Generational trends in the transition to womanhood in lowland rural Nepal: Changes in the meaning of early marriage.

OBJECTIVE: In South Asia, studies show secular trends toward slightly later women's marriage and first reproduction. However, data on related biological and social events, such as menarche and age of coresidence with husband, are often missing from these analyses. We assessed generational trends in key life events marking the transition to womanhood in rural lowland Nepal. METHODS: We used data on 110 co-resident mother-in-law (MIL) and daughter-in-law (DIL) dyads. We used paired t-tests and chi-squared tests to evaluate generational trends in women's education, and mean age at menarche, marriage, cohabitation with husband, and first reproduction of MIL and DIL dyads. We examined norms held by MILs and DILs on a daughter's life opportunities. RESULTS: On average, MIL was 29 years older than DIL (60 years vs. 31 years). Both groups experienced menarche at average age 13.8 years. MIL was married at average 12.4 years, before menarche, and cohabitated with husbands at average 14.8 years. DIL was simultaneously married and cohabitated with husbands after menarche, at average 15 years. DIL was marginally more educated than MIL but had their first child on average 0.8 years earlier (95% CI -1.4, -0.1). MIL and DIL held similar norms on daughters' education and marriage. CONCLUSION: While social norms remain similar, the meaning of "early marriage" and use of menarche in marriage decisions has changed in rural lowland Nepal. Compared to DIL, MIL who was married earlier transitioned to womanhood more gradually. However, DIL was still married young, and had an accelerated trajectory to childbearing.

There is an obstetrical dilemma: Misconceptions about the evolution of human childbirth and pelvic form.

Compared to other primates, modern humans face high rates of maternal and neonatal morbidity and mortality during childbirth. Since the early 20th century, this "difficulty" of human parturition has prompted numerous evolutionary explanations, typically assuming antagonistic selective forces acting on maternal and fetal traits, which has been termed the "obstetrical dilemma." Recently, there has been a growing tendency among some anthropologists to question the difficulty of human childbirth and its evolutionary origin in an antagonistic selective regime. Partly, this stems from the motivation to combat increasing pathologization and overmedicalization of childbirth in industrialized countries. Some authors have argued that there is no obstetrical dilemma at all, and that the difficulty of childbirth mainly results from modern lifestyles and inappropriate and patriarchal obstetric practices. The failure of some studies to identify biomechanical and metabolic constraints on pelvic dimensions is sometimes interpreted as empirical support for discarding an obstetrical dilemma. Here we explain why these points are important but do not invalidate evolutionary explanations of human childbirth. We present robust empirical evidence and solid evolutionary theory supporting an obstetrical dilemma, yet one that is much more complex than originally conceived in the 20th century. We argue that evolutionary research does not hinder appropriate midwifery and obstetric care, nor does it promote negative views of female bodies. Understanding the evolutionary entanglement of biological and sociocultural factors underlying human childbirth can help us to understand individual variation in the risk factors of obstructed labor, and thus can contribute to more individualized maternal care.

Patterns of childhood body mass index (BMI), overweight and obesity in South Asian and black participants in the English National child measurement programme: effect of applying BMI adjustments standardising for ethnic differences in BMI-body fatness associations.

BACKGROUND: The National Child Measurement Programme (NCMP) records weight and height and assesses overweight-obesity patterns in English children using body mass index (BMI), which tends to underestimate body fatness in South Asian children and overestimate body fatness in Black children of presumed African ethnicity. Using BMI adjustments to ensure that adjusted BMI was similarly related to body fatness in South Asian, Black and White children, we reassessed population overweight and obesity patterns in these ethnic groups in NCMP. METHODS: Analyses were based on 2012-2013 NCMP data in 582 899 children aged 4-5 years and 485 362 children aged 10-11 years. Standard centile-based approaches defined weight status in each age group before and after applying BMI adjustments for English South Asian and Black children derived from previous studies using the deuterium dilution method. FINDINGS: Among White children, overweight-obesity prevalences (boys, girls) were 23% and 21%, respectively, in 4-5 year olds and 33% and 30%, respectively, in 10-11 year olds. Before adjustment, South Asian children had lower overweight-obesity prevalences at 4-5 years (19%, 19%) and slightly higher prevalences at 10-11 years (42%, 34%), whereas Black children had higher overweight-obesity prevalences both at 4-5 years (31%, 29%) and 10-11 years (42%, 45%). Following adjustment, overweight-obesity prevalences were markedly higher in South Asian children both at 4-5 years (39%, 35%) and at 10-11 years (52%, 44%), whereas Black children had lower prevalences at 4-5 years (11%, 12%); at 10-11 years, prevalences were slightly lower in boys (32%) but higher in girls (35%). INTERPRETATION: BMI adjustments revealed extremely high overweight-obesity prevalences among South Asian children in England, which were not apparent in unadjusted data. In contrast, after adjustment, Black children had lower overweight-obesity prevalences except among older girls. FUNDING: British Heart Foundation, NIHR CLAHRC (South London), NIHR CLAHRC (North Thames).

