Short stature and obesity: positive association in adults but inverse association in children and adolescents

Evaluation of the MC3R gene pertaining to body weight and height regulation and puberty development

Recent studies reported an impact of the melanocortin 3 receptor (MC3R) on the regulation of body weight, linear growth and puberty timing. Previously, allele p.44Ile of a frequent non-synonymous variant (NSV) p.Val44Ile was reported to be associated with decreased lean body mass (LBM) and later puberty in both sexes. We Sanger sequenced the coding region of MC3R in 185 children or adolescents with short normal stature (SNS) or 258 individuals with severe obesity, and 192 healthy-lean individuals. Eleven variants (six NSVs) were identified. In-silico analyses ensued. Three rare loss-of-function (LoF) variants (p.Phe45Ser, p.Arg220Ser and p.Ile298Ser) were only found in severely obese individuals. One novel highly conserved NSV (p.Ala214Val), predicted to increase protein stability, was detected in a single lean female. In the individuals with SNS, we observed deviation from Hardy-Weinberg Equilibrium (HWE) (p = 0.012) for p.Val44Ile (MAF = 11.62%). Homozygous p.44Ile carriers with SNS had an increased BMI, but this effect did not remain significant after Bonferroni correction. In line with previous findings, the detected LoF NSVs may suggest that dysfunction in MC3R is associated with decreased body height, obesity and delayed puberty.

Association of Maternal Caffeine Consumption During Pregnancy With Child Growth

IMPORTANCE

Greater caffeine consumption in pregnancy is associated with reduced birth size, but potential associations with childhood growth are unclear.

OBJECTIVE

To evaluate the associations of pregnancy caffeine and paraxanthine measures with child growth in a contemporary cohort with low caffeine consumption and a historical cohort with high caffeine consumption.

DESIGN, SETTING, AND PARTICIPANTS

The Environmental Influences on Child Health Outcomes cohort of the National Institute of Child Health and Human Development Fetal Growth Studies (ECHO-FGS; 10 sites, 2009-2013) was a pregnancy cohort with 1 child measurement between ages 4 and 8 years (follow-up in 2017-2019). The Collaborative Perinatal Project (CPP) was a pregnancy cohort (12 sites, 1959-1965) with child follow-up through 8 years (1960-1974). The current secondary analysis was conducted in 2021 and 2022.

EXPOSURES

Concentrations of caffeine and its primary metabolite, paraxanthine, were quantified from plasma (ECHO-FGS) and serum (CPP) collected in the first trimester. Cut points for analyses were defined by quartiles in ECHO-FGS and quintiles in CPP.

MAIN OUTCOMES AND MEASURES

Child z scores for body mass index, weight, and height were evaluated, as well as fat mass index and percentage and obesity risk measured at 1 time between age 4 and 8 years in ECHO-FGS. In a secondary analysis of the CPP cohort, child z scores and obesity risk longitudinally through age 8 years were evaluated.

RESULTS

In ECHO-FGS (median caffeine intake <50 mg/d), 788 children (mean [SD] age, 6.8 [1.0] years; 411 boys [52.2%]) of women in the fourth vs first quartile of plasma caffeine concentrations had lower height z scores (β = -0.21; 95% CI, -0.41 to -0.02), but differences in weight z scores were only observed in the third quartile (β = -0.27; 95% CI, -0.47 to -0.07). In CPP, beginning at age 4 years, 1622 children (805 boys [49.7%]) of women in the highest caffeine quintile group had lower height z scores than their peers from the lowest group, with the gap widening with each successive year of age (β = -0.16 [95% CI, -0.31 to -0.01] at 4 years; β = -0.37 [95% CI, -0.57 to -0.16] at 8 years). There were slight reductions in weight at ages 5 to 8 years for children in the third vs first caffeine quintile (β = -0.16 to -0.22). Results were consistent for paraxanthine concentrations in both cohorts.

CONCLUSIONS AND RELEVANCE

Intrauterine exposure to increasing levels of caffeine and paraxanthine, even in low amounts, was associated with shorter stature in early childhood. The clinical implication of reductions in height and weight is unclear; however, the reductions were apparent even with levels of caffeine consumption below clinically recommended guidelines of less than 200 mg per day.

Early pregnancy body mass index and gestational weight gain: A mediating or moderating factor for short stature and risk of gestational diabetes mellitus?

This study examined the association between height and the risk of Gestational Diabetes Mellitus (GDM), and whether this association was mediated or moderated by early pregnancy body mass index (BMI) and gestational weight gain (GWG) that are known independent risk factors for GDM. Data of a retrospective cohort of pregnant women (N = 1,945) were extracted from antenatal clinic cards. The cut-off values of height in relation to risk of GDM were identified using receiver operating characteristic analysis and four categories of height were derived: < 150 cm, 150–155 cm, 156–160 cm, and > 160cm. Mediation analysis was performed using the Preacher and Hayes bootstrapping method while the moderation effect was tested with multiple regression analysis with interaction terms. Although there was no mediation effect of BMI and GWG on the association between height and risk of GDM, both factors moderated this association with a significant association between shorter height and risk of GDM was observed in overweight / obese women (height < 150 cm: AOR = 1.41, 95% CI = 1.03–2.44; height 156–160 cm: AOR = 1.48, 95% CI = 1.03–2.14). Overweight / obese women with height < 150 cm and excessive GWG at the end of the second trimester (AOR = 2.25, 95% CI = 1.45–4.17) had significantly higher risk of GDM than those without these factors. Short stature (< 150 cm) was significantly associated with GDM risk among OW/OB women with excessive gestational weight gain at the end of second trimester. This finding underscores the importance of maintaining a healthy BMI during reproductive age and gaining weight in recommended range during pregnancy.

Your height affects your health: genetic determinants and health-related outcomes in Taiwan

BACKGROUND

Height is an important anthropometric measurement and is associated with many health-related outcomes. Genome-wide association studies (GWASs) have identified hundreds of genetic loci associated with height, mainly in individuals of European ancestry.

METHODS

We performed genome-wide association analyses and replicated previously reported GWAS-determined single nucleotide polymorphisms (SNPs) in the Taiwanese Han population (Taiwan Biobank; n = 67,452). A genetic instrument composed of 251 SNPs was selected from our GWAS, based on height and replication results as the best-fit polygenic risk score (PRS), in accordance with the clumping and p-value threshold method. We also examined the association between genetically determined height (PRS₂₅₁) and measured height (phenotype). We performed observational (phenotype) and genetic PRS₂₅₁ association analyses of height and health-related outcomes.

RESULTS

GWAS identified 6843 SNPs in 89 genomic regions with genome-wide significance, including 18 novel loci. These were the most strongly associated genetic loci (EFEMP1, DIS3L2, ZBTB38, LCORL, HMGA1, CS, and GDF5) previously reported to play a role in height. There was a positive association between PRS₂₅₁ and measured height (p < 0.001). Of the 14 traits and 49 diseases analyzed, we observed significant associations of measured and genetically determined height with only eight traits (p < 0.05/[14 + 49]). Height was positively associated with body weight, waist circumference, and hip circumference but negatively associated with body mass index, waist-hip ratio, body fat, total cholesterol, and low-density lipoprotein cholesterol (p < 0.05/[14 + 49]).

CONCLUSIONS

This study contributes to the understanding of the genetic features of height and health-related outcomes in individuals of Han Chinese ancestry in Taiwan.

Association of short stature and obesity with cardio-metabolic risk factors in Iranian children and adolescents: the CASPIAN-V study

Purpose

The object of the present study was to examine the relationship of short stature and obesity with cardio-metabolic risk factors in children and adolescents from Iran.

Methods

Present nationwide cross-sectional study was conducted as a part of the fifth survey of CASPIAN study on 7 to 18 years old children and adolescents from 30 provinces of Iran in 2015. Short stature and excess weight were defined as age and sex-specific height lower than 5^th percentile and BMI higher than 85^th percentile respectively. The multivariate logistic regression model was applied to assess the aim of the study.

