Anatomical distribution of subcutaneous fat and its description by multivariate methods: how valid are principal components?

Shift in body fat distribution from lower body to upper body among urban Colombian women, 1988-1989 to 2007-2008

OBJECTIVE

Body fat distribution may be a stronger predictor of metabolic risk than BMI. Yet, few studies have investigated secular changes in body fat distribution in middle-income countries or how those changes vary by socioeconomic status (SES). This study evaluated changes in body fat distribution by SES in Colombia, a middle-income country where BMI is increasing rapidly.

DESIGN

We applied factor analysis to previously published data to assess secular changes in adiposity and body fat distribution in cross-sectional samples of urban Colombian women. Anthropometry was used to assess weight, height and skinfolds (biceps, triceps, subscapular, suprailiac, thigh, calf).

SETTING

Cali, Colombia.

PARTICIPANTS

Women (18-44 years) in 1988-1989 (n 1533) and 2007-2009 (n 577) from three SES groups.

RESULTS

We identified an overall adiposity factor, which increased between 1988-1989 and 2007-2008 in all SES groups, particularly in the middle SES group. We also identified arm, leg and trunk adiposity factors. In all SES groups, leg adiposity decreased, while trunk and arm adiposity increased.

CONCLUSIONS

Factor analysis highlighted three trends that were not readily visible in BMI data and variable-by-variable analysis of skinfolds: (i) overall adiposity increased between time periods in all SES groups; (ii) the adiposity increase was driven by a shift from lower body to upper body; (iii) the adiposity increase was greatest in the middle SES group. Factor analysis provided novel insights into secular changes and socioeconomic variation in body fat distribution during a period of rapid economic development in a middle-income country.

Anthropometry, lifestyles and fat patterning in Balinese women

BACKGROUND

In many parts of the developing world, modernization has resulted in an increase in the prevalence of overweight and obesity and a subsequent rise in nutrition-related, non-communicable diseases such as cardiovascular disease and Type 2 diabetes.

AIM

The study examined the impact of socio-economic and lifestyle changes associated with modernization on the body size and shape of Balinese women.

SUBJECTS AND METHODS

Anthropometric data including weight, height, body mass index (BMI) and seven skinfolds were collected from 564 Balinese women, aged between 15 and 45 years. The relationship between the degree of 'modernization' (using such parameters as household wealth and education level) and body size and shape was analysed using multiple regression analysis, as was the effect of age, family size and breast-feeding.

RESULTS

Using the WHO (WHO 1995) categories of BMI, 14% of Balinese women displayed Chronic Energy Deficiency (BMI < 18.5 kg m(-2)), 7% were overweight (BMI = 25.0-29.9 kg m(-2)) and less than 1% were obese (BMI > or = 30.0 kg m(-2)). Household wealth (p < 0.0001) and education level (p < 0.05) were significantly associated with fatness, while breast-feeding (p < 0.05) was significantly associated with leanness. Fat distribution was largely independent of biological and socio-economic variables.

CONCLUSIONS

The trend toward increasing fatness associated with greater household wealth and higher education has important health implications for Balinese women as they continue their rapid transition from subsistence agriculture towards a more 'western' lifestyle.

Padrões de adiposidade em mulheres atendidas em um Centro Municipal de Saúde de Belo Horizonte, 2000

O objetivo do estudo consiste em definir padrões de adiposidade em mulheres. O estudo foi realizado em um Centro Municipal de Saúde de Belo Horizonte, Minas Gerais, com 827 mulheres entre 12 e 65 anos. As participantes realizaram diversas medidas antropométricas e responderam a um questionário sobre condições socioeconômicas, demográficas, história obstétrica, estilo de vida. A técnica de análise fatorial de componentes principais (ACP) foi utilizada para identificar conglomerados e independência de variáveis antropométricas na definição de padrões de adiposidade em mulheres. Os três primeiros componentes principais independentes explicaram 85,97% da variância. O primeiro foi representado pelas pregas cutâneas, o segundo pelo Índice de Massa Corporal (IMC) e pela circunferência do braço (CB) e o terceiro pela razão cintura/quadril (RCQ). Os fatores explicaram 38,42%, 29,03% e 18,52% da inércia, respectivamente. Evidenciou-se associação positiva entre todas as variáveis. Observou-se associação de maior intensidade, justificado pela alta correlação, entre as pregas da coxa, peitoral, bicipital, subescapular e supra-ilíaca (Fator 1) e a CB e o IMC (Fator 2). A variável RCQ foi identificada como principal representante do terceiro fator. Conclui-se que a análise fatorial de componentes principais identificou adequadamente três padrões de adiposidade em mulheres: periférica, global e central. A forte associação entre o IMC e CB demonstra que essa última medida poderia substituir com vantagens o IMC no rastreamento populacional da obesidade. Os critérios diagnósticos para a obesidade em mulheres seriam mais precisos se considerassem simultaneamente a CB, a RCQ e a prega da coxa.

Body measurement variability, fatness, and fat-free mass in children 8, 11, and 14 years of age: Project HeartBeat!

