Impact of obesity on metabolism in men and women. Importance of regional adipose tissue distribution

Commingling and complex segregation analysis of fasting plasma glucose in the Lipid Research Clinics family study

Commingling and segregation patterns of fasting plasma glucose (GL) were examined in family data from 5 clinics (Cincinnati, Stanford, Iowa, Minnesota, and Oklahoma) of the Lipid Research Clinics (LRC) family study. In addition to the primary question of whether there was a major gene for GL, a secondary purpose was to investigate the possibility of genetic heterogeneity among the 5 clinics. No statistical support was found for heterogeneity among clinics, either in the commingling of distributions or in the segregation patterns. For the combined clinics sample, both a major effect and a multifactorial component were significant. However, the major effect (accounting for 73% of the variance) was not found to be consistent with a major gene, as the hypothesis of Mendelian transmission was rejected. The most parsimonious model involved equal transmission probabilities, which suggests that the major effect is not transmitted from parents to offspring. Possible sources of this major non-Mendelian effect were explored. The multifactorial component accounted for 10% of the variance in GL levels, and no generational differences were noted. Although our study was unable to provide evidence in favor of a major gene effect, it should be noted that a major gene cannot be firmly refuted. For example, a variety of interactions, such as genotype-dependent age effects, could have masked the transmission probabilities.

Uptake of glucose carbon in muscle glycogen and adipose tissue triglycerides in vivo in humans

Glucose disposal into muscle glycogen has previously been directly studied after intravenous, but not after physiological, oral administration. In this study 100 g glucose, containing 50 microCi [U-14C]glucose, were taken orally by premenopausal women in the overnight fasting state or after a carbohydrate-rich meal. After 4 h, biopsies were taken from the vastus lateralis muscle and abdominal and femoral subcutaneous adipose tissue for determinations of label in isolated glycogen and triglycerides, respectively. Uptake of administered glucose carbon in muscle glycogen was estimated to be approximately 20 g in the fasting and approximately 9 g in the carbohydrate-fed groups, respectively. Total uptake in adipose tissue triglycerides was approximately 2 g. Glucose carbon uptake in muscle glycogen correlated positively with glucose infusion rates during euglycemic hyperinsulinemic glucose clamps, glycogen synthase activity in vitro, and type I muscle fiber distribution and fiber area. Negative correlations were found between glucose uptake in adipose tissue triglycerides, type II fiber distribution and fiber area, as well as the waist-to-hip circumference ratio and degree of obesity. It was concluded that muscle glycogen is probably not a major pathway for disposal of oral glucose carbon in the sedentary condition.

Benefit from hypocaloric diet in obese men depends on the extent of weight-loss regarding cholesterol, and on a simultaneous change in body fat distribution regarding insulin sensitivity and glucose tolerance

Obesity and an android body fat distribution are related to metabolic disorders. We investigated the interdependences between metabolism, overweight, and body fat distribution in 40 moderately obese men before and after weight-loss. Correlations between metabolic parameters and body mass index (BMI) or waist to hip ratio (WHR) were much weaker in this exclusively obese population than in subjects of all weight categories, but the association between BMI and glucose tolerance (r = -.46, P less than .01) increased significantly after weight-loss. The improvement of metabolic parameters was much stronger in men who achieved normal weight (BMI less than 27 kg/m2) than in those who remained obese (BMI greater than 30 kg/m2, P less than .05). The WHR decreased during the diet (P less than .001), and this decrease and the extent of weight-loss were significantly correlated to an increase in insulin sensitivity (r = -.41, P less than .01) and a decrease in glucose area after an oral glucose load (r = .34, P less than .05). The decrease in apolipoprotein B, total cholesterol, and low-density lipoprotein (LDL) cholesterol was significantly correlated only to the extent of weight-loss (r = .34, .31, and .39, respectively; P less than .05). We conclude that it is best to reach normal weight for the normalization of metabolic aberrations. The reduction of cholesterol appears to be dependent on the extent of weight-loss, while the improvement in insulin sensitivity and glucose tolerance apparently is related to both the extent of weight-loss and to a change toward a less android body fat distribution.

Endoscopic and open stone surgery in morbidly obese patients

Management of urinary stone disease in the morbidly obese patient can be troublesome and problematic. We present 4 recent female patients with an average weight of 442 pounds and an average height of 5 feet 2 inches. The patients underwent a total of 8 open surgical or endoscopic procedures for partial or complete staghorn calculi. Complications encountered included inability to reach the stones with rigid or flexible ureteroscopes, inadvertent incision above the 10th rib for pyelolithotomy, intraoperative rhabdomyolysis during a flank incision, consecutive temporary renal failure and wound infection. We discuss the limitations of extracorporeal shock wave lithotripsy, retrograde endoscopic manipulation, percutaneous antegrade surgery and open surgical approaches. Such patients continue to represent diagnostic challenges and high risk therapeutic options.

Increased protein turnover in obese women

Some previous studies have indicated that rates of proteolysis and protein synthesis are greater in obese than in lean subjects, whereas others have not supported this finding. In the present study, we have measured postabsorptive protein turnover in a large group (n = 24) of obese women to establish more conclusively whether obese women have higher rates of protein turnover than lean women (n = 12), and to determine whether obese subjects with the greatest abdominal fat accumulation or those with the most severe insulin resistance (as determined by oral glucose tolerance testing) have the highest rates of protein turnover. Leucine appearance rate (Ra) was used as an index of whole-body proteolysis, and the fraction of Ra not oxidized was used as an index of whole-body protein synthesis. Leu Ra, oxidation, and incorporation into protein after an overnight fast were approximately 25% greater in obese than in lean women, and were approximately 10% to 15% greater after dividing by lean body mass (LBM) or adjusting for LBM by analysis of covariance. Among obese women, the degree of obesity (over the range of 30% to 47% fat) was not a significant determinant of protein turnover, nor were degree of insulin resistance, visceral fat accumulation (determined by magnetic resonance imaging [MRI]), or subcutaneous abdominal fat accumulation (also determined by MRI). However, the women with the highest rates of protein turnover also had higher waist to hip circumference ratios (WHR). We conclude that even moderate obesity is associated with increased protein turnover, and that this effect is not completely explained by the higher LBM in obese subjects.

Genetic aspects of susceptibility to obesity and related dyslipidemias

Obesity has a multifactorial origin. However, although environmental variables undoubtedly play a role in the development of obesity, it is now clear that genetic variation is also involved in the determination of an individual's susceptibility to body fat accumulation. In addition, it is also widely accepted that obesity is not a single homogeneous phenotype. It is also heterogeneous regarding its causes and metabolic complications. The regional distribution of body fat appears to be an important correlate of the metabolic complications that have been related to obesity. Due to their higher accumulation of abdominal fat, men are generally more at risk for the metabolic complications of obesity than women whereas some obese women, with large gluteal-femoral adipose depots may have a cosmetic problem which may not necessarily require medical intervention. Several studies have been conducted to understand the mechanisms by which abdominal obesity is related to diabetes, hypertension and cardiovascular disease. It appears that the increased risk of abdominal obesity is the result of complex hormonal and metabolic interactions. Studies in genetic epidemiology have shown that both total body fatness and the regional distribution of body fat have a significant genetic component. Standardized intervention studies using an identical twin design have shown that individuals that have the same genetic background tend to show similar changes in body fat and in plasma lipoprotein levels when exposed to standardized caloric excess or energy restriction. Finally, although abdominal obesity is a significant risk factor for cardiovascular disease, not every abdominal obese subject will experience metabolic complications, suggesting that some obese individuals may be more susceptible than others. Variation in several genes relevant to lipid and lipoprotein metabolism may alter the relation of abdominal obesity to dyslipoproteinemias. Abdominal obesity should therefore be considered as a factor that exacerbates an individual's susceptibility to cardiovascular disease.