Results

A total of 3844 children and adolescents (52.4%: boys, 72.2%: urban areas) with an average age of 12.45 ± 3.04 years were enrolled in this study. The prevalence of short stature, excess weight and combined-short stature and excess weight was estimated as 15.8%, 17.6% and 2.2%. Odds of abdominal obesity in children with only short stature (OR: 2.11, 95%CI: 1.59-2.80), only excess weight (OR: 17.38, 95%CI: 13.89-21.75) and combined-short stature and excess weight (OR: 22.83, 95%CI: 13.93-37.39) were higher than children with normal-height and weight. Moreover, odds of high BP and metabolic syndrome were further in the students with combined excess weight and short stature compared to the normal-height and weight group.

Conclusion

We found that abdominal obesity, hypertension, and metabolic syndrome in short stature and obese children and adolescents were greater than those with normal-height and weight. Further prospective evaluations are required to clarify the association between short stature and cardio-metabolic risk factors.

Total Energy Expenditure and Functional Status in Older Adults: A Doubly Labelled Water Study

OBJECTIVES

Higher total energy expenditure in free living conditions, regardless of any activity, has been strongly associated with a lower risk of mortality in healthy older adults. Also, a good performance in physical and functional tests is a marker of good functional prognosis. However, it is not yet clear what is the association between total energy expenditure and the performance in physical and functional tests. The objective of this study was to verify the association between the total energy expenditure of older adults measured by doubly labelled water and the performance in functional tests.

DESIGN

Cross-sectional study.

SETTINGS AND PARTICIPANTS

Fifty-six older people were recruited from health services linked to the participating institutions.

MEASUREMENTS

Socio-demographic, anthropometric and clinical characteristics were assessed through the application of a structured questionnaire. Body composition was evaluated by isotopic dilution of deuterium oxide and functional status was assessed by the gait speed test, 6-minute walk test and handgrip strength. Total energy expenditure (GET) was assessed using the doubly labelled water method and the physical activity profile was verified using an activity monitor based on accelerometery.

RESULTS

The results showed that the highest total energy expenditure correlated with the best performance in the gait speed tests (r = 0.266; p = 0.047), 6-minute walk test (r = 0.424; p = 0.001) and maximum handgrip strength (r = 0.478; p = 0.000). Multivariate regression analysis in a model adjusted for sex and fat-free mass revealed an association between total energy expenditure and the 6-minute walk test (ß = 1.790; t = 2.080; p = 0.044) and the number of sedentary events ( ß = 6.389; t = 2.147; p = 0.038).

CONCLUSION

The results of this study suggest that, in clinical practice, older individuals with lower gait speed, worse performance in the 6-minute walk test and lower handgrip strength, may have lower total energy expenditure, being the stimulus for its increase important for the prevention of possible problems related to low energy expenditure.

Evolution of perinatal outcomes and sociodemographic variables in Chile (1996-2017)

The evolution of birth weight (BW), birth length (BL), and gestational age at delivery (GAD) and their correlation with various maternal sociodemographic variables were studied in Chilean newborns from years 1996 to 2017. A slight decrease in the mean values of these perinatal outcomes was observed; however, their risk sub-categories increased significantly, especially for GAD, indicating an important deterioration. GAD was strongly correlated with BW and BL. In the contingency tables, all sociodemographic variables, with the exemption of sex, had a higher proportion of early term 37-38-week and late pre-term 34-36-week newborns in women with a higher socioeconomic level; the strongest positive association was observed between mother's years of education and the GAD risk category 37-38 weeks. Different maternal factors, such as a higher frequency of cesarean sections, including either obesity presence or smoking habit, could be influencing presented results.

High double burden of child stunting and maternal overweight in the Republic of the Marshall Islands

Many low‐ and middle‐income countries are faced with a double burden of malnutrition characterized by a stagnating burden of undernutrition and an increasing prevalence of overweight and obesity often observed both at population and household levels. We used data from the 2017 National Integrated Child Health and Nutrition Survey in the Republic of the Marshall Islands to explore the prevalence of overweight mother‐stunted child pairs (mother–child double burden, MCDB). We used bivariate analysis, multivariate logistic regression, and multinomial logistic regression analysis to explore associations between child‐, maternal‐, and household‐level variables and both stunting and MCDB and other types of maternal–child pairs. Our results indicate that nearly three out of four mothers were overweight or obese and one in four households is home to an overweight mother with a stunted child. The risk of child stunting and of MCDB were largely associated with maternal characteristics of lower maternal height, maternal age at birth, years of education, and marital status and household economic status as measured by wealth index and number of household members. These findings support the growing body of evidence showing that the coexistence of high maternal overweight and child stunting (MCDB) has linked root causes to early life undernutrition that are exacerbated by the nutrition transition.

Prospective Pathways to Depressive Symptoms and Disordered Eating in Adolescence: A 7-Year Longitudinal Cohort Study

Eating pathology and depressive symptoms increase during adolescence, yet predictive pathways remain predominantly unexplored, despite their implications for prevention. The present study aimed to identify shared risk factors for eating pathology and depressive symptoms by evaluating an adapted Dual-Pathway Model of disordered eating, which postulated that higher BMI would predict disordered eating and depressive symptoms via pathways between body dissatisfaction, later BMI, depressive symptoms, and visible indicators of puberty (breast development for girls, height for boys). The participants were 8915 children (49% girls) from the Avon Longitudinal Study of Parents and Children, a population-based cohort study of British children, who were assessed at different intervals between the age of 7 to 14 years. Path analyses revealed that, for girls, childhood BMI exerted indirect effects on disordered eating via body dissatisfaction, depressive symptoms, and more advanced breast development, with indirect pathways identified to depressive symptoms via earlier depressive symptoms and more advanced breast development. For boys, childhood BMI had indirect effects on disordered eating via later BMI and body dissatisfaction, while only earlier depressive symptoms were found to have an independent and direct effect on adolescent depressive symptoms. This study reveals shared and independent risk factors for eating pathology and depressive symptoms in adolescence and suggests targets for preventative interventions, including higher BMI, body dissatisfaction, and depressive symptoms, in addition to advanced breast development, for girls.

Association between fasting plasma glucose and nonalcoholic fatty liver disease in a nonobese Chinese population with normal blood lipid levels: a prospective cohort study

Background

Fasting plasma glucose (FPG) is an easily quantifiable and inexpensive metabolic marker, which is often used to assess cardiovascular disease and diabetes. However, there have been limited studies on the association between FPG and nonalcoholic fatty liver disease (NAFLD) risk in nonobese people, especially in Chinese individuals. The purpose of this study was to investigate the association between FPG and NAFLD in nonobese Chinese people with normal blood lipid levels.

Methods

In this prospective cohort study, 9767 nonobese participants with normal blood lipid levels without NAFLD were recruited and prospectively followed for 5 years. The Cox proportional hazard model was used to evaluate the risk factors of NAFLD. Moreover, a Cox model with cubic spline functions and smooth curve fitting (the cubic spline smoothing) were used to identify the nonlinear association between FPG and NAFLD.

Results

During the 5-year follow-up, 841 (8.61%) participants were diagnosed with NAFLD. The good functional results (without NAFLD) estimated by the Kaplan-Meier method for 1 year, 2 years, 3 years, 4 years, and 5 years were 98.84, 95.35, 91.67%, 87.57 and 74.86%, respectively. Additionally, through the Cox proportional hazard model, after adjusting for other covariates, there was an independent positive correlation between FPG and increased NAFLD risk (HR:1.21, 95% CI:1.15–1.28, P < 0.0001), and the NAFLD risk was incrementally higher with the rising FPG quartile. The nonlinear association between FPG and NAFLD was visualized by cubic spline smoothing technique. It was calculated that the inflection point of FPG was 5.54. When FPG ≤ 5.54, there was a positive correlation between FPG and the risk of NAFLD (HR:2.20, 95% CI:1.78–2.73, P < 0.0001). When FPG > 5.54, the risk of NAFLD increased by 50% (HR:1.10, 95% CI:1.02–1.18, P = 0.0159) compared with the left side of the inflection point and gradually leveled off.

