Maria Inês Varela-Silva

Leg length, body proportion, and health: a review with a note on beauty.

Decomposing stature into its major components is proving to be a useful strategy to assess the antecedents of disease, morbidity and death in adulthood. Human leg length (femur + tibia), sitting height (trunk length + head length) and their proportions, for example, (leg length/stature), or the sitting height ratio (sitting height/stature × 100), among others) are associated with epidemiological risk for overweight (fatness), coronary heart disease, diabetes, liver dysfunction and certain cancers. There is also wide support for the use of relative leg length as an indicator of the quality of the environment for growth during infancy, childhood and the juvenile years of development. Human beings follow a cephalo-caudal gradient of growth, the pattern of growth common to all mammals. A special feature of the human pattern is that between birth and puberty the legs grow relatively faster than other post-cranial body segments. For groups of children and youth, short stature due to relatively short legs (i.e., a high sitting height ratio) is generally a marker of an adverse environment. The development of human body proportions is the product of environmental x genomic interactions, although few if any specific genes are known. The HOXd and the short stature homeobox-containing gene (SHOX) are genomic regions that may be relevant to human body proportions. For example, one of the SHOX related disorders is Turner syndrome. However, research with non-pathological populations indicates that the environment is a more powerful force influencing leg length and body proportions than genes. Leg length and proportion are important in the perception of human beauty, which is often considered a sign of health and fertility.

Fatness biases the use of estimated leg length as an epidemiological marker for adults in the NHANES III sample

BACKGROUND We analyse the NHANES III sample to assess the suitability of measured stature and sitting height to estimate leg length (tibia + femur) and predict fatness. High rates of overweight in the United States population may lead to greater gluteo-femoral fat mass which will increase sitting height and artificially decrease estimates of both absolute and relative leg length. METHODS The analyses include 3076 women and 3233 men, 20.0-49.9 years of age of White, Black or Mexican-American ethnicity. The poverty index ratio, measured stature, sitting height, upper leg length, weight, four skinfolds, buttocks circumference and elbow, biacromial and biiliac breadths were extracted from the database. The sitting height ratio, % body fatness, % upper leg length (ULL/stature), and other indices were estimated. Correlation and principle component analysis were used to assess the relationship between measures of body fatness, relative leg length and the other variables. RESULTS For adults in the NHANES III % body fat is more strongly correlated with buttocks circumference (r = 0.87 and 0.78 for women and men), than with any measure of estimated leg length (rs range from -0.28 to -0.10 for both sexes). Principle components analysis separates fatness, stature and estimated leg length into uncorrelated factors for this sample. CONCLUSION Reports of a negative association between leg length and fatness for adults of the NHANES III are likely spurious, due to greater gluteo-femoral fat thickness increasing sitting height. Future rounds of the NHANES, and similar surveys in other nations with high body fat populations, should measure lower extremity length directly to better assess its relationship to health and disease risk.

Economic and Anthropological Assessments of the Health of Children in Maya Immigrant Families in the US

Immigration from developing countries to the US generally increases access to health care and clean water, but it also introduces some unhealthy lifestyle patterns, such as diets dense in energy and little regular physical activity. We present a transdisciplinary model of child health and examine the impact of immigration on the physical growth and health of Maya children in Guatemala and the US. Maya-American children are much taller and have longer legs, on average, than their counterparts in Guatemala. This suggests that immigration to the US improves their health. However, the Maya-American children also are much heavier than both Guatemalan Maya and White American children, and have high rates of overweight and obesity. Quantile regression analysis indicates that Maya are shorter except in the upper tail of the stature distribution, and have higher Body Mass Index (BMI) in the tails, but not in the middle of the BMI distribution. Leisure time spent in front of a television or computer monitor tends to raise BMI in the middle and lower tail of the distribution, but not in the upper tail.

Socio-demographic and behavioral risk factors associated with the high prevalence of overweight and obesity in Portuguese children.

Childhood obesity is a public health concern in Portugal. Socio‐demographic and behavioral factors are highly associated with obesity but are not clearly understood. This article aims to update the prevalence of overweight and obesity in Portuguese children and to explore the influence and risks of socio‐demographic factors and behavioral factors.

