HOMA insulin sensitivity index and the risk of all-cause mortality and cardiovascular disease events in the general population : the Australian diabetes, obesity and lifestyle study (AusDiab) study

Aims/hypothesis We assessed whether the relationships between insulin sensitivity and all-cause mortality as well as fatal or non-fatal cardiovascular disease (CVD) events are independent of elevated blood glucose, high blood pressure, dyslipidaemia and body composition in individuals without diagnosed diabetes.
Methods Between 1999 and 2000, baseline fasting insulin, glucose and lipids, 2 h plasma glucose, HbA1c, anthropometrics, blood pressure, medication use, smoking and history of CVD were collected from 8,533 adults aged >35 years from the population-based Australian Diabetes, Obesity and Lifestyle study. Insulin sensitivity was estimated by HOMA of insulin sensitivity (HOMA-%S). Deaths and fatal or non-fatal CVD events were ascertained through linkage to the National Death Index and medical records adjudication.
Results After a median of 5.0 years there were 277 deaths and 225 CVD events. HOMA-%S was not associated with all-cause mortality. Compared with the most insulin-sensitive quintile, the combined fatal or non-fatal CVD HR (95% CI) for quintiles of decreasing HOMA-%S were 1.1 (0.6–1.9), 1.4 (0.9–2.3), 1.6 (1.0–2.5) and 2.0 (1.3–3.1), adjusting for age and sex. Smoking, CVD history, hypertension, lipid-lowering medication, total cholesterol and waist-to-hip ratio moderately attenuated this relationship. However, the association was rendered non-significant by adding HDL. Fasting plasma glucose, but not HOMA-%S significantly improved the prediction of CVD, beyond that seen with other risk factors.
Conclusions/interpretation In this cohort, HOMA-%S showed no association with all-cause mortality and only a modest association with CVD events, largely explained by its association with HDL. Fasting plasma glucose was a better predictor of CVD than HOMA-%S.

Motivational interviewing and cognitive behaviour therapy in the treatment of adolescent overweight and obesity : study design and methodology

Background

Despite the high prevalence and negative physical and psychosocial consequences of overweight and obesity in adolescents, very little research has evaluated treatment in this population. Consequently, clinicians working with overweight and obese adolescents have little empirical research on which to base their practise. Cognitive behavioural therapy has demonstrated efficacy in promoting behaviour change in many treatment resistant disorders. Motivational interviewing has been used to increase motivation for change and improve treatment outcomes. In this paper we describe the rationale and design of a randomised controlled trial testing the efficacy of motivational interviewing and cognitive behaviour therapy in the treatment of overweight and obese adolescents.
Methods

Participants took part in a motivational interview or a standard semi-structured assessment interview and were then randomly allocated to a cognitive behavioural intervention or a wait-list control condition. The cognitive behavioural intervention, the CHOOSE HEALTH Program, consisted of 13 individual treatment sessions (12 face-to-face, 1 phone call) followed by 9 maintenance sessions (7 phone calls, 2 face-to-face). Assessments were conducted prior to participation, after the treatment phase and after the maintenance phase of intervention. Improvement in body composition was the primary outcome; secondary outcomes included improved cardiovascular fitness, eating and physical activity habits, family and psychosocial functioning.
Conclusion

Despite the demonstrated effectiveness of motivational interviewing and cognitive behavioural therapy in the long-term management of many treatment resistant disorders, these approaches have been under-utilised in adolescent overweight and obesity treatment. This study provides baseline data and a thorough review of the study design and treatment approach to allow for the assessment of the efficacy of motivational interviewing and cognitive behavioural therapy in the treatment of adolescent overweight and obesity. Data obtained in this study will also provide much needed information about the behavioural and psychosocial factors associated with adolescent overweight and obesity.

