Anthropometric predictors of body fat as measured by hydrostatic weighing in Guatemalan adults

Early life predictors of body composition trajectories from adolescence to mid-adulthood

OBJECTIVES

Guatemala has experienced rapid increases in adult obesity. We characterized body composition trajectories from adolescence to mid-adulthood and determined the predictive role of parental characteristics, early life factors, and a nutrition intervention.

METHODS

One thousand three hundred and sixty-four individuals who participated as children in a nutrition trial (1969-1977) were followed prospectively. Body composition characterized as body mass index (BMI), fat mass index (FMI), and fat-free mass indices (FFMI), was available at four ages between 10 and 55 years. We applied latent class growth analysis to derive sex-specific body composition trajectories. We estimated associations between parental (age, height, schooling) and self-characteristics (birth order, socioeconomic status, schooling, and exposure to a nutrition supplement) with body composition trajectories.

RESULTS

In women, we identified two latent classes of FMI (low: 79.6%; high: 20.4%) and BMI (low: 73.0%; high: 27.0%), and three of FFMI (low: 20.2%; middle: 55.9%; high: 23.9%). In men, we identified two latent classes of FMI (low: 79.6%; high: 20.4%) and FFMI (low: 62.4%; high: 37.6%), and three of BMI (low: 43.1%; middle: 46.9%; high: 10.0%). Among women, self's schooling attainment inversely predicted FMI (OR [being in a high latent class]: 0.91, 95% CI: 0.85, 0.97), and maternal schooling positively predicted FFMI (OR: 1.16, 95% CI: 0.97, 1.39). Among men, maternal schooling, paternal age, and self's schooling attainment positively predicted FMI. Maternal schooling positively predicted FFMI, whereas maternal age and paternal schooling were inverse predictors. The nutrition intervention did not predict body composition class membership.

CONCLUSIONS

Parents' age and schooling, and self's schooling attainment are small but significant predictors of adult body composition trajectories.

Prediction of body fat percentage: Development and validation of new anthropometric equations

INTRODUCTION

The aim of this study was to test the validity of existing equations, retrieved from the literature, in the Algerian adult population. To develop, and validate, new predictive equations for body fat percentage (%BF) using simple and easy-to-measure anthropometric parameters.

METHODS

This is a cross-sectional study including 877 Algerian adults who underwent a body composition assessment by the direct segmental multi-frequency bioelectrical impedance technique (Inbody-770). Participants were randomly divided into two groups: the development group (n = 577) and the validation group (n = 300). To develop the equations, multiple linear regression models were analyzed. The predictive performance of the developed equations was compared with the direct technique. The following validation tests were used: Student's t-test for paired samples, correlation, and Bland-Altman diagram. Diagnostic accuracy has also been assessed.

RESULTS

Four existing equations were tested, and all showed statically significant bias. Four new equations were developed; all had satisfactory predictive performance, with a correlation coefficient ranging from 0.72 to 0.94 in men and 0.87 to 0.93 in women. The best-fitting equation was based on body mass index, waist-to-hip ratio, and chest circumference. The diagnostic accuracy of this equation was 96.7% in men and 95.3% in women.

CONCLUSION

The newly developed equations based on anthropometric parameters can serve as a simple tool for the accurate prediction of BF% in adult subjects, at both individual and epidemiological levels.

Criterion-Related Validity of Field-Based Methods and Equations for Body Composition Estimation in Adults: A Systematic Review

PURPOSE OF REVIEW

Overweight and obesity are associated to health prognosis. Therefore, body composition assessment is an important health outcome, especially in adult population. We analyzed the criterion-related validity of existing field-based methods and equations for body composition estimation in adults aged 19-64 years.

RECENT FINDINGS

One hundred studies met inclusion criteria. The field-based methods, waist circumference (WC), body adiposity index (BAI), and body mass index (BMI) are valid to indicate body adiposity. Likewise, several equations, including the classical Durnin/Womersley equation, Jackson/Pollock equation (males), and Jackson, Pollock, and Ward equation (females), are valid to estimate total body fat mass or body fat percentage. Anthropometric field methods can provide a simple, quick, and easy informative indicators of adiposity in adults. Classical equations, such as Durnin/Womersley equation, Jackson/Pollock equation, and Jackson, Pollock, and Ward equation, are still valid to estimate total body fat mass or body fat percentage in adult population. When choosing estimation equations, specific population characteristics, such as age, weight status, or race ethnicity, should be taken into account. (Trial Registration: Registered on PROSPERO (CRD42020194272)).