Body mass index adjustments to increase the validity of body fatness assessment in UK Black African and South Asian children.

BACKGROUND/OBJECTIVES: Body mass index (BMI) (weight per height2) is the most widely used marker of childhood obesity and total body fatness (BF). However, its validity is limited, especially in children of South Asian and Black African origins. We aimed to quantify BMI adjustments needed for UK children of Black African and South Asian origins so that adjusted BMI related to BF in the same way as for White European children. METHODS: We used data from four recent UK studies that made deuterium dilution BF measurements in UK children of White European, South Asian and Black African origins. A height-standardized fat mass index (FMI) was derived to represent BF. Linear regression models were then fitted, separately for boys and girls, to quantify ethnic differences in BMI-FMI relationships and to provide ethnic-specific BMI adjustments. RESULTS: We restricted analyses to 4-12 year olds, to whom a single consistent FMI (fat mass per height5) could be applied. BMI consistently underestimated BF in South Asians, requiring positive BMI adjustments of +1.12 kg m-2 (95% confidence interval (CI): 0.83, 1.41 kg m-2; P<0.0001) for boys and +1.07 kg m-2 (95% CI: 0.74, 1.39 kg m-2; P<0.0001) for girls of all age groups and FMI levels. BMI overestimated BF in Black Africans, requiring negative BMI adjustments for Black African children. However, these were complex because there were statistically significant interactions between Black African ethnicity and FMI (P=0.004 boys; P=0.003 girls) and also between FMI and age group (P<0.0001 for boys and girls). BMI adjustments therefore varied by age group and FMI level (and indirectly BMI); the largest adjustments were in younger children with higher unadjusted BMI and the smallest in older children with lower unadjusted BMI. CONCLUSIONS: BMI underestimated BF in South Asians and overestimated BF in Black Africans. Ethnic-specific adjustments, increasing BMI in South Asians and reducing BMI in Black Africans, can improve the accuracy of BF assessment in these children.

Body composition and susceptibility to type 2 diabetes: an evolutionary perspective.

Type 2 diabetes is rapidly increasing in prevalence worldwide, in concert with epidemics of obesity and sedentary behavior that are themselves tracking economic development. Within this broad pattern, susceptibility to diabetes varies substantially in association with ethnicity and nutritional exposures through the life-course. An evolutionary perspective may help understand why humans are so prone to this condition in modern environments, and why this risk is unequally distributed. A simple conceptual model treats diabetes risk as the function of two interacting traits, namely 'metabolic capacity' which promotes glucose homeostasis, and 'metabolic load' which challenges glucose homoeostasis. This conceptual model helps understand how long-term and more recent trends in body composition can be considered to have shaped variability in diabetes risk. Hominin evolution appears to have continued a broader trend evident in primates, towards lower levels of muscularity. In addition, hominins developed higher levels of body fatness, especially in females in relative terms. These traits most likely evolved as part of a broader reorganization of human life history traits in response to growing levels of ecological instability, enabling both survival during tough periods and reproduction during bountiful periods. Since the emergence of Homo sapiens, populations have diverged in body composition in association with geographical setting and local ecological stresses. These long-term trends in both metabolic capacity and adiposity help explain the overall susceptibility of humans to diabetes in ways that are similar to, and exacerbated by, the effects of nutritional exposures during the life-course.

Body shape and size in 6-year old children: assessment by three-dimensional photonic scanning.