Hypertension induced by ω-3 polyunsaturated fatty acid deficiency is alleviated by α-linolenic acid regardless of dietary source

Ω-3 polyunsaturated fatty acid deficiency, particularly during the prenatal period, can cause hypertension in later life. This study examined the effect of different sources of α-linolenic acid (canola oil or flaxseed oil) in the prevention of hypertension and other metabolic symptoms induced by an ω-3 fatty acid-deficient diet. Dams were provided one of three experimental diets from 1 week before mating. Diets were either deficient (10% safflower oil-DEF) or sufficient (7% safflower oil+3% flaxseed oil-SUF-F; or 10% canola oil-SUF-C) in ω-3 fatty acids. The male offspring were continued on the maternal diet from weaning for the duration of the study. Body weight, ingestive behaviors, blood pressure, body composition, metabolic rate, plasma leptin and brain fatty acids were all assessed. The DEF animals were hypertensive at 24 weeks of age compared with SUF-F or SUF-C animals; this was not evident at 12 weeks. These results suggest that different sources of ALA are effective in preventing hypertension related to ω-3 fatty acid deficiency. However, there were other marked differences between the DEF and, in particular, the SUF-C phenotype including lowered body weight, adiposity, leptin and food intake in SUF-C animals. SUF-F animals also had lower, but less marked reductions in adiposity and leptin compared with DEF animals. The differences observed between DEF, SUF-F and SUF-C phenotypes indicate that body fat and leptin may be involved in ω-3 fatty acid deficiency hypertension.

Relationship between indices of adiposity obtained by peripheral quantitative computed tomography and dual-energy X-ray absorptiometry in pre-pubertal children

Background/Aim: The study investigated the relationship between indices of adiposity measured by peripheral quantitative computed tomography (pQCT) and dual-energy X-ray absorptiometry (DXA) in pre-pubertal children.

Subjects and methods: DXA-derived per cent body fat (%BF) was measured in 284 boys and 288 girls, aged 7–10 years. Cross-sections of the forearm (n=427) and lower leg (n=560) were obtained by pQCT to measure total cross-sectional area of the limb (Total CSA), Muscle CSA, Fat CSA, %Fat CSA (Fat CSA/Total CSA×100) and muscle density.

Results: Peripheral QCT-derived %Fat CSA in the forearm and lower leg correlated strongly with DXA-derived %BF (r=0.83–0.89, p<0.01) in both boys and girls. However, forearm and lower leg %Fat CSA were higher than whole body %BF by 5% and 10%, respectively. A better prediction of whole-body %BF was achieved by including %Fat CSA, muscle density and height into a hierarchical regression model. Using sex-specific regression equations, 87.7% of the boys and 83.7% of the girls had a predicted %BF within 3% units of the %BF obtained by DXA.

Conclusion: In pre-pubertal children, pQCT measures of adiposity are strongly associated with whole-body per cent body fat. This reproducible method could be an alternative technique to estimate body composition in this population.

Oral sensitivity to fatty acids, food consumption and BMI in human subjects

Fatty acids are the chemical moieties that are thought to stimulate oral nutrient sensors, which detect the fat content of foods. In animals, oral hypersensitivity to fatty acids is associated with decreased fat intake and body weight. The aims of the present study were to investigate oral fatty acid sensitivity, food selection and BMI in human subjects. The study included two parts; study 1 established in thirty-one subjects (29 (sem 1·4) years, 22·8 (sem 0·5) kg/m²) taste thresholds using 3-AFC (3-Alternate Forced Choice Methodology) for oleic, linoleic and lauric acids, and quantified oral lipase activity. During study 2, fifty-four subjects (20 (sem 0·3) years, 21·5 (sem 0·4) kg/m2) were screened for oral fatty acid sensitivity using oleic acid (1·4 mm), and they were defined as hypo- or hypersensitive via triplicate triangle tests. Habitual energy and macronutrient intakes were quantified from 2 d diet records, and BMI was calculated from height and weight. Subjects also completed a fat ranking task using custard containing varying amounts (0, 2, 6 and 10 %) of fat. Study 1 reported median lipase activity as 2 μmol fatty acids/min per l, and detection thresholds for oleic, linoleic and lauric acids were 2·2 (sem 0·1), 1·5 (sem 0·1) and 2·6 (sem 0·3) mm. Study 2 identified twelve hypersensitive subjects, and hypersensitivity was associated with lower energy and fat intakes, lower BMI (P < 0·05) and an increased ability to rank custards based on fat content (P < 0·05). Sensitivity to oleic acid was correlated to performance in the fat ranking task (r 0·4, P < 0·05). These data suggest that oral fatty acid hypersensitivity is associated with lower energy and fat intakes and BMI, and it may serve as a factor that influences fat consumption in human subjects.

