Intrabdominal fat is related to metabolic risk factors in Hispanic Americans, African Americans and in girls

Truncal-to-leg fat ratio and cardiometabolic disease risk factors in US adolescents: NHANES 2003-2006

BACKGROUND

This study aims to describe patterns of truncal versus peripheral fat deposition measured by truncal-to-leg fat ratio (TLR) in adolescents and examine associations of TLR with cardiometabolic (CMD) risk factors.

METHODS

Data were from 3810 adolescents (12-19 years old) in the National Health and Examination Survey (NHANES) 2003-2006. Body fat was assessed by dual-energy X-ray absorptiometry, and CMD risk factors were determined by blood samples and physical examination. Linear and logistic regressions adjusted for BMI z-score and other covariates were used to examine associations of TLR with CMD risk factors as continuous and dichotomized outcomes, respectively.

RESULTS

Adolescents who were Mexican American, who have lower income, and with obesity had the highest mean TLR (all p < 0.05). In linear regression, increasing TLR was associated positively with homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides, total cholesterol, systolic blood pressure (BP), c-reactive protein, and alanine aminotransferase (ALT), and negatively with high-density lipoprotein (HDL) cholesterol in both sexes (p < 0.05). TLR was also associated with diastolic BP in boys and low-density lipoprotein cholesterol in girls (p < 0.05). A similar pattern of findings resulted from logistic regression. When further stratified by race/ethnicity, TLR was positively associated with high triglycerides, total cholesterol, and ALT for White and/or Mexican American (p < 0.05), but not Black adolescents, while associations with HOMA-IR and HDL were significant for all race/ethnicities.

CONCLUSIONS

In this cohort of adolescents, TLR was associated with several risk factors independent of BMI z-score, although some findings were sex or race/ethnicity specific. Body fat distribution may be an important determinant of future CMD.

Relationship between fat distribution and cardiometabolic risk in Hispanic girls

OBJECTIVE

In adults, certain body fat depots have greater impact on cardiometabolic risk than total adiposity. Whether similar relationships exist in children is uncertain. The aim of this study was to examine the relationships among dual x-ray absorptiometry (DXA) measures of body fat distribution and total body adiposity with cardiometabolic risk factors in Hispanic girls.

METHODS

Measures of total percent body fat, percent of total fat within the android, gynoid, leg, and trunk regions, and cardiometabolic biomarkers (insulin, glucose, homeostatic model assessment of insulin resistance (HOMA-IR), triglycerides (TG), low and high lipoprotein cholesterol (LDL-C, HDL-C)) were obtained from 232 Hispanic girls (age 10.7 ±1.1 years). Regression models for each metabolic parameter were run against adiposity measures. Partial correlations of the adiposity measures were used to compare associations between adiposity measures and the cardiometabolic risk factors, controlling for somatic maturation.

RESULTS

Total and regional adiposity were significantly related with cardiometabolic risk factors (P < 0.05) except fasting glucose. The partial correlations of total and regional adiposity measures with each cardiometabolic biomarker were similar. More variance was explained for insulin and the HOMA-IR (33%-43%) than other risk factors. Partial correlations for the percentage of total fat in the gynoid and leg regions with insulin, HOMA-IR, TG, and LDL-C were negative, and positive with HDL-C.

CONCLUSION

Measures of total and regional fat perform similarly in predicting cardiometabolic risk in Hispanic girls. A higher proportion of fat distributed in the gynoid or leg region is associated with lower cardiometabolic risk.

Association between individual fat depots and cardio-metabolic traits in normal- and overweight children, adolescents and adults

OBJECTIVES

To determine age-related associations between fat mass (FM), regional fat depots and cardiometabolic traits in normal- and overweight children, adolescents and adults.

METHODS

Detailed body composition (regional subcutaneous and visceral adipose tissue; SAT, VAT) by whole-body magnetic resonance imaging (MRI), FM and fat-free mass by air-displacement plethysmography, systolic and diastolic blood pressure (SBP, DBP), triglycerides (TG), high-density lipoprotein cholesterol (HDL), plasma glucose and plasma insulin were measured in 433 subjects (BMI: 23.6 (21.0-27.7); 151 children and adolescents, aged 6-18 years, 150 young adults, aged 18-30 years and 132 adults, aged 30-60 years). Data were derived from pooled data of the 'Reference Center for Body Composition' in Kiel, Germany. Insulin resistance was determined by the homeostatic model assessment of insulin resistance (HOMA-IR). Partial correlations and multivariate linear regression analyses were used to evaluate the associations between body composition and cardiometabolic traits. A descriptive approach was used to demonstrate age-dependent differences in associations between body fat depots and insulin resistance, independent of BMI.