Project HeartBeat! is a four year mixed-longitudinal study of the development of cardiovascular risk factors in White and African American children who at baseline comprised three age cohorts 8, 11, and 14 years. This paper focuses on the anthropometric variables which were chosen to reflect body fat and fat-free mass. Selected anthropometric dimensions are compared with those of samples from the combined National Health and Nutrition Examination Surveys I and II to explore the similarities of the samples in terms of central tendencies and variances. The measurements were then explored in terms of their ability to estimate the two compartment model of body composition: fat-free mass (FFM) and body fat (BF) from bioelectrical impedance (BIA). Project HeartBeat! children are slightly larger than NHANES children and have variances that are generally comparable to the national surveys. Over seven percent (7.7%) of children were overweight (BMI) and 25% had 'mild obesity' by %BF. Three different factor analytic methods (incomplete principal components, alpha and maximum likelihood) produced two latent variables from 17 anthropometric dimensions which together accounted for 76-83% of the variation: (1) A body mass factor (F1) which was weighted highly on six circumferences, weight and six skinfolds, and (2) a linear growth factor (F2) which was strongly associated with height, arm length, and sitting height. Triceps, subscapular and midaxillary skinfolds were consistently highly loaded on the body mass factor and their sum was highly correlated to %BF and fat mass (0.90-0.99). This suggests that this sum could be used to estimate fatness in children in studies where the BIA or other body composition techniques are unavailable. FFM and %BF were predicted from the anthropometric factors. Both factors contributed to the estimate of FFM (R(2) = 0.81-0.93), although F2 contributed proportionately more. The 'body mass' factor (F1) was the main predictor of %BF (R(2) = 0.86-0.93), though at some ages the linear factor (F2) was significantly and negatively related to %BF. This set of anthropometric dimensions, taken for the purpose of estimating body composition and summarized as two latent vectors by factor analysis, strongly reflects body fat and FFM in children and adolescents. Am. J. Hum. Biol. 11:69-78, 1999. Copyright 1999 Wiley-Liss, Inc.

Stability of adiposity phenotypes from childhood and adolescence into young adulthood with contribution of parental measures

OBJECTIVE

The stability of several indicators of body composition and adipose tissue distribution over 12 years was quantified.

RESEARCH METHODS AND PROCEDURES

The participants were 77 boys and 76 girls who were evaluated along with their parents at baseline as children and adolescents (8 to 18 years of age) and remeasured as young adults 12 years later. Indicators of body composition included the body mass index, fat mass, fat free mass, percentage of body fat, sum of six skinfolds (SF6), and the first principal component of six age-adjusted skinfold residuals. Relative adipose tissue distribution was represented by the second principal component of skinfold residuals and a trunk-to-extremity skinfold ratio, adjusted for SF6.

RESULTS

Partial interage correlations, controlling for initial age and length of follow-up, were 0.65 and 0.59 for the body mass index, 0.59 and 0.64 for fat mass, 0.65 and 0.57 for fat free mass, 0.50 and 0.57 for percentage of body fat, 0.66 and 0.44 for SF6, 0.64 and 0.42 for the first principal component of six age-adjusted skinfold residuals, 0.19 and 0.31 for the second principal component of skinfold residuals, and 0.41 and 0.47 for trunk-to-extremity skinfold ratio, adjusted for SF6, in men and women, respectively. Multiple regression analyses indicated that the significant partial R(2) values of parental measurements on the prediction of their offspring in young adulthood ranged from 2% to 9%.

DISCUSSION

The results indicate moderately high stability of indicators of body composition and somewhat lower stability of measures of adipose tissue distribution. Overall, parental measures offer less predictive value than do measures of childhood and adolescent body composition and adipose tissue distribution.

Orthogonal factor coefficient development of subcutaneous adipose tissue topography (SAT-Top) in girls and boys

The new optical device Lipometer allows noninvasive, quick, and safe determination of the thickness of subcutaneous adipose tissue (SAT) layers (in mm) at any site of the human body. The specification of 15 evenly distributed body sites enables the precise measurement of subcutaneous body fat distribution, so-called subcutaneous adipose tissue topography (SAT-Top). SAT-Top was measured in 980 children aged 7-19 years. In this paper we describe the degree to which SAT-Top body sites are intercorrelated. We consider whether a meaningful reduction of data is possible using factor analysis, which factors can be extracted, and how SAT-Top data of children can be added to a factor value plot, depicting the essential results of age-dependent subcutaneous fat development. SAT layers situated on the same body area provide correlation coefficients up to +r = 0.91. Two factors are extracted: factor 1, containing all upper body sites (from neck to hip); and factor 2, consisting of all leg body sites. When all 980 children are divided into three age groups in a factor value plot, the first age group (7-11 years) shows almost equal SAT-Top development in boys and girls. Afterwards, for the consecutive age groups 2 (11-15 years) and 3 (15-19 years), the age-dependent subcutaneous fat development of boys and girls progresses into nearly orthogonal directions.

