Population differences in the relationship between height, weight, and adiposity: an application of Burton's model

Balance performance among horseback-rider compared to non-horseback-rider women in Saudi Arabia: A cross-sectional study

Horseback riding requires adapting to constant changes in balance conditions, maintaining equilibrium on the horse, and preventing falls. However, differences in balance performance among horseback riders and non-rider-healthy young women in Saudi Arabia have not been explored. This study investigates whether horseback-rider women would perform better on static and dynamic balance tests than non-rider women. Also, the study examined the effect of years of horseback riding on balance performance in the rider group. Twenty healthy young females participated in the study using a convenience sampling method. Ten were riders, and ten were non-riders. Static and dynamic balance tests, including the Berg balance scale (BBS), timed up and go (TUG), and unipedal stance test (UPST), was obtained from all subjects. Descriptive and inferential statistics were used to compare balance performance between the horseback riders and non-riders groups. The horseback-rider group had statistically significantly higher scores on both the static and dynamic tests than non-riders: BBS test (Z = -2.537, P = .011), TUG (t = -3.889, P = .001), and unipedal stance test with the eyes open and closed (t = 14.048, t = 13.639, P = .000). Our rider sample did not show a statistically significant correlation between years of riding and balance scores. The horseback riders have greater static and dynamic balance abilities than non-riders. Further study is needed to compare the balance performance between experienced riders versus beginners among healthy adults in Saudi Arabia.

Normative values and factors affecting Pediatric Reach Tests in Saudi children aged 6-11 years in the eastern province: cross-sectional study

Background

The Pediatric Reach Tests (PRTs) assess balance while standing-the Functional Reach Test (FRT) and Lateral Reach Test (LRT)-and in a sitting position-the Modified Functional Reach Test (MFRT) and Modified Lateral Reach Test (MLRT). Normative values have not been fully evaluated in Saudi children. The objectives are; to estimate the normative values for PRTs; investigate the correlation between the PRTs and demographic/anthropometric characteristics; and develop predictive equations for the PRTs.

Methods

In this cross-sectional study, 251 children aged 6-11 were recruited. The PRTs were measured and correlated with demographic/anthropometric variables. A stepwise regression was conducted to develop the predictive equations for the PRT scores.

Results

The mean and standard deviations (in cm) of the PRT scores were as follows: FRT = 20.02 ± 4.31; LRT = 13.42 ± 3.38; MFRT = 21.49 ± 4.70, and MLRT = 14.64 ± 3.66. Several significant correlations were found. Moderate correlations existed between the PRT scores and age, height, upper extremity length, lower extremity length, and foot length; there was a weak correlation with body mass index. Weight was moderately correlated with FRT and MFRT and weakly correlated with LRT and MLRT. The correlation between the base of support and LRT was moderate and was weak with FRT, MFRT, and MLRT. A weak correlation was found between sex and LRT. Age and height were the most predictive of PRT scores.

Conclusion

This study provided PRT normative values that can be used as a clinical reference for evaluating balance in typically developing children.

One size does not fit all. How universal standards for normal height can hide deprivation and create false paradoxes

Public health practitioners and social scientists frequently compare height against one-size-fits-all standards of human growth to assess well-being, deprivation, and disease risk. However, underlying differences in height can make some naturally tall populations appear well-off by universal standards, even though they live in severe states of deprivation. In this article, I describe the worldwide extent of these population differences in height and illustrate how using a universal yardstick to compare population height can create puzzling disparities (eg, between South Asia and sub-Saharan Africa) while also underestimating childhood stunting in specific world regions (eg, West Africa and Haiti). I conclude by discussing potential challenges of developing and implementing population-sensitive standards for assessing healthy development.

Deprivation or discrimination? Comparing two explanations for the reverse income-obesity gradient in the US and South Korea

In high-income countries, poverty is often associated with higher average body mass index (BMI). To account for this reverse gradient, deprivation theories posit that declining economic resources make it more difficult to maintain a healthy weight. By contrast, discrimination theories argue that anti-fat discrimination in hiring and marriage sorts heavier individuals into lower-income households. This study assesses competing predictions of these theories by examining how household income in representative samples from South Korea (2007-2014, N=20,823) and the US (1999-2014, N=6395) is related to BMI in two key contrasting groups: (1) currently-married and (2) never-married individuals. As expected by anti-fat discrimination in marriage, the reverse gradient is observed among currently-married women but not among never-married women in both countries. Also consistent with past studies no evidence was found for a reverse gradient among men. These findings are consistent with anti-fat discrimination in marriage as a key cause of the reverse gradient and raise serious challenges to deprivation accounts as well as explanations based on anti-fat discrimination in labour markets.

