Estimating body fat from anthropometry and isotopic dilution: a four-country comparison

OBJECTIVE: The goal was to assess the ability of BMI to predict body fat (BF) among youths in four countries and identify the degree to which additional anthropometric measures improve this prediction. BMI is widely recommended as an indicator of overweight. However, whether BMI adequately estimates BF and has the same meaning in different ethnic groups and youths has been questioned. RESEARCH METHODS AND PROCEDURES: Data come from 456 Filipino, Chinese, Russian, and black South African youths, 6 to 16 years old. Percentage BF and fat mass index (FMI) were estimated by the deuterium dilution method. Skinfold thicknesses (triceps, subscapular, and suprailiac) and weight and height measures were collected. Percentage BF was regressed first on BMI and age and then with the addition of the skinfold measures. Linear models were run separately by country and sex. The models were repeated with FMI as the outcome. RESULTS: The R2 values from the percentage BF models ranged from 0.13 to 0.69 in the first models to 0.38 to 0.81 in the full models. The values were lowest among Russian males > or = 13 years and Russian females > or = 13 years of age in the reduced and full models, respectively, and were highest among Chinese females. Using FMI as the outcome did not meaningfully change the results. DISCUSSION: The ability of BMI to adequately predict BF and the additional predictivity of anthropometric measures varied widely across the samples, making its uniform use as a proxy for BF in youths from different countries questionable.     

Birth size and accelerated growth during infancy are associated with increased odds of childhood overweight in Mexican children

OBJECTIVE: The associations of birth size, rate of growth during infancy, and odds of childhood overweight have not yet been thoroughly investigated in contemporary cohorts in low- and middle-income countries. The primary aim of this study was to evaluate the influence of birth size (using body mass index at birth) and accelerated growth during infancy (defined as upward growth curve percentile crossing between birth and age 1 year) on the odds of childhood overweight. A secondary goal was to characterize the sociodemographic correlates of accelerated growth during infancy. DESIGN: Observational prospective cohort. SUBJECTS/SETTING: Participants were 163 children and their mothers living in semiurban Mexico who were originally recruited between 1997 and 2000 and followed until 2005. MAIN OUTCOME MEASURES: Primary outcome was childhood overweight (as assessed by body mass index). Secondary outcome was accelerated growth during infancy. STATISTICAL ANALYSES PERFORMED: Multivariate linear regression and logistic regression were used to determine the associations among birth size, accelerated growth, and childhood overweight. RESULTS: Increased size at birth and accelerated growth during the first year of life increased the odds of childhood overweight (odds ratio [OR] 7.62, P<0.0005 and OR 2.23, P<0.05, respectively). The effect of accelerated growth on odds of childhood overweight varied by size at birth (OR for interaction term 0.63, P<0.05). Living in a "dual burden" household, where the child was underweight at birth and the mother was overweight 4 to 6 years after birth, was associated with accelerated growth during the first year of life. CONCLUSIONS: In a sample of Mexican children living in poverty, accelerated growth during infancy was associated with increased odds of childhood overweight among small and normal-sized babies. Among large babies, accelerated growth did not appear to pose an additional risk for overweight beyond that of high birth weight. Upward growth curve percentile crossing in infancy may be predictive of future childhood overweight status, particularly among smaller infants.     

Higher income is more strongly associated with obesity than with obesity-related metabolic disorders in Jamaican adults

OBJECTIVE: This study compares how income is related to obesity vs two obesity-related cardiovascular disease (CVD) risk factors-diabetes and hypertension-in adults from Jamaica. DESIGN: A cross-sectional population-based survey was used. In total, 847 men and 1249 women aged 25-74 y were randomly recruited from a periurban area in 1993-1998. MEASUREMENTS: Trained interviewers measured anthropometry and blood pressure, obtained fasting blood and collected self-reported data on income and disease history. RESULTS: Income was strongly and positively associated with obesity in men. In women, obesity levels were high even among the very poor, and the income gradient was more moderate. Although obesity-and particularly central fatness-was strongly associated with diabetes and hypertension prevalence, income was not significantly related to these disorders. CONCLUSIONS: Future research in developing countries should independently explore associations between income and obesity vs obesity-related disorders, and identify factors that explain any disparities.     