Measurement of subcutaneous adipose tissue topography (SAT-Top) by means of a new optical device, LIPOMETER, and the evaluation of standard factor coefficients in healthy subjects

The quantification of obesity in respect to subcutaneous adipose tissue and fat distribution is a matter of interest. We recently reported on a new optical device, LIPOMETER, and its ability to measure the thickness of subcutaneous adipose tissue and its advantages compared with other methods. To describe the subcutaneous adipose tissue distribution of the human body in a precise, reproducible, and comparable manner, 15 well-defined body sites distributed from neck to calf on the right body side were used. This set of sites defines subcutaneous adipose tissue topography (SAT-Top). To visualize SAT-Top for subjects or groups, special SAT-Top plots were used. Subcutaneous adipose tissue distribution can be recognized easily with these techniques. SAT-Top of 590 healthy men and women was measured. Factor analysis was used to extract the essential information from these 590*15 intercorrelated single measurements and to provide standard factor coefficients for later applications. As an example of how to use the results of factor analysis, the strong SAT-Top deviation of women with clinically proven type-2 diabetes mellitus (NIDDM) from healthy controls is described. Am. J. Hum. Biol. 12:231-239, 2000. Copyright 2000 Wiley-Liss, Inc.

Relation of circumferences and skinfold thicknesses to lipid and insulin concentrations in children and adolescents: the Bogalusa Heart Study

BACKGROUND

Although body fat patterning has been related to adverse health outcomes in adults, its importance in children and adolescents is less certain.

OBJECTIVE

We examined the relation of circumference (waist and hip) and skinfold-thickness (subscapular and triceps) measurements to lipid and insulin concentrations among 2996 children and adolescents aged 5-17 y.

DESIGN

This was a community-based, cross-sectional study conducted in 1992-1994.

RESULTS

A central or abdominal distribution of body fat was related to adverse concentrations of triacylglycerol, LDL cholesterol, HDL cholesterol, and insulin; these associations were independent of race, sex, age, weight, and height. These associations were observed whether fat patterning was characterized by using 1) waist circumference alone (after adjustment for weight and height), 2) waist-to-hip ratio, or 3) principal components analysis. Compared with a child at the 10th percentile of waist circumference, a child at the 90th percentile was estimated to have, on average, higher concentrations of LDL cholesterol (0.17 mmol/L), triacylglycerol (0.11 mmol/L), and insulin (6 pmol/L) and lower concentrations of HDL cholesterol (-0.07 mmol/L). These differences, which were independent of weight and height, were significant at the 0.001 level and were consistent across race-sex groups.

CONCLUSIONS

These findings emphasize the importance of obtaining information on body fat distribution, waist circumference in particular, in children. Waist circumference, which is relatively easy to measure, may help to identify children likely to have adverse concentrations of lipids and insulin.

Fat distribution in relation to sex and socioeconomic status in children 4-19 years

Fat distribution was studied in an urban sample of boys and girls 4.5 to 19.5 years from the Basque province of Biscay by means of Principal Component Analysis (PCA) of five skinfolds. The PCA extracted four components, which explained 99.1% of the total variance. The first principal component revealed strong stability across age and sex, and was related to a pattern of central body fat distribution. The three other components, upper-lower trunk fat, lateral-medial trunk fat, and upper-lower extremity fat, showed poor stability due largely to the influence of age and, to a lesser degree, sex. In both sexes, individual scores of the four factors did not show multivariate differences by socioeconomic status when a MANOVA with age, age² and age³ as covariates was done. Nevertheless, the first factor scores were significantly higher only in the poorer socioeconomic group of girls. The results are explained in the context of either different lifestyles related to socioeconomic status, a protective effect against environmental stress on urban males, or greater plasticity of trunk fat relative to extremity fat in females. Am. J. Hum. Biol. 10:799-806, 1998. © 1998 Wiley-Liss, Inc.

Familial aggregation of subcutaneous fat patterning: Principal components of skinfolds in the Québec family study

Familial resemblance was examined for each of the principal components arising from an analysis of six skinfolds (triceps, biceps, subscapular, abdominal, suprailiac, and medial calf) measured in 1,237 participants of the Québec Family Study. Most of the phenotypic variance among the skinfolds (83%) was accounted for by the first two principal components. Examination of the skinfold loadings on each principal component, as well as intraindividual cross-trait correlations with other body composition and fat pattern measures (body mass index; total fat mass and fat-free mass estimated from body density obtained through underwater weighing; the sum of six skinfolds; and the ratio of trunk to extremity skinfolds) support the interpretation of the first component as a general measure of adiposity and the second component as a trunk-extremity contrast. Parent-child and sibling correlations for each of the two principal components indicate that familial effects reach 46% (general) and 52% (trunk-extremity). Although the eigenvalues for the remaining four principal components (accounting for 17% of the variance) are <1.0, it is noteworthy that each exhibits significant familial resemblance (31-60%). Further, the intraindividual correlations for the additional four components with the other body size indicators are quite low, suggesting that they capture somewhat different aspects of relative fat distribution. © 1996 Wiley-Liss, Inc.