Height and Relative Leg Length as Indicators of the Quality of the Environment Among Mozambican Juveniles and Adolescents

The growth status of Mozambique adolescents was assessed to test the hypothesis that relative leg length is a more sensitive indicator of the quality of the environment than the total height. The sample comprised 690 boys and 727 girls, aged between 9 and 17 years, from Maputo. It is divided between those living in the Centre of Maputo and those living in the slums on the periphery of the city. Height, weight, and sitting height were measured and the sitting height ratio was calculated. The hypothesis that relative leg length is more sensitive than total stature as an indicator of environmental quality is not uniformly confirmed. Overall, mean stature is greater for the centre group than the slum group, but relative leg length as measured by the sitting height ratio does not differ. Compared with African‐American references (NHANES II), all centre girls, 9‐ to 14‐year‐old slum girls, all slum boys, and the oldest centre boys show relatively shorter legs. These findings show that within the Mozambique sample, relative leg length is not sensitive enough to distinguish the quality of the living environment. Mozambique was a colony of Portugal until 1975. Civil unrest and warfare characterized the late Colonial period and the postindependence period until a peace settlement was concluded in 1992. It is possible that all socioeconomic status groups within the country suffered sufficiently to reduce relative leg length compared with the better‐off African‐American reference sample. Possible genetic influences on relative leg length are also discussed. Am. J. Hum. Biol. 2009.

Nutritional status of Maya children, their mothers, and their grandmothers residing in the City of Merida, Mexico: Revisiting the leg‐length hypothesis

To test the hypothesis that leg length‐relative‐to‐stature is a more sensitive indicator of nutrition and health than is total height (HT) or sitting height (SH) in a sample of 109 triads of urban Maya children (6.0–8.99 years), their mothers, and maternal grandmothers from Merida, Mexico.

Fat free mass explains the relationship between stunting and energy expenditure in urban Mexican Maya children

Background: Childhood stunting has been associated with an increased risk of obesity in adulthood, but the causes are unclear. This study hypothesizes that stunting significantly reduces both resting and activity energy expenditure. Aim: To assess and describe energy expenditure of low socio-economic Maya children and to determine whether stunting is independently related to energy expenditure after controlling for lean mass. Subjects and methods: Thirty-three urban Maya children, 17 boys, aged 7–9 years, living in Merida, Mexico, were measured for height, weight and bioelectrical impedance analysis (BIA). Body composition was estimated from BIA. Energy expenditure was measured for one week using the Actiheart (combined heart rate and accelerometer). Results: Stunting (height-for-age below the 5th percentile of NHANES III based references) affected 35% of these physically active children. Using multiple linear regression analysis, greater lean body mass predicted higher resting and activity energy expenditure. Stature was not a significant predictor of resting energy expenditure. A lower height-for-age z-score, but not stunting as a categorical variable, significantly predicted lower activity energy expenditure. Conclusion: The hypothesis that stunting reduces total energy expenditure (resting + active) in children is not supported. Rather, children with shorter stature and less lean body mass have lower total energy expenditure. Complex interactions between body size, body composition, and metabolic activity appear to elevate the risk for later life obesity in these Maya children.

How useful is BMI in predicting adiposity indicators in a sample of Maya children and women with high levels of stunting

Body mass index (BMI) is used frequently to estimate adiposity levels in children and adults. However, the applicability of BMI to populations with high levels of stunting has been questioned. Stunted people can have disproportionately short legs, which may increase BMI without increasing body fat because of the relatively larger trunk compared with the legs.

Anthropometric Variation and Health: A Biocultural Model of Human Growth

This review is a synthesis of the many strands of evidence for a biocultural model of human growth. The model allows us to better understand the causes of variation and plasticity in human growth and development. The model helps us to identify and ameliorate factors that impair health, growth, and development. The biocultural perspective focuses on the recurring interaction between the biology of human development and the sociocultural environment. Not only does the latter influence the former, but human developmental biology modifies social and cultural processes as well. There are two essential messages of this synthesis. First, the biocultural nature of human growth and development is best understood via a life history perspective. The second essential message is that neither biology nor culture has primacy in human development. Rather, both work simultaneously and subtly during all stages of life to produce human phenotypic variability. That variability leads to individual and population differences i...

Growth and nutritional status of Portuguese children from Lisbon, and their parents. Notes on time trends between 1971 and 2001

Abstract Aim: To document time trends in growth and nutritional status among Portuguese children from Lisbon, and their parents. Subjects and methods: Two growth surveys were carried out in Lisbon, Portugal in 1991 and in 2001 at the request of the Municipality of Lisbon. The 1991 sample was composed of 2018 children (992 boys and 1026 girls) and the 2001 sample was composed of 3591 children (1787 boys and 1804 girls). The ages range from 4 to 11 years. The data from these surveys is compared with published data from 1971. Data on growth and nutritional status of the children and their parents were analysed. Nutritional status of the family clusters is also documented. Results: There was an increase in the average height of the children between 1971 and 2001, but a more severe increase in overweight and obesity. Stunting in height was virtually non-existent among the children, but leg stunting (leg length relative to height) was high. The main changes between 1991 and 2001 are towards a greater prevalence of overweight/obese family clusters and dual-burden family clusters (at least one underweight member and one overweight/obese member). Conclusions: In this biological survey article we present two growth databases that may be used in future studies. There is an urgent need to conduct a national growth survey in Portugal, including all age groups, with stratified samples by district and ethnic diversity.