Comparison of Several Prediction Equations Using Skinfold Thickness for Estimating Percentage Body Fat vs. Body Fat Percentage Determined by BIA in 6-8-Year-Old South African Children: The BC-IT Study

Body composition measurement is useful for assessing percentage body fat (%BF) and medical diagnosis, monitoring disease progression and response to treatment, and is essential in assessing nutritional status, especially in children. However, finding accurate and precise techniques remains a challenge. The study compares %BF determined by bioelectrical impedance analysis (BIA) and calculated from available prediction equations based on skinfolds in young South African children. A cross-sectional study performed on 202 children (83 boys and 119 girls) aged 6-8 years. Height and weight, triceps and subscapular skinfolds were determined according to standard procedures. %BF was determined with BIA and three relevant available equations. SPSS analyzed the data using paired samples tests, linear regression, and Bland-Altman plots. Significant paired mean differences were found for BIA and Slaughter (t₂₀₁ = 33.896, p < 0.001), Wickramasinghe (t₂₀₁ = 4.217, p < 0.001), and Dezenberg (t₂₀₁ = 19.910, p < 0.001). For all of the equations, the standards for evaluating prediction errors (SEE) were above 5. The Bland-Altman plots show relatively large positive and negative deviations from the mean difference lines and trends of systematic under- and over-estimation of %BF across the %BF spectrum. All three equations demonstrated a smaller %BF than the %BF measured by BIA, but the difference was smallest with the Wickramasinghe equation. In comparison, a poor SEE was found in the three %BF predicted equations and %BF derived from BIA. As such, an age-specific %BF equation incorporating criterion methods of deuterium dilution techniques or 'gold-standard' methods is needed to refute these findings. However, in the absence of developed %BF equations or 'gold-standard' methods, the available prediction equations are still desirable.

Overweight and Obesity, Cardiometabolic Health, and Body Composition: Findings From the Follow-Up Studies of the INCAP Longitudinal Study

BACKGROUND

There has been increased interest in the hypothesis that undernutrition in early life predisposes to cardiometabolic disease risk in adulthood. The Institute of Nutrition of Central America and Panama Longitudinal Study is able to address one critical aspect of this field, specifically whether improvements in nutrition can prevent this increased risk.

OBJECTIVE

To describe the main findings on obesity and body composition across 5 waves of field work (1988-1989, 1991-1994, 1998-1999, 2002-2004, and 2015-2017) and on cardiometabolic health across 3 waves (1998-1999, 2002-2004, and 2015-2017).

RESULTS

Body weight and body fat increased considerably in adulthood, especially among women with sedentary occupations. Adiposity and weight in adulthood were strongly predicted by weight gain after the first 1000 days of life. On the other hand, exposure to improved nutrition in early life reduced diabetes risk by approximately 50% but increased the risk of overweight and obesity.

CONCLUSIONS

Future research will aid in clarifying the underlying mechanisms that drive the opposite associations among diabetes and obesity with early-life nutrition.

Application of stable isotope dilution techniques to assess body fat and comparison with WHO BMI-for-age classification as a measure of obesity among schoolchildren in Nairobi, Kenya

OBJECTIVE

WHO BMI-for-age z score (BAZ) is widely used in epidemiology, yet it does not distinguish body fat-free mass and fat mass which are better indicators of obesity and related risks. The stable isotope dilution techniques (SIDT) are gold standard methods of assessing body composition. Main objective was to assess significant differences in measurement and validity of WHO BMI-for-age classification for defining childhood obesity by comparing with body fatness using SIDT among schoolchildren.

DESIGN

A cross-sectional analytical study. A questionnaire, anthropometry and body composition data were used. SPSS was used to analyse data at P < 0·05 at 95 % CI.

SETTING

Primary schools in Nairobi City County, Kenya.