BACKGROUND: Body shape and size are typically described using measures such as body mass index (BMI) and waist circumference, which predict disease risks in adults. However, this approach may underestimate the true variability in childhood body shape and size. OBJECTIVE: To use a comprehensive three-dimensional photonic scan approach to describe variation in childhood body shape and size. SUBJECTS/METHODS: At age 6 years, 3350 children from the population-based 2004 Pelotas birth cohort study were assessed by three-dimensional photonic scanner, traditional anthropometry and dual X-ray absorptiometry. Principal component analysis (PCA) was performed on height and 24 photonic scan variables (circumferences, lengths/widths, volumes and surface areas). RESULTS: PCA identified four independent components of children's body shape and size, which we termed: Corpulence, Central:peripheral ratio, Height and arm lengths, and Shoulder diameter. Corpulence showed strong correlations with traditional anthropometric and body composition measures (r>0.90 with weight, BMI, waist circumference and fat mass; r>0.70 with height, lean mass and bone mass); in contrast, the other three components showed weak or moderate correlations with those measures (all r<0.45). There was no sex difference in Corpulence, but boys had higher Central:peripheral ratio, Height and arm lengths and Shoulder diameter values than girls. Furthermore, children with low birth weight had lower Corpulence and Height and arm lengths but higher Central:peripheral ratio and Shoulder diameter than other children. Children from high socio-economic position (SEP) families had higher Corpulence and Height and arm lengths than other children. Finally, white children had higher Corpulence and Central:peripheral ratio than mixed or black children. CONCLUSIONS: Comprehensive assessment by three-dimensional photonic scanning identified components of childhood body shape and size not captured by traditional anthropometry or body composition measures. Differences in these novel components by sex, birth weight, SEP and skin colour may indicate their potential relevance to disease risks.

Association between Birth Interval and Cardiovascular Outcomes at 30 Years of Age: A Prospective Cohort Study from Brazil.

BACKGROUND: Birth interval is an important and potentially modifiable factor that is associated with child health. Whether an association exists with longer-term outcomes in adults is less well known. METHODS: Using the 1982 Pelotas (Brazil) Birth Cohort Study, the association of birth interval with markers of cardiovascular health at 30 years of age was examined. Multivariable linear regression was used with birth interval as a continuous variable and categorical variable, and effect modification by gender was explored. RESULTS: Birth interval and cardiovascular data were present for 2,239 individuals. With birth interval as a continuous variable, no association was found but stratification by gender tended to show stronger associations for girls. When compared to birth intervals of <18 months, as binary variable, longer intervals were associated with increases in height (1.6 cm; 95% CI: 0.5, 2.8) and lean mass (1.7 kg; 95% CI: 0.2, 3.2). No difference was seen with other cardiovascular outcomes. CONCLUSIONS: An association was generally not found between birth interval and cardiovascular outcomes at 30 years of age, though some evidence existed for differences between males and females and for an association with height and lean mass for birth intervals of 18 months and longer.

Associations of gender inequality with child malnutrition and mortality across 96 countries.

National efforts to reduce low birth weight (LBW) and child malnutrition and mortality prioritise economic growth. However, this may be ineffective, while rising gross domestic product (GDP) also imposes health costs, such as obesity and non-communicable disease. There is a need to identify other potential routes for improving child health. We investigated associations of the Gender Inequality Index (GII), a national marker of women's disadvantages in reproductive health, empowerment and labour market participation, with the prevalence of LBW, child malnutrition (stunting and wasting) and mortality under 5 years in 96 countries, adjusting for national GDP. The GII displaced GDP as a predictor of LBW, explaining 36% of the variance. Independent of GDP, the GII explained 10% of the variance in wasting and stunting and 41% of the variance in child mortality. Simulations indicated that reducing GII could lead to major reductions in LBW, child malnutrition and mortality in low- and middle-income countries. Independent of national wealth, reducing women's disempowerment relative to men may reduce LBW and promote child nutritional status and survival. Longitudinal studies are now needed to evaluate the impact of efforts to reduce societal gender inequality.

Body composition and the monitoring of non-communicable chronic disease risk.

