Haematological reference values in Spanish adolescents: the AVENA study

Objectives: To provide reference values for haematological indices in Spanish adolescents according to age and gender. Methods: A cross sectional study conducted in five Spanish cities was performed. Blood was drawn from a representative sample of 581 adolescents with age ranging from 13 to 17–18.5 yr. Age‐ and gender‐specific means, standard deviations and percentiles were determined for the following parameters: total red blood cell counts (RBC), haemoglobin concentration (Hb), haematocrit percentage (Hct), mean corpuscular volume (MCV), mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, red cell distribution width and total white blood cell (WBC) counts as well as counts and percentage of neutrophils, lymphocytes, monocytes, eosinophils and basophils; platelet count (PLT), mean platelet volume and plateletcrit percentage. Results: Younger male subjects presented lower RBC, Hb, Hct and MCV means that their older counterpart. By contrast these differences were not observed in female subjects. As expected, RBC, Hb and Hct mean values in males were found significantly higher than in girls for all studied age groups. No significant differences were observed in WBC by age and gender. PLT values gradually decreased with age, except for females aged 17–18.5 yr. Conclusion: The present study provides reference data on the distribution of haematological indices of Spanish adolescents. These data can be useful biomarkers of the nutritional status in adolescents.     

Body composition and physical performance of Spanish adolescents: the AVENA pilot study

In order to validate the physical fitness tests and anthropometric parameters of the AVENA multicenter study, a pilot study was carried out in 101 adolescents (48 girls and 53 boys) aged 15-18 years. Body composition was established by the sum of skinfolds (SS) in millimeters (biceps, triceps, subscapular, suprailiac) and body mass index (BMI, weight/height(2)) in kilograms per meters squared. Physical fitness was measured by means of the Course-Navette test (CNT). Median BMI was 22.5 and 20.3 for boys and girls, respectively, while their median SS was 32.5 and 47.47, respectively. The median CNT score was 8 and 4 for boys and girls, respectively. For both groups, there was a negative correlation between body fat and physical fitness, the correlation being stronger in boys ( r=-0.65) than in girls ( r=-0.43; p<0.01). SS appears to be more suitable than BMI in expressing body composition in this context. The CNT indicates physical fitness in adolescents satisfactorily. This subject will be explored in more depth during the final phase of the multicenter study.     

Overweight, obesity and body fat composition in spanish adolescents. The AVENA Study

OBJECTIVE: To describe the prevalence of overweight and obesity in the Spanish adolescent population and its relationship with the socioeconomic status, and to assess their body fat composition and compare these results with previous data from our own country. DESIGN: Cross-sectional multicenter study conducted in five Spanish cities (Granada, Madrid, Murcia, Santander and Zaragoza) in 2000-2002. SUBJECTS: 2,320 adolescents with complete set of anthropometric measurements, 1,192 boys and 1,128 girls. MEASUREMENTS: Body mass index calculated from weight and height measurements, and body fat percentage calculated from skinfold thickness measurements. RESULTS: Overweight + obesity prevalences were 25.69 and 19.13% in boys and girls, respectively. Overweight + obesity prevalence increased in boys from high to medium-low socioeconomic status categories (p = 0.015); meanwhile, there was not a significant effect of socioeconomic status in girls. In males, overweight + obesity prevalence changed from 1985 to 2000-2002 from 13 to 35% and in females from 16 to 32%. The rate of change in overweight + obesity prevalences seems to increase in the last years; from 0.88 (1985 to 1995) to 2.33%/year (1995 to 2000-2002) in males and from 0.5 (1985 to 1995) to 1.83%/year (1995 to 2000-2002) in females. The rate of body fat percentage increase was similar between 1980 and 1995 and between 1995 and 2000-2002: 0.26 and 0.23%/year, respectively, at 13 years of age, and 0.16 and 0.17%/year, respectively, at 14 years of age. CONCLUSION: We observed elevated overweight and obesity prevalences in Spanish adolescents, similar to those observed in other European countries. There is a significant inverse relationship between socioeconomic status and overweight + obesity, but only in boys. The rate of change in overweight prevalence in Spanish adolescents seems to increase, and the rate of increase of body fat percentage seems to be similar as in previous years.     