Body mass estimation for circum-Pacific Asian people based on somatometric data

OBJECTIVES

Multiple regression approaches for estimating body mass by somatometry typically use stature and biiliocristal breadth. However, these measures were obtained largely from Europeans, Africans, and Indo-Mediterraneans, whereas mid-latitude Asians were not broadly reflected. Thus, new estimation formulas for circum-Pacific Asians were devised, and the accuracy was evaluated using raw individual data.

MATERIALS AND METHODS

Targeting Asians in the traditional society or before the 1960s and performing multiple regression analysis (MRA) with body weight as the objective variable, and stature, body breadth, and product of head length/breadth (HLBpr) as explanatory variables. The target population was divided into four climate groups, and the formulas were prepared for each sex or the combined-sexes.

RESULTS

The MRA by stature and body breadth indicated significant multiple correlation coefficients (R) in many formulas. R was higher in the combined-sexes. Among the four climate groups, the temperate group showed the highest R. In the East/Southeast Asians, R exceeded 0.8 in the MRA by stature and HLBpr. Substituting the raw data of 19th-century Japanese males, the temperate group formulas presented the least error, and the error in all the formulas using body breadth was <2 kg.

CONCLUSIONS

As body mass index varies significantly depending on some climatic factors, estimation formulas mixed with various climate groups are not desirable because of the large errors. For the mid-latitude Asians, the temperate group formulas are expected to have a smaller error; however, in the group where the proportion of underweight individuals was originally high, any formula tends to be overestimated.

Relationships among fat mass, fat-free mass and height in adults: A new method of statistical analysis applied to NHANES data

OBJECTIVES

The positive influence of fat mass (FM) on fat-free mass (FFM) has been quantified previously by various methods involving regression analysis of population data, but some are fundamentally flawed through neglect of the tendency of taller individuals to carry more fat. Differences in FFM due to differences in FM-and not directly related to differences in height-are expressed as ΔFFM/ΔFM, denoted K_F . The main aims were to find a sounder regression-based method of quantifying K_F and simultaneously of estimating mean BMI₀ , the BMI of hypothetical fat-free individuals. Other, related, objectives were to check the linearity of FFM-FM relationships and to quantify the correlation between FM and height.

METHODS

New statistical methods, explored and verified by Monte Carlo simulation, were applied to NHANES data. Regression of height² on FFM and FM produced estimates of mean K_F and indirectly of BMI₀ . Both were then adjusted to allow for variability in K_F around its mean. Its standard deviation was estimated by a novel method.

RESULTS

Relationships between FFM and FM were linear, not semilogarithmic as is sometimes assumed. Mean K_F is similar in Mexican American men and women, but higher in men than women in non-Hispanic European Americans and African Americans. Mean BMI₀ is higher in men than in women. FM correlates more strongly with height than has been found previously.

CONCLUSIONS

A more accurate way of quantifying mean BMI₀ and the dependence of FFM on FM is established that may be easily applied to new and existing population data.

How much do universal anthropometric standards bias the global monitoring of obesity and undernutrition?

Each year, hundreds of articles in population health and nutrition, many in high-profile journals, use standard cutoffs based on weight and height as assessments of obesity and undernutrition. These global efforts to monitor overweight and underweight often rest on the assumption that ethnic differences in underlying body form are sufficiently small to permit universal anthropometric cutoffs for comparing excess and insufficient body fat across populations. However, a century of work in human biological variation suggests that human populations can vary dramatically in underlying body form in a way that may require population-sensitive cutoffs for monitoring. Here, we describe recently developed methods that can provide population-sensitive assessments of both excess and insufficient energy reserves in a wide range of countries. We use this approach to illustrate how worldwide variation in human body form is far more widespread than previously thought, and that it can occur at several geographic scales, including the level of world regions, countries and populations within countries. The findings also suggest that using standard cutoffs that ignore this variation can underestimate current obesity levels in adults by more than 400-500 million while also incorrectly prioritizing high-risk areas for undernutrition in children in key regions around the world.