Conclusions

In a nonobese Chinese population with normal lipid levels, there is an independent nonlinear association between FPG and NAFLD, and the increase in FPG may indicate an increased risk of NAFLD. Additionally, this independent association is more obvious in the short stature population.

Maternal height and risk of gestational diabetes: a systematic review and meta-analysis

AIMS

Identifying women at high risk of developing gestational diabetes mellitus (GDM) is a public health interest. This study aims to investigate the association between maternal height and risk of GDM through meta-analysis.

METHODS

We retrieved the studies that assessed maternal height in relation to GDM. Pooled risk estimates of the included articles and their 95% confidence intervals (95% CIs) were calculated using a fixed- or random-effects model. Subgroup analyses were conducted according to study design and study location. Quality of studies was determined using the Newcastle-Ottawa Scale. Publication bias was detected using the Egger's and Begg's tests.

RESULTS

A total of 10 studies including 7 cohort and 3 cross-sectional studies with a total of 126,094 women were included for meta-analysis. Combined, each 5-cm increase in height was associated with about 20% reduction in risk of GDM [pooled odds ratio = 0.80, (95% CI 0.76, 0.85)]. The analysis revealed high heterogeneity between studies which dissolved after subgroup analysis by study design. This significant association did not differ between Asian and non-Asian populations. Egger's and Begg's tests showed little evidence of publication bias.

CONCLUSIONS

The present meta-analysis supports the conception that short stature is associated with GDM. Further studies of high quality are needed to confirm the findings.

Evaluation of an HMGA2 variant for pleiotropic effects on height and metabolic traits in ponies

BACKGROUND

Ponies are highly susceptible to metabolic derangements including hyperinsulinemia, insulin resistance, and adiposity.

HYPOTHESIS/OBJECTIVES

Genetic loci affecting height in ponies have pleiotropic effects on metabolic pathways and increase the susceptibility to equine metabolic syndrome (EMS).

ANIMALS

Two hundred ninety-four Welsh ponies and 529 horses.

METHODS

Retrospective study of horses phenotyped for metabolic traits. Correlations between height and metabolic traits were assessed by Pearson's correlation coefficients. Complementary genome-wide analysis methods were used to identify a region of interest (ROI) for height and metabolic traits, determine the fraction of heritability contributed by the ROI, and identify candidate genes.

RESULTS

There was an inverse relationship between height and baseline insulin (-0.26) in ponies. Genomic signature of selection and association analyses for both height and insulin identified the same ~1.3 megabase region on chromosome 6 that contained a shared ancestral haplotype between these traits. The ROI contributed ~40% of the heritability for height and ~20% of the heritability for insulin. High-mobility group AT-hook 2 was identified as a candidate gene, and Sanger sequencing detected a c.83G>A (p.G28E) variant associated with height in Shetland ponies. In our cohort of ponies, the A allele had a frequency of 0.76, was strongly correlated with height (-0.75), and was low to moderately correlated with metabolic traits including: insulin (0.32), insulin after an oral sugar test (0.25), non-esterified fatty acids (0.19), and triglyceride (0.22) concentrations.

CONCLUSIONS AND CLINICAL IMPORTANCE

These data have important implications for identifying individuals at risk for EMS.

Human energy expenditure: advances in organ-tissue prediction models

Humans expend energy at rest (REE), and this major energy exchange component is now usually estimated using statistical equations that include weight and other predictor variables. While these formulas are useful in evaluating an individual's or group's REE, an important gap remains: available statistical models are inadequate for explaining underlying organ-specific and tissue-specific mechanisms accounting for resting heat production. The lack of such systems level REE prediction models leaves many research questions unanswered. A potential approach that can fill this gap began with investigators who first showed in animals and later in humans that REE reflects the summated heat production rates of individual organs and tissues. Today, using advanced imaging technologies, REE can be accurately estimated from the measured in vivo mass of 10 organ-tissue mass components combined with their respective mass-specific metabolic rates. This review examines the next frontier of energy expenditure models and discusses how organ-tissue models have the potential not only to better predict REE but also to provide insights into how perturbations in organ mass lead to structure-function changes across other interacting organ systems. The introductory ideas advanced in this review provide a framework for future human energy expenditure modelling research.

Life history trade-offs and the partitioning of maternal investment: Implications for health of mothers and offspring

Lay Summary: This review sets out the hypothesis that life history trade-offs in the maternal generation favour the emergence of similar trade-offs in the offspring generation, mediated by the partitioning of maternal investment between pregnancy and lactation, and that these trade-offs help explain widely reported associations between growth trajectories and NCD risk. Growth patterns in early life predict the risk of non-communicable diseases (NCDs), but adaptive explanations remain controversial. It is widely assumed that NCDs occur either because of physiological adjustments to early constraints, or because early ecological cues fail to predict adult environmental conditions (mismatch). I present an inter-generational perspective on developmental plasticity, based on the over-arching hypothesis that a key axis of variability in maternal metabolism derives from life history trade-offs, which influence how individual mothers partition nutritional investment in their offspring between pregnancy and lactation. I review evidence for three resulting predictions: (i) Allocating relatively more energy to growth during development promotes the capacity to invest in offspring during pregnancy. Relevant mechanisms include greater fat-free mass and metabolic turnover, and a larger physical space for fetal growth. (ii) Allocating less energy to growth during development constrains fetal growth of the offspring, but mothers may compensate by a tendency to attain higher adiposity around puberty, ecological conditions permitting, which promotes nutritional investment during lactation. (iii) Since the partitioning of maternal investment between pregnancy and lactation impacts the allocation of energy to 'maintenance' as well as growth, it is expected to shape offspring NCD risk as well as adult size and body composition. Overall, this framework predicts that life history trade-offs in the maternal generation favour the emergence of similar trade-offs in the offspring generation, mediated by the partitioning of maternal investment between pregnancy and lactation, and that these trade-offs help explain widely reported associations between growth trajectories and NCD risk.

Cardiorespiratory fitness and activity explains the obesity-deprivation relationship in children

This study examined the association between obesity and deprivation in English children and whether cardiorespiratory fitness or physical activity (PA) can explain this association. Obesity was assessed using IOTF criteria in 8,398 10-16 year olds. Social deprivation was measured using the Index of Multiple Deprivation (IMD) (subdivided into 3 groups; high, mid and low deprivation). Obesity was analysed using binary logistic regression with stature, age and sex incorporated as confounding variables. Children's fitness levels were assessed using predicted VO2 max (20-metre shuttle run test) and PA was estimated using the PA Questionnaire for Adolescents or Children (PAQ). A strong association was found between obesity and deprivation. When fitness and PA were added to the logistic regression models, increasing levels in both were found to reduce the odds of obesity, although it was only by including fitness into the model that the association between obesity and deprivation disappeared. Including estimated PA into the model was found to be curvilinear. Initial increases in PA increase the odds of obesity. Only by increasing PA to exceed the 71st percentile (PAQ = 3.22) did the odds of being obese start to decline. In order to reduce deprivation inequalities in children's weight-status, health practitioners should focus on increasing cardiorespiratory fitness via physical activity levels in areas of greater deprivation.

Stature in adults as an indicator of socioeconomic inequalities in Mexico

OBJECTIVE

To estimate the association between stature in Mexican adults and some sociodemographic factors.

METHODS

We studied a sample of 30 970 subjects, using anthropometric data from the 2012 National Health and Nutrition Survey (ENSANUT 2012). The first quartile was used as the cutoff to define short stature. We analyzed differences among stature strata for sociodemographic variables by using the Kruskal-Wallis test. We estimated odds ratios to measure the association between stature and sociodemographic variables, controlling for potential confounders.

