Energetic requirements for maintenance and premigratory body mass gain of waders wintering in Africa

The energy content of the deposited reserve tissue depended on the condition of the birds, since the energy required for body mass gain was low in lean birds and high in fat birds. Maintenance metabolism was relatively low compared to wader species wintering in temperate regions, suggested to be an adaptation towards reduced endogenous heat production, which may help in avoiding heat stress under tropical conditions. -from Authors

Habitat switching by Bewick's swans: Maximization of average long-term energy gain?

1. In a system where depletion drives a habitat shift, the hypothesis was tested that animals switch habitat as soon as the average daily net energy intake (or gain) drops below that attainable in the alternative habitat.

2. The study was performed in the Lauwersmeer area. Upon arrival during the autumn migration, Bewick's swans first feed on below-ground tubers of fennel pondweed on the lake, but subsequently switched to feeding on harvest remains in sugar beet fields.

3. The daily energy intake was estimated by multiplying the average time spent foraging per day with the instantaneous energy intake rate while foraging. In the case of pondweed feeding, the latter was estimated from the functional response and the depletion of tuber biomass. In the case of beet feeding, it was estimated from dropping production rate. Gross energy intake was converted to metabolizable energy intake using the assimilation as determined in digestion trials. The daily energy expenditure was estimated by the time-energy budget method. Energetic costs were determined using heart rate.

4. The daily gain of pondweed feeding at the median date of the habitat switch (i.e. when 50% of the swans had switched) was compared with that of beet feeding. The daily gain of beet feeding was calculated for two strategies depending on the night activity on the lake: additional pondweed feeding (mixed feeding) or sleeping (pure beet feeding).

5. The majority of the swans switched when the daily gain they could achieve by staying on the pondweed bed fell just below the average daily gain of pure beet feeders. However, mixed feeders would attain an average daily gain considerably above that of pondweed feeders. A sensitivity analysis showed that this result was robust.

6. We therefore reject the hypothesis that the habitat switch by swans can be explained by simple long-term energy rate maximization. State-dependency, predation risk, and protein requirements are put forward as explanations for the delay in habitat switch.

Bias and precision of measures of survival gain from right-censored data

In cost-effectiveness analyses of drugs or health technologies, estimates of life years saved or quality-adjusted life years saved are required. Randomised controlled trials can provide an estimate of the average treatment effect; for survival data, the treatment effect is the difference in mean survival. However, typically not all patients will have reached the endpoint of interest at the close-out of a trial, making it difficult to estimate the difference in mean survival. In this situation, it is common to report the more readily estimable difference in median survival. Alternative approaches to estimating the mean have also been proposed. We conducted a simulation study to investigate the bias and precision of the three most commonly used sample measures of absolute survival gain - difference in median, restricted mean and extended mean survival - when used as estimates of the true mean difference, under different censoring proportions, while assuming a range of survival patterns, represented by Weibull survival distributions with constant, increasing and decreasing hazards. Our study showed that the three commonly used methods tended to underestimate the true treatment effect; consequently, the incremental cost-effectiveness ratio (ICER) would be overestimated. Of the three methods, the least biased is the extended mean survival, which perhaps should be used as the point estimate of the treatment effect to be inputted into the ICER, while the other two approaches could be used in sensitivity analyses. More work on the trade-offs between simple extrapolation using the exponential distribution and more complicated extrapolation using other methods would be valuable.