PARTICIPANTS

One hundred seventy-nine schoolchildren aged 8-11 years were randomly sampled.

RESULTS

Prevalence of adiposity by reference SIDT (24·0 %) was significantly higher than that of obesity by BAZ > 2 sd (2·8 %) (Wilcoxon test, P < 0·05). Concordance coefficient between SIDT and BAZ > 2 sd in diagnosing obesity was poor (κ = 0·167). Only 11·6 % of children with excess body fat were correctly diagnosed as obese by BAZ > 2 sd. The use of BAZ > 1 sd for overweight and obesity showed fair concordance coefficient (κ = 0·409, P < 0·001) with 32·5% of children with excess fat positively identified as overweight and obese.

CONCLUSION

WHO BMI-for-age cut-off points severely underestimate the prevalence of overweight and obesity compared with body composition assessment by stable isotope dilution techniques. Evidence-informed interventions should be based on more accurate estimates of overweight and obesity than that can be provided by BAZ.

Development and validation of anthropometric equations to estimate body composition in adult women

Objective

To develop anthropometric equations to predict body fat percentage (BF%).

Methods

In 151 women (aged 18-59) body weight, height, eight- skinfold thickness (STs), six- circumferences (CIs), and BF% by hydrodensitometry were measured. Subjects data were randomly divided in two groups, equation-building group (n= 106) and validation group (n= 45). The equation-building group was used to run linear regression models using anthropometric measurements as predictors to find the best prediction equations of the BF%. The validation group was used to compare the performance of the new equations with those of Durnin-Womersley, Jackson-Pollock and Ramirez-Torun.

Results

There were two preferred equations: Equation 1= 11.76 + (0.324 x tricipital ST) + (0.133 x calf ST) + (0.347 x abdomen CI) + (0.068 x age) - (0.135 x height) and Equation 2= 11.37 + (0.404 x tricipital ST) + (0.153 x axilar ST) + (0.264 x abdomen CI) + (0.069 x age) - (0.099 x height). There were no significant differences in BF% obtained by hydrodensitometry (31.5 ±5.3) and Equation 1 (31.0 ±4.0) and Equation 2 (31.2 ±4.0). The BF% estimated by Durning-Womersley (35.8 ±4.0), Jackson-Pollock (26.5 ±5.4) and Ramirez-Torun (32.6 ±4.8) differed from hydrodensitometry (p <0.05). The interclass correlation coefficient (ICC) was high between hydrodensitometry and Equation 1 (ICC= 0.77), Equation 2 (ICC= 0.76), and Ramirez-Torun equation (ICC= 0.75). The ICC was low between hydrodensitometry and Durnin-Womersley (ICC= 0.51) and Jackson-Pollock (ICC= 0.53) equations.

Conclusion

The new Equations-1 and 2, performed better than the commonly used anthropometric equations to predict BF% in adult women.

Validation of equations and proposed reference values to estimate fat mass in Chilean university students

OBJECTIVES

(i) To propose regression equations based on anthropometric measures to estimate fat mass (FM) using dual energy X-ray absorptiometry (DXA) as reference method, and (ii)to establish population reference standards for equation-derived FM.

MATERIAL AND METHODS

A cross-sectional study on 6,713 university students (3,354 males and 3,359 females) from Chile aged 17.0 to 27.0years. Anthropometric measures (weight, height, waist circumference) were taken in all participants. Whole body DXA was performed in 683 subjects. A total of 478 subjects were selected to develop regression equations, and 205 for their cross-validation. Data from 6,030 participants were used to develop reference standards for FM. Equations were generated using stepwise multiple regression analysis. Percentiles were developed using the LMS method.

RESULTS

Equations for men were: (i) FM=-35,997.486 +232.285 *Weight +432.216 *CC (R²=0.73, SEE=4.1); (ii)FM=-37,671.303 +309.539 *Weight +66,028.109 *ICE (R2=0.76, SEE=3.8), while equations for women were: (iii)FM=-13,216.917 +461,302 *Weight+91.898 *CC (R²=0.70, SEE=4.6), and (iv) FM=-14,144.220 +464.061 *Weight +16,189.297 *ICE (R²=0.70, SEE=4.6). Percentiles proposed included p10, p50, p85, and p95.