The association of waist-hip ratio and risk factors for development of IDDM complications in an IDDM adult population

The role of waist-to-hip ratio (WHR) in the metabolic disturbance of IDDM has not been widely explored. Cross-sectional data from the Epidemiology of Diabetes Complications Study were used to examine the associations between WHR and risk factors for IDDM complications such as lipid or lipoprotein levels, blood pressure and fibrinogen. A total of 586 adults (greater than or equal to 18 years of age) were examined. WHR was calculated as the mean of duplicate waist circumference measurements made at mid-point between the iliac crest and the lower costal margin in mid-axillary line divided by the mean of duplicate maximum hip measures. WHR was positively correlated with total cholesterol, LDL-cholesterol, triglycerides, systolic and diastolic blood pressure and fibrinogen univariately for both sexes. WHR was negatively correlated with HDL-cholesterol. These correlations remained significant after adjustment for age among females and became less strong, although still significant, for males. The independent effects of WHR to these IDDM risk factors, assessed by multiple linear regression, indicated WHR was related to adverse lipid and lipoprotein levels, but not to fibrinogen or blood pressure. These findings underscore the importance of targeting intervention to IDDM individuals who have a high WHR to reduce known risk factors for IDDM complications especially those for cardiovascular disease, and is consistent with the hypothesis that insulin resistance may have a role to play in IDDM complications.

Relationship of glucose intolerance and hyperinsulinaemia to body fat pattern in south Asians and Europeans

Type 2 (non-insulin-dependent) diabetes mellitus and insulin resistance are associated with centrally-distributed obesity. These disturbances are especially prevalent in people of South Asian (Indian, Pakistani and Bangladeshi) descent. We examined the relationship of glucose intolerance to body fat pattern in a population survey of 2936 men and 537 women of South Asian and European origin living in London, UK. In both groups glucose intolerance (defined as diabetes or impaired glucose tolerance) was more strongly associated with waist-hip girth ratio than with skinfolds or body mass index. The associations between body mass index and glucose intolerance were fully accounted for by waist-hip ratio. In European men with normal glucose tolerance fasting insulin levels were more strongly correlated with body mass index than with waist-hip ratio. Physical activity scores were lower in South Asians than in Europeans but no statistically significant associations between glucose intolerance and low physical activity were detectable. Leisure-time physical activity scores were inversely correlated with 2 h insulin levels in both groups. In contrast with other studies these results suggest that a specific effect of intra-abdominal fat deposition underlies the association between glucose intolerance and obesity. The association between hyperinsulinaemia and obesity is less specific for centrally-distributed fat. When measured appropriately waist-hip ratio is the most valid anthropometric index for identifying individuals whose obesity predisposes them to glucose intolerance.

The effects of gender and age on associations between blood lipid levels and obesity in Danish men and women aged 35-65 years

The purpose of the study was to assess the influence of gender and age on the associations between different measures of obesity, and blood lipid levels. Overall obesity (body fat, body fat percentage and body mass index) or abdominal obesity (waist/hip-ratio, waist/thigh-ratio and waist-circumference) and lipid levels [high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), total cholesterol and triglyceride level] were measured in 1987/88 in a random Danish population sample of men and women (N = 2987), aged 35, 45, 55 and 65 yr. All lipid levels were dependent on gender and age. The associations between most measures of obesity and HDL or LDL were independent of gender and age, whereas, with a few exceptions, associations between measures of obesity and total cholesterol, VLDL or triglycerides were dependent on gender and/or age. Compared to levels of HDL, LDL and total cholesterol, abdominal obesity specifically affected levels of VLDL or triglycerides, whereas overall obesity affected HDL, LDL, VLDL, total cholesterol and triglyceride levels more evenly. When men and women were compared, associations between the measures of obesity and blood lipids were stronger in men than in women of the same age, except for the associations between measures of abdominal obesity and VLDL or triglycerides in 45-year-old women. No age trend was found for associations between the measures of obesity and VLDL or triglycerides, whereas young age-groups showed stronger associations between obesity and total cholesterol than older age-groups. Failure to consider age/gender effects induces bias and may lead to misleading conclusions regarding the bivariate association between obesity and lipids, and further may make results from population studies incomparable.

Reliability of the measurement of postprandial thermogenesis in men of three levels of body fatness

To determine the reliability of the measurement of postprandial thermogenesis by indirect calorimetry and to clarify further the relationship of obesity to thermogenesis in men, the thermic effect of a 720-kcal, mixed liquid meal was compared in 13 lean men (mean +/- SEM, 11.2% +/- 1.4% body fat), 10 average men (22.4% +/- 1.6% body fat), and 12 obese men (33.4% +/- 1.6% body fat) on two occasions. Resting metabolic rate (RMR) was measured for 3 hours: (1) in the fasted state, and (2) after a 720-kcal mixed liquid meal, on two occasions. The thermic effect of the meal, calculated as the postprandial energy expenditure minus the fasting RMR (kcal/3h), was greater for the lean and average men than for the obese men during both trials (P less than .001), but was only marginally different between the lean and average groups (P = .16). The mean values for the two trials were similar and the measurement of thermogenesis was highly reproducible with a reliability coefficient of r = .932 (P less than .001). Across all groups, thermogenesis correlated strongly with percent body fat (r = -.64, P less than .01), but within the average men, thermogenesis was uncorrelated with percent body fat (r = .09) but highly correlated with the glucose response to the meal (r = -.75, P less than .05). Thus, factors other than body fatness, such as insulin sensitivity, may determine thermogenesis within this heterogeneous middle group.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterogeneous glycaemic and insulinaemic responses to oral glucose in non-diabetic men: interactions between duration of obesity, body fat distribution and family history of diabetes mellitus

The interaction between environmental and genetic factors in the alterations of glucose-insulin homeostasis was studied in 104 non-diabetic men. Family history of diabetes mellitus was used as an index of genetic predisposition to diabetes. Body composition was measured by underwater weighing whereas subcutaneous and visceral adipose tissue areas were measured at the abdominal and femoral levels by computed tomography. The sample was first divided into two groups. The first group included subjects with "normal" glycaemic and insulinaemic responses during a 75 g oral glucose tolerance test. The second group was composed of subjects either with a high glucose response or high insulin response or both. Men included in the second group were different from the "normal" subjects for almost all body fatness variables. They also presented a prevalence of a positive family history of diabetes which was significantly higher than "normal" subjects. The second group was then divided into three distinct subgroups based on insulin and glucose responses of the subjects during the oral glucose tolerance test. Subjects with high insulin but "normal" glucose responses were characterized by significantly higher levels of total body fat and deep abdominal adipose tissue when compared to the "normal" group (p less than 0.05). Men with both high insulinaemic and glycaemic responses displayed higher body fatness values and higher deep and subcutaneous abdominal adipose tissue areas (p less than 0.05) in comparison with "normal" subjects. They also had a higher body mass index at age 20 years than control subjects and subjects with high insulin but "normal" glucose responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin resistance, hyperinsulinemia, dyslipidemia, hypertension, and accelerated atherosclerosis