RESULTS

FM, SAT, and VAT increased from childhood to adulthood with low VAT in children and adolescents. When compared to children, TG was higher in adults. HDL and DBP did not differ between age groups. Insulin resistance was highest in male adolescents and female young adults. Associations between body fat depots and cardiometabolic traits were seen after puberty with no associations in pre- and intrapubertal children. When compared to FM, SAT and VAT had the strongest association with insulin resistance in adults. This association was independent of BMI.

CONCLUSIONS

Associations between individual body fat depots and most cardiometabolic traits became evident after puberty only. The strongest associations were observed between insulin resistance and abdominal fat in adults. The impact of VAT was independent of BMI.

Intra-abdominal and subcutaneous abdominal fat as predictors of cardiometabolic risk in a sample of Mexican children

BACKGROUND/OBJECTIVE

Few studies in Latin American paediatric populations have differentiated fat deposits in specific areas, such as intra-abdominal fat (IAF) and subcutaneous abdominal fat (SAF). Research in diverse populations is needed, as patterns of fat accumulation vary by ethnicity. The aim of this study was to determine whether IAF and/or SAF are related to cardiometabolic risk factors, independent of total body fat (TBF), in a group of Mexican schoolchildren.

SUBJECTS/METHODS

A cross-sectional study was conducted in Mexico City with 94 children aged between 5 and 11 years. IAF and SAF were assessed by magnetic resonance using two different estimation methods: (a) at the midpoint of lumbar vertebras 4 and 5 (L4-L5) and (b) the sum of the areas of four slices (L1-L2, L2-L3, L3-L4 and L4-L5, which will be referred to as 'total' IAF and SAF). TBF was measured by dual-energy X-ray absorptiometry. The following cardiometabolic risk factors were assessed: total cholesterol, low-density lipoprotein-cholesterol, triglycerides, glucose, insulin, high-density lipoprotein-cholesterol, blood pressure, insulin resistance, number of risk factors and metabolic syndrome score.

RESULTS

After adjusting for sex, age and TBF, total SAF was related to the number of cardiometabolic risk factors and metabolic syndrome score. Although IAF at L4-L5 was also related to the number of cardiometabolic risk factors, there was evidence of collinearity with TBF.

CONCLUSIONS

In this sample of Mexican schoolchildren, TBF and SAF, but not IAF, were associated with higher cardiometabolic risk.

Common variants in the LAMA5 gene associate with fasting plasma glucose and serum triglyceride levels in a cohort of pre-and early pubertal children

Laminins are large glycoproteins found in basement membranes where they play a vital role in tissue architecture and cell behavior. Previously, we reported the association of two LAMA5 polymorphisms (rs659822 and rs944895) with anthropometric traits, fasting lipid profile, and plasma glucose levels in pre-menopausal women and elderly subjects. Furthermore, earlier work in mice showed that Lama5 is involved in organogenesis and placental function during pregnancy. The objective of this study was to investigate whether LAMA5 rs659822 or rs944895 are associated with inter-individual variability in birth weight as well as anthropometric, fasting lipid profile, and fasting glucose levels in children. Two hundred and eighty nine healthy children aged 7-12 years of European, Hispanic, and African-American ancestry were studied. Co-dominant models adjusted for genetic admixture, age, gender, and stages of puberty were used to test for the association of the polymorphisms with each trait. Our analysis showed significant associations of rs659822 with fasting plasma glucose levels (p = 0.0004) and of rs944895 with fasting serum triglycerides (p = 0.004) after Bonferroni correction for multiple testing. Our results corroborate our previous findings that genetic variants in LAMA5 contribute to variation in metabolic phenotypes and provide evidence that this may occur early in life.

Waist-to-Height Ratio Is a Better Anthropometric Index than Waist Circumference and BMI in Predicting Metabolic Syndrome among Obese Mexican Adolescents

Objective. To identify the degree of association between anthropometric indices and components of metabolic syndrome (MS) and to determine optimal cut-off points of these indices for predicting MS in obese adolescents. Methods. A cross-sectional study with a sample of (n = 110) Mexican obese adolescents grouped by sex and the presence/absence of MS. BMI percentile, waist circumference (WC), and waist-to-height ratio (WHtR) were tested. ROC curves of the anthropometric indices were created to identify whether an index was a significant predictor of MS. Results. BMI percentile, WC, and WHtR were significantly correlated with systolic and diastolic blood pressure. As predictors of MS overall patients, the BMI percentile generated an area under curve (AUC) of 0.651 (P = 0.008), cut-off point above the 99th percentile. WC generated an AUC of 0.704 (P < 0.001), cut-off point of ≥90 cm. WHtR demonstrated an AUC of 0.652 (P = 0.008), cut-off point of 0.60. WHtR ≥0.62 and WHtR ≥0.61 generate AUC of 0.737 (P = 0.006) and AUC of 0.717 (P = 0.014) for predicting hypertension and insulin resistance, respectively, in females. Conclusion. WHtR is a better tool than WC and BMI for identifying cardiometabolic risk. The overall criterion (WHtR ≥ 0.6) could be appropriate for predicting MS in obese Mexican adolescents.