There is a need for simple proxies of health status, in order to improve monitoring of chronic disease risk within and between populations, and to assess the efficacy of public health interventions as well as clinical management. This review discusses how, building on recent research findings, body composition outcomes may contribute to this effort. Traditionally, body mass index has been widely used as the primary index of nutritional status in children and adults, but it has several limitations. We propose that combining information on two generic traits, indexing both the 'metabolic load' that increases chronic non-communicable disease risk, and the homeostatic 'metabolic capacity' that protects against these diseases, offers a new opportunity to improve assessment of disease risk. Importantly, this approach may improve the ability to take into account ethnic variability in chronic disease risk. This approach could be applied using simple measurements readily carried out in the home or community, making it ideal for M-health and E-health monitoring strategies.

Body composition in young female eating-disorder patients with severe weight loss and controls: evidence from the four-component model and evaluation of DXA.

BACKGROUND/OBJECTIVES: Whether fat-free mass (FFM) and its components are depleted in eating-disorder (ED) patients is uncertain. Dual energy X-ray absorptiometry (DXA) is widely used to assess body composition in pediatric ED patients; however, its accuracy in underweight populations remains unknown. We aimed (1) to assess body composition of young females with ED involving substantial weight loss, relative to healthy controls using the four-component (4C) model, and (2) to explore the validity of DXA body composition assessment in ED patients. SUBJECTS/METHODS: Body composition of 13 females with ED and 117 controls, aged 10-18 years, was investigated using the 4C model. Accuracy of DXA for estimation of FFM and fat mass (FM) was tested using the approach of Bland and Altman. RESULTS: Adjusting for age, height and pubertal stage, ED patients had significantly lower whole-body FM, FFM, protein mass (PM) and mineral mass (MM) compared with controls. Trunk and limb FM and limb lean soft tissue were significantly lower in ED patients. However, no significant difference in the hydration of FFM was detected. Compared with the 4C model, DXA overestimated FM by 5 ± 36% and underestimated FFM by 1 ± 9% in ED patients. CONCLUSION: Our study confirms that ED patients are depleted not only in FM but also in FFM, PM and MM. DXA has limitations for estimating body composition in individual young female ED patients.

Windows of opportunity for physical activity in the prevention of obesity.

Tackling increasing rates of obesity is likely to be a defining feature of health care over the next several decades. Adult obesity is a persistent and treatment-resistant problem. Consequently, an emerging theme in the literature is to commence prevention efforts earlier in the developmental time course. This view is based primarily on epidemiological data demonstrating a link between traits manifesting early during development and increased obesity risk in adulthood. Physical activity is a perennial factor in discussions of obesity prevention. However, the optimal timing and type of physical activity interventions to commence remains unclear. Critical developmental windows of plasticity may afford time-limited opportunities to shape body composition across the life course; however, physical activity has not been explicitly considered in these discussions. Although animal models suggest that physical activity commenced earlier in development has differential effects on obesity onset compared to physical activity commenced in adulthood, human research is lacking. In this conceptual review, we consider physical activity during critical developmental periods as a way to mitigate obesity risk later in life.

Calibration of bioelectrical impedance analysis for body composition assessment in Ethiopian infants using air-displacement plethysmography.

BACKGROUND/OBJECTIVES: Assessment of infant body composition (BC) is crucial to understand the consequences of suboptimal nutritional status and postnatal growth, and the effects of public health interventions. Bioelectrical impedance analysis (BIA) is a feasible, relatively inexpensive and noninvasive method for assessing BC. However, very little research has been conducted in low- and middle-income populations, where efforts to prevent or treat malnutrition in early life are a public health priority. We aimed to develop equations for predicting fat-free mass (FFM) and fat mass (FM) based on BIA in 0- to 6-month-old Ethiopian infants. SUBJECTS/METHODS: The study comprised a total of 186 BC assessments performed in 101 healthy infants, delivered at Jimma University Specialized Hospital. Infant air-displacement plethysmography (IADP) was the criterion method, whereas weight, length, sex, age and an impedance index (L(2)/Z50) were predictors. Prediction equations were developed using stepwise multiple linear regression and the accuracy was evaluated with a 10-fold cross-validation approach. RESULTS: A linear regression model based on body weight, age and sex predicted FFM, estimated by IADP, with an adjusted R(2) and root mean square error (RMSE) of 0.94 and 200 g, respectively. Adding impedance index to the model resulted in a significantly improved model fit (R(2)=0.95; RMSE=181 g). For infants below 3 months of age, inclusion of impedance index did not contribute to an improved model fit for predicting FFM compared with a model already comprising weight, sex and age. CONCLUSIONS: The derived equations predicted FFM with acceptable accuracy and may be used in future field surveys, epidemiological studies and clinical trials conducted in similar sub-Saharan African population groups aged 0-6 months.