Hypertension is only one component of a multifaceted metabolic-hemodynamic complex that also includes obesity, subtle and overt glucose intolerance, dyslipidemia, enhanced vascular resistance and accelerated atherosclerosis. Results of a number of studies in the past 5 years have shown that even nonobese, nondiabetic individuals with hypertension display insulin resistance, which is located in peripheral tissues (primarily skeletal muscle), is limited to nonoxidative pathways of glucose disposal, and appears to be directly correlated with the severity of hypertension. Insulin resistance and associated hyperinsulinemia in hypertensive individuals are also associated with increased plasma triglyceride levels and decreased high-density lipoprotein concentrations, which likely contributes to enhanced atherosclerosis. Hyperinsulinemia may directly promote atherosclerosis by enhancing LDL-cholesterol accumulation in vessel walls, vascular smooth muscle migration, and proliferation, augmenting connective tissue synthesis in the vascular wall, and decreasing the regression of lipid plaques. The enhanced peripheral vascular resistance that characterizes insulin resistance/hyperinsulinemic states may be related to decreased vascular smooth muscle responses to insulin, which normally modulates (attenuates) vascular contractile responses to vasoactive agents.

Cardiovascular risk factors in obese children in relation to weight and body fat distribution

To assess the relationship between obesity and body fat distribution with cardiovascular risk factors in children, various measures of obesity and waist-to-hip circumference ratio (WHR) were related to serum lipids, lipoproteins, apolipoproteins, glucose, insulin, uric acid, systolic (SBP) and diastolic blood pressure (DBP). In boys univariate analysis revealed an association of triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein B (ApoB), the ratio ApoAI/ApoB, cholesterol/HDL-C, glucose and insulin to WHR. SBP and DBP and serum uric acid correlated with all measures of obesity [body mass index (BMI), percent overweight, percent body fat, skinfolds], but not with WHR. In girls lipid parameters (triglycerides, LDL-C, HDL-C, HDL2, ApoAI, ApoB) and atherogenic ratios correlated with measures of obesity and WHR. Glucose, insulin, SBP and DBP showed the highest correlation with WHR (r = 0.598, p less than 0.001 and r = 0.713, p less than 0.001). Multivariate analysis in girls revealed a first step dependency of ApoAI, the ratio cholesterol/ApoAI, insulin, SBP and DBP on WHR, triglycerides, HDL-C, LDL-C and the ratio ApoAI/ApoB, a first step dependency on percent body fat mass. In boys triglycerides, ApoB and the ratio ApoAI/ApoB were related to WHR for insulin, SBP and DBP, but a positive association with the WHR was found, explaining 33, 21.8, and 22.6% of the variance. This study demonstrates that cardiovascular risk factors in obese children are related to obesity and body fat distribution. Obese children with predominantly abdominal fat mass show a risk profile that is less favorable than gluteal-femoral fat distribution. Evaluation of body fat distribution in obese children, therefore, may help to identify persons most susceptible to cardiovascular risk in adulthood.

Effect of intensive endurance training on lipoprotein profiles in young and older men

Although there are considerable data concerning the effects of endurance exercise training (ET) on plasma lipoproteins, the results have been quite inconsistent. The observed variability of response may be related to the age, sex, adiposity, or diet of the subjects tested, or to the type and intensity of the exercise intervention. Furthermore, there is relatively little such data in older individuals. Therefore, in the present study, we investigated the effects of intensive ET on lipoprotein profiles in healthy young (n = 12; 28.2 +/- 2.4 years) and older (n = 15; 67.5 +/- 5.8 years) men. Unlike subjects in most similar studies, our subjects were weight-stabilized on a constant-composition diet for 21 days prior to determination of the lipoprotein profile before and after the ET program. At baseline, the two groups were not significantly different with respect to any individual component of their lipoprotein profiles, relative weight, or percent body fat, but the older men had a more central distribution of fat by both waist to hip ratio (WHR) and computed tomography (CT). Maximal aerobic power, expressed per kilogram of body weight (VO2 max), was 33% lower (P less than .001) in the older men at baseline. Following the 6-month, walk/jog/bike ET program (5 d/wk), both the young (+18%, P less than .001) and the older (+22%, P less than .001) men increased their VO2 max. This was associated with small, but significant, decrements in weight, percent body fat, and WHR only in the older men.(ABSTRACT TRUNCATED AT 250 WORDS)

Severe obesity: the use of very low energy diets or standard kilojoule restriction diets

OBJECTIVES

To determine the efficacy of two dietary therapies in both the short term (hospitalisation) and the longer term treatment of severe obesity.

DESIGN

A descriptive study of two patient groups with obesity defined by a body mass index of greater than 30 kg/m2.

SETTING

A multidisciplinary weight control program in a tertiary care hospital.

PATIENTS

All admissions to hospital of patients on the weight control program for initiation of weight loss during a period of 48 months.

INTERVENTION

A standard kilojoule reduction regimen or the use of complete, followed by partial, long term meal substitution with a very low energy liquid diet (VLED), coupled with an exercise and a behavioural modification program.

OUTCOME MEASURES

Weight loss during and after hospitalisation was measured in both dietary regimen groups.

RESULTS

Both diets induced weight loss in hospital. Men prescribed VLED lost significantly more weight, 8.3 +/- 0.8 kg (mean +/- SEM) than women prescribed this diet (5.5 +/- 0.5 kg) or standard kilojoule restriction (5.1 +/- 0.8 kg).

CONCLUSIONS

VLED and standard kilojoule restriction are both effective for the treatment of severe obesity, particularly in a controlled environment (hospitalisation). In the longer term, VLED is an effective method of maintaining weight loss. Lack of continuing weight loss may reflect the patients who were initially placed on this regimen--small eaters with a presumed high metabolic efficiency.

Visceral fat accumulation measured by magnetic resonance imaging in relation to serum lipids in obese men and women

In 91 apparently healthy obese subjects (45 premenopausal women and 46 men) the associations between specific fat depots and serum lipids were studied. Magnetic resonance imaging was used to quantify fat depots at abdominal and hip level. In women, an accumulation of visceral fat was associated with a less favourable lipid profile, even after adjustment for age and body fat percentage: higher triglycerides levels (P less than 0.001), lower levels of HDL-cholesterol (P less than 0.01) and a diminished HDL-cholesterol/LDL-cholesterol ratio (P less than 0.01). In men, however, the significant inverse relationship between an abundance of visceral fat and the HDL-cholesterol/LDL-cholesterol ratio and the significant positive correlations with total-, LDL-cholesterol and triglycerides disappeared after adjustment for age and fat percentage. Within each sex, subcutaneous fat neither at abdominal level nor at hip level was significantly related to serum lipids. It is concluded that there are gender differences in the associations between visceral fat accumulation and serum lipids.