The importance of body fat distribution in early life

It is possible that many of the conflicting findings concerning obesity and cardiovascular disease may be the result of the heterogeneous nature of obesity, adn that only certain subgroups of the obese are at increased risk. Over the last several decades, much attention has focused on the distribution of body fat as an important characteristic in the metabolic and clinical alterations associated with obesity. Several studies have shown that a relative excess of adipose tissue in the upper body, abdominal region, or at various truncal sites is associated with an increased risk of disease; furthermore, these associations are independent of the general level of obesity. This article presents a brief historical overview of the idea of body fat distribution, the measurement techniques that have been used, and the complications associated with an adverse distribution of body fat distribution; particular emphasis is given to studies that have examined fat patterning in early life. Although most investigators recognize that body fat distribution is important in the development of cardiovascular disease, several questions remain.

The precision of anthropometric assessment of body fat distribution in children

Precision estimates are given for indices of body mass, fatness and body fat distribution in a sample of n = 19 subjects selected at random from a larger study of cardiovascular disease risk in school-aged children. The value of this study is that little is known about the measurement precision of ratio indices and multivariate constructs of body fat distribution in children or any other age group. Intra- and inter-observer precisions were highest for weight, height, body mass index and six body circumferences (0.95-0.99), and were lower and more variable for five skinfold thicknesses (0.80-0.99). The measurement precision of ratio indices derived from the circumferences (waist/hip and waist/thigh) and the skinfolds (subscapular/thigh and triceps/subscapular) were lower and more variable than precisions of the single variables. Circumference ratio precisions varied from 0.81 to 0.96 and skinfold ratios varied from 0.28 to 0.94. Precisions of a multivariate construct of central fat distribution from five skinfold measures were better (0.77-0.95), suggesting its greater efficacy. Inter-examiner precisions tended to be significantly lower than intra-examiner precisions for skinfold thicknesses and all composite indices. The lower precisions of ratio indices, compared to the measurement accuracy of the variables which make them up, needs to be considered in epidemiological studies of body fat distribution.

A review of the association between abdominal fat distribution, health outcome measures, and modifiable risk factors

PURPOSE OF THE REVIEW. This review of the literature examines the relationship between abdominal fat distribution and specific health outcome measures, modifiable risk factors, the impact of intervention efforts, and the significance of measurement methods. SEARCH METHODS USED. The research material that was received was found through several on-line data bases, including MEDLINE and CINAHL, an examination of references from selected articles, a manual review of recent relevant journals, and interviews with several physicians and epidemiologists who are experts in this field of inquiry. Forty-three research articles were reviewed for the section on health risk outcomes and abdominal fat distribution. Twenty studies were reviewed in the section on modifiable variables associated with fat distribution. Finally, 10 studies which examined the effect of behavior change on fat distribution were included in this review. SUMMARY OF IMPORTANT FINDINGS. Recent research indicates that people whose body fat is deposited more in the central or abdominal area, especially the intra-abdominal area, than it is in the gluteofemoral area are at increased risk for cardiovascular disease. This risk is independent of, but exacerbated by, the degree of obesity. Several nonmodifiable factors such as age, gender, and menopause as well as some modifiable factors such as obesity, smoking, physical inactivity, and alcohol intake are positively associated with abdominal fat deposition. MAJOR CONCLUSIONS. Intervention results indicate that it is possible to decrease abdominal fat with total weight loss or smoking cessation.

Body fat distribution in men and women of the Hispanic health and nutrition examination survey of the United States: associations with behavioural variables

Body fat distribution is a biological risk factor for cardiovascular disease and diabetes. There are known genetic factors influencing body fat distribution, but variation in this characteristic is also attributable to human behavioural and socioeconomic variables such as social class. Björntorp has proposed that these associations may be due to a series of physiological responses to psychosocial stress, most prominently chronic stimulation of the adrenal-cortical system. This system is known to affect body fat distribution. Elsewhere we have shown that general socioeconomic status is related to body fat distribution in men and women of the Hispanic Health and Nutrition Examination Survey (HHANES) of the United States. In this paper we explore the relationship with those behavioural variables available from the HHANES which could hypothetically serve as indicators of psychosocial stress: smoking, drinking and depression. For both sexes in all Hispanic ethnic groups except Puerto Rican men, as socioeconomic status declined, subcutaneous fat became more centrally distributed. This relationship continued to be significant after controlling for the behavioural variables. A positive relationship was also found between smoking and central body fat distribution which was independent of socioeconomic status. This relationship was statistically significant for all subsamples except Cuban-American women. No consistent relationships were found between body fat distribution, drinking and depression. The data support the hypothesis that body fat distribution may be linked to the social stress of low socioeconomic status, independent of the behavioural factors tested.

Is body fat distribution associated with cardiovascular risk factors in childhood?