Relationships between direct and indirect measures of central and total adiposity in children: what are we measuring?

OBJECTIVE

The relationship between central and total fat measured by anthropometry, dual energy X-ray absorptiometry, and magnetic resonance imaging (MRI) with each other and systolic blood pressure (SBP) was examined.

DESIGN AND METHODS

Participants of the Avon Longitudinal Study of Parents and Children were examined at ages 9, 11, 13, and 15 years (n = 3,796-6,567). MRI was available on a subset of children at 11 (n = 156) and 13 (n = 95).

RESULTS

Body mass index (BMI) and waist circumference (WC) were highly correlated (r = 0.84-0.91, across ages), and total body fat mass (TBFM) and trunk fat mass (TFM) were very strongly correlated (r ≥ 0.98). Among boys, BMI vs. WC explained a similar degree of variation in TBFM and TFM (41-71% vs. 43-76%, across age and overweight groups); in girls, BMI accounted for 62-73% variance and WC 47-69%. Adiposity measures were generally similarly correlated with SBP within age groups. Further, the relationship between intra-abdominal adipose tissue (IAAT) volume and adiposity measures did not vary greatly at 11 (0.65-0.67) and 13 (0.64-0.67).

CONCLUSIONS

BMI and WC contain a large amount of overlapping information as evidenced by their high correlation and similarly sized associations with fat mass, SBP, and IAAT. This suggests that WC may be an inadequate marker of central adiposity during childhood.

Dual-energy X-ray absorptiometry prediction of adipose tissue depots in children and adolescents

BACKGROUND

The measurement of adipose tissue (AT) depots in vivo requires expensive imaging methods not accessible to most clinicians and researchers. The study aim was to derive mathematical models to predict total AT (TAT) and subdepots from total body fat derived from a dual-energy X-ray absorptiometry (DXA) scan.

METHODS

Models were developed to predict magnetic resonance imaging-derived TAT and subdepots subcutaneous AT, visceral AT, and intermuscular AT from DXA total body fat (Fat(DXA)) using cross-sectional data (time 0 (T0)) and validated results using 1 (T1) and 2 (T2) y follow-up data. Subjects were 176 multiethnic healthy children ages 5-17 y at T0. Twenty-two were measured at T1 and T2. TAT was compared with Fat(DXA).

RESULTS

At T0, TAT was greater than Fat(DXA) (12.5 ± 8.4 vs.12.0 ± 9.4 kg; P < 0.0001), with a quadratic relationship between TAT and Fat(DXA) that varied by sex. Predicted mean TATs were not different from measured TATs: T1: (9.84 ± 4.45 kg vs. 9.50 ± 4.37 kg; P = 0.11); T2: (12.94 ± 6.75 kg vs. 12.89 ± 7.09 kg; P = 0.76). The quadratic relationship was not influenced by race or age.

CONCLUSION

In general, the prediction equations for TAT and subdepots were consistent with the measured values using T1 and T2 data.

Ethnic differences in the accumulation of fat and lean mass in late gestation

OBJECTIVES

Lower birth weight within the normal range predicts adult chronic diseases, but the same birth weight in different ethnic groups may reflect different patterns of tissue development. Neonatal body composition was investigated among non-Hispanic Caucasians and African Americans, taking advantage of variability in gestational duration to understand growth during late gestation.

METHODS

Air displacement plethysmography assessed fat and lean body mass among 220 non-Hispanic Caucasian and 93 non-Hispanic African American neonates. The two ethnic groups were compared using linear regression.

RESULTS

At 36 weeks of gestation, the average lean mass of Caucasian neonates was 2,515 g vs. that of 2,319 g of African American neonates (difference, P = 0.02). The corresponding figures for fat mass were 231 and 278 g, respectively (difference, P = 0.24). At 41 weeks, the Caucasians were 319 g heavier in lean body mass (P < 0.001) but were also 123 g heavier in fat mass (P = 0.001). The slopes for lean mass vs. gestational week were similar, but the slope of fat mass was 5.8 times greater (P = 0.009) for Caucasian (41.0 g/week) than for African American neonates (7.0 g/week).

CONCLUSIONS

By 36 weeks of gestation, the African American fetus developed similar fat mass and less lean mass compared with the Caucasian fetus. Thereafter, changes in lean mass among the African American fetus with increasing gestational age at birth were similar to the Caucasian fetus, but fat accumulated more slowly. We hypothesize that different ethnic fetal growth strategies involving body composition may contribute to ethnic health disparities in later life.

