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PubMed1999

Evaluation of the body composition and fat distribution in long-term users of hormone replacement therapy.

The aim of the study was to evaluate the body composition and fat distribution in long-term users of hormonal replacement therapy (HRT). 18 healthy menopausal women, long-term users of HRT (transdermal estradiol 50 microg continuously administered and 10 mg/day of medroxyprogesterone acetate for 12 days/month) and 18 healthy menopausal women, who had never used HRT were included in the study. Age, menopausal age, parity, weight and height (body mass index, weight/height2), and lifestyle habits were similar. Waist and hip circumference, body composition and waist/hip ratio were measured and the results were analyzed. No significant difference was demonstrated in fat and water percentage, and waist/hip ratio. Nevertheless, the waist circumference of long-term HRT users was significantly lower than that of non-users. In conclusion, abdominal fat in long-term HRT users is lower than that of non-users of similar age, menopausal age and body mass index.

Adipose Tissue↗

PubMed2002

Impact of visceral fat on blood pressure and insulin sensitivity in hypertensive obese women.

OBJECTIVE: The relationship among body fat distribution, blood pressure, serum leptin levels, and insulin resistance was investigated in hypertensive obese women with central distribution of fat. RESEARCH METHODS AND PROCEDURES: We studied 74 hypertensive women (age, 49.8 +/- 7.5 years; body mass index, 39.1 +/- 5.5 kg/m(2); waist-to-hip ratio, 0.96 +/- 0.08). All patients were submitted to 24-hour blood pressure ambulatory monitoring (24h-ABPM). Abdominal ultrasonography was used to estimate the amount of visceral fat (VF). Fasting blood samples were obtained for serum leptin and insulin determinations. Insulin resistance was estimated by homeostasis model assessment insulin resistance index (HOMA-r index). RESULTS: Sixty-four percent of the women were postmenopausal, and all patients showed central distribution of fat (waist-to-hip ratio > 0.85). The VF correlated with systolic 24h-ABPM values (r = 0.28, p = 0.01) and with HOMA-r index (r = 0.27; p = 0.01). VF measurement (7.5 +/- 2.3 vs. 5.9 +/- 2.2 cm, p < 0.001) and the systolic 24h-ABPM (133 +/- 14.5 vs. 126 +/- 9.8 mm Hg, p = 0.04), but not HOMA-r index, were significantly higher in the postmenopausal group (n = 48) than in the premenopausal group (n = 26). No correlations were observed between blood pressure levels and HOMA-r index, leptin, or insulin levels. In the multiple regression analysis, visceral fat, but not age, body fat mass, or HOMA-r index, correlated with the 24h-ABPM (p = 0.003). DISCUSSION: In centrally obese hypertensive women, the accumulation of VF, more often after menopause, is associated with higher levels of blood pressure and insulin resistance. The mechanism through which VF contributes to higher blood pressure levels seems to be independent of leptin or insulin levels.

Adipose Tissue↗

PubMed2006

Body fat measurements in children as predictors for the metabolic syndrome: focus on waist circumference.

The global epidemic of obesity in children will see a rise in the number of cases of metabolic syndrome, which is a clustering of CVD risk factors, including atherogenic levels of blood lipids, hyperinsulinaemia and raised blood pressure. Rather than excess general fatness (assessed by BMI), more specifically it is excess abdominal fatness, quantified by waist circumference measurement, which is a better measure of risk for these metabolic abnormalities in children of all ages. Insulin resistance, a consequence of excess visceral fat, is understood to be the driving force underpinning the metabolic syndrome. Consequently, assessment of abdominal fatness in children is proving to be more clinically useful. Waist circumference centile charts have now been developed for the UK and other paediatric populations to assist in this process. Furthermore, studies in the UK and elsewhere have shown that abdominal fatness has increased in infants, children and adolescents to a greater extent than overall fatness over the past 10-20 years, suggesting that obesity prevalence may be underestimated when based entirely on BMI. Additionally, ethnic differences in fat distribution have been demonstrated in children, with those from south Asian backgrounds having a greater abdominal distribution compared with Caucasian children and consequently having a much greater risk for type 2 diabetes. The information that can be provided by waist circumference measurement in children, as in adults, together with the recent changes in body fat distribution should provide the impetus for its measurement to be standardised and routinely taken in clinical and epidemiological settings.