Excessive adiposity at low BMI levels among women in rural Bangladesh

Asian populations have a higher percentage body fat (%BF) and are at higher risk for CVD and related complications at a given BMI compared with those of European descent. We explored whether %BF was disproportionately elevated in rural Bangladeshi women with low BMI. Height, weight, mid-upper arm circumference, triceps and subscapular skinfolds and bioelectrical impedance analysis (BIA) were measured in 1555 women at 3 months postpartum. %BF was assessed by skinfolds and by BIA. BMI was calculated in adults and BMI Z-scores were calculated for females <20 years old. Receiver operating characteristic (ROC) curves found the BMI and BMI Z-score cut-offs that optimally classified women as having moderately excessive adipose tissue (defined as >30 % body fat). Linear regressions estimated the association between BMI and BMI Z-score (among adolescents) and %BF. Mean BMI was 19·2 (sd 2·2) kg/m², and mean %BF was calculated as 23·7 (sd 4·8) % by skinfolds and 23·3 (sd 4·9) % by BIA. ROC analyses indicated that a BMI value of approximately 21 kg/m² optimised sensitivity (83·6 %) and specificity (84·2 %) for classifying subjects with >30 % body fat according to BIA among adults. This BMI level is substantially lower than the WHO recommended standard cut-off point of BMI ≥ 25 kg/m². The equivalent cut-off among adolescents was a BMI Z-score of –0·36, with a sensitivity of 81·3 % and specificity of 80·9 %. These findings suggest that Bangladeshi women exhibit excess adipose tissue at substantially lower BMI compared with non-South Asian populations. This is important for the identification and prevention of obesity-related metabolic diseases.

Interethnic differences in pharmacokinetics of antibacterials

BACKGROUND

Optimal antibacterial dosing is imperative for maximising clinical outcome. Many factors can contribute to changes in the pharmacokinetics of antibacterials to the extent where dose adjustment may be needed. In acute illness, substantial changes in important pharmacokinetic parameters such as volume of distribution and clearance can occur for certain antibacterials. The possibility of interethnic pharmacokinetic differences can further complicate attempts to design an appropriate dosing regimen. Factors of ethnicity, such as genetics, body size and fat distribution, contribute to differences in absorption, distribution, metabolism and elimination of drugs. Despite extensive previous work on the altered pharmacokinetics of antibacterials in some patient groups such as the critically ill, knowledge of interethnic pharmacokinetic differences for antibacterials is limited.

OBJECTIVES

This systematic review aims to describe any pharmacokinetic differences in antibacterials between different ethnic groups, and discuss their probable mechanisms as well as any clinical implications.

METHODS

We performed a structured literature review to identify and describe available data of the interethnic differences in the pharmacokinetics of antibacterials.

RESULTS

We found 50 articles that met our inclusion criteria and only six of these compared antibacterial pharmacokinetics between different ethnicities within the same study. Overall, there was limited evidence available. We found that interethnic pharmacokinetic differences are negligible for carbapenems, most β-lactams, aminoglycosides, glycopeptides, most fluoroquinolones, linezolid and daptomycin, whereas significant difference is likely for ciprofloxacin, macrolides, clindamycin, tinidazole and some cephalosporins. In general, subjects of Asian ethnicity achieve drug exposures up to two to threefold greater than Caucasian counterparts for these antibacterials. This difference is caused by a comparatively lower volume of distribution and/or drug clearance.

CONCLUSION

Interethnic pharmacokinetic differences of antibacterials are likely; however, the clinical relevance of these differences is unknown and warrants further research.

Genetic population structure accounts for contemporary ecogeographic patterns in tropic and subtropic-dwelling humans

Contemporary human populations conform to ecogeographic predictions that animals will become more compact in cooler climates and less compact in warmer ones. However, it remains unclear to what extent this pattern reflects plastic responses to current environments or genetic differences among populations. Analyzing anthropometric surveys of 232,684 children and adults from across 80 ethnolinguistic groups in sub-Saharan Africa, Asia and the Americas, we confirm that body surface-to-volume correlates with contemporary temperature at magnitudes found in more latitudinally diverse samples (Adj. R² = 0.14-0.28). However, far more variation in body surface-to-volume is attributable to genetic population structure (Adj. R² = 0.50-0.74). Moreover, genetic population structure accounts for nearly all of the observed relationship between contemporary temperature and body surface-to-volume among children and adults. Indeed, after controlling for population structure, contemporary temperature accounts for no more than 4% of the variance in body form in these groups. This effect of genetic affinity on body form is also independent of other ecological variables, such as dominant mode of subsistence and household wealth per capita. These findings suggest that the observed fit of human body surface-to-volume with current climate in this sample reflects relatively large effects of existing genetic population structure of contemporary humans compared to plastic response to current environments.

