Elaine Rush

Body size, body composition and fat distribution: comparative analysis of European, Maori, Pacific Island and Asian Indian adults.

Although there is evidence that Asian Indians, Polynesians and Europeans differ in their body fat (BF)-BMI relationships, detailed comparative analysis of their underlying body composition and build characteristics is lacking. We investigated differences in the relationships between body fatness and BMI, fat distribution, muscularity, bone mineral mass, leg length and age-related changes in body composition between these ethnic groups. Cross-sectional analysis of 933 European, Maori, Pacific Island and Asian Indian adult volunteers was performed for total and percentage of BF, abdominal fat, thigh fat, appendicular muscle mass, bone mineral content and leg length measured by dual-energy X-ray absorptiometry. Asian Indian men and women (BMI of 24 and 26 kg/m2, respectively) had the same percentage of BF as Europeans with a BMI of 30 kg/m2 or Pacific men and women with BMI of 34 and 35 kg/m2, respectively. Asian Indians had more fat, both total and in the abdominal region, with less lean mass, skeletal muscle and bone mineral than all other ethnic groups. Leg length was relatively longer in Pacific men and Asian and Pacific women than in other ethnic groups. In Asian Indians, abdominal fat increased with increasing age, while the percentage of BF showed little change. In the other ethnic groups, both abdominal and total BF increased with age. In conclusion, ethnic differences in fat distribution, muscularity, bone mass and leg length may contribute to ethnic-specific relationships between body fatness and BMI. The use of universal BMI cut-off points may not be appropriate for the comparison of obesity prevalence between ethnic groups.

Estimating the changes in energy flux that characterize the rise in obesity prevalence

BACKGROUND The daily energy imbalance gap associated with the current population weight gain in the obesity epidemic is relatively small. However, the substantially higher body weights of populations that have accumulated over several years are associated with a substantially higher total energy expenditure (TEE) and total energy intake (TEI), or energy flux (EnFlux = TEE = TEI). OBJECTIVE The objective was to develop an equation relating EnFlux to body weight in adults for estimating the rise in EnFlux associated with the obesity epidemic. DESIGN Multicenter, cross-sectional data for TEE from doubly labeled water studies in 1399 adults aged 5.9 +/- 18.8 y (mean +/- SD) were analyzed in linear regression models with natural log (ln) weight as the dependent variable and ln EnFlux as the independent variable, adjusted for height, age, and sex. These equations were compared with those for children and applied to population trends in weight gain. RESULTS ln EnFlux was positively related to ln weight (beta = 0.71; 95% CI: 0.66, 0.76; R2 = 0.52), adjusted for height, age, and sex. This slope was significantly steeper than that previously described for children (beta = 0.45; 95% CI: 0.38, 0.51). CONCLUSIONS This relation suggests that substantial increases in TEI have driven the increases in body weight over the past 3 decades. Adults have a higher proportional weight gain than children for the same proportional increase in energy intake, mostly because of a higher fat content of the weight being gained. The obesity epidemic will not be reversed without large reductions in energy intake, increases in physical activity, or both.

Metformin in Gestational Diabetes: The Offspring Follow-Up (MiG TOFU): Body composition at 2 years of age

OBJECTIVE In women with gestational diabetes mellitus, who were randomized to metformin or insulin treatment, pregnancy outcomes were similar (Metformin in Gestational diabetes [MiG] trial). Metformin crosses the placenta, so it is important to assess potential effects on growth of the children. RESEARCH DESIGN AND METHODS In Auckland, New Zealand, and Adelaide, Australia, women who had participated in the MiG trial were reviewed when their children were 2 years old. Body composition was measured in 154 and 164 children whose mothers had been randomized to metformin and insulin, respectively. Children were assessed with anthropometry, bioimpedance, and dual energy X-ray absorptiometry (DEXA), using standard methods. RESULTS The children were similar for baseline maternal characteristics and pregnancy outcomes. In the metformin group, compared with the insulin group, children had larger mid-upper arm circumferences (17.2 ± 1.5 vs. 16.7 ± 1.5 cm; P = 0.002) and subscapular (6.3 ± 1.9 vs. 6.0 ± 1.7 mm; P = 0.02) and biceps skinfolds (6.03 ± 1.9 vs. 5.6 ± 1.7 mm; P = 0.04). Total fat mass and percentage body fat assessed by bioimpedance (n = 221) and DEXA (n = 114) were not different. CONCLUSIONS Children exposed to metformin had larger measures of subcutaneous fat, but overall body fat was the same as in children whose mothers were treated with insulin alone. Further follow-up is required to examine whether these findings persist into later life and whether children exposed to metformin will develop less visceral fat and be more insulin sensitive. If so, this would have significant implications for the current pandemic of diabetes.