CONCLUSION

The developed equations provide valid and accurate estimation of FM in both sexes. The values obtained using the equations may be analyzed from percentiles that allow for categorizing body fat levels by age and sex.

Development and Validation of a Skinfold Model for Estimation of Body Density for a Safe Weight Reduction in Young Iranian Wrestlers

Background:

Adverse effects of excessive body mass reduction among wrestlers dictate minimum weight determination through body composition. Although skinfold equations are essential to estimate body composition in the field setting, they are mostly derived from Western societies and may lack generalizability to other populations.

Purpose:

Previously published skinfold equations lacked external validity in predicting body density of Iranian wrestlers. We aimed to derive a new anthropometric model specific to young Iranian male wrestlers.

Study design:

Cross-sectional cohort study.

Level of evidence:

Level 3.

Methods:

One hundred twenty-six Iranian male wrestlers with at least 1 year of experience and a mean age of 19 ± 4.0 years underwent underwater weight analysis for body density estimation and anthropometric measurements. The previously published equations were validated, followed by new regression modeling, using multivariable fractional polynomials, with body density as the criterion predicted by common anthropometric variables. The final model was validated throughout the modeling procedure using 1000 bootstrap replications.

Results:

The mean body fat percentage (%BF) was 12.6% (95% CI, 11.9%-13.4%), lower than that of previous studies. Six previously published equations each had significant deviations from the line of identity (all P < 0.001). The new prediction equation combined subscapular, tricipital, and midaxillary skinfolds and body mass index cubed to predict body density.

Conclusion:

The development of ethnicity-specific equations, using statistically unbiased and comprehensive validation methods, is imperative for body composition estimation to determine the minimum weight for regulation of health in athletes.

Clinical Relevance:

Using equations without external validation can bias the prediction of minimum weight, leading to unsafe weight reduction by athletes. Compared with a previous study, much lower mean %BF was found using an ethnicity-specific equation (12.6% vs 15.9%). This difference observed in %BF prediction could affect safe fat reduction in athletes.

Estimating total body fat using a skinfold prediction equation in Brazilian children

BACKGROUND

The double burden of obesity and underweight is increasing in developing countries and simple methods for the assessment of fat mass in children are needed.

AIM

To develop and validate a new anthropometric predication equation for assessment of fat mass in children.

SUBJECTS AND METHODS

Body composition was assessed in 145 children aged 9.8 ± 1.3 (SD) years from São Paulo, Brazil using dual energy X-ray absorptiometry (DEXA) and skinfold measurements. The study sample was divided into development and validation sub-sets to develop a new prediction equation for FM (PE).

RESULTS

Using multiple linear regression analyses, the best equation for predicting FM (R(2) = 0.77) included body weight, triceps skinfold, height, gender and age as independent variables. When cross-validated, the new PE was valid in this sample (R(2) = 0.80), while previously published equations were not.

CONCLUSION

The PE was more valid for Brazilian children that existing equations, but further studies are needed to assess the validity of this PE in other populations.

Cardiovascular risk factors in middle age obese Indians: a cross-sectional study on association of per cent body fat and intra-abdominal fat mass

OBJECTIVES

To determine the association of per cent total body fat (TBF), intra-abdominal fat (IAF) mass and subcutaneous abdominal fat with cardiovascular risk factors in middle age obese Indians.

DESIGN

Cross-sectional study.

SETTING

Hydrostatic Laboratory, Department of Sports Medicine and Physiotherapy, Guru Nanak Dev University, India.

PARTICIPANTS

51 subjects aged 30-55 years with a body mass index value 23 and above.

METHODOLOGY

In all the participants, TBF was estimated by underwater weighing machine and IAF and subcutaneous fat were measured by ultrasonography. Lipid profile was determined by a semiautomated analyser. Main outcome measures were: IAF, per cent body fat to TBF ratio, lipid profile and risk of developing cardiovascular diseases.