Glycerol production in subcutaneous adipose tissue in lean and obese humans

To estimate the regional subcutaneous glycerol production rate in normal and obese humans, the venous arterialized plasma glycerol, interstitial glycerol in the subcutaneous adipose tissue together with adipose tissue blood flow (ATBF, ml/100 g.min) were measured in the postabsorptive state and for 2 h after ingestion of 100 g of oral glucose. Eight lean and eight obese men with normal oral glucose tolerance tests were investigated with the subcutaneous microdialysis technique and 133Xe clearance. In the postabsorptive state, the interstitial glycerol concentrations in lean and obese subjects were 170 +/- 21 vs. 282 +/- 28 microM (P less than 0.01) and 156 +/- 23 vs. 225 +/- 12 microM (P less than 0.05) in the abdominal and femoral subcutaneous adipose tissue, respectively. The corresponding arterial glycerol levels were 54 +/- 4 vs. 75 +/- 14 microM (NS). Abdominal ATBF was greater in lean subjects (3.2 +/- 0.6 vs. 1.6 +/- 0.3; P less than 0.05), whereas femoral ATBF was similar in both groups (2.7 +/- 0.4 vs. 2.4 +/- 0.7). Estimated mean local glycerol release (mumol/100 g.min) was similar in the lean and obese group (0.16 +/- 0.03 vs. 0.20 +/- 0.05 and 0.18 +/- 0.02 vs. 0.17 +/- 0.04) in the abdominal and femoral site, respectively. We conclude that glycerol production from the subcutaneous tissue is increased in obesity, irrespective of adipose tissue distribution. This enhancement is due to the increased adipose tissue mass.

Effects of in vivo estrogen treatment on adipose tissue metabolism and nuclear estrogen receptor binding in isolated rat adipocytes

We have previously demonstrated the existence of nuclear estrogen receptors in isolated adipocytes (Pedersen et al. (1991) Biochim. Biophys. Acta 1093, 80-86). In the present study we have investigated the regulatory properties of these nuclear estrogen receptors, in addition to the metabolic effects of estrogen on adipose tissue metabolism. Estrogen treatment (20 micrograms 17 beta-estradiol in NaCl for 7 days) decreased lipoprotein lipase activity (LPL) in the adipose tissue by 62% (p less than 0.05), decreased adipocyte size by 27% (p less than 0.01) and diminished the normal postovariectomy weight gain. Furthermore, estrogen treatment increased the nuclear estrogen receptor binding in adipocytes; in addition, there was a tendency for increased cytosolic estrogen receptor content as well. Time course studies revealed that already 6 h after a single estrogen injection the Bmax increased from 3.82 +/- 0.3 fmol/10(6) cells to 9.8 +/- 3.6 fmol/10(6) cells (p less than 0.1) and 24 h after a single injection the Bmax was maximally increased to 12.7 +/- 5.5 fmol/10(6) cells (p less than 0.05). The Kd was similar at all time points (about 3-5 nM). Furthermore, the specific insulin receptor binding was increased in adipocytes from estrogen treated rats. The specific insulin binding was maximally increased by 149 +/- 6% (p less than 0.001) after 4 days of daily estrogen injections. The increased binding seemed to be due to an increased number of insulin receptors on adipocytes from estrogen treated rats with no alteration of the ED50 value. In conclusion it was found that estrogen treatment has a positive feedback effect on its own nuclear receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of nuclear corticosteroid receptors in rat adipocytes. Regional variations and modulatory effects of hormones

The corticosteroid receptor was investigated in isolated rat adipocytes with a new technique which characterizes the corticosteroid receptors that can be activated and tightly bound to the nucleus. The binding reaction with [3H]triamcinolone was performed with intact isolated adipocytes and the radioactivity associated with nucleus was subsequently determined after cell lysis. Scatchard analysis revealed a homogeneous class of nuclear corticosteroid receptors in rat epididymal adipocytes with an apparent Kd of 4.93 +/- 1.5 nM and a Bmax of 21.8 +/- 6.6 fmol/10(6) cells corresponding to about 13,000 receptors per nucleus. The corticosteroid binding exhibited regional variations in isolated adipocytes. The highest receptor number was found in epididymal adipocytes (Bmax 25.8 +/- 3.9 fmol/10(6) cells) whereas there were significantly lower nuclear binding sites in perirenal adipocytes (16.5 +/- 5.5 fmol/10(6) cells) (P less than 0.05) and subcutaneous adipocytes (4.8 +/- 1.5 fmol/10(6) cells) (P less than 0.01). The apparent affinity in the three fat depots were similar with Kd values about 4 nM. The nuclear corticosteroid receptor in adipocytes was steroid specific, as neither unlabelled estradiol nor testosterone were able to displace the [3H]triamcinolone binding at concentrations up to 100 microM. However, unlabelled progesterone and promegestrone (R5020) were able to compete with triamcinolone-binding (by 50-80%). In order to investigate whether the nuclear corticosteroid binding in adipocytes were under influence of other hormones we examined the effects of lipolytic and antilipolytic compounds on the binding. Preincubation with isoproterenol and dibutryl-cAMP for 1 h was able to decrease the corticosteroid binding by 30-50%. However, the antilipolytic hormone insulin had no effect in preincubations performed for up to 2 h. In conclusion, high affinity nuclear corticosteroid receptors were found in rat adipocytes. These receptors exhibited regional variations and were modulated by lipolytic hormones.

Body fat assessment in women. Special considerations

Methods of in vivo body fat estimation are based on simple assumptions about body composition which work reasonably well for men, while estimations in women have been largely extrapolated from the male studies so that women are treated as men with just more of the same fat. Compared to men, fat regulation in women is considerably more elaborate, with more and different sites for storage and a larger proportion of fat distributed to the extremities and in subcutaneous locations. Thus, a ratio of waist-to-hips girth which reflects increasing fatness in men only specifies 2 different extremes of a broader spectrum of possibilities for fat distribution in women. This complicates anthropometric prediction of total fatness and clearly limits the generalisability of any female equations. Anthropometric methods are further confounded by difficulties in the criterion methods against which they are developed. For example, the validity of assumptions about the fractional contributions of bone mineral and body water to fat-free mass and density may not hold through the reproductive cycles. Women athletes involved in weight-bearing or strength training may increase bone mineral content above average values but if they become amenorrhoeic, bone mineral density may fall significantly below average values. Fit premenopausal women distribute fat differently and have a higher bone mineral content than unfit postmenopausal women. Genetic factors which also affect criterion method assumptions in men are superimposed on these additional complications in women. Body fat in female athletes extends across almost the entire range of female fatness, with some of the lowest measurements in distance runners and body builders which fall into the normal male range, but also with some relatively high values in swimmers and strength athletes, which would classify these women as obese by male standards. Thus, total body fat reflects a more complex regulation and has a different meaning to health and performance in women than it does for men. Predictive equations for women athletes should be developed with a view to the specific group and ultimate purpose to which they will be applied.

Relationship of sex hormone-binding globulin to lipid, lipoprotein, glucose, and insulin concentrations in postmenopausal women

Sex hormones play a major role in determining the risk of cardiovascular disease. While several studies have shown that reduced sex hormone-binding globulin (SHBG) is associated with increased insulin and triglyceride and decreased high-density lipoprotein cholesterol (HDLC) in premenopausal women, little data are available for postmenopausal women. We hypothesized that in postmenopausal women decreased SHBG would be associated with an atherogenic pattern of cardiovascular risk factors. We measured SHBG, lipids, lipoproteins, glucose, and insulin concentrations, and systolic and diastolic blood pressure in 101 postmenopausal women. SHBG was negatively associated with triglyceride (r = -.21) and insulin (r = -.47) concentrations and positively associated with HDLC concentrations (r = .47). After adjustment for overall adiposity (body mass index) and upper body adiposity (as measured by the ratio of waist to hip circumferences), SHBG was still associated with HDLC and insulin, but not with triglyceride. Sex hormones were not related to systolic and diastolic blood pressure. The results may help to explain an association of increased androgenicity, as measured by a lower SHBG concentration, with diabetes and risk of cardiovascular disease in older women.