RESULTS

Persons from the southern region of the country were some three times as likely to be of short stature than were subjects in the northern region. The stature difference between the Mexican states with the highest and the lowest average stature was larger than the average difference in stature between Mexico and the United States of America. Adults who had had less than six years of schooling presented the highest prevalence of short stature, regardless of sex, region of the country, place of residence (rural or urban), or the proportion of indigenous language speakers in a state. In addition, the stratum with the highest marginalization (percentage of the population lacking education and services, with a low income, and living in a small community) showed the highest prevalence of short stature.

CONCLUSION

In Mexico, adults who are of short stature have unequal living conditions when compared to those of average or high stature, and this could drive increases in health inequity.

The influence of stunting on obesity in adulthood: results from the EPIPorto cohort

Objective

To retrospectively investigate the association between short stature and increased sitting height ratio (SHR) – indicators of stunting – and obesity markers in adults.

Design

Cross-sectional evaluation of the EPIPorto cohort. Weight, height, sitting height and waist circumference were measured. Obesity was assessed for men and women through BMI and waist-to-height ratio (WHtR). Short stature (women, <152 cm; men, <164 cm) and high SHR (women, ≥54·05 %; men, ≥53·25 %) were taken as stunting measures. OR with 95 % CI were computed using logistic regression models.

Setting

Representative sample of adults from EPIPorto, an adult cohort study from Porto, Portugal.

Subjects

A sample of 1682 adults, aged 18–86 years, was analysed.

Results

Higher obesity prevalence was found among women (BMI≥30·0 kg/m2: 25·5v.13·3 %,P<0·001) and a higher proportion of men presented abdominal obesity (WHtR≥0·5: 80·1v.71·1 %,P<0·001). A positive association was found between short stature and obesity measures for women (multivariate-adjusted OR; 95 % CI: 1·75; 1·17, 2·62 for BMI≥30·0 kg/m2; 1·89; 1·24, 2·87 for WHtR≥0·5). Increased SHR was associated with higher likelihood of having BMI≥30·0 kg/m2in both sexes (multivariate-adjusted OR; 95 % CI: 2·10; 1·40, 3·16 for women; 1·92; 1·07, 3·43 for men) but not with WHtR≥0·5.

Conclusions

Different growth markers are associated with obesity in adults. However, this association depends on the population and anthropometric measures used: short stature is associated with a higher risk of presenting excessive weight in women but not in men; SHR is more sensitive to detect this effect in both sexes.

Body Mass Disorders in Healthy Short Children and in Children with Growth Hormone Deficiency

The aim of the study was to determine the degree of adiposity and the incidence of body mass disorders, including abdominal obesity, in healthy short children and children with growth hormone deficiency. The study included 134 short children (height < 10th percentile) aged 7-15. In this cohort there were 63 (31 boys and 32 girls) children without diagnosed hormonal disorders and 71 patients (35 boys and 36 girls) with growth hormone deficiency. Basic somatic features were assessed and the study participants were categorized according to the percentage of body fat (%FAT), body mass index (BMI), and waist-to-height ratio (WHtR). We found that there were no significant differences in %FAT and the incidence of body weight disorders depending on gender or diagnosis. %FAT deficit was observed in 12-21% of the participants and underweight in almost every fourth child. Overweight involved 3-14% of the participants and obesity was diagnosed in isolated cases (0-3%); both were considerably lower compared to the estimates based on %FAT. Using the cut-off points of WHtR, abdominal adiposity was observed in 3-15% of the participants. In conclusion, quite a large number of short children (between 25 and 50%) are characterized by abnormal body fat or body mass index values. The results indicate a limited usefulness of BMI in evaluating the incidence of overweight and obesity in children characterized by a height deficit.

Isometric thermogenesis at rest and during movement: a neglected variable in energy expenditure and obesity predisposition

Isometric thermogenesis as applied to human energy expenditure refers to heat production resulting from increased muscle tension. While most physical activities consist of both dynamic and static (isometric) muscle actions, the isometric component is very often essential for the optimal performance of dynamic work given its role in coordinating posture during standing, walking and most physical activities of everyday life. Over the past 75 years, there has been sporadic interest into the relevance of isometric work to thermoregulatory thermogenesis and to adaptive thermogenesis pertaining to body-weight regulation. This has been in relation to (i) a role for skeletal muscle minor tremor or microvibration - nowadays referred to as 'resting muscle mechanical activity' - in maintaining body temperature in response to mild cooling; (ii) a role for slowed skeletal muscle isometric contraction-relaxation cycle as a mechanism for energy conservation in response to caloric restriction and weight loss and (iii) a role for spontaneous physical activity (which is contributed importantly by isometric work for posture maintenance and fidgeting behaviours) in adaptive thermogenesis pertaining to weight regulation. This paper reviews the evidence underlying these proposed roles for isometric work in adaptive thermogenesis and highlights the contention that variability in this neglected component of energy expenditure could contribute to human predisposition to obesity.

Height, BMI, and relative economic standing in children from developing countries

OBJECTIVES

The purpose of this study was to estimate a height-BMI association in child and female adolescent populations in developing countries, and to evaluate the potential role of relative economic status in this association.

METHODS

Flexible structured additive regression models were used to estimate associations between height, BMI, and relative wealth. Linear regression models were used to evaluate height-wealth interactions on BMI outcomes. The models were applied to pooled samples of 971,180 children under 5 years of age and 225,718 adolescent females between 15 and 19 years. Samples were taken from Demographic and Health Surveys from 64 developing countries.

RESULTS

Children exhibited a strong inverse association between height and BMI over the entire distribution of height. Female adolescents showed a weak inverse association. Relative economic status was associated with a stronger height-BMI relationship in early-life (<3 years) and a weaker relationship as children age into their fifth year.

CONCLUSIONS

Relative economic status may protect against consequences of a negative height-BMI association in young children in developing countries, first by promoting higher body weight among shorter children during the risk period for early-life mortality, and afterwards by limiting body weight in shorter children when overweight and obesity become longer-term health issues.

Patterns and Determinants of Double-Burden of Malnutrition among Rural Children: Evidence from China

Chinese children are facing dual burden of malnutrition—coexistence of under-and over-nutrition. Little systematic evidence exists for explaining the simultaneous presence of under-and over-nutrition. This study aims to explore underlying mechanisms of under-and over-nutrition among children in rural China. This study used a nationwide longitudinal dataset of children (N = 5,017) from 9 provinces across China, with four exclusively categories of nutritional outcomes including under-nutrition (stunting and underweight), over-nutrition (overweight only including obesity), paradox (stunted overweight), with normal nutrition as reference. Multinomial logit models (Level-1: occasions; Level-2: children; Level-3: villages) were fitted which corrected for non-independence of observations due to geographic clustering and repeated observations of individuals. A mixture of risk factors at the individual, household and neighbourhood levels predicted under-and over-nutrition among children in rural China. Improved socioeconomic status and living in more urbanised villages reduced the risk of stunted overweight among rural children in China. Young girls appeared to have higher risk of under-nutrition, and the risk decreased with age more markedly than for boys up to age 5. From age 5 onwards, boys tended to have higher risk of under-nutrition than girls. Girls aged around 12 and older were less likely to suffer from under-nutrition, while boys’ higher risk of under-nutrition persisted throughout adolescence. Children were less likely to suffer from over-nutrition compared to normal nutrition. Boys tended to have an even lower risk of over-nutrition than girls and the gender difference widened with age until adolescence. Our results have important policy implications that improving household economic status, in particular, maternal education and health insurance for children, and living environment are important to enhance rural children’s nutritional status in China. Investments in early years of childhood can be effective to reduce gender inequality in nutritional health in rural China.

A novel approach for measuring energy expenditure of a single sit-to-stand movement

PURPOSE

The purpose of this study was to quantify the energy expenditure (EE) of a sit-to-stand (STS) movement using a recently developed method and to examine the relationship between physical characteristics and the physiological demands of STS.