Predictors of body composition changes during tuberculosis treatment in Mwanza, Tanzania.

BACKGROUND/OBJECTIVES: Gains in fat mass and lean mass during tuberculosis (TB) treatment may determine functional recovery and survival; yet, data are scarce. We aimed to assess predictors of fat and fat-free mass during 2 months of intensive TB treatment in a cohort in Mwanza, Tanzania. SUBJECTS/METHODS: Fat and fat-free mass were determined at the start of TB treatment and repeated after 2 months using the deuterium dilution technique. Gains in fat and fat-free mass were determined and predictors assessed using regression analysis. RESULTS: Data for 116 patients were available at baseline and during follow-up. Of these, 38.8% were females, mean age was 37.3 (s.d. 13.5) years, 69% (81) had sputum-positive TB, 45.7% (53) were HIV infected and 25% (29) were current smokers. The mean weight gain was 3.3 kg (95% confidence interval: 2.7; 3.8), and it did not differ by sex. However, compared with females, males had 1.0 (0.4; 1.6) kg/m(2) lower fat mass but 0.7 (0.2; 1.3) kg/m(2) higher fat-free mass gain. Current smoking was associated with higher fat mass (0.7 kg/m(2), 0.04; 1.4) but lower fat-free mass (-0.5 kg/m(2), -1.2; 0.07) gain. Among HIV-infected patients, antiretroviral therapy (ART) led to a lower fat gain (-1.2 kg/m(2), -2.2; -0.2) but to a higher fat-free mass among sputum-negative (2.9 kg/m(2), 0.8; 5.1) but not sputum-positive patients. CONCLUSIONS: During intensive phase of TB treatment, sex, smoking and ART were predictors of body composition. Larger studies are needed to further understand predictors of body composition during recovery, to help design interventions to improve treatment outcomes.

Association between worldwide dietary and lifestyle patterns with total cholesterol concentrations and DALYs for infectious and cardiovascular diseases: an ecological analysis.

Global dietary and lifestyle trends are primary risk factors for communicable and non-communicable diseases. An ecological analysis was conducted to examine the association of global dietary and lifestyle patterns with total cholesterol concentrations. This study also investigated whether total cholesterol modified the association between dietary and lifestyle habits with disability-adjusted-life-years-lost (DALYs) for infectious and cardiovascular diseases (CVDs). Country-specific mean total cholesterol concentrations and DALYs for infectious and CVDs were obtained. Data were then matched to country-specific food and energy availability for consumption and information on obesity, physical inactivity, urbanization, gross domestic product (GDP), life expectancy and smoking. Stepwise multiple regression models were developed to identify significant predictors of total cholesterol concentrations and DALYs for infectious and CVDs. Life expectancy and egg and meat consumption were significantly associated with cholesterol concentrations. DALYs for infectious diseases were associated with smoking, life expectancy and per capita GDP. Smoking was the only predictor of DALYs for CVDs. The improvement of socio-demographic conditions and economic growth is likely to reduce the burden of communicable diseases in developing countries. A concurring increase in non-communicable diseases is expected, and these results have, yet again, identified smoking as a primary risk factor for CVDs.

Shifts in population dietary patterns and physical inactivity as determinants of global trends in the prevalence of diabetes: an ecological analysis.