The role of parity in gestational weight gain and postpartum weight retention

OBJECTIVES: Parity, excessive gestational weight gain (GWG), and postpartum weight retention (PPWR) have been identified as risk factors for maternal obesity. The aim of this study was to explore whether GWG and PPWR at 6 and 12 months after birth differed for primiparous and multiparous Australian women. METHODS: One hundred thirty-eight Australian women provided weight measures in early to mid pregnancy (M = 16.7 weeks, SD = 2.3), late pregnancy (M = 37.7 weeks, SD = 2.4), 6 months postpartum (M = 6.1 months, SD = 1.4), and 12 months postpartum (M = 12.6 months, SD = 0.7). Height, parity, and demographic information were also collected. Prepregnancy body mass index (BMI), total GWG, incidence of excessive GWG, as well as change in BMI and BMI category from prepregnancy to 6 and 12 months postpartum were computed. Differences between primiparous and multiparous women were compared using analysis of covariance (controlling for age, prepregnancy BMI, and GWG) and χ(2) test of independence. RESULTS: Seventy women (50.7%) were primiparous and 68 women (49.3%) were multiparous. Primiparous women were more likely to retain weight at 12 months postpartum than multiparous women (p = .021; Cohen's d = .24). This difference was not reflected when analyzing change in BMI categories from prepregnancy to the postpartum. CONCLUSIONS: Evidence for the role of parity in PPWR is inconclusive. Future research should consider the temporal development of PPWR in primiparous and multiparous women, leading to tailored care in the postpartum period to help women return to a healthy prepregnancy weight.

Psychosocial factors and excessive gestational weight gain: the effect of parity in an Australian cohort

OBJECTIVES: psychosocial variables can be protective or risk factors for excessive gestational weight gain (GWG). Parity has also been associated with GWG; however, its effect on psychosocial risk factors for GWG is yet to be determined. The aim of this study was to investigate if, and how, psychosocial factors vary in their impact on the GWG of primiparous and multiparous women. DESIGN/PARTICIPANTS: pregnant women were recruited in 2011 via study advertisements placed in hospitals, online, in parenting magazines, and at baby and children's markets, resulting in a sample of 256 women (113 primiparous, 143 multiparous). Participants completed questionnaires at 16-18 weeks' gestation and their pregravid BMI was recorded. Final weight before delivery was measured and used to calculate GWG. FINDINGS: the findings revealed that primiparous women had significantly higher feelings of attractiveness (a facet of body attitude; p=0.01) than multiparous women. Hierarchical regressions revealed that in the overall sample, increased GWG was associated significantly with lower pre-pregnancy BMI (standardised coefficient β=-0.39, p<0.001), higher anxiety symptoms (β=0.25, p=0.004), and reduced self-efficacy to eat a healthy diet (β=-0.20, p=0.02). Although higher GWG was predicted significantly by decreased feelings of strength and fitness for primiparous women (β=-0.25, p=0.04) and higher anxiety was related significantly to greater GWG for multiparous women (β=0.43, p<0.001), statistical comparison of the model across the two groups suggested the magnitude of these effects did not differ across groups (p>0.05). CONCLUSIONS/IMPLICATIONS FOR PRACTICE: the findings suggest that psychosocial screening and interventions by healthcare professionals may help to identify women who are at risk of excessive GWG, and there may be specific psychosocial factors that are more relevant for each parity group.

The influence on population weight gain and obesity of the macronutrient composition and energy density of the food supply

Rates of overweight and obesity have increased dramatically in all regions of the world over the last few decades. Almost all of the world's population now has ubiquitous access to low-cost, but highly-processed, energy-dense, nutrient-poor food products. These changes in the food supply, rather than decreases in physical activity, are most likely the primary driver of population weight gain and obesity. To-date, the majority of prevention efforts focus on personalised approaches targeting individuals. Population-wide food supply interventions addressing sodium and trans fat reduction have proven highly effective and comparable efforts are now required to target obesity. The evidence suggests that strategies focusing upon reducing the energy density and portion size of foods will be more effective than those targeting specific macronutrients. Government leadership, clearly specified targets, accountability and transparency will be the key to achieving the food supply changes required to address the global obesity epidemic.

