genetic in origin, but are the result of changes in the environments in which we live. While acknowledging the importance of environmental factors, the central role of behaviour in the obesity epidemic cannot be ignored. It is our eating, physical activity and sedentary behaviours that form the interface between our biology and the environments to which we are exposed. However, a lack of understanding of the specific behaviours that are important in the aetiology of obesity poses a major constraint to preventing obesity. A better understanding of the behaviours that contribute to weight gain and obesity is critical in order to plan and implement effective obesity prevention initiatives.Theory-driven investigations of eating, physical activity and sedentary behaviours, their determinants, and their role in weight gain and obesity among different population groups are urgent research priorities. Without an understanding of the key behaviours that contribute to weight gain, and the influences on these behaviours, it will remain difficult to identify where to intervene in the environment and be confident that action will prevent obesity.

Preventive strategies against weight gain and obesity

A well-resourced, comprehensive, population-based set of strategies is needed to
attenuate and eventually reverse the current trends of increasing obesity prevalence
now apparent in most countries. The Epidemiological Triad (host, vector,
environment) has proven to be a robust model for other epidemics and is applied
to obesity. Host-based strategies are primarily educational and these tend to
be most effective among people with higher incomes and higher educational
attainment. The main vectors for a high-energy intake are energy-dense foods and
drinks and large portion sizes and, for low energy expenditure, machines that
promote physical inactivity. Vector-based strategies that alter food formulation
can have a significant impact, particularly through influencing common, highvolume
foods. The increasingly ‘obesogenic’ environments are probably the main
driving forces for the obesity epidemic. There are many environmental strategies
that can influence the physical, economic, policy or socio-cultural environments,
but the evidence base for these potentially powerful interventions is small.
Children should be the priority population for interventions, and improving the
general socio-economic conditions for disadvantaged, marginalized or poor population
sectors is also a central strategy for obesity prevention. The key settings
for interventions are schools, homes, neighbourhoods, primary health care services
and communities. The key macroenvironments for interventions are the
transport and infrastructure sector, the media and the food sector.

The taq IA and Ser311Cys polymorphisms in the dopamine D2 receptor gene and obesity

Dopamine D2 receptors (DRD2) in the central nervous system are involved in the regulation of feeding. It remains to be elucidated if mutations in the DRD2 gene contribute to the development of obesity. The aim of the present study was to investigate whether the Taq IA and Ser311Cys polymorphisms in the DRD2 gene are associated with obesity in Nauruan and Australian subjects. Subjects were selected based on extremes of the body mass index (BMI) distribution. Two groups of Australian women were selected. The leanest group had a mean BMI of 22.5 kg/m2 (range: 20.3-24.3) and the heaviest group had a mean of 36.1 kg/m2 (32.5-44.1). Four groups of Nauruan subjects were selected. Leanest men had a mean BMI of 33.0 kg/m2 (28.4-36.9), heaviest men had a mean of 52.8 kg/m2 (46.5-69.2), leanest women had a mean of 34.8 kg/m2 (28.2-41.8) and heaviest women had a mean of 55.1 kg/m2 (49.3-73.8). Subjects were genotyped for the Taq IA and Ser311Cys polymorphisms using polymerase chain reaction (PCR) restriction fragment length polymorphism analysis and allelic discrimination TaqmanTM PCR respectively. Leanest and heaviest groups were examined for differences in genotype frequency. Taq IA and Ser311Cys genotype frequencies did not differ significantly between leanest and heaviest Nauruan groups, or between leanest and heaviest Australians. Haplotype frequencies of these polymorphisms did not differ between leanest and heaviest groups. The Taq IA and Ser311Cys polymorphisms in the DRD2 gene are unlikely to be common causes of obesity in these populations.