Abdominal Fat↗

PubMed2006

Early programming of body composition and fat distribution in adolescents.

Size at birth and early postnatal growth are determinants of adult height and BMI. The aim of this study was to evaluate the effect of birth weight on body composition and fat distribution in a group of Spanish adolescents. Current body composition was assessed by both skinfold thickness and dual X-ray absorptiometry in 234 adolescents born at term (140 girls and 94 boys), now aged 13-18 y and living in the city of Zaragoza. Relative fat distribution was estimated using the ratio of the subscapular to triceps skinfolds (S:T). Birth weight and gestational age were assessed by a questionnaire. Birth weight was inversely associated with the S:T ratio (P < 0.05) in boys and directly associated with bone mass (P < 0.01) and fat-free mass (P < 0.05) in girls. This association was independent of factors such as age, Tanner stage, gestational age, socioeconomic status, physical activity, and height. In conclusion, our data support the hypothesis that impaired fetal growth, measured by birth weight, may be related to central fat distribution in boys and decreased bone and fat-free mass in girls.

Absorptiometry, Photon↗

PubMed1997

Fitness, fatness, and the effect of training assessed by magnetic resonance imaging and skinfold-thickness measurements in healthy adolescent females.

The relation between fitness and adiposity is particularly relevant to adolescent females in whom fitness is known to decrease and fatness to increase. However, little is known about the interaction of these variables in normally active, nonobese subjects. Our major hypotheses were that adiposity would be inversely correlated with physical fitness and that even a relatively brief intervention would lead to measurable, site-specific changes in body fat. We used a cross-sectional protocol to correlate body adiposity with indexes of fitness and a prospective study design to examine body adiposity before and after a 5-wk period of endurance training in 44 nonobese females aged 15-17 y (control group, n = 22; training group, n = 22). Adiposity was assessed by magnetic resonance imaging of the abdomen and thigh as well as by standard skinfold-thickness measuring techniques. Fitness was assessed by using cycle ergometer measurements of maximal oxygen uptake (VO2max). There were significant negative correlations between VO2max normalized to body weight and subcutaneous abdominal, thigh, and skinfold estimates of fat. However, when VO2 max was normalized to muscle volume these correlations were not significant. Abdominal fat increased in direct proportion to body weight (scaling factor = 1.14 +/- 0.16) but thigh fat increased proportionately less (scaling factor = 0.38 +/- 0.12, P < 0.05). Training increased thigh muscle mass significantly only in the midmuscle region and prevented the observed fat increase in the distal thigh of the control subjects. Body fat distribution in adolescent females appeared to be affected by many factors, including overall body weight and the level of physical activity.

Adipose Tissue↗

PubMed2001

Long-term effects of childhood obesity on morbidity and mortality.

Obesity tracks from childhood into adulthood, and the persistence of obesity rises with age among obese children. Early onset obesity was suggested as a risk factor for morbidity and mortality later in life. In both sexes, rates of diabetes, coronary heart disease, atherosclerosis, hip fracture and gout were increased in those who were overweight as adolescents. Especially in females, obesity at late adolescence was associated with several and relevant psychosocial consequences in adulthood. Finally, a higher mortality risk for all causes of death, especially atherosclerotic cerebrovascular disease and colorectal cancer, was demonstrated in males but not in females who were overweight during high school years. Although the persistence of excess adiposity from childhood to adulthood is a morbidity risk factor, it is not known if total body fat or body fat distribution is the main factor responsible. In particular, a specific role for the intra-abdominal adipose tissue (IAAT) in childhood, independently from that of total body fat, on morbidity risk in adulthood was not demonstrated yet. The association between childhood obesity and adult morbidity and mortality strongly suggests that a more effective prevention and treatment of childhood obesity should be pursued.