RESULTS

IAF was found to be significantly associated with lipid variables (95% CI, p<0.01) and risk of developing cardiovascular diseases (95% CI, p≤0.05) in both male and female subjects. TBF and subcutaneous fat thickness showed no significant results (95% CI, p>0.05) with either lipid variables or risk of developing cardiovascular diseases (tables 1 and 2). IAF mass showed significant association with age (95% CI, p<0.01) and significant negative association with physical activity (95% CI, p<0.05) in male subjects (tables 3 and 4).

CONCLUSION

An ultrasonic measurement of IAF is a better predictor of the risk of developing cardiovascular diseases in middle aged Indian population. In male subjects, physical activity of 5 or more days a week showed lesser amount of IAF as compared with those with physical activity <5 days a week.

Birth weight, postnatal weight gain, and adult body composition in five low and middle income countries

OBJECTIVES

To evaluate the associations between birth weight (BW), infancy, and childhood weight gain and adult body composition.

METHODS

Subjects included participants of five birth cohort studies from low and middle income nations (Brazil, Guatemala, India, Philippines, and South Africa; n = 3432). We modeled adult body composition as a function of BW and conditional weight gain (CW), representing changes in weight trajectory relative to peers, in three age intervals (0-12 months, 12-24 months, 24 months-mid childhood).

RESULTS

In 34 of 36 site- and sex-specific models, regression coefficients associated with BW and CWs were higher for adult fat-free than for fat mass. The strength of coefficients predicting fat-free mass relative to those predicting fat mass was greatest for BW, intermediate for CWs through 24 months, and weaker thereafter. However, because fat masses were smaller and showed larger variances than fat-free masses, weaker relationships with fat mass still yielded modest but significant increases in adult % body fat (PBF). CW at 12 months and mid-childhood tended to be the strongest predictors of PBF, whereas BW was generally the weakest predictor of PBF. For most early growth measures, a 1 SD change predicted less than a 1% change in adult body fat, suggesting that any health impacts of early growth on changes in adult body composition are likely to be small in these cohorts.

CONCLUSIONS

BW and weight trajectories up to 24 months tend to be more strongly associated with adult fat-free mass than with fat mass, while weight trajectories in mid-childhood predict both fat mass and fat-free mass.

Infant-feeding patterns and cardiovascular risk factors in young adulthood: data from five cohorts in low- and middle-income countries

BACKGROUND

Infant-feeding patterns may influence lifelong health. This study tested the hypothesis that longer duration of breastfeeding and later introduction of complementary foods in infancy are associated with reduced adult cardiovascular risk.

METHODS

Data were pooled from 10 912 subjects in the age range of 15-41 years from five prospective birth-cohort studies in low-/middle-income countries (Brazil, Guatemala, India, Philippines and South Africa). Associations were examined between infant feeding (duration of breastfeeding and age at introduction of complementary foods) and adult blood pressure (BP), plasma glucose concentration and adiposity (skinfolds, waist circumference, percentage body fat and overweight/obesity). Analyses were adjusted for maternal socio-economic status, education, age, smoking, race and urban/rural residence and infant birth weight.

RESULTS

There were no differences in outcomes between adults who were ever breastfed compared with those who were never breastfed. Duration of breastfeeding was not associated with adult diabetes prevalence or adiposity. There were U-shaped associations between duration of breastfeeding and systolic BP and hypertension; however, these were weak and inconsistent among the cohorts. Later introduction of complementary foods was associated with lower adult adiposity. Body mass index changed by -0.19 kg/m(2) [95% confidence interval (CI) -0.37 to -0.01] and waist circumference by -0.45 cm (95% CI -0.88 to -0.02) per 3-month increase in age at introduction of complementary foods.

CONCLUSIONS

There was no evidence that longer duration of breastfeeding is protective against adult hypertension, diabetes or overweight/adiposity in these low-/middle-income populations. Further research is required to determine whether 'exclusive' breastfeeding may be protective. Delaying complementary foods until 6 months, as recommended by the World Health Organization, may reduce the risk of adult overweight/adiposity, but the effect is likely to be small.