The authors studied the association of cardiovascular risk variables with body fat distribution (BFD) in a cross-sectional sample of 743 Texas schoolchildren of both sexes ages 6-14 years. This association is well known in adults and several useful indices of BFD are available. Whether they are applicable to children remains a question of importance for epidemiological investigations in this age group. Canonical correlations between anthropometric (five skinfolds, four circumferences) and risk (blood pressures, cholesterol, pulse) variables ranged from 0.37 to 0.82 depending on sex/age group (p < 0.01). The skinfold vector suggested an association of risk with central fat at most but not all ages. The circumference vectors, on the other hand, suggest that size or fatness, not BFD, was related to risk. Partial correlation and stepwise regression of fatness and BFD indices with cardiovascular risk factors as dependent variables, showed that 'fatness' or 'size' was more clearly associated with risk factors than BFD. The variables most consistently entering the regression were hip circumference and sum of skinfolds. These results contrast with studies of adults or sexually mature adolescents, in which BFD is more clearly related to CV risk variables and the hip circumference is a 'low-risk' variable.

Cephalometric measurements in snorers, non-snorers, and patients with sleep apnoea

Cephalometry is often used to assess patients with sleep apnoea but whether these measurements differ from those in non-apnoeic snorers and how they are influenced by age is not clear. Cephalometric radiographs of patients with sleep apnoea were compared with those of snorers without sleep apnoea and those of non-snorers. Fifty two snorers with suspected sleep apnoea had a conventional sleep study and were divided into two groups: those with an apnoea-hypopnoea index greater than 10/h (n = 40, sleep apnoea group) and those whose apnoea-hypopnoea index was 10/h or less (n = 12, snorer group). The cephalometric measurements in these patients were compared with those of 34 non-snoring control subjects. Controls were subdivided into two groups: control group 1 included 17 subjects similar in age to the sleep apnoea and snorer groups (mean (SD) age 50.0 (10.9), 50.7 (9.4), and 50.6 (9.7) years); control group 2 included 15 young men (25.4 (2.6) years). The distance from the mandibular plane to the hyoid bone (MP-H) and the length of the soft palate were greater in the patients with sleep apnoea (28.7 (7.8) and 43.6 (5.0) mm) than in the snorers (23.7 (4.2) and 40.3 (4.9 mm). The MP-H was similar in snorers and age matched control subjects, but was significantly greater in the older than in the younger control subjects (22.1 (6.1) vs 17.0 (6.8]. The soft palate was longer in subjects who snored (both sleep apnoea patients and snorers) than in control subjects. The MP-H distance significantly correlated with age for all subjects (snorers and controls) and for the control subjects alone. This study shows that non-apnoeic snorers have cephalometric abnormalities that differ from those of patients with sleep apnoea and that cephalometric values are influenced by the subject's age.

The sleep apnea syndrome. Part II: Treatment

An increase in the number of obstructive sleep apnea patients has brought a paralleled demand for timely and effective treatment. Conservative measures to maintain airway patency during sleep include weight loss, lateral decubitus sleep posture, drug therapy, nasal continuous positive airway pressure, and the use of intraoral prostheses. Surgical measures are used to correct gross anatomic defects that cause or contribute to obstruction, remove redundant tissues (uvulopalatopharyngoplasty), or provide an airway below the suspected area of obstruction (tracheostomy). Part II of this article examines the rationale, benefits, disadvantages, and potential complications of each modality of treatment.

Body circumferences as alternatives to skinfold measures of body fat distribution in children

The ratios of circumferences (waist/hip, waist/thigh) have been proposed in lieu of skinfold measurements for studies of obesity and body fat distribution in adults. The skinfold method has been used successfully in children to study the growth and development of patterns of body fat distribution, but circumferences have not. We studied the relationship between these two methodologies as indicators of body fat and its anatomical distribution among 365 normal children aged 6-11 years, using canonical correlation analysis. With this method, weighted vectors of four body circumferences on the one hand and five skinfolds on the other are formed in such a way that the correlation between the two sets of variables is maximized. Weights (regression coefficients) are assigned each variable and their strength and sign help us to select the best combination of circumferences which describe a component of centralised obesity. A first canonical correlation was substantial in both boys and girls (0.84) and was independent of age. It appeared to relate to fatness level. A second canonical correlation was low (0.34 in boys, 0.35 in girls) (p less than 0.01). It too was age independent and in both sexes it reflected differences between fat on the trunk and on the lower extremity, and was thus a component of centralised fat distribution. The simple waist/thigh ratio correlated better with this canonical variable (0.67-0.88) than the more commonly used waist/hip ratio (0.45-0.79). The 'best' index of centralised fat in children is therefore, the waist/thigh circumference ratio, the same one that has been suggested for adults.

Health risks of obesity

Evidence implicating obesity as a risk-factor disease is critically reviewed. Possible reasons for the many conflicting findings are addressed. The classification of obesity, based upon the site of body fat distribution, and possible biologic mechanisms associating regional adiposity with morbidity, are discussed.

Fat patterning in Papua New Guineans: effects of age, sex and acculturation

For the renewed interest in fat patterning to be fruitful, more information on the biology of fat patterning, particularly normative data are required. Nine skinfold thicknesses were measured in 2312 coastal and highland Papua New Guineans of all ages undergoing acculturation. Principal component analysis of the skinfold data revealed components of fatness and fat patterning. First component scores were typical of the changes in fatness with age and the sex differences expected in these populations. Second component scores of limb-trunk fat patterning showed marked changes with age in both sexes but they stabilised in adulthood. This pattern seemed more affected by maturity although it is usually thought to be a sex-specific pattern. The third component, upper-lower body patterning, was more sexually dimorphic in adults. Marked differences were not observed between the two communities but over a 15-year period fatness levels increased slightly and subcutaneous fat tended to be deposited more centrally.