Aging↗

PubMed2006

Regulation of adenosine 5',monophosphate-activated protein kinase and lipogenesis by androgens contributes to visceral obesity in an estrogen-deficient state.

Menopause is associated with an accumulation of visceral fat. An emerging concept suggests that relatively elevated levels of circulating androgens, compared with estrogens in postmenopausal women, underlie this shift in body fat distribution. In this study we administered dihydrotestosterone (DHT) to ovariectomized mice to examine the effect of relative androgen excess on adipose tissue distribution and function in estrogen-deficient mice. Compared with controls, DHT-treated mice exhibited increased body weight and visceral fat mass associated with triglyceride accumulation. Phosphorylation of AMP-activated protein kinase (AMPK) and acetyl CoA carboxylase was significantly decreased by DHT in visceral fat. In 3T3-L1 cells, DHT decreased phosphorylation of AMPK in a dose-dependent manner. In addition, DHT increased the expression of lipogenic genes (fatty acid synthase, sterol regulatory element binding protein-2, and lipoprotein lipase) in visceral fat. These data provide the first in vivo evidence that an increased androgen to estrogen ratio can promote visceral fat accumulation by inhibiting AMPK activation and stimulating lipogenesis.

AMP-Activated Protein Kinases↗

PubMed1987

[Relation between adipose tissue distribution and and circulating lipids in obese women].

Adipose tissue distribution was determined in 50 pre--or post--menopausal women by measuring the waist/hip and arm/thigh circumference ratios and the brachial-femoral adipo-muscular ratio. These three ratios correlated with plasma triglycerides levels irrespective of the women's age and degree of obesity. Total cholesterol, LDL-cholesterol and HDL-cholesterol were related to age and not to weight or adipose tissue distribution. Compared to pre-menopausal women with the same weight excess, post-menopausal women had a more android type of body fat distribution and higher plasma triglycerides and total cholesterol values. The influences of age and menopause are difficult to separate, since the three distribution ratios are age-related. The correlation between plasma triglycerides and adipose tissue distribution in obese women reflects the metabolic consequences of an abdominal predominance of fat.

Adult↗

PubMed1991

Relationship of regional fat distribution and obesity to electrocardiographic parameters in healthy premenopausal women.

Abdominal obesity is an independent cardiovascular risk factor. The coexistence of abdominal obesity and electrocardiographic abnormalities may facilitate the development of cardiac arrhythmias and sudden death. We determined the relationship of body fat distribution and obesity to ECG indices in 27 obese premenopausal women on an isocaloric diet. Intra-abdominal fat distribution was assessed by computerized tomography, and obesity was assessed by hydrostatic weighing. The PR, QRS, and QTc intervals, the P and QRS axes, and the P-QRS angle were determined from a resting electrocardiogram. Cardiovascular risk profile was assessed by systolic and diastolic blood pressure and plasma cholesterol and triglyceride levels. Increased deposition of intra-abdominal fat was significantly associated with prolongation of the QTc interval independent of obesity and other cardiovascular risk factors. The prolongation of the QTc interval seen with increasing intra-abdominal fat distribution may enhance susceptibility to cardiac arrhythmias. These subjects should have electrocardiographic monitoring during periods of weight loss achieved by intensive regimens.

Abdomen↗

PubMed2004

Metabolic and behavioral characteristics of metabolically obese but normal-weight women.