METHODS

Nineteen participants completed a multi-stage test at different STS frequencies of 6, 10, 15, 20 and 30 repetitions per minute. The expired gas, heart rate (HR) and rating of perceived exertion (RPE) were measured. The relationship between EE and STS frequency was obtained and the slope of the regression was quantified as the EE of an STS.

RESULTS

The gross EE and HR increased linearly as the STS frequency increased in all participants. The net EE of an STS was 0.92 ± 0.37 kJ. The EE of an STS increased as the height and weight increased, and these relationships were well fit by quadratic regression. The metabolic equivalent (Met) of performing 15 STSs per minute was 4.3 ± 1.0 Mets and RPE was 12 ± 1 over a total of 20.

CONCLUSION

This study demonstrated that the EE of an instantaneous movement can be quantified by relating the gross EE and different frequencies of movement. Using this method, we quantified the EE of an STS, which varied depending on participants' anthropometrics. Mets of repetitive STS movement ranged from 2.6 to 7.2. This physiological profile is useful when performing repetitive STS movements as a form of exercise.

Why are there race/ethnic differences in adult body mass index-adiposity relationships? A quantitative critical review

Body mass index (BMI) is now the most widely used measure of adiposity on a global scale. Nevertheless, intense discussion centers on the appropriateness of BMI as a phenotypic marker of adiposity across populations differing in race and ethnicity. BMI-adiposity relations appear to vary significantly across race/ethnic groups, but a collective critical analysis of these effects establishing their magnitude and underlying body shape/composition basis is lacking. Accordingly, we systematically review the magnitude of these race-ethnic differences across non-Hispanic (NH) white, NH black and Mexican American adults, their anatomic body composition basis and potential biologically linked mechanisms, using both earlier publications and new analyses from the US National Health and Nutrition Examination Survey. Our collective observations provide a new framework for critically evaluating the quantitative relations between BMI and adiposity across groups differing in race and ethnicity; reveal new insights into BMI as a measure of adiposity across the adult age-span; identify knowledge gaps that can form the basis of future research and create a quantitative foundation for developing BMI-related public health recommendations.

Association between Adult Stature and Energy Expenditure in Low-Income Women from Northeastern Brazil

Background

Perinatal undernutrition may lead to important metabolic adaptations in adult life, short stature being the most visible. The present study aimed to evaluate the association between stature and total energy expenditure of low-income women.

Method

Women aged 19–45 years from low-income communities in Maceió-AL were recruited. A sample of 67 volunteers was selected and divided into either short stature (≤152.4 cm; n = 34) or non-short stature (≥158.7 cm; n = 33) group. Data on socioeconomic status, anthropometric variables, and hormonal profiles was collected. Total energy expenditure and body composition were assessed by the doubly labeled water technique with multiple points over 14 days. In addition, physical activity levels were measured with triaxial accelerometers and dietary intake data were collected using three 24-hour food records.

Results

The mean subject age was 30.94 years. Women of short stature had lower body weight and lean body mass compared to non-short women, but there were no differences in thyroid hormone concentrations or daily energy intake between the two groups. Short-stature women showed lower total energy expenditure (P = 0.01) and a significantly higher physical activity level (P = 0.01) compared to non-short women. However, the difference in total energy expenditure was no longer significant after statistical adjustment for age, lean body mass, and triiodothyronine concentrations.

Conclusion

Women with short stature present the same energy intake, but lower total energy expenditure than non-short women, even with a higher physical activity level, which suggests that they are more prone to weight gain.

Height-obesity relationship in school children in Sub-Saharan Africa: results of a cross-sectional study in Cameroon

BACKGROUND

In developed nations, taller children exhibit a greater propensity to overweight/obesity. This study investigates whether this height-adiposity relationship holds true for Cameroon children using two parameters of adiposity including body mass index (BMI) and waist circumference (WC).

METHODS

In 557 children (287 boys and 270 girls, mean age 9.0 ± 1.8 years) from the North West Region of Cameroon height, weight and WC were measured and BMI calculated. Variables were converted to standard deviation scores (SDS). Participants were divided into quartiles of height SDS, then mean of age and sex-standardized body fat parameters compared across quartiles. The frequency of excess adiposity was calculated within each quartile. Correlation and regression analysis were used to assess height-adiposity relationships.

RESULTS

Multiple comparisons indicated a significant increase in mean BMI (-0.08 to 0.65) and WC (-0.11 to 0.87) SDSs with increasing quartiles of height SDS. Frequency of overweight/obesity and abdominal overweight/obesity was highest among children with highest height SDS (30.2 - 33.1%) and lowest in their shortest peers (0.7 - 5.0%). There was a linear relationship between height SDS and BMI SDS (R(2) = 0.087, p < 0.001); height SDS and WC SDS (R(2) = 0.356, p < 0.001) among both boys and girls.

CONCLUSIONS

This study shows that in Cameroon just as in developed economies a higher height SDS is associated with a higher frequency of overweight/obesity. This is independent of the parameter used to evaluate overweight/obesity (BMI SDS or WC SDS).

Examining variations of resting metabolic rate of adults: a public health perspective

PURPOSE

There has not been a recent comprehensive effort to examine existing studies on the resting metabolic rate (RMR) of adults to identify the effect of common population demographic and anthropometric characteristics. Thus, we reviewed the literature on RMR (kcal·kg(-1)·h(-1)) to determine the relationship of age, sex, and obesity status to RMR as compared with the commonly accepted value for the metabolic equivalent (MET; e.g., 1.0 kcal·kg(-1)·h(-1)).

METHODS

Using several databases, scientific articles published from 1980 to 2011 were identified that measured RMR, and from those, others dating back to 1920 were identified. One hundred and ninety-seven studies were identified, resulting in 397 publication estimates of RMR that could represent a population subgroup. Inverse variance weighting technique was applied to compute means and 95% confidence intervals (CI).

RESULTS

The mean value for RMR was 0.863 kcal·kg(-1)·h(-1) (95% CI = 0.852-0.874), higher for men than women, decreasing with increasing age, and less in overweight than normal weight adults. Regardless of sex, adults with BMI ≥ 30 kg·m(-2) had the lowest RMR (<0.741 kcal·kg(-1)·h(-1)).

CONCLUSIONS

No single value for RMR is appropriate for all adults. Adhering to the nearly universally accepted MET convention may lead to the overestimation of the RMR of approximately 10% for men and almost 15% for women and be as high as 20%-30% for some demographic and anthropometric combinations. These large errors raise questions about the longstanding adherence to the conventional MET value for RMR. Failure to recognize this discrepancy may result in important miscalculations of energy expended from interventions using physical activity for diabetes and other chronic disease prevention efforts.

Assessment of physical activity and sedentary behavior at preschools in Cape Town, South Africa

BACKGROUND

Overweight and obesity among young South African (SA) children have reached concerning levels. Preschool interventions to promote physical activity (PA) and reduce sedentary behavior (SB) could help curb these trends. However, research has not been conducted to assess these behaviors in SA preschools and how these might differ across income settings. This study aimed to (1) assess, by direct observation, PA and SB patterns of children in a range of preschool settings; (2) determine the influence of socioeconomic status on PA and SB; and (3) identify contextual and individual-level factors associated with PA.

METHODS

Eighty children (4-5 years old) from four low-income and four mid-/high-income preschools in Cape Town were observed using the Observational System for Recording Physical Activity in Children-Preschool Version.

RESULTS

Children spent 73% of their time engaged in SB. Low-income children spent 93% of their time indoors, compared to 79% among mid-/high-income children (p<0.001). Low-income children spent 11% of their time in moderate-to-vigorous PA (MVPA), compared to 8% among mid-/high-income children (p<0.05). Children across all settings were significantly more likely to engage in light PA (LPA) and MVPA if they were outside (relative risk ratio [RRR]=2.48 for LPA; RRR=6.95 for MVPA) and if their activity was adult-initiated (RRR=1.74 for LPA; RRR=1.66 for MVPA). Obese children were significantly less likely to do LPA (RRR=0.47); underweight children were significantly less likely to do LPA (RRR=0.63) and MVPA (RRR=0.26).