Body fat reference curves for children

OBJECTIVE: To refine the diagnosis of childhood obesity by creating new sex-specific centile curves for body fat and to base these references on a simple and affordable method that could be widely adopted in clinical practice and surveys. DESIGN: Body fat was measured by bio-impedance in 1985 Caucasian children aged 5-18 years from schools in Southern England. Smoothed centile charts were derived using the LMS method. RESULTS: The new body fat curves reflect the known differences in the development of adiposity between boys and girls. The curves are similar by sex until puberty but then diverge markedly, with males proportionately decreasing body fat and females continuing to gain. These sex differences are not revealed by existing curves based on body mass index. We present charts in which cutoffs to define regions of 'underfat', 'normal', 'overfat' and 'obese' are set at the 2nd, 85th and 95th centiles. These have been designed to yield similar proportions of overweight/overfat and obese children to the IOTF body mass index cutoffs. CONCLUSIONS: Direct assessment of adiposity, the component of overweight that leads to pathology, represents a significant advance over body mass index. Our new charts will be published by the Child Growth Foundation for clinical monitoring of body fat, along with the software to convert individual measurements to Z-scores.     

Low level of physical fitness in Spanish adolescents. Relevance for future cardiovascular health (AVENA study)

INTRODUCTION AND OBJECTIVES: Several studies have demonstrated that physical fitness in childhood and adolescence is related to cardiovascular risk in adulthood. Current data on the physical fitness of Spanish adolescents are not available. Therefore, the aims of this study were: a) to assess the physical fitness of Spanish adolescents and establish reference values for use in health and educational settings as indicators of cardiovascular health, and b) to determine the percentage of Spanish adolescents below the minimum level of aerobic fitness needed to guarantee future cardiovascular health. SUBJECTS AND METHOD: The modified EUROFIT battery of tests was used to assess physical fitness in a representative sample of Spanish adolescents (n=2859; 1357 boys and 1502 girls) taking part in the AVENA (Alimentación y Valoración del Estado Nutricional de los Adolescentes) study. RESULTS: Standard parameters for the physical condition of Spanish adolescents are reported in this study. The 5th percentile for maximum aerobic capacity (Course Navette test) ranged from 2.0-3.3 palier in boys and from 1.4-1.9 palier in girls. The findings indicate that, on the basis of aerobic fitness, approximately 20% of Spanish adolescents have an increased risk of future cardiovascular disease. This subgroup also performed poorly in all other tests of physical fitness used. CONCLUSIONS: The results reported in this study enable the level of physical fitness in adolescents to be interpreted as an indicator of future cardiovascular health. They also indicate that the physical fitness of Spanish adolescents must be improved to help protect against cardiovascular disease in adulthood.     

Body fat distribution in relation to serum lipids and blood pressure in 38-year-old European men: the European fat distribution study

A study on 512 38-year-old European men selected from 6 different towns was conducted. There were significant differences between the centers in averages of anthropometric variables (except for thigh circumference), serum lipids (except for LDL-cholesterol), and blood pressure. In the pooled material, body mass index (BMI) as well as waist circumference, waist/hip ratio and waist/thigh ratio and subscapular skinfold were positively correlated to serum triglycerides, total cholesterol, LDL-cholesterol, and blood pressure and negatively with HDL-cholesterol. After adjustment for BMI, waist, waist/hip, and waist/thigh were all still significantly correlated with serum triglycerides (P less than 0.001). In addition, waist/hip and waist/thigh ratio showed significant partial correlations with total cholesterol (r = 0.16, P less than 0.001, r = 0.10, P less than 0.05 respectively), and diastolic blood pressure (r = 0.10, P less than 0.05, r = 0.09, P less than 0.05 respectively). In addition, waist/hip was, independently of BMI, correlated to LDL-cholesterol (r = 0.12, P less than 0.01), and waist/thigh ratio with HDL-cholesterol (r = -0.12, P less than 0.01). The partial association between waist/thigh with HDL cholesterol became insignificant after adjustment for smoking habits and physical activity. Adjustment for differences in anthropometric measurements did not explain the differences in serum lipids and blood pressure between the centers. The authors conclude that indicators of body fat distribution are associated with unfavorable risk profiles for cardiovascular disease in European men covering a large geographical and cultural variety and a wide range of body measurements and cardiovascular risk factors.     

Body fat distribution and the prognosis for weight reduction: preliminary observations

In a preliminary study the influence of body fat distribution on the degree of weight reduction, blood lipids and blood glucose was investigated in 17 premenopausal obese women (BMI greater than 27 kg/m2), who followed an energy-reduced diet of 4.2 MJ/day for 8 weeks. Body fat distribution was distinguished in an abdominal and gluteal-femoral type using a cut-off point of 0.80 for the ratio of waist-to-hips girth. Mean weight reduction was about 10 kg. Body fat distribution was not related to the ability to lose weight. Body weight reduction was 10.2 +/- 3.3 kg (mean +/- s.d.) in the abdominal obese (n = 8) and 9.6 +/- 2.4 kg in the gluteal-femoral obese women (n = 8). In abdominal obese women, body fat distribution became more intermediate. This change in body fat distribution coincided in the abdominal obese, after weight loss, with greater decreases in blood glucose and serum lipids than in the gluteal-femoral obese.     