A unique subset of individuals termed metabolically obese but normal weight (MONW) has been identified. These young women are potentially at increased risk for development of the metabolic syndrome despite their young age and normal body mass index. We seek to determine metabolic and behavioral factors that could potentially distinguish MONW women from young women with a normal metabolic profile.Ninety-six women were classified as MONW (n = 12) or non-MONW (n = 84) based on a cut point of insulin sensitivity (as estimated by the homeostasis model assessment). Potentially distinguishing phenotypes between groups measured included serum lipids, ghrelin, leptin, adiponectin, body composition and body fat distribution, resting and physical activity energy expenditure, peak oxygen uptake, dietary intake, dietary behavior, and family history and lifestyle variables. Despite a similar body mass index between groups, MONW women showed higher percent body fat, lower fat-free mass, lower physical activity energy expenditure, and lower peak oxygen uptake than non-MONW women. Plasma cholesterol level was higher in MONW women, whereas no differences were noted for other blood lipids, ghrelin, leptin, adiponectin, and resting energy expenditure. MONW women had lower dietary restraint scores than non-MONW women, but no differences were noted in disinhibition, hunger, and dietary intake. Stepwise regression analysis performed on all subjects showed that 33.5% of the unique variance of the homeostasis model assessment was explained with the variables of percentage of body fat (17.1%), level of dietary restraint (10.4%), and age (6%). Both metabolic and dietary behavioral variables contribute to the deleterious metabolic profile of MONW women. They display lower insulin sensitivity due potentially to a cluster of sedentary behavior patterns that contribute to their higher adiposity. Furthermore, cognitive attitudes toward food (i.e. dietary restraint) and concomitant lifestyle behaviors may play a role in regulating insulin sensitivity in MONW women.

Adiponectin↗

PubMed2005

Effects of agar (kanten) diet on obese patients with impaired glucose tolerance and type 2 diabetes.

AIM: The aim of this study was to evaluate the efficacy of agar diet in combination with a conventional diet (traditional Japanese food) for obese patients with impaired glucose tolerance and type 2 diabetes. METHODS: After a 4-week run-in period on their habitual diets, 76 patients were randomly assigned to have conventional diet or conventional diet with agar. Both groups were on these diets for 12 weeks. Body weight, body mass index (BMI), glycaemic control, blood pressure, insulin resistance, total body fat, fat distribution and lipids were assessed before and after the experimental period. RESULTS: In both groups, after 12 weeks, mean body weight, BMI, fasting glucose levels, homeostasis model assessment-insulin resistance, and systolic and diastolic blood pressures had decreased significantly from their baseline values. HbA(1)c, visceral fat area, subcutaneous fat area, total body fat, insulin area under the curve after oral glucose tolerance test and total cholesterol decreased significantly in the agar-diet group. After 12 weeks, mean changes of body weight (-2.8 +/- 2.7 kg vs. -1.3 +/- 2.3 kg, p = 0.008), BMI values (-1.1 +/- 1.1 kg/m(2) vs. -0.5 +/- 0.9 kg/m(2), p = 0.009) and total cholesterol (-7.6 +/- 27.5 mg/dl vs. + 2.4 +/- 23.4 mg/dl, p = 0.036) were significantly greater in the agar-diet group than in the conventional diet group. CONCLUSIONS: The agar diet resulted in marked weight loss due to the maintenance of reduced calorie intake and to an improvement in metabolic parameters.

Agar↗

PubMed2006

Effects of obesity phenotype on fat metabolism in obese men during endurance exercise.