BACKGROUND AND AIMS: The worldwide epidemiology of diabetes is rapidly changing as a result of the spreading of westernised nutritional and lifestyle habits. We conducted an ecological analysis to identify dietary, lifestyle and socio-economic factors associated with global diabetes prevalence. METHODS AND RESULTS: Country-specific estimates of diabetes prevalence were obtained. Data were then matched to year- and country-specific food and energy availability for consumption, and to year-specific information on obesity, physical inactivity, urbanisation, gross domestic product (GDP), and smoking. Data were obtained from publicly available databases compiled by the Food Agricultural Organisation (FAO), World Health Organisation (WHO) and World Bank. Cluster analysis was used to derive dietary patterns of global food consumption. The association with diabetes prevalence was evaluated. Stepwise multiple regression analysis was conducted to identify predictors associated with worldwide diabetes prevalence. 96 countries were eligible for inclusion in the analysis. The average diabetes prevalence was 7.0% and the highest rate was observed in the Middle-Eastern region (13.1%). The worldwide prevalence of obesity and physical inactivity was 15.1% and 36.1%, respectively. Diabetes prevalence was associated with age and physical inactivity prevalence in a fully adjusted multiple regression model. Three dietary patterns (agricultural, transitional and westernised) were identified by the cluster analysis. Diabetes prevalence showed a direct dose-response association with the degree of exposure to a westernised dietary pattern. CONCLUSIONS: The adoption of sedentary lifestyle and westernised dietary patterns appears to be closely linked to the global rise in diabetes prevalence.

The effect of maternal prenatal smoking and alcohol consumption on the placenta-to-birth weight ratio.

BACKGROUND: Maternal influence on fetal growth is mediated through the placenta and this influence may have an implication for the offspring's long-term health. The placenta-to-birth weight ratio has been regarded as an indicator of placental function. However, few studies have examined the effect of maternal lifestyle exposures on the placenta-to-birth weight ratio. This study aims to examine the associations of maternal prenatal smoking and alcohol consumption with the placenta-to-birth weight ratio. METHODS: Data for 7945 term singletons, gestation≥37 weeks, were selected from the Tasmanian Infant Health Survey; a 1988-1995 Australian cohort study. Placenta and birth weight were extracted from birth notification records. RESULTS: Maternal smoking during pregnancy was strongly associated with a 6.77 g/kg higher (95% CI 4.83-8.71) placenta-to-birth weight ratio when compared to non-smoking mothers. Maternal prenatal smoking was associated with lower placental (ß = -15.37 g; 95% CI -23.43 to -7.31) and birth weights (ß = -205.49 g; 95% CI -232.91 to -178.08). Mothers who consumed alcohol during pregnancy had a lower placenta-to-birth weight ratio (ß = -2.07 g/kg; 95% CI -4.01 to -0.12) than mothers who did not consume alcohol. The associations of maternal alcohol consumption during pregnancy with placental and birth weight did not reach statistical significance. DISCUSSION: Maternal prenatal smoking and alcohol consumption may influence fetal growth by either directly or indirectly altering the function of the placenta. CONCLUSIONS: The alteration of the in utero environment induced by smoking and alcohol consumption appears to affect placental and fetal growth in differing ways. Further studies are needed to elucidate the mechanism.

Adjustment of directly measured adipose tissue volume in infants.

BACKGROUND: Direct measurement of adipose tissue (AT) using magnetic resonance imaging is increasingly used to characterise infant body composition. Optimal techniques for adjusting direct measures of infant AT remain to be determined. OBJECTIVES: To explore the relationships between body size and direct measures of total and regional AT, the relationship between AT depots representing the metabolic load of adiposity and to determine optimal methods of adjusting adiposity in early life. DESIGN: Analysis of regional AT volume (ATV) measured using magnetic resonance imaging in longitudinal and cross-sectional studies. SUBJECTS: Healthy term infants; 244 in the first month (1-31 days), 72 in early infancy (42-91 days). METHODS: The statistical validity of commonly used indices adjusting adiposity for body size was examined. Valid indices, defined as mathematical independence of the index from its denominator, to adjust ATV for body size and metabolic load of adiposity were determined using log-log regression analysis. RESULTS: Indices commonly used to adjust ATV are significantly correlated with body size. Most regional AT depots are optimally adjusted using the index ATV/(height)(3) in the first month and ATV/(height)(2) in early infancy. Using these indices, height accounts for<2% of the variation in the index for almost all AT depots. Internal abdominal (IA) ATV was optimally adjusted for subcutaneous abdominal (SCA) ATV by calculating IA/SCA(0.6). CONCLUSIONS: Statistically optimal indices for adjusting directly measured ATV for body size are ATV/height(3) in the neonatal period and ATV/height(2) in early infancy. The ratio IA/SCA ATV remains significantly correlated with SCA in both the neonatal period and early infancy; the index IA/SCA(0.6) is statistically optimal at both of these ages.