The case for using waist to hip ratio measurements in routine medical checks

OBJECTIVE

To provide a rationale for using waist:hip ratio (WHR) measurements in clinical practice.

DATA SOURCES

The article reviews the literature on body fat distribution back to the mid 1950s.

STUDY SELECTION

Studies are reviewed which show a clear association between abdominal obesity and a range of ailments including coronary events, hypertension, blood lipid levels, cholecystectomy, diabetes and gallbladder disease.

DATA EXTRACTION

Key data on the correlation of body fat distribution and health risks are summarised.

DATA SYNTHESIS

Abdominal fat measured by a WHR may be a better single predictor of many diseases than other risk factors such as overall obesity, hypertension, smoking, or hypercholesterolaemia.

CONCLUSIONS

The association between WHR and risk indicators appears to be "dose" related, and independent of sex, race and age. High WHRs, however, are more characteristic of men with lower socioeconomic status, whereas weight control programs are more commonly developed for women. A reorientation of weight control initiatives based on health rather than aesthetic priorities is needed. Measurement of WHR should be a routine part of clinical assessments. The predictability of the measure can be improved by combining it with a measure of body mass.

Influence of free testosterone on antigen levels of plasminogen activator inhibitor-1 in premenopausal women with central obesity

Women with upper body obesity are at increased risk for cardiovascular disease (CVD). Several studies have demonstrated a reduced fibrinolytic activity in these patients, mainly due to an enhanced activity of plasminogen activator inhibitor-1 (PAI-1). Since an increase of androgenic activity is a feature of central obesity in women, the present study was aimed at evaluating the possibility of a relationship between androgens and PAI-1 (antigen and activity) in 20 premenopausal women, 10 with upper body obesity and 10 controls. In obese women, PAI-1 antigen showed a positive Pearson correlation with free testosterone (FT), insulin, c-peptide, triglycerides (TG), and waist to hip ratio (WHR) (P less than .01), whereas PAI-1 activity correlated positively only with insulin and WHR (P less than .01). In control women, PAI-1 antigen and activity were positively related only to TG (P less than .01). When we applied the multiple regression model with stepwise backward method to our data, both PAI-1 antigen and activity did not maintain any significant association. However, when the data from both the groups were pooled (n = 20), and PAI-1 antigen was considered as the dependent variable, body weight (Sig T = 0.0001), TG (Sig T = 0.0053), FT (Sig T = 0.013), and luteinizing hormone (LH) (Sig T = 0.0474) met the stepwise criteria, suggesting an independent effect of each of these parameters on PAI-1 antigen. On the other hand, when PAI-1 activity was tested as the dependent variable, only body weight maintained a significant relationship with this parameter (Sig T = 0.0006).(ABSTRACT TRUNCATED AT 250 WORDS)

The growing prevalence of non-insulin-dependent diabetes in migrant Asian populations and its implications for Asia

Many of the prevalence studies of diabetes in Asian populations are reviewed. When compared to Whites, Asians have an even greater predominance of non-insulin-dependent (NIDDM) over insulin-dependent diabetes (IDDM). Diabetes prevalence is higher among migrant Asians than in their homelands, and is often higher than in the majority population of their new homes. It is hypothesized that when a vulnerable population experiences environmental influences accompanying 'westernization', insulin resistance and eventually glucose intolerance develop. Asians are postulated to be a vulnerable ethnic group. Since many portions of Asia are also becoming westernized, it is postulated that insulin resistance and glucose intolerance will become more common in Asia. If this prediction is correct, then NIDDM will be a major health problem in Asia in the near future.

Body fat distribution and serum lipoproteins in relation to age and body weight

Android obesity is reported to be a risk factor for coronary heart disease and aberrations in lipid metabolism, but so far its association with other risk factors such as age and overweight has not been clearly analyzed. We therefore investigated the relationship between the waist-to-hip ratio, age, body mass index and serum lipoproteins in 305 probands (158 men, 147 women), while body mass index was kept constant in all age groups. Waist-to-hip ratio correlated with both age (r = 0.441) and body mass index (r = 0.532) in simple linear correlation analysis (P less than 0.001). In stepwise multiple regression analysis we found in both sexes a first step dependence on age for total and LDL-cholesterol (P less than 0.001), a first step dependence on waist-to-hip ratio for triglycerides (P less than 0.001), VLDL-triglycerides (P less than 0.001) and VLDL-cholesterol (P less than 0.001 for men, P less than 0.05 for women), and an inverse first step dependence on body mass index for HDL-cholesterol (P less than 0.05 for men, P less than 0.001 for women). From these results we propose an independent association between waist-to-hip ratio and triglycerides while the relation to total and LDL-cholesterol is determined by age. HDL-cholesterol, on the other hand, is influenced by body fat mass and independent from age or body fat distribution.

Central rather than generalized obesity is related to hyperglycaemia in Asian Indian subjects

The relationship of body mass index and waist-hip ratio with plasma glucose concentrations during an oral glucose tolerance test (OGTT) was studied in native Indian (Asian) subjects. A total of 389 subjects (131 non-diabetic, 74 impaired glucose tolerant (IGT) and 184 Type 2 diabetic (newly diagnosed and untreated] were studied. Prevalence of obesity (BMI greater than or equal to 27.0 kg m-2 in men and greater than or equal to 25.0 kg m-2 in women, 21% and 47%, respectively) was lower in people with Type 2 diabetes than that reported in white Caucasian and migrant Asian populations. Body mass index was highest in IGT subjects (26.1 (19.7-34.3) kg m-2, median (5-95th centile] and was higher in diabetic subjects (24.2 (19.3-32.2) kg m-2) than in non-diabetic control subjects (23.5 (17.1-30.0) kg m-2). However, waist-hip ratio was higher in both IGT (0.88 (0.75-0.98)) and diabetic subjects (0.88 (0.75-1.00)) than in non-diabetic control subjects (0.83 (0.70-0.97)), with no difference between the hyperglycaemic groups. On multivariate analysis, fasting as well as 2-h plasma glucose concentrations during OGTT were found to be related to waist-hip ratio (p less than 0.01) and subscapular fat thickness (p less than 0.01) but not to body mass index (or triceps fat thickness). Thus, in native Indians central obesity seems to be a more important association of hyperglycaemia than generalized obesity.

Hyperinsulinemia, sex, and risk of atherosclerotic cardiovascular disease

BACKGROUND

The possibility that hyperinsulinemia may be involved in the etiology of atherosclerotic cardiovascular disease (CVD) was first suggested 20 years ago. During the last decade, this possibility has received support from three large prospective studies.

METHODS AND RESULTS

In the present study, the association between CVD, glucose intolerance, obesity, and hypertension (the GOH conditions) and hyperinsulinemia was examined cross-sectionally in a representative sample (n = 1,263) of the adult Jewish population aged 40-70 years in Israel. Previously known diabetics were excluded. CVD comprising clinical or ECG evidence of ischemic heart disease, as well as clinical evidence of cerebrovascular or peripheral vascular disease, was identified in 97 men and 39 women. A significant (p less than 0.01) hyperinsulinemia-sex interaction was found for CVD rate, with the adjusted risk ratios (followed by 95% confidence limits), relative to the rate in 298 normoinsulinemic women, being 1.15 (0.68-1.95) in 328 normoinsulinemic men, 0.85 (0.48-1.49) in 277 hyperinsulinemic women, and 2.27 (1.33-3.08) in 360 hyperinsulinemic men. Age-adjusted CVD rates in men versus women were: a) similar and low among all normoinsulinemic normotensives and hyperinsulinemics free of any of the GOH conditions (all rates less than or equal to 6.5%); b) similar and high among normoinsulinemic hypertensives (13.4% versus 10.4%); c) significantly higher in men among hyperinsulinemic normotensives with glucose intolerance and/or obesity (15.2% versus 3.3%; p = 0.02) and all hyperinsulinemic hypertensives (21.5% versus 12.8%; p = 0.04). These trends remained significant after adjusting for age, ethnic group, and blood lipids.