Estimation of body fatness from body mass index and bioelectrical impedance: comparison of New Zealand European, Maori and Pacific Island children

Objective: To compare percentage body fat (%BF) for a given body mass index (BMI) among New Zealand European, Maori and Pacific Island children. To develop prediction equations based on bioimpedance measurements for the estimation of fat-free mass (FFM) appropriate to children in these three ethnic groups.Design: Cross-sectional study. Purposive sampling of schoolchildren aimed at recruiting three children of each sex and ethnicity for each year of age. Double cross-validation of FFM prediction equations developed by multiple regression.Setting: Local schools in Auckland.Subjects: Healthy European, Maori and Pacific Island children (n=172, 83 M, 89 F, mean age 9.4±2.8(s.d.), range 5–14 y).Measurements: Height, weight, age, sex and ethnicity were recorded. FFM was derived from measurements of total body water by deuterium dilution and resistance and reactance were measured by bioimpedance analysis.Results: For fixed BMI, the Maori and Pacific Island girls averaged 3.7% lower %BF than European girls. For boys a similar relation was not found since BMI did not significantly influence %BF of European boys (P=0.18). Based on bioimpedance measurements a single prediction equation was developed for all children: FFM (kg)=0.622 height (cm)2/resistance+0.234 weight (kg)+1.166, R 2=0.96, s.e.e.=2.44 kg. Ethnicity, age and sex were not significant predictors.Conclusions: A robust equation for estimation of FFM in New Zealand European, Maori and Pacific Island children in the 5–14 y age range that is more suitable than BMI for the determination of body fatness in field studies has been developed.Sponsorship: Maurice and Phyllis Paykel Trust, Auckland University of Technology Contestable Grants Fund and the Ministry of Health.

International Physical Activity Questionnaire (IPAQ) and New Zealand Physical Activity Questionnaire (NZPAQ): A doubly labelled water validation

BackgroundAccurate measurement of physical activity is a pre-requisite for monitoring population health and for evaluating effective interventions. The International Physical Activity Questionnaire (IPAQ) is used as a comparable and standardised self-report measure of habitual physical activity of populations from different countries and socio-cultural contexts. The IPAQ has been modified to produce a New Zealand physical activity questionnaire (NZPAQ). The aim of this study was to validate the IPAQ and NZPAQ against doubly labelled water (DLW). Method: Total energy expenditure (TEE) was measured over a 15-day period using DLW. Activity-related energy expenditure (AEE) was estimated by subtracting the energy expenditure from resting metabolic rate and thermic effect of feeding from TEE. The IPAQ (long form) and NZPAQ (short form) were completed at the end of each 7-day period. Activity-related energy expenditure (IPAQAEE and NZPAQAEE) was calculated from each questionnaire and compared to DLWAEE.ResultsThirty six adults aged 18 to 56 years (56% female) completed all measurements. Compared to DLWAEE, IPAQAEE and NZPAQAEE on average underestimated energy expenditure by 27% and 59%, respectively. There was good agreement between DLWAEE and both IPAQAEE and NZPAQAEE at lower levels of physical activity. However there was marked underestimation of questionnaire-derived energy expenditure at higher levels of activity.ConclusionBoth the IPAQ and NZPAQ instruments have a demonstrated systematic bias toward underestimation of physical activity-related energy expenditure at higher levels of physical activity compared to DLW. Appropriate calibration factors could be used to correct for measurement error in physical activity questionnaires and hence improve estimation of AEE.

BMI, fat and muscle differences in urban women of five ethnicities from two countries

Objective:To investigate body composition differences, especially the relationship between body mass index (BMI) and percent body fat (%BF), among five ethnic groups.Design:Cross-sectional.Subjects:Seven hundred and twenty-one apparently healthy women aged 18–60 years (BMI: 17.4–54.0 kg/m2) from South Africa (SA, 201 black, 94 European) and New Zealand (NZ, 173 European, 76 Maori, 84 Pacific, 93 Asian Indian).Measurements:Anthropometry, including waist circumference, and total, central and peripheral body fat, bone mineral content and total appendicular skeletal muscle mass (ASMM) derived from dual X-ray absorptiometry.Results:Regression analysis determined that at a BMI of 30 kg/m2, SA European women had a %BF of 39%, which corresponded to a BMI of 29 for SA black women. For a BMI of 30 kg/m2 in NZ Europeans, equivalent to 43% body fat, the corresponding BMIs for NZ Maori, Pacific and Asian Indian women were 34, 36 and 26 kg/m2, respectively. Central fat mass was lower in black SA than in European SA women (P<0.001). In NZ, Pacific women had the lowest central fat mass and highest ASMM, whereas Asian Indian women had the highest central fat mass, but lowest ASMM and bone mineral content.Conclusions:The relationship between %BF and BMI varies with ethnicity and may be due, in part, to differences in central fatness and muscularity. Use of universal BMI or waist cut-points may not be appropriate for comparison of obesity prevalence among differing ethnic groups, as they do not provide a consistent reflection of adiposity and fat distribution across ethnic groups.