Prediction equation for calculating fat mass in young Indian adults

PURPOSE

Accurate measurement or prediction of fat mass is useful in physiology, nutrition and clinical medicine. Most predictive equations currently used to assess percentage of body fat or fat mass, using simple anthropometric measurements were derived from people in western societies and they may not be appropriate for individuals with other genotypic and phenotypic characteristics. We developed equations to predict fat mass from anthropometric measurements in young Indian adults.

METHODS

Fat mass was measured in 60 females and 58 males, aged 20 to 29 yrs by using hydrostatic weighing and by simultaneous measurement of residual lung volume. Anthropometric measure included weight (kg), height (m) and 4 skinfold thickness [STs (mm)]. Sex specific linear regression model was developed with fat mass as the dependent variable and all anthropometric measures as independent variables.

RESULTS

The prediction equation obtained for fat mass (kg) for males was 8.46+0.32 (weight) - 15.16 (height) + 9.54 (log of sum of 4 STs) (R2= 0. 53, SEE=3.42 kg) and - 20.22 + 0.33 (weight) + 3.44 (height) + 7.66 (log of sum of 4 STs) (R2=0.72, SEE=3.01kg) for females.

CONCLUSION

A new prediction equation for the measurement of fat mass was derived and internally validated in young Indian adults using simple anthropometric measurements.

Size at birth, weight gain in infancy and childhood, and adult blood pressure in 5 low- and middle-income-country cohorts: when does weight gain matter?

BACKGROUND

Promoting catch-up growth in malnourished children has health benefits, but recent evidence suggests that accelerated child weight gain increases adult chronic disease risk.

OBJECTIVE

We aimed to determine how birth weight (BW) and weight gain to midchildhood relate to blood pressure (BP) in young adults.

DESIGN

We pooled data from birth cohorts in Brazil, Guatemala, India, the Philippines, and South Africa. We used conditional weight (CW), a residual of current weight regressed on prior weights, to represent deviations from expected weight gain from 0 to 12, 12 to 24, 24 to 48 mo, and 48 mo to adulthood. Adult BP and risk of prehypertension or hypertension (P/HTN) were modeled before and after adjustment for adult body mass index (BMI) and height. Interactions of CWs with small size-for-gestational age (SGA) at birth were tested.

RESULTS

Higher CWs were associated with increased BP and odds of P/HTN, with coefficients proportional to the contribution of each CW to adult BMI. Adjusted for adult height and BMI, no child CW was associated with adult BP, but 1 SD of BW was related to a 0.5-mm Hg lower systolic BP and a 9% lower odds of P/HTN. BW and CW associations with systolic BP and P/HTN were not different between adults born SGA and those with normal BW, but higher CW at 48 mo was associated with higher diastolic BP in those born SGA.

CONCLUSIONS

Greater weight gain at any age relates to elevated adult BP, but faster weight gains in infancy and young childhood do not pose a higher risk than do gains at other ages.

Detection of cardio-metabolic risk by BMI and waist circumference among a population of Guatemalan adults

BACKGROUND

BMI and waist circumference (WC) are used to screen for cardio-metabolic risk; however it is unclear how well these indices perform in populations subject to childhood stunting.

OBJECTIVES

To evaluate BMI and WC as indicators of cardio-metabolic risk and to determine optimal cut-off points among 1,325 Guatemalan adults (44 % stunted: 162 cm men).

METHODS

Cardio-metabolic risk factors were systolic/diastolic blood pressure 85 mmHg, glucose 5 mmol/l, TAG 7 mmol/l, ratio of total cholesterol to HDL-cholesterol 0, and the presence of two or more and three or more of the preceding risk factors. Receiver operating characteristic (ROC) curve analysis was used.

RESULTS

Areas under the ROC curve were in the range of 005978 for WC among men and 006472 among women, respectively. Optimal cut-off points for BMI were 242651 kg/m2 stunted; 242656 kg/m2 among women (262769 kg/m2 non-stunted). Optimal cut-off points for WC were 879134 cm stunted; 889333 cm among women (909486 cm non-stunted).

CONCLUSION

Optimal cut-off points for BMI were slightly higher among women than men with no meaningful differences by stature. Optimal cut-off points for WC were several centimetres lower for stunted compared with non-stunted men, and both were substantially lower than the current recommendations among Western populations. Cut-off points derived from Western populations may not be appropriate for developing countries with a high prevalence of stunting.