CONCLUSIONS

Therefore, hyperinsulinemia was associated with excess CVD risk in men but not in women, and all excess CVD risk in men was confined to hyperinsulinemic individuals in the presence of glucose intolerance, obesity, or hypertension.

Effects of body fat distribution on regional lipolysis in obesity

To determine the contribution of the major body fat depots to systemic free fatty acid (FFA) availability, palmitate ([1-14C]-palmitate) release was measured from leg (lower body) and non-leg (upper body) fat in eight upper body obese (UB Ob), six lower body obese (LB Ob), and six nonobese (Non Ob) age-matched premenopausal women in the overnight postabsorptive state. Splanchnic palmitate release was determined in 16 of these subjects.

RESULTS

total palmitate release was greater in UB Ob (P less than 0.005) than LB Ob or Non Ob women (161 +/- 16 vs. 111 +/- 9 vs. 92 +/- 9 mumol/min, respectively). Despite increased leg fat mass in obese women, leg palmitate release was similar in each group. Therefore, leg fat palmitate release was greater in Non Ob women than LB Ob (P less than 0.01) or UB Ob (P = 0.06) women (3.7 +/- 0.3 vs. 2.4 +/- 0.2 vs. 2.7 +/- 0.2 mumol.kg fat-1.min-1, respectively). Upper body fat palmitate release was less (P less than 0.01) in LB Ob than Non Ob or UB Ob women (3.0 +/- 0.4 vs. 5.0 +/- 0.3 vs. 4.9 +/- 0.4 mumol.kg fat-1.min-1, respectively). Splanchnic palmitate release accounted for 20-32% of upper body fat palmitate release in each group (P = NS between groups). Leg fat palmitate release was significantly less than upper body fat palmitate release. We conclude that the major difference in resting FFA metabolism between UB Ob and LB Ob women is the ability of the later to down-regulate upper body fat lipolysis to maintain normal FFA availability.

Effects of fitness level and the regional distribution of fat on carbohydrate metabolism and plasma lipids in middle- to older-aged men

Many cross-sectional studies have demonstrated the influences of fitness level or the regional distribution of fat on lipid and carbohydrate metabolism; however, the relative contribution of these two variables in the same subjects has not been extensively examined. The purpose of this study was to determine the impact of regional adiposity on plasma lipids and carbohydrate metabolism in middle- to older-aged men with a wide range of fitness levels. Forty-six sedentary and exercise-trained men (age [mean +/- SE], 52.8 +/- 0.88 years) were included in this study. Fitness level was assessed by (a) time to exhaustion, and (2) maximal oxygen uptake achieved during an incremental treadmill test. Plasma lipid levels were determined in the basal, fasting state. Carbohydrate metabolism was evaluated by the glucose and insulin responses (total glucose and insulin areas under the curve, insulin sensitivity index [ISI]) to a 75-g, 2-hour oral glucose tolerance test (OGTT). Abdomen to hip ratio (AHR) was used as the index of regional adiposity. Multiple regression analysis indicated that fitness level and the percentage of body fat were significant predictors (approximately 56% of total variance) for total insulin area under the curve and the ISI. A comparison between the sedentary and trained subjects showed that training resulted in an improved ISI at an equal AHR. Fitness level was also the only significant multiple regression predictor for high-density lipoprotein (HDL)-cholesterol (25% of total variance) and accounted for the greatest amount of variance in triglyceride levels (34%), although AHR was also a significant predictor (6%).(ABSTRACT TRUNCATED AT 250 WORDS)

Relations of body habitus, fitness level, and cardiovascular risk factors including lipoproteins and apolipoproteins in a rural and urban Costa Rican population

Increased general and abdominal obesity has been independently associated with diabetes, increased risk of stroke, and coronary artery disease (CAD). It is more prevalent in developed countries and in urban areas of nonindustrialized nations than in less developed and rural areas. To evaluate the associations between general and abdominal obesity (as determined by total body fat, waist to hip ratio, umbilical to triceps ratio, and umbilical to subscapular ratio) with glucose, plasma lipoproteins, apolipoprotein (apo) A-I and B concentrations, and low density lipoprotein (LDL) particle size (LDL 1-7), we randomly selected 222 men and 243 women from rural and urban areas of Puriscal, Costa Rica. Abdominal obesity, as assessed by the waist to hip ratio, was independently and significantly associated with higher triglyceride levels (p less than 0.01) and with lower high density lipoprotein cholesterol levels (p less than 0.05) in men and women and with higher glucose levels (p less than 0.05) and smaller LDL particle size (p less than 0.01) in women. Abdominal obesity, as assessed by the umbilical to subscapular ratio, was independently and significantly associated with higher total cholesterol (p less than 0.005) and apo B (p less than 0.01) levels. Umbilical to triceps ratio was positively associated with blood pressure in men. Urban men had increased general and abdominal obesity (p less than 0.0001), number of cigarettes smoked per day (p less than 0.0001), and diastolic blood pressure (p less than 0.05) and had a decreased fitness level (p less than 0.0001) as well as higher (p less than 0.05) plasma glucose, triglyceride, and total cholesterol concentrations and lower (p less than 0.05) apo A-I and HDL cholesterol levels compared with rural men. The differences between rural and urban women were not as striking. Urban women had increased general and abdominal obesity, glucose, and apo B levels (p less than 0.05) and a decreased fitness level (p less than 0.0001). Our data indicate that general and abdominal obesity, increased cigarette smoking, diastolic blood pressure, and decreased fitness level are more prevalent in an urban than in a rural area in Costa Rica, particularly in men. The higher prevalence of such risk factors in the urban area is associated with a more atherogenic plasma lipoprotein profile.