OBJECTIVE: The effects of obesity phenotype on fat metabolism during endurance exercise are unclear. This study aimed to investigate in obese men whether body fat distribution would influence plasma fat availability and oxidation during endurance exercise. DESIGN: Fourteen sedentary men (body mass index (BMI) > 25 kg/m2) were divided into two groups by visceral fat (VF) area: VF obese (VF-Ob) (n = 7, age; 52.0 +/- 2.5 (s.e.) years) and abdominal subcutaneous fat obese (SF-Ob) (n = 7, age; 57.3 +/- 2.8 (s.e.) years). All participants performed stationary cycling exercise for 60 min at 50% of peak oxygen uptake. MEASUREMENTS: Blood and respiratory gas samples were taken for analysis of hormone, metabolite and substrate oxidation in each participant at rest and during exercise. RESULTS: There is a significant group x time interaction in the plasma concentration of free fatty acid (FFA) (P < 0.05) and glycerol (P < 0.05) during the exercise bout. In addition, total plasma concentration of FFA (area under the curve) was 59.2% higher in VF-Ob compared with SF-Ob men during endurance exercise (1.99 +/- 0.24 and 1.25 +/- 0.13 mEq/l/min, respectively; P < 0.05). Total plasma concentration of glycerol (area under the curve) was 102.3% higher in VF-Ob than SF-Ob men during the exercise (69.6 +/- 12.5 and 34.4 +/- 5.1 mg/dl/min, respectively; P < 0.05). However, fat oxidation was not different throughout the exercise between VF-Ob and SF-Ob men (176.5 +/- 25.7 and 183.0 +/- 12.8 kcal/60 min, respectively). CONCLUSION: During moderate endurance exercise, plasma fat availability may be higher in men with VF obesity compared to men with SF obesity. However, total fat oxidation is similar between obesity phenotype.

Analysis of Variance↗

PubMed2006

[In vivo proton MR spectroscopy of normal liver parenchyma: technique and results].

PURPOSE: To analyze the proton magnetic resonance spectroscopic data ( (1)H MRS) of normal liver parenchyma with regard to age, sex, body mass index and location in the liver. MATERIALS AND METHODS: 45 healthy volunteers age 24 to 65 years were examined with an optimized single-voxel (1)H MRS using a 1.5-T scanner. A spin echo sequence with a TR of 1500 ms and a TE of 135 ms was used, allowing in-phase detection of the choline signal. Weak water suppression was achieved using a chemical shift selective suppression (CHESS) technique. Each examination included the measurement of three voxels with a voxel size of 18 x 18 x 18 mm (3) in different areas of the liver. The volunteers were divided into different age-based groups (young: < or = 44 years; older: > or = 44 years), BMI (normal weighted: < 25 kg/m (2); obese: > 25 kg/m (2)) and sex. RESULTS: In the acquired spectra different lipid (e. g. [CH (2)] (n)), choline, glutamine, glutamate and glycogen-glucose-complex resonances were detected. The analysis of the spectra, however, only focused on the concentrations of choline and (CH (2)) (n) and the relative concentrations of the choline-to-(CH (2)) (n)-ratios. In the older volunteers the relative concentration of the choline-to-(CH (2)) (n)-ratio was significantly decreased by 0.213 +/- 0.193 in comparison to the younger subjects (p = 0,031). Further statistical analysis confirmed a significant decrease of the choline-to-(CH (2)) (n)-ratio by 0.223 +/- 0.180 in obese volunteers compared to volunteers of a standard weight (p = 0,016). The significant difference between the choline-to-(CH (2)) (n)-ratio in female versus male volunteers was calculated with an increase of 0.483 +/- 0.172 (p = 0,000). The location of the voxel in the liver parenchyma did not yield a significant difference in the choline-to-(CH (2)) (n)-ratio. CONCLUSION: The analysis of the proton liver MRS of healthy volunteers indicated a significant difference in the choline-to-(CH (2)) (n)-ratio depending on age, sex, and BMI with a confidence interval of 95 %. The different choline-to-(CH (2)) (n)-ratio could be the result of the body fat distribution depending on age and sex and also of the increased fat portion of the body in obese volunteers.

Adult↗

PubMed1990

Body fat and its distribution in relation to casual and ambulatory blood pressure.

This study was undertaken to evaluate the associations of body fat and its distribution with casual and ambulatory blood pressure in nonobese men. One hundred and thirty-five normotensive or mildly hypertensive (but untreated) men employed at three work sites were studied. Casual blood pressure was measured at the work site at initial screening and on a second occasion by a nurse. Ambulatory blood pressure was measured noninvasively for 24 hours on a workday and analyzed as work, home, and sleep blood pressure measurements. Anthropometric measurements included height, weight, and waist and hip circumferences. Blood pressure was highest while at work; home blood pressure was higher than screening blood pressure or nurse blood pressure, and sleep blood pressure was lowest. Weight and both waist and hip circumferences (but not their ratio) were all significantly correlated with screening, nurse, and sleep blood pressures but not with work or home blood pressures. Stepwise regression analysis showed that waist circumference was the best overall predictor of blood pressure. We suggest that in situations where blood pressure is the dependent variable, correlations with other variables may be closest for "basal" measures of blood pressure and may be obscured by the effects of daily activities on blood pressure.