Five-year changes in adiposity and cardio-metabolic risk factors among Guatemalan young adults

BACKGROUND

Rapidly transitioning societies are experiencing dramatic increases in obesity and cardio-metabolic risk; however, few prospective studies from developing countries have quantified these increases or described their joint relationships.

METHODS

We collected dietary, physical activity, demographic, anthropometric and cardio-metabolic risk factor data from 376 Guatemalan young adults in 1997-98 (aged 20-29 years) and in 2002-04 (aged 25-34 years).

RESULTS

In total, 42 % of men and 56 % of women experienced weight gain >5 kg in 5 years. Percent body fat (%BF) and waist circumference (WC) increased by 4.2 % points and 5.5 cm among men, and 3.2 % points and 3.4 cm among women, respectively. Five-year increases in both %BF and WC were associated with lower physical activity, urban residence and shorter height among men but not among women (test for heterogeneity P < 0.05 for residence and physical activity). Changes in %BF and WC and concomitant changes in cardio-metabolic risk factors were similar for men and women. In standardised regression, change in %BF was associated with changes in TAG (beta=0.19; 95 % CI 0.08, 0.30), total:HDL cholesterol (beta=0.22; 95 % CI 0.12, 0.33) and systolic (beta=0.22; 95 % CI 0.12, 0.33) and diastolic (beta=0.18; 95 % CI 0.08, 0.28) blood pressure, but not with glucose; associations were similar for WC.

CONCLUSIONS

Over 5 years this relatively young population of Guatemalan adults experienced rapid increases in multiple measures of adiposity, which were associated with adverse changes in lipid and blood pressure levels.

Relation of ratio indices of anthropometric measures to obesity in a stunted population

The ratios of anthropometric measures are used to estimate obesity while controlling for allometric scaling. A good index should be uncorrelated with its denominator; this often requires exponentiation of the denominator. The stability of the derived exponents across populations is not known. We obtained subscapular (SUBS) and triceps (TRI) skinfolds, weight (WT), height (HT), waist circumference (WC), fat mass (FM), and fat-free mass (FFM) in a population of Guatemalan adults [height 1.63 +/- 0.06 m (868 males); 1.51 +/- 0.06 m (1047 females)]. We derived exponents for the indices WT/HT(P), SUBS/TRI(P), TRI/SUBS(P), WC/HT(P), FM/WT(P), and FM/FFM(P) such that the ratios were free from association with their denominators. The derived exponents were (Men: SUBS/TRI(0.88), FM/WT(2.69), FM/FFM(2.86), WC/HT(0.68), and WT/HT(2.17); Women: SUBS/TRI(0.93), FM/WT(2.01), FM/FFM(3.37), WC/HT(0.47), WT/HT(2.03)). For all examined indices the derived exponents differed (P < 0.05) from 1 and differed (P < 0.05) between men and women. The exponents for the men also differed from those previously published for Brazilian men (JCK Wells and CG Victora [2005]: Int J Obes 29:483-489). The derived indices were not more strongly correlated with adiposity than were simple unexponentiated ratios. Although exponentiation of the denominator eliminates the association of index with its denominator, the resulting exponents lack generalizability across populations, especially those where stunting remains prevalent.

Body fat measurement by bioelectrical impedance and air displacement plethysmography: a cross-validation study to design bioelectrical impedance equations in Mexican adults

BACKGROUND

The study of body composition in specific populations by techniques such as bio-impedance analysis (BIA) requires validation based on standard reference methods. The aim of this study was to develop and cross-validate a predictive equation for bioelectrical impedance using air displacement plethysmography (ADP) as standard method to measure body composition in Mexican adult men and women.

METHODS

This study included 155 male and female subjects from northern Mexico, 20-50 years of age, from low, middle, and upper income levels. Body composition was measured by ADP. Body weight (BW, kg) and height (Ht, cm) were obtained by standard anthropometric techniques. Resistance, R (ohms) and reactance, Xc (ohms) were also measured. A random-split method was used to obtain two samples: one was used to derive the equation by the "all possible regressions" procedure and was cross-validated in the other sample to test predicted versus measured values of fat-free mass (FFM).