Energy expenditure in adults living in developing compared with industrialized countries: a meta-analysis of doubly labeled water studies

BACKGROUND There is an assumption that people in developing countries have a higher total energy expenditure (TEE) and physical activity level (PAL) than do people in developed nations, but few objective data for this assertion exist. OBJECTIVE We conducted a meta-analysis of TEE and PAL by using data from countries that have a low or middle human development index (HDI) compared with those with a high HDI to better understand how energy-expenditure variables are associated with development status and population differences in body size. DESIGN We performed a literature search for studies in which energy expenditure was measured by using doubly labeled water. Mean data on age, weight, body mass index (BMI; in kg/m(2)), TEE, and PAL were extracted, and HDI status was assessed. Pooled estimates of the mean effect by sex were obtained, and the extent to which age, weight, HDI status, and year of publication explained heterogeneity was assessed. RESULTS A total of 98 studies (14 studies from low- or middle-HDI countries) that represented 183 cohorts and 4972 individuals were included. Mean (±SE) BMI was lower in countries with a low or middle HDI than in those with a high HDI for both men and women (22.7 ± 1.0 compared with 26.0 ± 0.7, respectively, in men and 24.3 ± 0.7 compared with 26.6 ± 0.4, respectively, in women). In meta-regression models, there was an inverse association of age (P < 0.001) and a positive association of weight (P < 0.001) with TEE for both sexes; there was an association of age only in men with PAL (P < 0.001). There was no association of HDI status with either TEE or PAL. CONCLUSION TEE adjusted for weight and age or PAL did not differ significantly between developing and industrialized countries, which calls into question the role of energy expenditure in the cause of obesity at the population level.

Vitamin B12: one carbon metabolism, fetal growth and programming for chronic disease

This review brings together human and animal studies and reviews that examine the possible role of maternal vitamin B12 (B12) on fetal growth and its programming for susceptibility to chronic disease. A selective literature review was undertaken to identify studies and reviews that investigate these issues, particularly in the context of a vegetarian diet that may be low in B12 and protein and high in carbohydrate. Evidence is accumulating that maternal B12 status influences fetal growth and development. Low maternal vitamin B12 status and protein intake are associated with increased risk of neural tube defect, low lean mass and excess adiposity, increased insulin resistance, impaired neurodevelopment and altered risk of cancer in the offspring. Vitamin B12 is a key nutrient associated with one carbon metabolic pathways related to substrate metabolism, synthesis and stability of nucleic acids and methylation of DNA which regulates gene expression. Understanding of factors regulating maternal–fetal one carbon metabolism and its role in fetal programming of non communicable diseases could help design effective interventions, starting with maternal nutrition before conception.

Correspondence between human diet, body composition and stable isotopic composition of hair and breath in Fijian villagers

The main aim of this work was to describe the relationship between diet, and hair and breath isotopic composition. From one Fijian rural village, hair and breath samples were procured from 20 women. Physical anthropometrics were made, and hair 13C/12C and 15N/14N and breath 13C/12C were measured. Individual diet diaries were kept for two of the four preceding weeks, and isotopic compositions of items which accounted for most of the diet were measured. Individual average diets were analysed for macronutrient and energy content and conform to reasonable nutritional expectation. Characteristics of the diet are described in terms of protein and energy, their patterning with respect to different clusters of food items and their relationship to individuals’ anthropometry. Breath CO2 is depleted in 13C by 1–2‰ on average with respect to the total diet. Hair was enriched on average by 4.1‰ in nitrogen and 4.5‰ in carbon with respect to the total diet. There was insufficient population variation in hair isotopic composition to establish individual hair–diet isotopic differences. The definite relationship that we establish in this work, between dietary and tissue isotopic values for a human community, provides a basis for determining and validating dietary regimes more generally within non-industrial, non-global-‘supermarket’ economies.

Body composition and physical activity in New Zealand Maori, Pacific and European children aged 5–14 years

Body fatness and the components of energy expenditure in children aged 5-14 years were investigated. In a group of seventy-nine healthy children (thirty-nine female, forty male), mean age 10.0 (sd 2.8) years, comprising twenty-seven Maori, twenty-six Pacific Island and twenty-six European, total energy expenditure (TEE) was determined over 10 d using the doubly-labelled water method. Resting metabolic rate (RMR) was measured by indirect calorimetry and physical activity level (PAL) was calculated as TEE:RMR. Fat-free mass (FFM), and hence fat mass, was derived from the (18)O-dilution space using appropriate values for FFM hydration in children. Qualitative information on physical activity patterns was obtained by questionnaire. Maori and Pacific children had a higher BMI than European children (P<0.003), but % body fat was similar for the three ethnic groups. The % body fat increased with age for girls (r 0.42, P=0.008), but not for boys. Ethnicity was not a significant predictor of RMR adjusted for FFM and fat mass. TEE and PAL, adjusted for body weight and age, were higher in Maori than European children (P<0.02), with Pacific children having intermediate values. PAL was inversely correlated with % body fat in boys (r -0.43, P=0.006), but was not significantly associated in girls. The % body fat was not correlated with reported time spent inactive or outdoors. Ethnic-related differences in total and activity-related energy expenditure that might account for higher obesity rates in Maori and Pacific children were not seen. Low levels of physical activity were associated with increased body fat in boys but not in girls.