Height, adiposity and hormonal cardiovascular risk markers in childhood: how to partition the associations?

OBJECTIVE: Obesity is associated with rapid growth during childhood. There is uncertainty over how to adjust for body size, when using adiposity as a proxy for cardiovascular risk. We studied associations of height, body composition (by dual-energy X-ray absorptiometry) and cardiovascular risk markers (insulin resistance (IR), leptin) in children. METHODS: Using partial correlations in 172 children aged 7-12 years, we investigated associations of (a) fat mass with IR or leptin, adjusting for height or lean mass, and (b) height or lean mass with IR or leptin, adjusting for fat mass. Analyses were conducted both cross-sectionally at each age, and for changes between 7 and 12 years. RESULTS: Height, fat mass, lean mass, IR and leptin were all inter-correlated at all ages. Although fat mass was strongly associated with IR and leptin, height was independently negatively associated with leptin (whole sample, adjusting for age: boys r=-0.12, girls r=-0.13; P<0.001). Independent of adiposity, height was also associated with insulin IR (whole sample, adjusting for age: boys r=0.11, girls r=0.20; P<0.001). When analysed by year of age, these associations tended to remain significant at older ages. Change in height from 7 to 12 years was also associated with change in IR (boys: r=0.18, P<0.05; girls: r=0.34, P<0.01), independently of change in adiposity, with similar findings for lean mass. CONCLUSIONS: During childhood, markers of cardiovascular risk have a complex profile, associated with growth as well as fat accumulation. Taller and faster-growing children have elevated risk markers, independently of their adiposity. These findings have implications for the interpretation of pediatric indices of adiposity that aim to adjust for body size. Adiposity indices that perform best at summarizing metabolic risk may not be those that perform best at understanding the developmental aetiology of risk.

Acute effects of violent video-game playing on blood pressure and appetite perception in normal-weight young men: a randomized controlled trial.

Watching television and playing video game being seated represent sedentary behaviours and increase the risk of weight gain and hypertension. We investigated the acute effects of violent and non-violent video-game playing on blood pressure (BP), appetite perception and food preferences. Forty-eight young, normal-weight men (age: 23.1±1.9 years; body mass index: 22.5±1.9 kg/m(2)) participated in a three-arm, randomized trial. Subjects played a violent video game, a competitive, non-violent video game or watched TV for 1 h. Measurements of BP, stress and appetite perception were recorded before a standardized meal (∼300 kcal) and then repeated every 15 min throughout the intervention. Violent video-game playing was associated with a significant increase in diastolic BP (Δ±s.d.=+7.5±5.8 mm Hg; P=0.04) compared with the other two groups. Subjects playing violent video games felt less full (P=0.02) and reported a tendency towards sweet food consumption. Video games involving violence appear to be associated with significant effects on BP and appetite perceptions compared with non-violent gaming or watching TV.

Obesity as malnutrition: the dimensions beyond energy balance.

The aetiology of obesity is seemingly simple to understand: individuals consume more energy than they expend, with the excess energy being stored in adipose tissue. Public health campaigns therefore promote dietary restraint and physical exercise, and emphasize individual responsibility for these behaviours. Increasingly, however, researchers are switching from thermodynamic to metabolic models of obesity, thereby clarifying how specific environmental factors promote lipogenesis. Obesity can best be explained not by counting 'calories in and out', but by understanding how specific dietary products and activity behaviours perturb cellular metabolism and promote net lipogenesis. This metabolic approach can furthermore be integrated with more sophisticated models of how commercial practices drive the consumer trends that promote obesogenic behaviours. Notably, obesity treatment has proven more effective if it bypasses individual responsibility, suggesting that a similar approach placing less emphasis on individual responsibility would improve the efficacy of obesity prevention. Successful obesity prevention campaigns are likely to emerge only when the public receive better 'protection' from the commercial practices that are driving the global obesity epidemic. Rather than populations failing to heed governments' public health advice, governments are currently failing the public by abandoning their responsibility for regulating commercial activities.