Body fat distribution in healthy young and older men

Central and/or intraabdominal (IA) fat is an independent predictor of obesity-related metabolic abnormalities in young and middle-aged subjects. The elderly are "fatter" at any given relative weight and often have similar metabolic abnormalities. In this study we compare body composition, circumferences, and specific fat depots areas in a population of healthy young and older men. Although the two groups were similar in body mass index and percent body fat, their distribution of adiposity was different. The young subjects had 16% and 10% larger thigh (p = .0001) and arm (p less than .01) circumferences respectively, while the ratio of waist-to-hip circumference was greater in the older subjects (0.93 +/- 0.04 vs 0.97 +/- 0.04, p = less than .01). The most striking differences between the groups were noted on computed tomography, with a twofold greater IA fat area (72.6 +/- 38.2 vs 143.6 +/- 56.2 cm2, p less than .0001), and a twofold lesser thigh subcutaneous fat area (156.3 +/- 69.3 vs 82.4 +/- 29.7 cm2, p less than .001) in the older subjects. We conclude there is an age-related central and intraabdominal redistribution of adipose mass, even in healthy older subjects. Since these changes occur in the absence of clinical disease, the associations between metabolic abnormalities and a central and or IA distribution of adiposity in the elderly must be investigated further.     

Body fat distribution and flow-mediated endothelium-dependent vasodilation in older men

OBJECTIVE: Recent studies indicate that abdominal fat accumulation, in particular intra-abdominal fat, is related to impaired endothelial function in young healthy volunteers. The aim of this study was to examine whether the distribution of body fat depots is related to impaired endothelial function in older men. METHODS: Cross-sectional sample of 38 older (68+/-1 y) sedentary (VO(2max)=2.4+/-0.1 l/min) men. Flow-mediated endothelial dependent vasodilation (EDD) was assessed in the brachial artery in response to reactive hyperemia using high-resolution ultrasound. Abdominal subcutaneous and visceral fat depots were assessed by computed tomography scan (CT-scan) at the L(4)-L(5) region in the supine position. Percentage body fat was assessed via dual-energy X-ray absorptiometry (DEXA). RESULTS: Flow-mediated percentage change in brachial artery was 7.6+/-0.7%, suggesting an impaired flow-mediated EDD. Using simple linear regression analysis, there were no statistically significant relationship observed between flow-mediated EDD and the indices of total and abdominal adiposity (percentage body fat=29.3+/-0.9%, r=-0.11; total abdominal fat area=465+/-23 cm(2), r=-0.1; intra-abdominal fat area=200+/-14 cm(2), r=-0.14; subcutaneous fat area=265+/-13 cm(2), r=-0.05; BMI=29.3+/-0.9 kg/m(2), r=-0.07; and waist to hip ratio=0.98+/-0.01, r=-0.20). CONCLUSION: These findings suggest that in older sedentary men there is no clear correlation between adiposity and body fat distribution and impairment of flow-mediated endothelium dependent vasodilation.     

Body fat distribution in Alaskan Eskimos of the Bering Straits region: the Alaskan Siberia Project

OBJECTIVE: To describe the body fat content and distribution of adult Alaska Natives of the Bering Straits Region. DESIGN: Cross-sectional screening in the spring of 1994. SUBJECTS: 454 non-pregnant native residents from four rural Alaskan villages. MEASUREMENTS: Height, weight, waist, hip and thigh circumference, bioelectrical impedance, sagittal abdominal diameter, and triceps, biceps, suprailiac, subscapular and thigh skinfolds. RESULTS: Mean height, weight and subscapular-to-triceps ratio were higher in men than women. The women had larger waist, hip and thigh circumferences, higher body fatness, as well as larger skinfolds than the men. There were no demonstrable differences between men and women in measures of body fat distribution. The proportions of women and men with high waist-to-hip ratio (>/=0.8 for women, >/=0.9 for men) for low (<25 kg/m2), medium (25-30 kg/m2) and high (>30 kg/m2) body mass index (BMI) groups were compared with a Canadian study of all races. 1 In the lowest BMI subgroup (<25 kg/m2) a much higher proportion of Eskimo women exhibited a high waist-to-hip ratio (91%) than Eskimo men (42%) or Canadian women (29%) or men (51%). In the highest BMI subgroup (>30 kg/m2) Eskimo women were similar in proportion of high waist-to-hip ratio (99%) compared to Eskimo men (100%), but still demonstrated a much greater proportion of subjects with high waist-to-hip ratio than either Canadian men (90%) or women (76%). CONCLUSIONS: The large abdominal fat depots found in Eskimo women were similar to men, and may indicate that future increases in diabetes mellitus and other metabolic alterations can be anticipated. International Journal of Obesity (2000) 24, 171-179     