Adipose Tissue↗

PubMed2004

The relationship of ghrelin to biochemical and anthropometric markers of adult growth hormone deficiency.

INTRODUCTION: Ghrelin is the natural ligand of the growth hormone secretagogue receptor (GHS-R) and potently stimulates GH release in humans. Ghrelin is found in the hypothalamus, but most circulating ghrelin is derived from the stomach. Ghrelin stimulates food intake but circulating levels are low in obesity. We hypothesized that GH deficiency (GHD) might be associated with increased circulating ghrelin concentrations as a result of low GH levels. We therefore measured circulating ghrelin concentrations, leptin and body composition in subjects with GHD and healthy controls. METHODS: Subjects with GHD (n = 18) were compared to healthy control subjects (n = 18), matched for body mass index (BMI). They underwent assessment of body composition [waist circumference, BMI and percentage body fat (using bioimpedance)]. Plasma ghrelin, leptin, insulin, GH and IGF-1 were measured in the fasting state. Plasma ghrelin was measured using a specific radioimmunassay, and the other hormones using commercially available assays. RESULTS: The groups were well-matched for BMI (GHD vs. control; 32.9 +/- 10.8 vs. 31.3 +/- 11.7, P = ns) and waist circumference (GHD vs. control; 102.9 +/- 20.0 vs. 99.8 +/- 25.2, P = ns), but percentage body fat (GHD vs. control; 37.0 +/- 9.1 vs. 29.4 +/- 13.0, P = 0.06) tended to be higher in the GHD group. As expected, IGF-1 was lower in GHD (GHD vs. control; 12.5 +/- 6.8 vs. 19.2 +/- 5.8 nmol/l, P = 0.003). Ghrelin [GHD vs. controls; geometric mean (95% CI); 828.8 (95% CI 639.9-1074.2) vs. 487.9 (95% CI 297.2-800.2) pmol/l] and leptin [GHD vs. controls; 13.2 (95% CI 6.6-26.5) vs. 7.9 (95% CI 3.7-16.9) ng/ml] were similar in the two groups. Plasma ghrelin correlated inversely with waist circumference and waist hip ratio in GHD subjects (r = -0.6, P = 0.02) but not with IGF-1 or GH concentrations. There was no significant correlation in the control subjects. CONCLUSION: Circulating ghrelin concentrations are influenced by body fat distribution, but not by levels of either GH or IGF-1. However, given that obesity is associated with reduced ghrelin concentrations and that GHD is commonly associated with increased body fat, it is possible that these two opposing influences on circulating ghrelin levels result in normal concentrations in subjects with GHD.

Adult↗

PubMed2005

Plasma visfatin concentrations and fat depot-specific mRNA expression in humans.