Children's binge eating and development of metabolic syndrome

BACKGROUND

Binge eating predisposes children to excessive weight gain. However, it is unknown if pediatric binge eating predicts other obesity-associated adverse health outcomes.

OBJECTIVE

The objective of this study was to investigate the relationship between binge eating and metabolic syndrome (MetS) in children.

METHOD

Children aged 5-12 years at high risk for adult obesity, either because they were overweight/obese when first examined or because their parents were overweight/obese, were recruited from Washington, DC and its suburbs. Children completed a questionnaire assessment of binge eating at baseline and underwent measurements of MetS components at baseline and at a follow-up visit approximately 5 years later. Magnetic resonance imaging was used to measure the visceral adipose tissue (VAT) in a subset.

RESULTS

In all, 180 children were studied between July 1996 and August 2010. Baseline self-reported binge eating presence was associated with a 5.33 greater odds of having MetS at follow-up (95% confidence interval (CI): 1.47, 19.27, P=0.01). The association between binge eating and body mass index (BMI) only partially explained changes in MetS components: baseline binge eating predicted higher follow-up triglycerides, even after accounting for baseline triglycerides, baseline BMI, BMI change, sex, race, baseline age and time in study (P = 0.05). Also, adjusting for baseline VAT and demographics, baseline binge eating predicted greater follow-up L(2-3) VAT (P = 0.01).

DISCUSSION

Children's reports of binge eating predicted development of MetS, worsening triglycerides and increased VAT. The excessive weight gain associated with children's binge eating partly explained its adverse metabolic health outcomes. Reported binge eating may represent an early behavioral marker upon which to focus interventions for obesity and MetS.

Does body mass index accurately reflect body fat? A comparison of anthropometric measures in the longitudinal assessment of fat mass

OBJECTIVE

To determine which anthropometric measure best correlates with change in fat mass (FM) over time.

METHODS

The authors performed a retrospective cohort study of 76 obese patients (mean body mass index [BMI] 38 kg/m(2) and mean age 13 years) presenting to an obesity clinic between 2005 and 2010. For each patient, during 2 visits, FM was measured by bioelectrical impedance analysis and the following measures obtained: BMI, waist circumference, hip circumference, and neck circumference. Correlation coefficients and linear regression analyses were calculated to examine the relationship between each measure and FM.

RESULTS

Change in BMI correlated better with change in FM than any other measure and had the strongest effect on change in FM (P < .01, R (2) = .887). The best regression model included BMI only (R (2) = .891); without BMI, the model was significantly worse (R (2) = .521).

DISCUSSION

In the clinical management of obese children, BMI is an adequate measure of change in FM.

Parental feeding practices and socioeconomic status are associated with child adiposity in a multi-ethnic sample of children

Parental feeding practices have been associated with children's weight status, but results have been inconsistent across populations. Research is needed to elucidate the relationship between parental feeding practices and adiposity in diverse populations. The present study tested if: (1) parental feeding practices differed by race/ethnicity, (2) parental pressure to eat and parental restriction were associated with adiposity levels, and (3) to investigate the relationship between parental feeding practices and/or child adiposity with socioeconomic status (SES). Structural equations modeling was conducted to test the model in 267 children aged 7-12 years self-identified as African American (AA), European American (EA), or Hispanic American (HA) from economically diverse backgrounds. Dual energy X-ray absorptiometry and computed tomography scanning were used to determine body composition and abdominal fat distribution, respectively. Parental restriction was a significant predictor of child adiposity while parental pressure to eat had an inverse relationship with child adiposity. HA parents reported significantly higher levels of restriction and pressure to eat, whereas EA parents reported the lowest. SES was positively associated with child adiposity and inversely related to parental restriction and pressure to eat. Thus, parental feeding practices differ across racial/ethnic groups and SES and may contribute to population differences in child adiposity.

Epidemic of metabolic syndrome in Latin America

PURPOSE OF REVIEW

Description of the epidemiology, etiological factors, and consequences of the metabolic syndrome in Latin America.

RECENT FINDINGS

Latin American populations exhibit a high prevalence of abdominal obesity, and some genetic variations exacerbated by environmental factors have been claimed as main etiological factors of this condition.

SUMMARY

Actually, the Latin American populations exhibit a high prevalence of abdominal obesity and metabolic syndrome, similar or even higher than developed countries. It is attributed to changes in their lifestyle, migration from rural to urban areas and a higher susceptibility to accumulate abdominal fat and develop more insulin resistance compared to other ethnically different populations. Some genetic factors and metabolic adaptations during fetal life can be claimed as etiological factors of this condition. Consequently, a greater burden of type 2 diabetes and cardiovascular disease is expected to occur in the near future. Thus, it is important to establish scientific-based criteria for the diagnosis of metabolic syndrome in the region to implement the best preventive and therapeutical strategies to combat this epidemic disease.