Seasonal reduction in physical activity and flow-mediated dilation in children

Purpose: Cardiovascular disease is a process that has its origins in childhood. Endothelial dysfunction is the earliest detectable manifestation of cardiovascular disease. This study aimed to assess the impact of seasonal changes in physical activity (PA) and body composition on conduit artery endothelial function in children.

Method: We studied 116 children (70 girls aged 10.7 ± 0.3 yr and 46 boys aged 10.7 ± 0.3 yr) on two occasions; in the northern summer (June) and late autumn (November). We assessed flow-mediated dilation (FMD) using high-resolution Doppler ultrasound. Body composition was measured by dual-energy x-ray absorptiometry. PA was assessed using accelerometry.

Results: FMD (10.0% ± 4.3% to 7.9% ± 3.9%, P < 0.001) and PA (94.1 ± 34.8 to 77.8 ± 33.7 min·d-1, P < 0.01) decreased, while percentage body fat increased (27.6% ± 6.8% to 28.0% ± 6.6%, P < 0.001) between summer and autumn. Decreases in FMD correlated with decreases in high-intensity PA (r = 0.23, P = 0.04), and change in high-intensity PA was the only predictor of change in FMD. No relationships were evident between changes in body composition and FMD.

Conclusions: Vascular function decreased between summer and autumn in this cohort. There were no relationships between change in FMD and changes in body composition or low/moderate-intensity PA. The associations between FMD and high-intensity PA suggests that future interventions should encourage this form of behavior, particularly at the times of year associated with lower PA.

Leptin in depressed women : Cross-sectional and longitudinal data from an epidemiologic study

Background There is conflicting evidence regarding levels of leptin in depression. In this study we aimed to investigate the relationship between serum leptin level and depression in a community sample of women using both cross-sectional and longitudinal data.

Methods From among 510 women aged 20–78 yr, 83 were identified with a lifetime history of major depressive disorder or dysthymia, ascertained using the Structured Clinical Interview for DSM-IV-TR Research Version, Non-patient edition (SCID-I/NP). Serum leptin levels were measured by radioimmunoassay. Medication use and lifestyle were self-reported and body mass index (BMI) determined from measures of height and weight.

Results Using multiple linear regression, serum leptin levels were greater among women with a lifetime history of depression compared to women without any history of depression, independent of BMI. Adjusted geometric mean values of serum leptin were 16.37 (95%CI 14.70–18.23) ng/mL for depressed and 14.46 (95%CI 13.79–15.16) ng/mL for non-depressed women (P = 0.039). The hazard ratio (HR) for a de novo depressive disorder over five years increased 2.56-fold for each standard deviation increase in log-transformed serum leptin among non-smokers and this was not explained by differences in BMI, medications or other lifestyle factors (HR = 2.56, 95%CI 1.52-4.30). No association was observed for smokers.

Limitations There is potential for unrecognised confounding, recall bias and transient changes in body composition.

Conclusion Women with a lifetime history of depression have elevated levels of serum leptin, and elevated serum leptin predicts subsequent development of a depressive disorder.

Psychological responses to acute resistance exercise in men and women who are obese

The purpose of the study was to investigate the psychological response to the very first session of resistance exercise on positive well-being (PWB), psychological distress (PD), and perception of fatigue in untrained men and women who are obese. Forty-five (male = 22, female = 23) untrained, middle-aged volunteers (mean ± SEM, 51.0 ± 1.0; range, 40-69 years) participated in the study. Participants were divided into 4 groups according to sex and obesity level (i.e., men who are obese, men who are nonobese, women who are obese, women who are nonobese). The threshold for obesity was defined as waist circumference ≥94 cm for men and 80 cm for women. Measures included body composition, aerobic power, muscle strength, and quality of life (Short Form 36, SF-36). Before and after resistance exercise, participants completed the Subjective Exercise Experience Scale (SEES). Paired sample t-tests were used to assess changes in SEES scores within group pre- and post-exercise and repeated-measures analysis of variance were used to assess changes in SEES scores between groups. Exercise increased the perception of PWB in both women who are obese and nonobese, without changes in PD or fatigue. In women, the change in PWB after exercise was negatively correlated with most scales of the SF-36, particularly with the mental health dimension (r = -0.55, p < 0.01). No significant changes in PWB, PD, or fatigue were found in men who are obese. Acute resistance exercise improved PWB in women who are obese and nonobese and those with lower self-perceived quality of life scores at the start improved the most. In addition, resistance exercise did not increase feelings of distress in either women or men who are obese.