A path model of psychosocial and health behaviour change predictors of excessive gestational weight gain

This study aimed to evaluate a conceptual model of psychosocial, behaviour change, and behavioural predictors of excessive gestational weight gain (GWG). Background: Excessive GWG can place women and their babies at risk of poor health outcomes, including obesity. Models of psychosocial and behaviour change predictors of excessive GWG have not been extensively explored; understanding the mechanisms leading to excess GWG will provide crucial evidence towards the development of effective interventions. Method: Two hundred and eighty-eight pregnant women (≤18 weeks gestation) were recruited to a prospective study. Demographic, psychosocial, health behaviour change, and behavioural factors were assessed at 17 (Time 1, T1) and 33 weeks (Time 2, T2) gestation. Pre-pregnancy and final pregnancy weight were obtained and women were classified with/without excessive GWG. Logistic regressions refined the list of predictors of excessive GWG; variables with p < .1 were included in a path analysis. Results: Age, family income, T2 depression, T2 pregnancy-specific coping, T1 buttocks dissatisfaction, T2 GWG-specific self-efficacy, T1 dietary readiness, T1 dietary importance, and T1 vegetable intake predicted excessive GWG in the logistic regressions and were included in the path model. The baseline path model demonstrated poor fit. Once statistically and theoretically plausible paths were added, adequate model fit was achieved (χ² = 21.61(9), p < .05; RMSEA = .07; CFI = .93); this revised model explained 19.5% of the variance in excessive GWG. Women with high T1 buttocks dissatisfaction were more likely to exhibit low levels of dietary readiness. Women with low dietary readiness were more likely to have a lower vegetable intake, which predicted excessive GWG. Women with higher T2 depressive symptoms were more likely to report lower GWG self-efficacy and gain excessively. Conclusion: Future behavioural GWG trials should consider combining psychosocial and health behaviour change factors to optimise GWG.

Nutritional intervention to prevent weight gain in patients commenced on olanzapine: a randomized controlled trial

Objective: Olanzapine is the most commonly prescribed atypical antipsychotic medication in Australia. Research reports an average weight gain of between 4.5 and 7 kg in the 3 months following its commencement. Trying to minimize this weight gain in a population with an already high prevalence of obesity, mortality and morbidity is of clinical and social importance. This randomized controlled trial investigated the impact of individual nutrition education provided by a dietitian on weight gain in the 3 and 6 months following the commencement of olanzapine.


Method: Fifty-one individuals (29 females, 22 males) who had started on olanzapine in the previous 3 months (mean length of 27 days ± 20) were recruited through Peninsula Health Psychiatric Services and were randomly assigned to either the intervention (n = 29) or the control group (n = 22). Individuals in the intervention group received six 1 hour nutrition education sessions over a 3-month period. Weight, waist circumference, body mass index (BMI) and qualitative measures of exercise levels, quality of life, health and body image were collected at baseline at 3 and 6 months.


Results: After 3 months, the control group had gained significantly more weight than the treatment group (6.0 kg vs 2.0 kg, p ≤ 0.002). Weight gain of more than 7% of initial weight occurred in 64% of the control group compared to 13% of the treatment group. The control group's BMI increased significantly more than the treatment group's (2 kg/m2vs 0.7 kg/m2, p ≤ 0.03). The treatment group reported significantly greater improvements in moderate exercise levels, quality of life, health and body image compared to the controls. At 6 months, the control group continued to show significantly more weight gain since baseline than the treatment group (9.9 kg vs 2.0 kg, p ≤ 0.013) and consequently had significantly greater increases in BMI (3.2 kg/m2vs 0.8 kg/m2, p ≤ 0.017).

An investigation of major factor of influence of strength gain or loss of geopolymer when exposed to 800° C

When fly ash based geopolymer mortars were exposed to an elevated temperature of 800oC, it was found that the strength after the exposure sometimes decreased, but at other times increased compared to the original strength. The aim of this investigation is to find the reason for this contrasting behaviour. Fol-lowing exposure to high temperature, residual strengths of specimens prepared with two different fly ashes, with initial strengths ranging from 5MPa to 60MPa, were investigated. The parameter that was found to have a major influence on the contrasting behaviour was the ductility of the mortars. The results indicate that the higher the ductility the lower the strength loss. This correlation is attributed to the fact that mortars with high ductility could provide higher capacity to accommodate thermal incompatibility than mortars with low ductil-ity. Beyond the particular threshold of ductility, some mortars even increased strength after the exposure, pos-sibly due to sintering.