Dramatic rise in overweight and obesity in adult filipino women and risk of hypertension

OBJECTIVE: To assess trends in BMI of adult Filipino women over a 16-year period of rapid socioeconomic change; to identify factors associated with those trends; and to estimate the risk of hypertension associated with overweight, obesity, and high waist-to-hip ratio (WHR). RESEARCH METHODS AND PROCEDURES: Women from randomly selected urban and rural communities of Metro Cebu, Philippines were recruited during a 1983 to 1984 index pregnancy, then followed prospectively for 16 years. Overweight and obesity were defined using BMI cut-off points of 25 and 30, respectively. The analysis sample included women 15 to 45 years of age when measured 4 months postpartum. Weight change in subsequent intervals from 1985 to 1999 was modeled using linear regression. The relationship of BMI and WHR to risk of hypertension in the last survey was modeled using logistic regression. RESULTS: The prevalence of overweight and obesity combined increased nearly 6-fold from approximately 6% in 1983 to 1984 to 35% in 1998 to 1999. Weight gain was positively associated with urban residence, improved socioeconomic status, fewer pregnancies and months of lactation, and more away-from-home work hours. Risk of hypertension was independently elevated by high WHR and overweight/obesity. DISCUSSION: The dramatic trend of increasing overweight and obesity in this sample of women represents a serious health concern, especially in light of the strong association of excess weight, particularly in the truncal region, to risk of hypertension.     

Size at birth and growth trajectories to young adulthood.

Few studies in developing countries follow growth trajectories from birth to adulthood. Such studies are important because size at birth and postnatal growth affect risk of chronic disease in adulthood. This study examines the inter-relationships of maternal factors during pregnancy, infant birth weight and length, early postnatal growth, and young adult height, weight, BMI, and skinfold thicknesses, with particular attention to patterns of growth associated with increased chronic disease risk. Women were recruited in pregnancy, and offspring were followed from birth to age 21 in the community-based Cebu (Philippines) Longitudinal Health and Nutrition Survey. Birth weight and length are independently, positively associated with height, BMI and sum of skinfolds in young adult males and females, and inversely associated with the subscapular to triceps ratio in males only. The effects of size at birth on adult size were modified by birth order, and remained significant after adjusting for maternal nutritional status, socioeconomic status at birth and throughout the growth period, and maturation. Early postnatal growth was strongly influenced by BMI at birth, with rapid early infant weight gain associated with thinness. The growth pattern of the at-risk group most often associated with increased risk of chronic disease (small at birth, relatively heavy as an adult), was characterized by more rapid growth in the first 4 postnatal months. The high level of inter-relatedness of maternal nutrition in pregnancy, prenatal growth, and postnatal growth emphasizes the need to consider the full growth trajectory in studies of developmental origins of adult disease.     

Secular trends in the association between nativity/length of US residence with body mass index and waist circumference among Mexican-Americans, 1988–2008

Objectives

We investigated whether associations between nativity/length of US residence and body mass index (BMI) and waist circumference (WC) varied over the past two decades.

Methods

Mexican-Americans aged 20–64 years from the National Health and Nutrition Survey (NHANES) III (1988–1994), and NHANES (1999–2008). Sex-stratified multivariable linear regression models further adjusted for age, education, and NHANES period.

Results

We found no evidence of secular variation in the nativity/length of US residence gradient for men or women. Foreign-born Mexican-Americans, irrespective of residence length, had lower mean BMI and WC than their US-born counterparts. However among women, education modified secular trends in nativity differentials: notably, in less-educated women, nativity gradients widened over time due to alarming increases in BMI among the US-born and little increase in the foreign-born.

Conclusions

Associations between nativity/length of US residence and BMI/WC did not vary over this 20-year period, but we noted important modifications by education in women. Understanding these trends is important for identifying vulnerable subpopulations among Mexican-Americans and for the development of effective health promotion strategies in this fast-growing segment of the population.