CONCLUSIONS

These findings provide information useful for the development of interventions to address PA and SB in SA preschool children.

Scaling of adult body weight to height across sex and race/ethnic groups: relevance to BMI

BACKGROUND

Body mass index (BMI) is formulated on the assumption that body weight (BW) scales to height with a power of 2 (BW∝height(2)), independent of sex and race-ethnicity. Powers differing from 2 are observed in studies of selected samples, thus raising the question if BMI is a generalizable metric that makes BW independent of height across populations.

OBJECTIVES

The objectives were to test the hypothesis that adult BW scales to height with a power of 2 independent of sex and race-ethnicity and to advance an understanding of BMI as a measure of shape by extending allometric analyses to waist circumference (WC).

DESIGN

We conducted cross-sectional subject evaluations, including body composition, from the NHANES and the Korean NHANES (KNHANES). Variations of the allometric model (Y = αX(β)) were used to establish height scaling powers (β ± SE) across non-Hispanic white and black, Mexican American, and Korean men and women.

RESULTS

Exploratory analyses in population samples established age and adiposity as important independent determinants of height scaling powers (i.e., β). After age and adiposity in the next series of analyses were controlled for, BW scaling powers were nonsignificantly different between race/ethnic groups within each sex group; WC findings were similar in women, whereas small but significant between-race differences were observed in the men. Sex differences in β values were nonsignificant except for BW in non-Hispanic blacks and WC in Koreans (P < 0.05). Nationally representative powers for BW were (NHANES/KNHANES) 2.12 ± 0.05/2.11 ± 0.06 for men and 2.02 ± 0.04/1.99 ± 0.06 for women and for WC were 0.66 ± 0.03/0.67 ± 0.05 for men and 0.61 ± 0.04/0.56 ± 0.05 for women.

CONCLUSIONS

Adult BW scales to height with a power of ∼2 across the 8 sex and race/ethnic groups, an observation that makes BMI a generalizable height-independent measure of shape across most populations. WC also follows generalizable scaling rules, a finding that has implications for defining body shape in populations who differ in stature.

Are chronic diseases related to height? Results from the Portuguese National Health Interview Survey

This paper analyze the association between height and chronic diseases in Portugal and the extent to which this relationship is mediated by education. The sample upon which the analysis is based comprised those participants in the 2005/2006 Portuguese National Health Interview Survey (n=28,433) aged 25-79. Logistic regressions measured the association of height with ten chronic diseases, adjusting for age, lifestyle, education, and other socioeconomic factors. Among women, an additional centimeter in stature significantly decreased the prevalence of asthma, chronic pain, and acute cardiac disease, by 0.057, 0.221, and 0.033 percentage points, respectively. Also, mental disorders were significantly less prevalent in the last quartile of height. Among men, an additional centimeter in height was associated with a 0.074 lower prevalence of asthma, and men in the last quartile of height were significantly less at risk of acute cardiovascular disease. There was no significant association between height and the risk of diabetes, high blood pressure, cancer, and pulmonary diseases. As for the impact of education, women with a tertiary level were on average 5.3cm taller than those with no schooling; among men, the difference was almost 9cm. Adjusting for education reduced the height-related excess risk of ill health by 36% on average among men, and by 7% among women. The analysis indicates that there is a significant association of height with several chronic conditions, and that education plays a mediating role in the height-health connection. By emphasizing the role of height and education as determinants of chronic conditions, this paper also highlights the role of conditions related to childhood health and socioeconomic background.

Associations of prenatal growth with metabolic syndrome, insulin resistance, and nutritional status in Chilean children

Introduction. The association of prenatal growth with nutritional status, metabolic syndrome (MS), and insulin resistance (IR) was studied in school-age children. Methods. A retrospective cohort study was designed linking present data of children with perinatal records. 3325 subjects were enrolled. Anthropometry, blood pressure (BP), and pubertal status were assessed. Blood lipids, glucose, and insulin were measured. Linear associations were assessed using the Cochran-Armitage test. Odds ratios and nonlinear associations were computed. Results. 3290 children (52% females, mean age of 11.4 ± 1 years) were analyzed. Prevalence of obesity, stunting, MS, and IR was 16.0%, 3.6%, 7.3%, and 25.5%, respectively. The strongest positive association was between birth weight (BW) and obesity (OR 2.97 (95% CI 2.01–4.40) at BW ≥ 4,000 g compared to BW 2,500–2,999). The strongest inverse association was between birth length (BL) and stunting (OR 8.70 (95% CI 3.66–20.67) at BL < 48 cm compared to BL 52-53 cm). A U-shaped association between BL and BP ≥ 90th percentile was observed. Significant ORs were also found for MS and IR. Adjustments for present fat mass increased or maintained the most prenatal growth influences. Conclusions. Prenatal growth influences MS, IR, and nutritional status. Prenatal growth was more important than present body composition in determining these outcomes.

Adult fat content: reinterpreting and modelling the Benn Index and related sex differences

BACKGROUND

In women, the height exponent, p, of the Benn Index, (body mass)/height(p), is typically lower than in men, body masses are more weakly correlated with height and fat masses tend to be higher. In both sexes fat masses correlate only weakly with height. Changes in fat mass are typically accompanied by changes in fat-free mass.

AIMS

To integrate these facts, together with other published findings relating to fat content and to explain why p is lower in women.

METHODS

Data and statistics are taken from the literature. The differences in p are explored by Monte Carlo and algebraic modelling. Mean transverse areas of the body (MTAs), calculated as (body mass)/height, are related to height.

RESULTS AND CONCLUSIONS

The body can be modelled as consisting of a component, M1, varying roughly with the cube of height and another, M2, varying little with height. The low correlation between total body mass and height is due both to M2 and to data scatter. The low p values in women relate especially to M2. Relationships amongst height, fatness, MTAs and girths of body parts generally conform to this interpretation. Questions are raised as to how health risks are best related to fat mass.

The impact of height during childhood on the national prevalence rates of overweight

BACKGROUND

It is known that height and body mass index (BMI) are correlated in childhood. However, its impact on the (trend of) national prevalence rates of overweight and obesity has never been investigated. The aim of our study is to investigate the relation between height and national prevalence rates of overweight and obesity in childhood between 1980, 1997, and 2009, and to calculate which fixed value of p (2.0,2.1, …,3.0) in kg/m(p) during childhood is most accurate in predicting adult overweight.

METHODS AND FINDINGS

Cross-sectional growth data of children from three Dutch nationwide surveys in 1980, 1997, and 2009, and longitudinal data from the Terneuzen Birth Cohort and the Harpenden Growth Study were used. Relative risks (RR) and 95% confidence intervals (CI) were calculated. Our study showed that tall (>1 standard deviation (SD)) girls aged 5.0-13.9 y were more often overweight (RR = 3.5,95%CI:2.8-4.4) and obese (RR = 3.9,95%CI:2.1-7.4) than short girls (<-1 SD). Similar results were found in boys aged 5.0-14.9 y (RR = 4.4,95%CI:3.4-5.7 and RR = 5.3,95%CI:2.6-11.0). No large differences were found in the other age groups and in comparison with children with an average stature. Tall boys aged 2.0-4.9 y had a significantly higher positive trend in overweight between 1980 and 1997 compared to short boys (RR = 4.0,95%CI:1.38-11.9). For other age groups and in girls, no significant trends were found. The optimal Area Under the Curve (AUC) to predict adult overweight was found for p = 2.0.

CONCLUSIONS AND SIGNIFICANCE

Tall girls aged 5.0-13.9y and tall boys aged 5.0-14.9y have much higher prevalence rates of overweight and obesity than their shorter peers. We suggest taking into account the impact of height when evaluating trends and variations of BMI distributions in childhood, and to use BMI to predict adult overweight.

Children's body fatness and prevalence of obesity in relation to height for age

BACKGROUND

Children who are taller for their age tend to have higher BMI and, as a group, a greater prevalence of overweight/obesity.