Relationship of upper body fat distribution to serum glucose and lipids in a Costa Rican population

Present models of the relation between subcutaneous fat distribution and serum biochemistries have been based largely on U.S. White populations. To determine interpopulational differences in that relation, we measured 68 clinically normal adult Costa Ricans aged 17-32. Data collected included six skinfolds: triceps, subscapular, suprailiac, umbilical, anterior mid-thigh, and medial calf; height, weight, and four fasting serum parameters: glucose, triglyceride, cholesterol, and high-density lipoprotein (HDL). Correlations between standardized skinfold ratios and biochemistries were highest--on the order of 0.40-0.50--for upper-lower body contrasts to triglyceride and cholesterol in males and to glucose and HDL in females. Canonical correlation analysis, with body mass index partialed out, found significant correlations for the first male variate and the first two female variates. The first male variate was positively weighted on subscapular fatness and on triglyceride and cholesterol, respectively. The two female skinfold variates were positively weighted on subscapular and on outer limbs, respectively, while their corresponding biochemical variates were weighted on glucose and triglyceride and on cholesterol and HDL, respectively. These findings are generally consistent with those based on U.S. populations but suggest that in non-Anglo populations, upper trunk fatness may be more relevant than anterior waist fatness to biochemical dysfunction.

The skinfold: myth and reality

The interest in skinfolds, given the easy accessibility of the subcutaneous layer and its non-invasive nature, has led to a proliferation of 'skinfold' applications and formulae. To obtain data to investigate body composition methods, particularly the use of skinfolds, two separate cadaver dissection studies were undertaken, allowing for the analysis of data from 32 cadavers with more than 2500 data per cadaver. In addition, 40 elderly 'living' subjects of the same age range were compared with the cadaver population and no significant macro-morphological differences were found. The available data have clearly demonstrated that skinfold compressibility is by no means constant. Adipose tissue patterning by assessment of skinfold thickness using calipers and incision confirms significant sex differences but emphasizes the neglected importance of skin thickness. It appears that the best adipose tissue predictors are different from those used in general. Also the problem of estimating body fat content by skinfold is compounded by the fact that two identical thicknesses of adipose tissue may contain significantly different concentrations of fat. Skinfolds are significantly related to external (subcutaneous) adipose tissue. However, the relation to internal tissue is less evident and the relation with intramuscular adiposity is unknown.

Principal components analysis of physical growth in savannah baboons

Morphometric data collected from 118 male and 169 female savannah baboons (Papio cynocephalus anubis) aged between birth and 5.5 years were analyzed to describe the morphology and physical growth of this species. Measurements included weight, crown-rump length, triceps circumference, and skinfolds at the neck, subscapular, suprailiac, and triceps anatomical sites. Principal components analyses were applied to the data to provide multivariate assessments of morphological patterning among the variables. These analyses resulted in the extraction of two unrotated orthogonal components that accounted for 88% of the overall sample variation. The first component accounted for 77% of the variation and represents an axis of overall body size. The second component represents an axis of shape variation that contrasts body size with fat patterning, and was interpreted as a measure of body leanness. Individual component scores were computed for determining age, gender, and age-by-gender interaction effects. Both components were found to be age dependent for both genders. Males and females shared similar age patterning along the two components; however, gender differences did occur in patterning along the two components; however, gender differences did occur in respect to leanness. The multivariate measure of overall body size increased for both genders similarly with advancing age. Age patterning along the leanness component was described as a decrease from birth to 1 year, followed by an increase in leanness in older ages. Females had a delayed and significantly less intense increase in leanness relative to males.

Relationship of fat patterning to coronary artery disease risk in obese adolescents

Fatness and fat patterning of 27 male and 33 female obese adolescents were identified by principal-components analysis of five skinfolds (triceps, subscapular, iliac, abdominal, and thigh). Correlations were computed between the component scores, based on the eigen vectors, and anthropometric and physiological variables. Overall fatness, component I, was highly correlated with all anthropometric and body composition variables. Also, component I significantly correlated with fasting insulin and VO2 max for both sexes and with basal metabolism and HDL-cholesterol for females and males, respectively. Extremity fat patterning, component II, was poorly correlated with all the anthropometric and physiological variables except diastolic blood pressure for the females. Upper-lower body fat patterning, component III, was correlated with the fewest physiological variables.