Height and glucose tolerance in adult subjects

In a prospective study concerning the pathogenesis of impaired glucose tolerance and Type 2 (non-insulin-dependent) diabetes mellitus, 346 subjects with no clinical history of diabetes were given a standard 75 g oral glucose tolerance test. The expected positive associations between 120-min plasma glucose concentration and age and body mass index were observed in both sexes and between 120-min plasma glucose and waist/hip ratio in male subjects. An unexpected negative correlation was found between 120-min plasma glucose and height in both sexes (r = -0.23, (95% confidence interval, -0.38 - -0.07) p less than 0.007 for male subjects and r = -0.24, (-0.37 - -0.11) p less than 0.006 for female subjects). These negative associations with height remained significant after controlling for age and body mass index in male subjects but not in female subjects. In the latter a highly significant negative relationship of height with age was recorded (r = -0.33, (-0.45 - -0.20) p less than 0.0001). Comparison between individuals with impaired glucose tolerance and control subjects matched for sex, age and body mass index showed that subjects with impaired glucose tolerance are significantly shorter. Mean (+/- SEM) height in the male subjects with impaired glucose tolerance (n = 29) was 173.4 +/- 1.1 cm vs 176.9 +/- 1.3 cm in control subjects, p = 0.02. In the female subjects (n = 39) mean (+/- SEM) height was 159.4 +/- 1.0 cm vs 162.4 +/- 1.0 cm in control subjects, p = 0.02. The negative relationship between height and glucose tolerance is a new epidemiological observation which has not been previously reported.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic regulation of lipolysis in a patient with lipoatrophy of the upper body

A patient with lipoatrophy of the upper body had laboratory evidence of increased activity of the adrenergic nervous system. Because the adrenergic nervous system is important in the regulation of lipolysis, studies were performed to determine whether lipolysis of the upper body was ongoing in this patient and whether pharmacologic reduction of activity of the adrenergic nervous system would affect lipolysis of adipose tissue. Release of free fatty acids from systemic and forearm adipose tissue was measured before and after the administration of guanfacine hydrochloride. Forearm adipose tissue, although decreased in quantity, was found to release normal amounts of free fatty acids. Systemic and forearm release of free fatty acids decreased after 3 days of treatment with guanfacine. These results suggest that lipoatrophy of the upper body in some patients may be mediated through dysfunction of the adrenergic nervous system. These findings also emphasize the potential for heterogeneous responses of adipose tissue to hormonal regulatory factors.

Contributions of regional adipose tissue depots to plasma lipoprotein concentrations in overweight men and women: possible protective effects of thigh fat

Anthropometry and dual-photon absorptiometry (DPA) were used to examine associations of regional adiposity with plasma lipid, lipoprotein, and lipoprotein subfraction mass concentrations in moderately overweight men and women. Among 130 women, waist to thigh girth ratio (WTR) correlated with triglycerides (TG) (r = .33, P less than .0001) and negatively with high-density lipoprotein (HDL)-cholesterol (HDL-C) (r = -.37, P less than .0001) concentration, as expected. While WTR did not correlate with low-density lipoprotein (LDL)-cholesterol (LDL-C) it correlated positively with the mass subfraction of small (Sfo, 0 to 7) LDL (r = .38, P less than .0001), and negatively with large (Sfo, 7 to 12) LDL (r = -.31, P less than .01). Among 133 men, similar though weaker relationships were found. Thigh girth correlated positively with HDL and HDL2-C and mass, and with LDL particle size among women. Multivariate analysis suggests that association of WTR with lipoprotein values known to carry risk of coronary heart disease (CHD) are due at least as much to effects of thigh girth as to deleterious effects of waist girth. Estimates of fat weight in thigh and abdominal regions by DPA support thigh fat as contributing to these effects of thigh girth. Thigh fat may contribute to lipoprotein profiles that predict lower risk of cardiovascular disease.

Nuclear estradiol binding in rat adipocytes. Regional variations and regulatory influences of hormones

The nuclear estrogen receptor was characterised in isolated rat adipocytes. The binding reaction with [3H]estradiol was performed with intact isolated rat adipocytes and the radioactivity associated with the nucleus was subsequently determined after cell lysis. The nuclear uptake of [3H]estrogen in rat adipocytes was temperature dependent and steroid specific. The steady-state binding was achieved after 30 min at 37 degrees C and was constant for several hours. Estradiol was found to bind to a homogeneous class of nuclear receptors in epididymal adipocytes with an apparent Kd of 3.1 +/- 0.76 nM and a Bmax of 7.98 +/- 1.11 fmol/10(6) cells corresponding to about 4800 receptors per nucleus. The estradiol binding exhibited regional variations in isolated adipocytes. In lean rats the highest receptor number was found in epididymal adipocytes, whereas there was a significantly lower number of nuclear binding sites in perirenal and subcutaneous adipocytes (P less than 0.05), unlike in older and more obese rats where the nuclear estradiol binding was greatest in adipocytes from the perirenal fat depot. Incubations with isoproterenol (10 microM) and dibutyryl-cAMP (2.5 mM) both reduced estradiol binding by 56% (P less than 0.005), while insulin (1 nM) enhanced the estradiol binding by 37% (P less than 0.01). In conclusion, a specific and high affinity nuclear estradiol receptor was demonstrated in rat adipocytes and regional differences in nuclear estradiol binding were detected. Furthermore, it was demonstrated that nuclear estradiol binding could be modulated by other agents known to affect adipocyte metabolism.

Intra-abdominal fat is associated with decreased insulin sensitivity in healthy young men

To distinguish the relative role of intra-abdominal and subcutaneous abdominal fat in metabolic aberrations in upper body fat localization, we measured the relationship between regional fat distribution and insulin sensitivity in nine young men (28.6 +/- 0.7 years; body mass index [BMI], 24.7 +/- 1.3 kg/m2). Regional fat distribution was measured by anthropometric measurement and computed tomography (CT). Insulin sensitivity was measured by euglycemic hyperinsulinemic glucose clamp. Insulin sensitivity, expressed as the ratio of rate of glucose utilization to the mean plasma insulin concentration during the second hour of glucose clamp (M/I) was negatively correlated with BMI (r = -.91, P less than .001), waist to hip girth ratio (WHR) (r = -.80, P less than .01), subcutaneous abdominal fat area (r = -.90, P less than .001), and intra-abdominal fat area (r = -.88, P less than .01). Stepwise forward regression analysis showed that in addition to BMI, intra-abdominal fat area was a significant correlate of decrease in insulin sensitivity. These findings suggest that intra-abdominal fat play an important role in decreasing insulin sensitivity, even in healthy young men.

Impact of pubertal development on body fat distribution among white, Hispanic, and Asian female adolescents

Variation in the waist/hip ratio (WHR) may be related to changes in hormonal secretion associated with pubertal maturation. We therefore studied the effects of race, pubertal development, and body fatness on WHR during adolescence in a multiethnic population. A total of 688 white, Asian, and Hispanic female adolescents (mean (+/- SD) 12.4 +/- 0.7 years), participating in the evaluation of a multisite school-based health education program, were included in these analyses. Self-assessed stage of puberty and measurements of height, weight, waist circumference, and hip circumference were obtained from each participant. The WHR and age-adjusted body mass index were calculated. Analysis of covariance demonstrated that puberty significantly affects hip circumference and WHR but not waist circumference among female adolescents. Age and fatness, as reflected by age-adjusted body mass index, contributed significantly to both circumferences and to the WHR. There was a significant effect of ethnicity on hip circumference but not on waist circumference or the WHR. These results confirm that pubertal stage exerts a significant effect on the hip circumference and WHR in female adolescents, even after the effects of fatness and age are controlled. Studies of body fat distribution during late childhood and adolescence should include assessments of pubertal maturation.