AIM

To examine the relationship between height for age with three measures of adiposity.

SUBJECTS AND METHODS

Height, weight, BMI, % body fat (%BF) (by bioimpedance) and waist circumference (WC) were measured in 2298 Caucasian children (1251 boys) aged 4-14 years. Standard deviation scores (SDS) were derived and cases divided into quartiles of height SDS. Mean BMI, %BF and WC SDSs were compared across quartiles. Prevalence of overweight/obesity, over-fat/obesity and abdominal overweight/obesity within each height for age quartile was determined.

RESULTS

Mean BMI, %BF and WC SDSs increased with increasing quartile of height SDS. Overweight/obesity, overfat/obesity and abdominal overweight/obesity prevalence increased from the first quartile (8.8-13%) to the fourth quartile (32.7-45.5%) of height SDS. A significant rising trend in mean SDSs for BMI, %BF and WC was also observed with increasing height SDS in overweight/obese children only.

CONCLUSION

A higher prevalence of excess weight, measured by BMI SDS among children taller for their age, is replicated when using %BF and WC. Height for age measurement has potential in screening children for later risk of obesity.

Underweight, overweight and obesity in paediatric dialysis and renal transplant patients

BACKGROUND

The prevalence of childhood overweight is rising worldwide, but in children on renal replacement therapy (RRT) a poor nutritional status is still the primary concern. We aimed to study the prevalence of, and factors associated with, underweight and overweight/obesity in the European paediatric RRT population. Moreover, we assessed the evolution of body mass index (BMI) after the start of RRT.

METHODS

We included 4474 patients younger than 16 years from 25 countries of whom BMI data, obtained between 1995 and 2010, were available within the European Society for Paediatric Nephrology/European Renal Association-European Dialysis and Transplant Association Registry. Prevalence estimates for under- and overweight/obesity were calculated using age and sex-specific criteria of the World Health Organization (WHO, 0-1 year olds) and the International Obesity Task Force cut-offs (2-15 year olds).

RESULTS

The prevalence of underweight was 3.5%, whereas 20.8% of the patients were overweight and 12.5% obese. Factors associated with being underweight were receiving dialysis treatment and infant age. Among transplanted recipients, a very short stature (OR: 1.64, 95% CI: 1.40-1.92) and glucocorticoid treatment (OR: 1.23, 95% CI: 1.03-1.47) were associated with a higher risk of being overweight/obese. BMI increased post-transplant, and a lower BMI and a higher age at the start of RRT were associated with greater BMI changes during RRT treatment.

CONCLUSIONS

Overweight and obesity, rather than underweight, are highly prevalent in European children on RRT. Short stature among graft recipients had a strong association with overweight, while underweight appears to be only a problem in infants. Our findings suggest that nutritional management in children receiving RRT should focus as much on the prevention and treatment of overweight as on preventing malnutrition.

Application of body mass index according to height-age in short and tall children

Background

In children with either delayed or accelerated growth, expressing the body mass index (BMI) to chronological age might lead to invalid body composition estimates. Reference to height-age has been suggested for such populations; however its validity has not been demonstrated.

Methods

Anthropometric data of healthy children were obtained from the German KiGGS survey. We selected three samples with different height distributions representing short stature (mean height SDS: -1.6), normal stature (height SDS: 0), and tall stature (height SDS: +1.6), and compared BMI-for-age and BMI-for-height-age between these samples across the paediatric age range. Differences between samples were tested using Kruskal-Wallis one-way analysis of variance and permutation tests.

Results

At a given age, BMI was distributed towards lower values in short, and towards higher values in tall subjects as compared to a population with average height distribution. Expressing BMI to height-age eliminated these differences in boys with a short stature from 4 years to 14 years of age, in tall boys from 4 to 16 years, in short girls aged 2-10 years or tall girls aged 2-17 years.

Conclusion

From late infancy to adolescent age, BMI distribution co-varies with height distribution and referencing to height-age appears appropriate within this age period. However, caution is needed when data about pubertal status are absent.

Implication of high-body-fat percentage on cardiometabolic risk in middle-aged, healthy, normal-weight adults

OBJECTIVE

This study investigated the number of Korean adults who had a normal body mass index (BMI) but high body-fat percentage (BF%) and determined their increased risk factors for cardiovascular diseases, including high blood pressure, hyperglycemia, and dyslipidemia.

DESIGN AND METHODS

This cross-sectional study was based on 12,386 subjects (6,534 men and 5,852 women), with a normal BMI, between 30 and 49 years of age. Subjects were categorized into two groups by BF% (normal BF% group, BF% <25 for men, and BF% <30 for women; high BF(%) group, BF% ≥25 for men, and BF% ≥30 for women).

RESULTS

The proportion of subjects with a normal BMI and high BF% was 12.7% (n = 1,572; 291 [4.5%] men and 1,281 [21.9%] women). Subjects with a high BF% had a significantly higher prevalence of high blood pressure (men only), hyperglycemia, and dyslipidemia. Multiple logistic regression analyses revealed that subjects with a normal BMI and high BF% had a 1.63 (adjusted odds ratio, 95% confidence interval: 1.21-2.19) in men and 1.56 (adjusted odds ratio, 95% confidence interval: 1.36-1.80) in women increased risk of one or more cardiovascular risk factors compared to subjects in the normal BMI and normal BF% group, even after adjusting for abdominal obesity.

CONCLUSION

High BF% is associated with a high cardiometabolic risks, regardless of abdominal obesity, in normal-weight Korean adults. Thus, follow-up screening of those with a high BF% may be necessary to detect and prevent cardiometabolic diseases, particularly for women with a normal BMI.

A standardized approach to study human variability in isometric thermogenesis during low-intensity physical activity

Limitations of current methods: The assessment of human variability in various compartments of daily energy expenditure (EE) under standardized conditions is well defined at rest [as basal metabolic rate (BMR) and thermic effect of feeding (TEF)], and currently under validation for assessing the energy cost of low-intensity dynamic work. However, because physical activities of daily life consist of a combination of both dynamic and isometric work, there is also a need to develop standardized tests for assessing human variability in the energy cost of low-intensity isometric work.

EXPERIMENTAL OBJECTIVES

Development of an approach to study human variability in isometric thermogenesis by incorporating a protocol of intermittent leg press exercise of varying low-intensity isometric loads with measurements of EE by indirect calorimetry.

RESULTS

EE was measured in the seated position with the subject at rest or while intermittently pressing both legs against a press-platform at 5 low-intensity isometric loads (+5, +10, +15, +20, and +25 kg force), each consisting of a succession of 8 cycles of press (30 s) and rest (30 s). EE, integrated over each 8-min period of the intermittent leg press exercise, was found to increase linearly across the 5 isometric loads with a correlation coefficient (r) > 0.9 for each individual. The slope of this EE-Load relationship, which provides the energy cost of this standardized isometric exercise expressed per kg force applied intermittently (30 s in every min), was found to show good repeatability when assessed in subjects who repeated the same experimental protocol on 3 separate days: its low intra-individual coefficient of variation (CV) of ~ 10% contrasted with its much higher inter-individual CV of 35%; the latter being mass-independent but partly explained by height.

CONCLUSION

This standardized approach to study isometric thermogenesis opens up a new avenue for research in EE phenotyping and metabolic predisposition to obesity.

Associations between household income, height, and BMI in contemporary US schoolchildren

This paper evaluates the association between income and physical development in a nationally representative sample of contemporary US schoolchildren followed from kindergarten to eighth grade (average ages of 6-14). A generalized linear mixed modeling framework is used to evaluate height and body mass index (BMI) as both levels and annualized growth in a pooled sample. Contemporary US schoolchildren show income variation in height that is significant but modest at around .1cm (in kindergarten) to .4cm (eighth grade) increases per doubling of income. An exception is found for Hispanic children who show faster height velocity associated with higher income through childhood yielding a 1.0cm increase per doubling of income by the eighth grade. All groups except black males show a negative relationship between income and BMI that becomes stronger with age with an average .8kg/m(2) lower BMI per doubling of income by the eighth grade. These results are robust to the inclusion of baseline anthropometric controls. The analysis suggests that higher-income US schoolchildren enter mid-adolescence as taller but with lower proportional body mass relative to their lower-income counterparts.