Classification tree analysis of postal questionnaire data to identify risk of excessive gestational weight gain

OBJECTIVE: overweight/obese weight status during pregnancy increases risk of a range of adverse health outcomes for mother and child. Whereas identification of those who are overweight/obese pre-pregnancy and in early pregnancy is straightforward, prediction of who will experience excessive gestational weight gain (EGWG), and thus be at greater risk of becoming overweight or obese during pregnancy is more challenging. The present study sought to better identify those at risk of EGWG by exploring pre-pregnancy BMI as well as a range of psychosocial risk factors identified as risk factors in prior research. METHODS: 225 pregnant women completed self-reported via postal survey measures of height, weight, and psychosocial variables at 16-18 weeks gestation, and reported their weight again at 32-34 weeks to calculate GWG. Classification and regression tree analysis (CART) was used to find subgroups in the data with increased risk of EGWG based on their pre-pregnancy BMI and psychosocial risk factor scores at Time 1. FINDINGS: CART confirmed that self-reported BMI status was a strong predictor of EGWG risk for women who were overweight/obese pre-pregnancy. Normal weight women with low motivation to maintain a healthy diet and who reported lower levels of partner support were also at considerable risk of EGWG. IMPLICATIONS FOR PRACTICE: present findings offer support for inclusion of psychosocial measures (in addition to BMI) in early antenatal visits to detect risk of EGWG. However, these findings also underscore the need for further consideration of effect modifiers that place women at increased or decreased risk of EGWG. Proposed additional constructs are discussed to direct further theory-driven research.

Changes in the rates of weight and waist circumference gain in Australian adults over time: a longitudinal cohort study

OBJECTIVE: To assess in a single cohort whether annual weight and waist circumference (WC) change has varied over time.

DESIGN: Longitudinal cohort study with three surveys (1) 1999/2000; (2) 2004/2005 and (3) 2011/2012. Generalised linear mixed models with random effects were used to compare annualised weight and WC change between surveys 1 and 2 (period 1) with that between surveys 2 and 3 (period 2). Models were adjusted for age to analyse changes with time rather than age. Models were additionally adjusted for sex, education status, area-level socioeconomic disadvantage, ethnicity, body mass index, diabetes status and smoking status.

SETTING: The Australian Diabetes, Obesity and Lifestyle study (AusDiab)-a population-based, stratified-cluster survey of 11247 adults aged ≥25 years. PARTICIPANTS: 3351 Australian adults who attended each of three surveys and had complete measures of weight, WC and covariates.

PRIMARY OUTCOME MEASURES: Weight and WC were measured at each survey. Change in weight and WC was annualised for comparison between the two periods.

RESULTS: Mean weight and WC increased in both periods (0.34 kg/year, 0.43 cm/year period 1; 0.13 kg/year, 0.46 cm/year period 2). Annualised weight gain in period 2 was 0.11 kg/year (95% CI 0.06 to 0.15) less than period 1. Lesser annual weight gain between the two periods was not seen for those with greatest area-level socioeconomic disadvantage, or in men over the age of 55. In contrast, the annualised WC increase in period 2 was greater than period 1 (0.07 cm/year, 95% CI 0.01 to 0.12). The increase was greatest in men aged 55+ years and those with a greater area-level socioeconomic disadvantage.

CONCLUSIONS: Between 2004/2005 and 2011/2012, Australian adults in a national study continued to gain weight, but more slowly than 1999/2000-2004/2005. While weight gain may be slowing, this was not observed for older men or those in more disadvantaged groups, and the same cannot be said for WC.

Can a health coaching intervention delivered during pregnancy help prevent excessive gestational weight gain?

This study evaluated: (1) the efficacy of a health coaching (HC) intervention designed to prevent excessive gestational weight gain (GWG); and (2) whether there were improved psychological, motivational, and behavioural outcomes for women in the HC intervention compared to a "usual care" control group. In this quasi-experimental study, 267 pregnant women ≤18 weeks gestation were recruited between August 2011 and June 2013 from two hospital antenatal clinics in Melbourne, Australia. Intervention women received four individual HC and two group HC/educational sessions informed by theories of behaviour change. Women completed questionnaires assessing psychological, motivational and behavioural outcomes at 16-18 (baseline) and 33 (post-intervention) weeks gestation. Weight measures were collected. Compared to usual care, the intervention did not limit GWG or prevent excessive GWG. However, HC women reported greater use of active coping skills post-intervention. Despite lack of success of the HC intervention, given the risks associated with excessive weight gain in pregnancy, health professionals should continue to recommend appropriate GWG.