Visceral and subcutaneous adipose tissue display important metabolic differences that underlie the association of visceral obesity with obesity-related cardiovascular and metabolic alterations. Recently, visfatin was identified as an adipokine, which is predominantly secreted from visceral adipose tissue both in humans and mice. In this study, we examined whether visfatin plasma concentrations (using enzyme immunosorbent assay) and mRNA expression (using RT-PCR) in visceral and subcutaneous fat correlates with anthropometric and metabolic parameters in 189 subjects with a wide range of obesity, body fat distribution, insulin sensitivity, and glucose tolerance. Visfatin plasma concentration correlates positively with the visceral visfatin mRNA expression (r(2) = 0.17, P < 0.0001), BMI (r(2) = 0.062, P = 0.004), percent body fat (r(2) = 0.048, P = 0.01), and negatively with subcutaneous visfatin mRNA expression (r(2) = 0.18, P < 0.0001). However, in a subgroup of 73 individuals, in which visceral fat mass was calculated from computed tomography scans, there was no correlation between plasma visfatin concentrations and visceral fat mass. We found no significant correlation between visfatin plasma concentrations and parameters of insulin sensitivity, including fasting insulin, fasting plasma glucose concentrations, and the glucose infusion rate during the steady state of an euglycemic-hyperinsulinemic clamp independent of percent body fat. Visfatin gene expression was not different between visceral and subcutaneous adipose tissue in the entire study group nor in selected subgroups. We found a significant correlation between visceral visfatin gene expression and BMI (r(2) = 0.06, P = 0.001) and percent body fat (measured using dual-energy X-ray absorptiometry) (r(2) = 0.044, P = 0.004), whereas no significant association between BMI or percent body fat and subcutaneous visfatin mRNA expression existed (both P >0.5). In conclusion, visfatin plasma concentrations and visceral visfatin mRNA expression correlated with measures of obesity but not with visceral fat mass or waist-to-hip ratio. In addition, we did not find differences in visfatin mRNA expression between visceral and subcutaneous adipose tissue in humans.

Absorptiometry, Photon↗

PubMed1988

Heredity and body fat.

The genetics of human obesity was reviewed here in terms of studies dealing with body fat and fat distribution. The role of heredity was examined by reviewing genetic disorders in which obesity is a clinical feature. Two kinds of genetic effects were discussed: the additive genetic effect and the genotype-environment interaction effect. Several indicators of body fat exist, including body mass index, amount of subcutaneous fat, percentage body fat, fat mass, regional fat distribution, and subcutaneous fat pattern. A low additive genetic effect of less than 10% of human phenotypic variation is found in body mass index and amount of subcutaneous fat, while percentage body fat, fat mass, fat distribution, and fat patterning are characterized by heritability estimates of about 25%. On the other hand, a recent study demonstrates that there is an important genotype-environment interaction effect in human body fat variation induced by overfeeding. Limitations of current approaches to the study of the genetics of human body fat and obesity are considered and comments are offered concerning promising areas of future research.

Adipose Tissue↗

PubMed1995

Central adiposity and its metabolic correlates in obese adolescent girls.

To establish whether alterations in insulin action and secretion and their relationship to body fat distribution occur early in the course of developing obesity, we studied 14 obese adolescent girls [13.2 +/- 0.7 yr, body mass index (BMI) 32 +/- 1.4], 16 nonobese young women (24.0 +/- 0.6 yr, BMI 21.0 +/- 0.9). Insulin action was assessed by a sequential two-step (8 and 40 mU,m-2.min-1) euglycemic insulin clamp in combination with [1-13C]glucose and indirect calorimetry. Insulin secretion was determined by the hyperglycemic clamp technique (6.9 mmol/l). Magnetic resonance imaging was used to quantify visceral and subcutaneous abdominal fat depots. In obese girls, an impairment in glucose disposal was present with both insulin doses; at the higher dose, rates of glucose uptake were reduced by 30% in nonobese girls (240 +/- 30 vs. 340 +/- 19 mg.m-2.min-1, P < 0.05) and by an additional 29% (170 +/- 17 mg.m-2.min-1, P < 0.05) in obese girls. Insulin infusion failed to stimulate glucose oxidation and to suppress lipid oxidation only in obese girls. Suppression of free fatty acid levels, but not hepatic glucose production, was decreased in obese girls compared with controls. Fasting and glucose-stimulated insulin responses were greater in obese than in nonobese adolescents, who, in turn, had greater responses than lean women. In obese girls, visceral fat, but neither waist-to-hip circumference ratio nor subcutaneous fat, was highly correlated with basal insulin secretion (r = 0.89, P < 0.001), stimulated insulin secretion (r = 0.61, P < 0.05), and insulin resistance (r = -0.87, P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