Stunting and obesity in childhood: a reassessment using longitudinal data from South Africa

BACKGROUND

A series of cross-sectional studies have found a relationship between stunting and obesity in childhood. Because height appears in both the numerator of indices of stunting and the denominator of indices of obesity, random errors made by fieldworkers measuring heights can produce negative bias in estimates of this relationship.

METHODS

With longitudinal data, height can be instrumented with its lagged value in a two-stage probit regression model, purging the estimated association between the probability of being obese or underweight and the height-for-age z-score of this errors-in-variables bias. Such a model is fitted to a cohort of 1110 primary-school-age children measured in 1993-2004 in a panel study in KwaZulu-Natal, South Africa. The study also collected detailed data on households' demographic and socio-economic characteristics.

RESULTS

Risk factors for stunting, wasting and obesity differed in this population. Stunting was not associated with childhood obesity in either the cross-sectional or two-stage models. In the cross-sectional analysis, however, random measurement errors masked a negative association between children's height-for-age and their probability of being underweight or wasted that emerged in the two-stage instrumental variable models. This association was further amplified, rather than attenuated, by controlling for children's household income, racial group, residence and mother's education.

CONCLUSIONS

The validity of the findings of earlier cross-sectional studies of the association between stunting and obesity in childhood is dependent on the precision with which they measured height. Random measurement error can also mask an association between being stunted and underweight in cross-sectional studies.

Risk factors for obesity: further evidence for stronger effects on overweight children and adolescents compared to normal-weight subjects

BACKGROUND

We recently showed that in preschoolers risk factors for overweight show stronger associations with BMI in children with high BMI values. However, it is unclear whether these findings might also pertain to adolescents.

METHODS

We extracted data on 3-10 year-old (n = 7,237) and 11-17 year-old (n = 5,986) children from a representative cross-sectional German health survey (KiGGS) conducted between 2003 and 2006 and calculated quantile regression models for each age group. We used z-scores of children's body mass index (BMI) as outcome variable and maternal BMI, maternal smoking in pregnancy, low parental socioeconomic status, exclusive formula-feeding and high TV viewing time as explanatory variables.

RESULTS

In both age groups, the estimated effects of all risk factors except formula-feeding on BMI z-score were greatest for children with the highest BMI z-score. The median BMI z-score of 11-17 year-old children with high TV viewing time, for example, was 0.11 [95% CI: 0.03, 0.19] units higher than the median BMI z-score of teenage children with low TV viewing time. This risk factor was associated with an average difference of 0.18 [0.06, 0.30] units at the 90(th) percentile of BMI z-score and of 0.20 [0.07, 0.33] units at the 97(th) percentile.

CONCLUSIONS

We confirmed that risk factors for childhood overweight are associated with greater shifts in the upper parts of the children's BMI distribution than in the middle and lower parts. These findings pertain also to teenagers and might possibly help to explain the secular shift in the upper BMI percentiles in children and adolescents.

Trends in the associations between family income, height and body mass index in US children and adolescents: 1971-1980 and 1999-2008

AIM

This paper evaluates trends in the childhood and adolescent associations between family income, height and body mass index (BMI) between the periods 1971-1980 and 1999-2008.

SUBJECTS AND METHODS

US-born children (aged 2-11) and adolescents (aged 12-19) in the NHANES I, NHANES II and 1999-2008 NHANES are evaluated for BMI and height using flexibly-estimated structured additive regression models.

RESULTS

Three trends are identified: BMI gains have been greater in lower-income relative to higher-income children and adolescents; height has increased more in lower-income relative to higher-income children (but not in adolescents); and BMI has increased more in taller children than shorter children (but not in adolescents). Following from these trends is that contemporary children exhibit a negative height-income interaction effect on BMI such that the inverse association between income and BMI is larger in taller children. Similar results hold when categorical obesity is considered but with modest height-related changes and income-height interaction effect in adolescents. Race-sex differences are explored and descriptive evidence on the potential role of changes in caloric intake is presented.

CONCLUSION

The relationship between the economic environment and growth in US youth has changed in recent decades. Contemporary taller and lower-income children exhibit greater body mass and obesity.

The prevalence of stunting, overweight and obesity, and metabolic disease risk in rural South African children

BACKGROUND

Low- to middle-income countries are undergoing a health transition with non-communicable diseases contributing substantially to disease burden, despite persistence of undernutrition and infectious diseases. This study aimed to investigate the prevalence and patterns of stunting and overweight/obesity, and hence risk for metabolic disease, in a group of children and adolescents in rural South Africa.

METHODS

A cross-sectional growth survey was conducted involving 3511 children and adolescents 1-20 years, selected through stratified random sampling from a previously enumerated population living in Agincourt sub-district, Mpumalanga Province, South Africa. Anthropometric measurements including height, weight and waist circumference were taken using standard procedures. Tanner pubertal assessment was conducted among adolescents 9-20 years. Growth z-scores were generated using 2006 WHO standards for children up to five years and 1977 NCHS/WHO reference for older children. Overweight and obesity for those <18 years were determined using International Obesity Task Force BMI cut-offs, while adult cut-offs of BMI > or = 25 and > or = 30 kg/m2 for overweight and obesity respectively were used for those > or = 18 years. Waist circumference cut-offs of > or = 94 cm for males and > or = 80 cm for females and waist-to-height ratio of 0.5 for both sexes were used to determine metabolic disease risk in adolescents.

RESULTS

About one in five children aged 1-4 years was stunted; one in three of those aged one year. Concurrently, the prevalence of combined overweight and obesity, almost non-existent in boys, was substantial among adolescent girls, increasing with age and reaching approximately 20-25% in late adolescence. Central obesity was prevalent among adolescent girls, increasing with sexual maturation and reaching a peak of 35% at Tanner Stage 5, indicating increased risk for metabolic disease.

CONCLUSIONS

The study highlights that in transitional societies, early stunting and adolescent obesity may co-exist in the same socio-geographic population. It is likely that this profile relates to changes in nutrition and diet, but variation in factors such as infectious disease burden and physical activity patterns, as well as social influences, need to be investigated. As obesity and adult short stature are risk factors for metabolic syndrome and Type 2 diabetes, this combination of early stunting and adolescent obesity may be an explosive combination.

Relationship between short stature and obesity in Brazil: a multilevel analysis

To ascertain the association of BMI and obesity with short stature, a cross-sectional telephone survey was conducted in 2006, using a multilevel approach, adjusting for individual- and city-level measures of socio-economic status. The study probabilistic sample consisted of 54 369 adults (>18 years) living in households with access to telephone lines in each urban area of the twenty-six Brazilian state capitals and federal district. Odds of being currently obese and obese at age 20 years were compared between short stature individuals (5th percentile) and those with normal stature. After controlling for individual- and city-level sociodemographic characteristics and behaviours, high BMI was strongly associated with short stature individuals (P = 0·001). Among short stature women the adjusted OR of being obese was 3·0 (95 % CI 2·2, 4·2) compared with those with stature greater than the 5th percentile. Among men this adjusted OR was 2·0 (95 % CI 1·5, 2·6). When comparisons were made for BMI at age 20 years the OR were even larger (6 for men and 8 for women). Despite the growing body of evidence that environmental factors such as poor food choices and physical inactivity are the main determinants of the worldwide obesity epidemic, the greater difference in BMI and prevalence of obesity in the Brazilian capitals was explained mainly by individual factors. We found a strong association between obesity and short stature after adjustment for diet, physical activity, and many environmental factors. Intra- and inter-generational consequences of undernutrition are an alternative explanation for the regional disparities in obesity in Brazil.