Effects of a daily school based physical activity intervention program on muscle development in prepubertal girls

This 12-month prospective controlled intervention evaluated the effect of a general school based physical activity program on muscle strength, physical performance and body composition in prepubertal girls. Fifty-three girls aged 7–9 years involved in a school based exercise program [40 min/day of general physical activity per school day (200 min/week)] were compared with 50 age-matched girls who participated in the general Swedish physical education curriculum (mean 60 min/week). Body composition (DXA), isokinetic peak torque (PT) of the knee extensors and flexors at 60 and 180°/s, and vertical jump height (VJH) were assessed at baseline and 12 months. The annual gain in weight was similar between the groups, but there was a greater increase in total body and regional lean mass (P < 0.05) and fat mass (P < 0.01) in the exercise group. Mean gains in knee extensor PT at 60 and 180°/s were 7.0–7.6% greater in the exercise group (P ranging <0.05–<0.001). No significant differences were detected in VJH. In conclusion, increasing school based physical education to at least 3 h/week provides a feasible strategy to enhance the development of muscle strength and lean mass in prepubertal girls.

Patterns of alcohol use and associated physical and lifestyle characteristics according to new Australian guidelines

Objective: To describe the pattern of alcohol consumption and associated physical and lifestyle characteristics in a population-based sample of Australian men.
Method: A community-based age-stratifi ed random sample of 1420 men (median age 56 years, range 20 – 93) participating in the Geelong Osteoporosis Study, an epidemiological study set in south-eastern Australia. Daily alcohol intake was ascertained from a detailed food frequency questionnaire and categorized according to the Australian National Health and Medical Research Council 2009 guidelines (non-drinkers, greater than zero but ≤ 2 drinks per day, > 2 drinks per day), with a standard drink equivalent to 10 g of ethanol. Anthropometry was measured and lifestyle factors self-reported. Body composition was determined using dual energy absorptiometry. Socio-economic status was categorized according to the Australian Bureau of Statistics data. Results were age standardized to the Australian male population figures.
Results: The median daily ethanol consumption was 12 g (IQR 2 – 29) per day with a range of 0 – 117 g/day. The age-standardized proportion of non-drinkers was 8.7%, 51.5% consumed up to two drinks per day ( ≤ 20 g ethanol/day), and 39.9% exceeded 2 standard drinks per day ( > 20 g ethanol/day). Alcohol consumption was positively associated with cigarette smoking, weight, higher SES and inversely with age and physical activity.
Conclusions: Approximately, 40% of Australian men consume alcohol at levels in excess of current recommendations, which in combination with other risk factors may adversely impact upon health.

Influence of maternal mass and condition on energy transfer in Weddell seals

* 1
Environmental variation influences food abundance and availability, which is reflected in the reproductive success of top predators. We examined maternal expenditure, offspring mass and condition for Weddell seals in 2 years when individuals exhibited marked differences in these traits.
* 2
For females weighing 355 kg there was a positive relationship between maternal post-partum mass (MPPM) and lactation length, but below this there was no relationship, suggesting that heavier females were able to increase lactation length but lighter females were restricted to a minimum lactation period of 33 days.
* 3
Overall, females were heavier in 2002, but in 2003 shorter females were lighter than similar-sized females in 2002 suggesting that the effects of environmental variability on foraging success and condition are more pronounced in smaller individuals.
* 4
There was no relationship between MPPM and pup birth mass, indicating pre-partum investment did not differ between years. However, there was a positive relationship between MPPM and pup mass gain. Mass and energy transfer efficiency were 10·2 and 5·4% higher in 2002 than 2003, which suggests costs associated with a putatively poor-resource year were delayed until lactation.
* 5
Heavier females lost a higher proportion of mass during lactation in both years, so smaller females may not have been able to provide more to their offspring to wean a pup of similar size to larger females.
* 6
MPPM had only a small influence on total body lipid; therefore, regardless of mass, females had the same relative body composition. Females with male pups lost a higher percentage of lipid than those with female pups, but by the end of lactation female pups had 4·5% higher lipid content than males.
* 7
It appears that for Weddell seals the consequences of environmentally induced variation in food availability are manifested in differences in maternal mass and expenditure during lactation. These differences translate to changes in pup mass and condition at weaning with potential consequences for future survival and recruitment.