High blood pressure and insulin resistance: influence of ethnic background

Hyperinsulinaemia links non-insulin dependent diabetes (NIDDM), obesity, and hypertension, each an insulin-resistant state in its own right. Insulin resistance predicts the occurrence of NIDDM, and plays a major role in its pathogenesis. We tested the hypothesis that hyperinsulinaemia may also predict hypertension in a sample (n = 2905) of the mixed population of San Antonio, in which hyperinsulinaemia and NIDDM are more prevalent among Mexican-Americans than non-Hispanic whites. Whilst in the whole sample the hypertensives had significantly (P less than 0.001) higher plasma insulin concentrations than the normotensives, high blood pressure was significantly (P less than 0.01) more frequent among non-Hispanic whites than Mexican-Americans regardless of diabetes status. After adjusting for factors (age, sex, body mass, and body fat distribution) known to affect insulin levels, a direct relationship between post-glucose plasma insulin concentrations and prevalence of hypertension was still present in both ethnic groups. In Mexican-Americans, however, the standardized prevalence of hypertension was significantly (P less than 0.001) lower at any given insulin concentration. Post-glucose plasma glucose levels also were directly related to hypertension prevalence in both groups; again, the regression line was shifted downward and, furthermore, less steep (P less than 0.02) in Mexican-Americans, suggesting relative protection against the negative effect of hyperglycaemia on blood pressure. Dyslipidaemia (higher total cholesterol and triglyceride, and lower HDL-cholesterol concentrations) was strongly associated with hyperinsulinaemia and blood pressure in both ethnic groups. After adjusting for plasma insulin, only hypertriglyceridaemia was associated with high blood pressure, with no inter-ethnic difference.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of regional adiposity on atherogenic risk factors in men and women with type 2 diabetes

To determine firstly whether body fat distribution could predict the presence of atherogenic risk factors better than overall adiposity in Type 2 diabetes, and secondly whether sex differences in these risk factors could be explained by sex differences in fat distribution, waist-to-hip girth ratio (WHR), serum lipids, lipoproteins, apolipoproteins, plasma lipolytic activity, and blood pressure were assessed in 47 patients with Type 2 diabetes, 21 women matched for age, body mass index (BMI) and blood glucose control with 26 men. The men had higher WHR (0.95 (range 0.83-1.07) vs 0.82 (0.74-0.94), p less than 0.001), lower HDL-cholesterol (1.03 +/- 0.05 vs 1.38 +/- 0.06 mmol l-1, p less than 0.001) and apolipoprotein A1 (1.40 +/- 0.06 vs 1.76 +/- 0.06 gl-1, p less than 0.001) concentrations, and higher hepatic lipase activities (16.2 (6.4-38.0) vs 8.6 (2.3-23.1) mmol h-1 l-1, p less than 0.01). In both men and women, BMI and WHR were positively related to serum triglyceride, insulin and C-peptide concentrations. In women, HDL-cholesterol was negatively related to BMI (r = -0.45, p less than 0.05) but only possibly related to WHR (r = -0.33, NS). In men, by contrast, WHR was related negatively to HDL-cholesterol (r = -0.60, p less than 0.005), HDL2-cholesterol (r = -0.43, p less than 0.05), and apolipoprotein A1 (r = -0.70, p less than 0.001) and positively to hepatic lipase activity (r = 0.65, p less than 0.001), whereas the same relationships with BMI were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Asymptomatic hyperglycemia and cardiovascular risk factors in the elderly

We studied the levels of cardiovascular risk factors in a population sample of 511 men and 920 women aged 65-74 years and living in East Finland. Altogether 312 men and 515 women had normal glucose tolerance, 84 men and 158 women impaired glucose tolerance (IGT), 33 men and 59 women newly diagnosed non-insulin-dependent diabetes (NIDDM) detected at the survey, and 82 men and 188 women previously diagnosed NIDDM. Subjects with IGT or newly diagnosed NIDDM had higher levels of total triglycerides and apolipoprotein B and lower levels of HDL cholesterol and apolipoprotein A1 than subjects with normal glucose tolerance, similarly as in previously diagnosed NIDDM. Furthermore, subjects with IGT or newly diagnosed NIDDM were more obese, had higher waist-hip ratio, and more frequently hypertension than subjects with normal glucose tolerance. Thus, asymptomatic hyperglycemia in the elderly is not a benign phenomenon, but is associated with similar adverse changes in cardiovascular risk factors as in middle-aged subjects.

Decreased hepatic insulin extraction in upper body obesity: relationship to unbound androgens and sex hormone binding globulin

Hyperinsulinemia is a well-recognized entity of simple obesity. It is demonstrated that hyperinsulinemia is associated with upper body fat and fat cell hypertrophy. Androgen excess and lower levels of sex hormone binding globulin (SHBG) may produce fat cell hypertrophy and hyperinsulinemia as well. We measured serum insulin and C-peptide levels during an OGTT in two groups of obese premenopausal women to determine whether the hyperinsulinemia is due to hypersecretion or due to a diminished hepatic extraction of insulin. In this study, we found no correlation between the insulin and C-peptide levels or their ratio and the degree of obesity. However, a significant correlation was found between the waist-to-hip circumference ratio (WHR), used as an index of body fat distribution, and the areas of insulin (r = 0.55; P less than 0.001) and C-peptide (r = 0.51; P less than 0.001). SHBG and free androgen index (FAI) were also significantly related to these areas. The peripheral C-peptide/insulin molar ratio has been assumed to reflect changes in hepatic insulin extraction while the corrected C-peptide response reflects beta-cell function. WHR was negatively related to this ratio (r = -0.44; P less than 0.005) and SHBG showed a positive correlation (r = 0.34; P less than 0.05). Stepwise multiple regression analysis revealed that the 2-h insulin and C-peptide values and both curve areas can be explained up to 40-80% by sex hormones and anthropometric variables. Also the C-peptide/insulin molar ratio is dependent in a first step on WHR (r2 = 0.23; P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of intensive endurance exercise training on body fat distribution in young and older men

Little is known about the effects of exercise interventions on the distribution of central and/or intra-abdominal (IA) fat, and until now there were no studies in the elderly. Therefore, in this study we investigated the effects of an intensive 6-month endurance training program on overall body composition (hydrostatic weighing), fat distribution (body circumferences), and specific fat depots (computed tomography [CT]), in healthy young (n = 13; age, 28.2 +/- 2.4 years) and older (n = 15; age, 67.5 +/- 5.8 years) men. At baseline, overall body composition was similar in the two groups, except for a 9% smaller fat free mass in the older men (P less than .05). The thigh and arm circumferences were smaller (P = .001 and P less than .05, respectively), while the waist to hip ratio (WHR) was slightly greater in the older men (0.92 +/- 0.04 v 0.97 +/- 0.04, P less than .01). Compared with the relatively small baseline differences in body composition and circumferences, CT showed the older men to have a twofold greater IA fat depot (P less than .001), 48% less thigh subcutaneous (SC) fat (P less than .01), and 21% less thigh muscle mass (P less than .001). Following endurance (jog/bike) training, both the young (+18%, P less than .001) and the older men (+22%, P less than .001) significantly increased their maximal aerobic power (VO2max). This was associated with small but significant decrements in weight, percent body fat, and fat mass (all P less than .001) only in the older men.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of carbamazepine on resting metabolic rate and thyroid function in depressed patients

Resting metabolic rate and thyroid hormone levels were studied in 11 patients with affective disorders before and during treatment with carbamazepine (CBZ). CBZ has been previously reported to reduce thyroid hormones, but the metabolic consequence of this effect has not been explored. During CBZ treatment, thyroid hormones decreased significantly (T4, 7.53 versus 5.74 micrograms/dl, p less than 0.001), whereas the resting metabolic rate (RMR) did not (31.6 versus 30.7 kcal/m2/hr). Baseline RMRs were low and the expected positive relationship between RMR and weight was disrupted in females. The extent of previous exposure to tricyclic and monoamine oxidase inhibitors antidepressant treatment was significantly associated with lower baseline RMRs. We conclude that CBZ has no significant effect on RMR despite robust decreases in thyroid function.