Obesity and hormonal factors in sleep and sleep apnea

The presence of obesity, defined as weight 20 per cent or more above ideal body weight or increased body fat content, significantly increases risk of pulmonary, cardiovascular, metabolic, and gastrointestinal problems. Obesity is a major cause of shortened life expectancy. While obesity is not essential for the development of the obstructive sleep apnea syndrome, a significant percentage of patients with obstructive sleep apnea are obese. When evaluating these patients who have obstructive sleep apnea, it is important to search diligently for medical problems that are commonly found among the obese. While there is an increased incidence of obese patients among those who have obstructive sleep apnea, the exact reason for this is uncertain. The study of endorphins and enkephalins may expand our understanding of obesity, ventilatory regulation, and obstructive sleep apnea. This may, in fact, enable us to understand better the interrelationship between obesity and obstructive sleep apnea. The role that thyroid hormone, testosterone, and progesterone play in obstructive sleep apnea has also been reviewed. Patients who have obstructive sleep apnea should not be treated with testosterone. All patients given testosterone should be observed quite closely for the possible signs and symptoms of obstructive sleep apnea. Progesterone seems to be of some help in patients who have obesity hypoventilation syndrome. Its effectiveness in patients with obstructive sleep apnea is less clear. The obesity hypoventilation syndrome as described by Burwell is relatively uncommon. Many of the manifestations of the obesity hypoventilation syndrome, however, are found in patients with obstructive sleep apnea. The recognition that the symptoms stem from underlying obstructive sleep apnea offers great potential for therapy. Weight reduction is valuable therapy for patients with obesity and pulmonary dysfunction, obesity and obstructive sleep apnea, and obesity hypoventilation syndrome. Weight reduction and weight maintenance, while difficult, are essential in patients with obesity, obesity and obstructive sleep apnea, and the hypoventilation syndrome. Obesity should be viewed as a medical problem deserving medical attention and long-term medical follow-up.

Subcutaneous fat remodelling in Southeast Asian infants and children

Longitudinal data on 1,048 Thai children were evaluated for evidence of subcutaneous fat remodelling. Fat distribution, as defined by 100 (triceps/[triceps + subscapular]), was more pronounced in the limbs during infancy but shifted toward the trunk thereafter. Subsequent stepwise regression analysis indicated that biological age--as measured by Gruelich-Pyle bone age--and weight together explained between 0.8% and 14.5% of variance in fat distribution, with generally larger R2 values over age and for males. Relationships were curvilinear, with sex differences in slope. Path analysis supported the model that weight was a major causal agent primarily after infancy, whereas biological age had a small influence both in infancy and in late childhood. These findings indicate that trunk fat deposition is a normal feature of childhood. They also suggest that hypotheses which associate elevated trunk fatness with disorders of glucose metabolism are invalid for younger children.

Androgyny in fat patterning is associated with obesity in adolescents and young adults

Recent work suggests that android or male-type obesity is characterized by fat cell enlargement on the trunk and upper body. This implies adult differences in patterns of body fat distribution may have developmental origins connected with differences in maturation or age of onset of obesity. To investigate this, we studied adolescent females (N = 455, 12 years), males (N = 527, 14 years) and young adults (N = 393 females and N = 413 males, 17 years) of the US Health Examination Survey. Five skinfolds and five maturity indicators were available. Individuals were classed as normal weight, overweight or obese on the basis of the body mass index (WT/HT2). Fat patterning was studied by principal components analysis of the log residual skinfold thickness at the five sites, which revealed trunk/extremity and upper/lower trunk fat distribution components in all sex/age groups studied. The means of both components were significantly (P less than 0.05) greater in obese than in normal weight individuals indicating that obesity in adolescence and young adulthood consists of fat concentrated on the upper aspect of the trunk. The effect was independent of maturity, which was a significant correlate of the trunk/extremity patterning component only and in males only. Advanced physiological maturity is probably not a determinant of adult patterns of body fat distribution, but obesity which occurs in adolescence may be.

The Diabetes Alert study: growth, fatness, and fat patterning, adolescence through adulthood in Mexican Americans

Diabetes Alert is a multidisciplinary genetic and epidemiological study of Type II (non insulin-dependent) diabetes in Texas Mexican Americans. We report the anthropometry of 1,155 individuals 10 to 70 or more years with particular reference to overweight, fatness, and anatomical fat patterning in the sample. Children ages 10-18 of both sexes are growing at the 50th percentile of the reference data (U.S. Health and Nutrition Examination Survey-1) for height, Wt/Ht2, and triceps and subscapular skinfolds. Adults are well below median height but well above median Wt/Ht2 and skinfolds. Prevalence of obesity (Wt/Ht2 greater than or equal to 30) among adults is typically 30% or higher by age 30. Diabetics compared to age/sex-matched non diabetics have shorter sitting heights, have more upper body fat (subscapular skinfold), have less lower body fat (lateral calf skinfold), and were heavier at maximum weight and at age 18. The ratio of lower to upper body fat distribution decreases over the life cycle, being highest at adolescence and lowest at ages 40-50 in both sexes. Our results show a precipitous weight gain after maturity in the sample and an association of diabetes with differences in anatomical fat patterning. The age-related changes in fat patterning need to be explained in terms of their ecological and genetic influences.