RESULTS AND DISCUSSION

The final model was: FFM (kg) = 0.7374 * (Ht2 /R) + 0.1763 * (BW) - 0.1773 * (Age) + 0.1198 * (Xc) - 2.4658. R2 was 0.97; the square root of the mean square error (SRMSE) was 1.99 kg, and the pure error (PE) was 2.96. There was no difference between FFM predicted by the new equation (48.57 +/- 10.9 kg) and that measured by ADP (48.43 +/- 11.3 kg). The new equation did not differ from the line of identity, had a high R2 and a low SRMSE, and showed no significant bias (0.87 +/- 2.84 kg).

CONCLUSION

The new bioelectrical impedance equation based on the two-compartment model (2C) was accurate, precise, and free of bias. This equation can be used to assess body composition and nutritional status in populations similar in anthropometric and physical characteristics to this sample.

Occupation is more important than rural or urban residence in explaining the prevalence of metabolic and cardiovascular disease risk in Guatemalan adults

Diet and activity pattern changes consequent to urbanization are contributing to the global epidemic of cardiovascular disease; less research has focused on activity within rural populations. We studied 527 women and 360 men (25-42 y), all rural-born and currently residing in rural or urban areas of Guatemala. We further classified rural male occupations as agricultural or nonagricultural. Overweight status (BMI > or = 25 kg/m(2)) differed by residence/occupation among men (agricultural-rural, 27%; nonagricultural-rural, 44%; and urban, 55%; P< 0.01) and women (rural, 58%; and urban, 68%; P= 0.04). A moderate-to-vigorous lifestyle was reported by 76, 37, and 20% of men (agricultural-rural, nonagricultural-rural, and urban, respectively; P< 0.01); most women were sedentary, with no difference by residence. Prevalence of the metabolic syndrome was 17, 24, and 28% in agricultural-rural, nonagricultural-rural, and urban men, respectively (P= 0.2), and 44 and 45% in rural and urban women (P= 0.4). Dietary variables were largely unassociated with adiposity or cardio-metabolic risk factors; physical activity was inversely associated with the percentage of body fat in men. Percent body fat was inversely associated with HDL-cholesterol, and positively associated with triglycerides, blood pressure, and the metabolic syndrome in both men and women, and with LDL-cholesterol and fasting glucose in women. Differences in physical activity level, mainly attributable to occupation, appear more important than residence, per se, in influencing the risk for cardiovascular disease among men; differences among these sedentary women are likely related to other factors associated with an urban environment.

Size at birth, infant, early and later childhood growth and adult body composition: a prospective study in a stunted population

BACKGROUND

Pre-natal and post-natal growth are associated with adult body composition, but the relative importance of growth in different periods of childhood is still unclear, particularly in stunted populations.

METHODS

We studied 358 women and 352 men measured as children in 1969-77 in four villages in Guatemala, and re-measured as adults in 2002-04 (mean age 32.7 years). We determined the associations of body mass index (BMI) and length at birth, and changes in BMI and length during infancy (0-1.0 year) and early (1.0-3.0 years) and later (3.0-7.0 years) childhood, with adult BMI ((a)BMI), percentage of body fat ((a)PBF), abdominal circumference ((a)AC) and fat-free mass ((a)FFM).

RESULTS

Prevalence of stunting was high (64% at 3 years; HAZ < -2SD). Obesity (WHZ > 2SD) prevalence in childhood was <2%, while overweight prevalence in adulthood was 52%. BMI at birth was positively associated with (a)BMI and (a)FFM while length at birth was positively associated with (a)AC and (a)FFM. Increased BMI in infancy and later childhood were positively associated with all four adult body composition measures; associations in later childhood with fatness and abdominal fatness were stronger than those with (a)FFM. Change in length during infancy and early childhood was positively associated with all four adult body composition outcomes; the associations with (a)FFM were stronger than those with fat mass.

CONCLUSIONS

Increases in BMI between 3.0 and 7.0 years had stronger associations with adult fat mass and abdominal fat than with (a)FFM; increases in length prior to age 3.0 years were most strongly associated with increases in (a)FFM.