Sensory and consumer research update : A quick and easy way to gain consumer understanding

To develop new foods or to improve existing products, it is necessary to understand how consumers perceive innovative foods, what their expectations are, which packaging they find most attractive as well as what information positively affects the purchasing decision and the acceptability of present or potential consumers.

Infant adiposity at birth and early postnatal weight gain predict increased aortic intima-media thickness at 6 weeks of age: a population-derived cohort study

Infant body composition and postnatal weight gain have been implicated in the development of adult obesity and cardiovascular disease, but there are limited prospective data regarding the association between infant adiposity, postnatal growth and early cardiovascular parameters. Increased aortic intima-media thickness (aortic IMT) is an intermediate phenotype of early atherosclerosis. The aim of the present study was to investigate the relationship between weight and adiposity at birth, postnatal growth and aortic IMT. The Barwon Infant Study (n=1074 mother-infant pairs) is a population-derived birth cohort. Infant weight and other anthropometry were measured at birth and 6 weeks of age. Aortic IMT was measured by trans-abdominal ultrasound at 6 weeks of age (n=835). After adjustment for aortic size and other factors, markers of adiposity including increased birth weight (β=19.9 μm/kg, 95%CI 11.1, 28.6; P<0.001) and birth skinfold thickness (β=6.9 μm/mm, 95%CI 3.3, 10.5; P<0.001) were associated with aortic IMT at 6 weeks. The association between birth skinfold thickness and aortic IMT was independent of birth weight. In addition, greater postnatal weight gain was associated with increased aortic IMT, independent of birth weight and age at time of scan (β=11.3 μm/kg increase, 95%CI 2.2, 20.3; P=0.01). Increased infant weight and adiposity at birth, as well as increased early weight gain, were positively associated with aortic IMT. Excessive accumulation of adiposity during gestation and early infancy may have adverse effects on cardiovascular risk.

Colon cancer surveillance in inflammatory bowel disease: unclear gain but no psychological pain?

BACKGROUND: Surveillance for colorectal neoplasia in inflammatory bowel disease (IBD) is widely practised despite a lack of convincing mortality reduction. The psychological impact of this approach is largely unexplored. AIM: To examine psychological well-being among IBD subjects undergoing colonoscopic surveillance for colorectal cancer (CRC). METHODS: A cross-sectional study was performed by interrogating an IBD database for subjects currently enrolled in colonoscopic surveillance programmes. Identified surveillance subjects were age- and gender-matched with IBD control subjects not meeting surveillance criteria. Subjects were mailed a questionnaire including demographic details, the Short Form 36 (SF-36) survey to assess quality of life, the Spielberger State-Trait Personality Inventory, the Multidimensional Health Locus of Control, and a Risk Perception Questionnaire. RESULTS: One hundred and thirty-nine of 286 (49%) subjects responded, 53% male, 46% Crohn disease. Fifty-six per cent respondents were in the surveillance group. Surveillance subjects were older (55.4 vs 51.1 years; P = .048) with longer disease duration, but otherwise had comparable demographics with controls. Overall, quality of life was not significantly different between cohorts (mean SF-36 63.82 vs 65.48; P = 0.70). Groups did not differ on any locus of control classification (P = 0.52), nor was there any difference between mean scores on 'state' subscales of the Spielberger State-Trait Personality Inventory: anxiety (P = 0.91), curiosity (P = 0.12), anger (P = 0.81) or depression (P = 0.70). Both groups grossly overestimated their perceived lifetime risk of CRC at 50%, with no difference between surveillance and control subjects (P = 1.0). CONCLUSIONS: Enrolment in colonoscopic colon cancer surveillance does not appear to impair psychological well-being in individuals with IBD despite longer disease duration. IBD patients overestimate their risk of CRC.