Longitudinal trends in subcutaneous fat thickness during adolescence

Longitudinal principal components (LPC) analysis is used to summarize adolescent trends in subcutaneous fat thickness at three sites (biceps, suprailiac, and abdominal). For each site, component 1 (C1) represents fatness level, and component 2 (C2) represents an increase followed by a decrease (fat wave) in fatness. Components 3-5 (retained for girls only) represent more complicated patterns of change (multiple increases and decreases). Correlations among scores for C1 for each site and among scores for C2 for each site indicate a high correspondence of fatness level and the magnitude of the fat wave. Associations between components and other indicators of maturity are apparent, indicating that serial fat patterns are controlled to some degree by influences affecting other pubescent events. Continuity between childhood fatness levels and adolescent patterns of fatness are relatively weak. Continuity between adolescent and adulthood fatness is somewhat greater.

Taxonomic identification of human fat patterns

The utility of taxonomic approaches in identification of fat patterning was evaluated using hierarchical cluster analysis on a sample of 64 female and 31 male subjects from 18 to 29 years of age. Four clusters, each composed of subjects with similar distributions of 17 skinfold thicknesses corrected for sex, size and total body fat, showed mean pattern profiles that variously contrasted fatness of the trunk and extremities. Average anthropometric differences between clusters corroborated differences in pattern profile. For comparison, principal-components analysis was carried out on these same data. The results suggest that a taxonomic approach offers advantages in initial interpretation and in design flexibility.

Fat patterning in athletes in relation to ethnic origin and sport

Six skinfold measurements of 92 White, Black and Mexican-American high school varsity female athletes were analysed to identify principal components of fatness and relative fat patterning. As in other athletic and non-athletic samples, two principal components were evident: a first component, accounting for 69% of the variation, was positively related to all skinfold sites, and a second principal component, accounting for 11% of the variation, was correlated positively with extremity sites (particularly lower limb sites) and negatively with trunk sites. The first component (fatness) was significantly related to sport (P less than 0.02) but not ethnicity. The second component (extremity/trunk) was significantly related to ethnicity (P less than 0.01) but not sport. These results, although tentative due to the limited sample size, support our earlier findings on Olympic athletes, i.e., fatness is more influenced by sport and by training than is fat patterning.

Blood pressure, fatness, and fat patterning among USA adolescents from two ethnic groups

Many studies have explored the relationship between blood pressure and body size and composition in adults and preadults, but none has inquired into the relationship of blood pressure and the anatomical distribution of subcutaneous fat (fat patterning). Fat patterning has an association with chronic diseases (diabetes and cardiovascular disease) in adults. We sought the relationship between fatness, fat patterning, weight, and height among adolescents (12 to 17 years of age) of two ethnic groups (black and white) from the Health Examination Survey. Systolic blood pressure adjusted for age was related to body build variables in all sex/ethnic groups in decreasing order of importance as follows: body weight (independent of height), fatness (as assessed by a two skinfold index), and an excess of fat on trunk relative to fat on the leg (pattern index). Neither fatness nor fat patterning was significantly related to blood pressure after weight entered the regression equation. Relative fat patterning may be less important in predicting cardiovascular risk factors in adolescents than it is in adults. The fact that body weight was more important than fatness suggests that the weight/blood pressure association is due to components of body mass other than body fat.

Growth and body composition of Mexican-American boys 9 through 14 years of age

The growth status and densitometric estimates of body composition are considered in a cross-sectional sample of 95 Mexican-American boys, 9 through 14 years of age, from lower socioeconomic circumstances. A series of 19 measurements were taken on each boy, including measures of size, proportions, skeletal breadths, limb circumferences, skinfolds, and grip strength. Body density was determined by underwater weighing and residual volume was predicted. Density determinations were converted to percentage body fat using the average of two estimates from the equations of Brozek et al. (1963) and Siri (1956). Relative fatness was also converted to lean body mass and fat weight in kilograms. The growth status of the boys was compared to reference data for American White boys in the U. S. Health examination Survey. The Mexican-American boys are shorter and lighter than the reference data, and smaller in all anthropometric dimensions except skinfolds, which are variable. The subscapular and midaxillary skinfolds are similar in the two samples, while the triceps, medial calf, and suprailiac skinfolds are thinner in Mexican-American boys. Regressions of the four body composition estimates on age show significant age effects only for lean body mass and fat weight. Density and percentage fat do not vary significantly with age. Compared to samples of boys in the same age range, the Mexican-American boys generally have a greater body density. Correlations between skinfold thicknesses and body density are generally lower in the Mexican-American boys compared to other samples. Two equations for the prediction of body density in Mexican-American boys are offered.

The changes with age of the anatomical distribution of fat

During adolescence and the third decade of life a redistribution of bodily fat is occurring away from the extremities towards the trunk. During this time the process is occurring in both sexes although more rapidly in males than females, hence it is a masculinizing process. The process is seen in human populations from various ethnic and cultural backgrounds. Masculinizing characteristics like this one are predictors of chronic diseases such as diabetes and atherosclerosis late in life. The period from adolescence through young adulthood may be a sensitive time for the development of characteristics that predispose one to the chronic diseases of aging. Socioanthropological investigations of chronic disease related to human obesity may benefit by focusing on this developmental period.