Relationship between body fat distribution and blood lipids in obese adolescents

Associations between body fat distribution, measured by waist/hip circumference ratio (WHR), and plasma lipids and lipoproteins were examined in 74 grossly obese adolescents. WHR was positively correlated in adolescent girls with total triglycerides (r = 0.44, P less than 0.01), total cholesterol (r = 0.49, P less than 0.001), and LDL-cholesterol (r = 0.59, P less than 0.001). In adolescent boys no correlation was found for total cholesterol but there were correlations for triglycerides (r = 0.41, P less than 0.05), LDL-cholesterol (r = 0.49, P less than 0.001), HDL-cholesterol (r = -0.66, P less than 0.001) and the ratio cholesterol/HDL-cholesterol (r = 0.62, P less than 0.001). Waist/hip ratio was not correlated with BMI or percentual overweight in obese girls, but a significant association was found in obese boys for both (r = -0.46, P less than 0.03 and r = 0.53, P less than 0.02). These results indicate that in obese girls a prevalence of abdominal fat distribution is correlated with increased triglycerides, serum cholesterol and LDL-C. In male adolescents total cholesterol is only slightly influenced but HDL-C concentrations are lower and LDL-C and the ratio CHOL/HDL-C higher.     

Body fat distribution, liver enzymes, and risk of hypertension: evidence from the Western New York Study

Gamma-glutamyltransferase (GGT) has been associated with hypertension (HTN); however, the nature of this association remains unclear. GGT is a marker of alcohol consumption, but it is also related to the infiltration of fat in the liver (fatty liver). The association between GGT and HTN was examined in a 6-year longitudinal investigation among 1455 men and women who returned for the follow-up visit. Baseline variables included serum GGT, blood pressure, and anthropometric measures. Incident HTN was defined as blood pressure > or =140/90 or on antihypertensive medication at the follow-up visit. To eliminate individuals with potential liver pathology, analyses focused only on individuals with GGT within its normal range (n=897). Participants were divided in quintiles (Q) based on their baseline GGT levels. Multiple logistic regression analyses [odds ratio (95% confidence intervals)] revealed a significant association of GGT with incident hypertension [2.1 (1.1 to 4.0) Q5 versus Q1]. In subgroup analyses, GGT and HTN were significantly associated among both noncurrent and current drinkers, but only for participants above the median of anthropometric measures [eg, body mass index >26.4, 2.3 (0.9 to 5.7), waist circumference >86.1 cm, 3.7 (1.4 to 9.9), and abdominal height >19.8 cm, 3.1 (1.2 to 8.5), for Q5 versus Q1, in fully adjusted models]. These findings suggest that the association between GGT and hypertension is not caused solely by alcohol consumption and indicate that serum GGT, within its normal range, may predict hypertension among individuals with increased central fat distribution, suggesting that fatty liver may represent an important underlying mechanism for this association.     

Body fat distribution in men with angiographically confirmed coronary artery disease

Body fat distribution and its relationship to coronary artery disease and established cardiovascular risk factors have been studied in a cohort of 286 men aged between 30 and 74 years undergoing coronary angiography. 207 (72.4%) patients showed stenosis (greater than 30%) or occlusion of one or more coronary arteries. whereas the remaining 79 (27.6%) men were free of coronary lesions and served as a control group. 112 men with angiographically defined coronary artery disease had an additional history of myocardial infarction. Body fat distribution was assessed by determining the waist-to-hip circumference ratio. A stepwise logistic regression analysis revealed that in addition to LDL-cholesterol (P = 0.0001) and age (P = 0.0005) an abdominal type of body fat distribution (P = 0.0129) is also a significant risk indicator for the occurrence of coronary artery disease (CAD) independent of body weight and other factors such as total cholesterol, HDL-cholesterol, triglycerides, insulin, systolic and diastolic blood pressure. The results of this study suggest that an abdominal type of fat distribution is associated with an increased risk of coronary artery disease.