Socioeconomic status and risk factors for obesity and metabolic disorders in a population-based sample of adult females

Objectives : The association between lower socioeconomic status (SES), obesity, lifestyle choices and adverse health consequences are well documented, however to date the relationship between these variables and area-based SES (equivalised for advantage and disadvantage) has not been examined simultaneously in one population or with more than tertiary divisions of SES. We set out to examine the risk factors for obesity and metabolic disorders in the same population across quintiles of area-based SES.

Methods : We performed a descriptive cross-sectional study using existing data from a population-based random selection of women aged 20–92 years (n = 1110) recruited from the Barwon Statistical Division, South Eastern Australia.

Results : All measures of adiposity were inversely associated with SES, and remained significant after adjusting for age. Lifestyle choices associated with adiposity and poorer health, including smoking, larger serving sizes of foods, and reduced physical activity, were significantly associated with individuals from lower SES groups.

Conclusions : Greater measures of adiposity and less healthy lifestyle choices were observed in individuals from lower SES. Significant differences in body composition were identified between quintiles 1 and 5, whereas subjects in the mid quintiles had relatively similar measures. The inverse relationship between SES, obesity and less healthy lifestyle underscores the possibility that these associations may be causal and should be investigated further.

Socioeconomic status, obesity and lifestyle in men : the Geelong Osteoporosis Study

Background : Although the association between lower socioeconomic status (SES) and obesity in women in developed countries is well-documented, current evidence regarding the relationship between obesity in men and area-based SES (equivalised for advantage and disadvantage) is inconsistent. Therefore, we aimed to examine obesity, lifestyle behaviours, physical activity in different domains and demographics in men using area-based SES.

Methods : We performed a descriptive cross-sectional study of 1467 randomly selected white men (mean age 56 year (inter-quartile range (IQR) = 39–73 year)) recruited from the Barwon Statistical Division, South Western Victoria, Australia between 2001–06.

Results : Age-adjusted BMI, waist circumference, % fat and lean mass and blood pressure were inversely associated with SES, with differences between low and upper SES (P for difference <0.05), independent of country of birth. Age-adjusted lifestyle behaviours associated with obesity and/or adverse health (especially cardiovascular disease), were also associated with lower SES.

Conclusions : Subjects from lower SES had greater measures of obesity despite being more physically active at work, but were less likely to be physically active in the domains of sports and/or leisure. These findings suggest the possible influence of lifestyle behaviours and occupation upon obesity in men and should be investigated further.

Determination of lung volume by hydrogen dilution at the time of underwater weighing

A method for measuring the volume of air in the lungs at the time of underwater weighing is described. A low concentration of hydrogen is used as a tracer gas in a closed-circuit rebreathing system. At the end of a normal exhalation the subject is connected to a respiratory bladder containing 2 L of air with a small admixture of hydrogen. After an equilibration period of five breaths the subject submerges completely, together with the bladder, and underwater weight is measured. Lung volume, at the time of weighing, is determined by hydrogen dilution. Using this method, the coefficient of variation for body density in the same individual was 0.23%.

Maternal vitamin D in pregnancy may influence not only offspring bone mass but other aspects of musculoskeletal health and adiposity

Osteoporotic fractures, falls and obesity are major health problems in developed nations. Evidence suggests that there are antenatal factors predisposing to these conditions. Data are emerging from Australia and elsewhere to suggest that maternal vitamin D status in pregnancy affects intrauterine skeletal mineralisation and skeletal growth together with muscle development and adiposity. Given that low levels of vitamin D have been documented in many urbanised populations, including those in countries with abundant sunlight, an important issue for public health is whether maternal vitamin D insufficiency during pregnancy has adverse effects on offspring health. The developing fetus may be exposed to low levels of vitamin D during critical phases of development as a result of maternal hypovitaminosis D. We hypothesise that this may have adverse effects on offspring musculoskeletal health and other aspects of body composition. Further research focused on the implications of poor gestational vitamin D nutrition is warranted as these developmental effects are likely to have a sustained influence on health during childhood and in adult life. We suggest that there is a clear rationale for randomised clinical trials to assess the potential benefits and harmful effects of vitamin D supplementation during pregnancy.