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.

Body composition and depressive/anxiety symptoms in overweight and obese individuals with metabolic syndrome

BACKGROUND

Several studies point to a correlation between obesity and the severity of depressive and anxiety symptoms in children and adults, but there are still some controversial points about this association. The aim of this study is to investigate the relationship between body composition and the severity of anxiety/depressive symptoms in overweight and obese individuals with Metabolic Syndrome (MS).

METHODS

Fifty patients, 18-50 years old, overweight or obese and with the diagnosis of MS based on the International Diabetes Federation (IDF) criteria were selected for this study. Body composition was evaluated using Dual Energy X-ray Absorptiometry (DXA). Depressive symptoms were evaluated using the Hospital Anxiety and Depression Scale (HADS-Depression) and the Beck Depression Inventory (BDI). Anxiety symptoms were evaluated using HADS-Anxiety.

RESULTS

No correlation was found between depressive symptoms (HADS-Depression or BDI) and Body Mass Index (BMI) (r = 0.01; p = 0.94 and r = -0.12, p = 0.38; respectively), Waist Circumference (WC) (r = -0.06, p = 0.67 and r = -0.22, p = 0.12; respectively), and Waist-to-Hip Ratio (WHR) (r = -0.12, p = 0.40 and r = -0.17, p = 0.23; respectively). Additionally, no correlation was found among anxiety symptoms (HADS-Anxiety) and BMI (r = -0.15, p = 0.27), and WHR (r = -0.17, p = 0.24). In contrast, a significant correlation was found between percentage of total fat (DXA) and HADS-Depression (r = 0.34, p = 0.019) and HADS-Anxiety (r = 0.30, p = 0.039). Additionally, an inverse and strong correlation was found between lean mass (in grams) and HADS-Depression (r = -0.42, p = 0.004), HADS anxiety (r = -0.57, p < 0.0001), and BDI (r = -0.44, p = 0.026).

CONCLUSIONS

In individuals with MS, the percentage of body fat, and not central fat, BMI, WC, or WHR, was associated with an increased severity of anxiety and depressive symptoms. In contrast, total lean mass was strongly associated with fewer anxiety/depressive symptoms, suggesting that body composition might be related to psychiatric comorbidity in overweight individuals with MS.

Disentangling basal and accumulated body mass for cross-population comparisons

Measures of human body mass confound 1) well-established population differences in body form and 2) exposure to obesogenic environments, posing challenges for using body mass index (BMI) in cross-population studies of body form, energy reserves, and obesity-linked disease risk. We propose a method for decomposing population BMI by estimating basal BMI (bBMI) among young adults living in extremely poor, rural households where excess body mass accumulation is uncommon. We test this method with nationally representative, cross-sectional Demographic and Health Surveys (DHS) collected from 69,916 rural women (20-24 years) in 47 low-income countries. Predicting BMI by household wealth, we estimate country-level bBMI as the average BMI of young women (20-24 years) living in rural households with total assets <400 USD per capita. Above 400 USD per capita, BMI increases with both wealth and age. Below this point, BMI hits a baseline floor showing little effect of either age or wealth. Between-country variation in bBMI (range of 4.3 kg m(-2) ) is reliable across decades and age groups (R(2)  = 0.83-0.88). Country-level estimates of bBMI show no relation to diabetes prevalence or country-level GDP (R(2)  < 0.05), supporting its independence from excess body mass. Residual BMI (average BMI minus bBMI) shows better fit with both country-level GDP (R(2)  = 0.55 vs. 0.40) and diabetes prevalence (R(2)  = 0.23 vs. 0.17) than does conventional BMI. This method produces reliable estimates of bBMI across a wide range of nationally representative samples, providing a new approach to investigating population variation in body mass.