Visceral obesity: a "civilization syndrome"

Waist circumference and obesity-associated risk factors among whites in the third National Health and Nutrition Examination Survey: clinical action thresholds

BACKGROUND

Waist circumference (WC) is strongly linked to obesity-associated risks. However, currently proposed WC risk thresholds are not based on associations with obesity-related risk factors but rather with body mass index (BMI; in kg/m(2)).

OBJECTIVE

The objective was to determine the relations of WC to obesity-associated risk factors in a representative sample of US whites and to derive comparable risk thresholds for WC and BMI.

DESIGN

Data on 9019 white participants of the third National Health and Nutrition Examination Survey were divided into 2 groups according to the presence of >or= 1 of 4 obesity-associated risk factors: low HDL cholesterol, high LDL cholesterol, high blood pressure, and high glucose. Odds ratio (OR) equations were derived from logistic regression models for WC and BMI with the use of the 25th percentile in the study population as the reference. Receiver operating characteristic curves for identifying risk factors were computed for WC and BMI.

RESULTS

At BMIs of 25 and 30, ORs were 1.19 (95% CI: 1.06, 1.35) and 2.37 (95% CI: 1.33, 4.22) for men and 1.56 (95% CI: 1.29, 1.91) and 3.16 (95% CI: 1.94, 5.28) for women, respectively. The corresponding ORs for WC were at 90 and 100 cm for men and at 83 and 93 cm for women. Minima on the receiver operating characteristic curves for men were at 96 cm for WC and at 26 for BMI and for women were at 86 cm for WC and 25 for BMI.

CONCLUSION

WC is more closely linked to cardiovascular disease risk factors than is BMI.

Interrelationship between serum lipid profile, serum hormones and other components of the metabolic syndrome

The aim of the present study was to investigate the association between the serum lipid profile and components of the metabolic syndrome, such as central obesity (anthropometric, computed tomography and fat cell data), insulin, sex-hormone-binding-globulin (SHBG) and different hormones influencing this important syndrome, e.g. sex steroids, leptin and tumor necrosis factor-alpha (TNF-alpha). The sample consisted of 85 obese patients (30 men and 55 women) who had undergone abdominal surgery. Fasting serum lipids were analysed, as well as anthropometric and computed tomography data, perivisceral and subcutaneous fat cell size and serum glucose and hormones. Abdominal fat revealed itself as an important correlator of the adverse changes in plasma lipoprotein levels, the waist-to-hip-ratio and waist-to-thigh-ratio being the best morphological correlators in men and women, respectively. Intra-abdominal fat (VA) correlated significantly and positively to perivisceral fat cell size in women, while no correlation was found between subcutaneous fat accumulation (SA) and adipocyte size in both genders. Perivisceral fat cell size showed the greatest number of correlations with the adverse plasma lipid profile compared to that in the subcutaneous depot. SHBG and sex steroids showed a negative correlation with serum lipids considered a cardiovascular risk. In contrast, TNF-alpha and C-peptide were inversely correlated with potential protector lipids. In conclusion, abdominal obesity, adipocyte hypertrophy from visceral fat, serum TNF-alpha and C-peptide seem to be the best correlators of the lipoprotein disturbance characteristic of the metabolic syndrome, whereas SHBG and sex steroids could play a protective role regarding the lipid profile associated to this syndrome.

Relationships between changes in weight and changes in cardiovascular risk factors in middle-aged French subjects: effect of dieting

OBJECTIVE

To investigate relationships between changes in weight and changes in cardiovascular risk factors in adults, taking intentionality of weight loss into account.

DESIGN

Longitudinal study in middle-aged French subjects from the SU.VI.MAX cohort.

SUBJECTS

A total of 1773 men (body mass index (BMI) 25.4+/-3.1 kg/m(2), mean+/-s.d) and 2316 women (BMI 23.3+/-3.8 kg/m(2)) aged 45 y and over at baseline.

MEASUREMENTS

Weight, height, blood pressure, serum total cholesterol and fasting blood glucose were measured at baseline and after a 2 y follow-up. Self-reported dieting in order to lose weight, smoking status, leisure-time physical activity, health events and current treatments were assessed through questionnaires.

RESULTS

In multivariate analyses, weight change was positively associated with changes in systolic and diastolic blood pressure (P=0.0002 in women, P=0.0001 in men) and with changes in serum total cholesterol (P=0.008 in women, P=0.02 in men), after adjustment for age, baseline level of each cardiovascular risk factor and current treatments. For example, in men, a weight loss of 5 kg was associated with a decrease of 2.5 mmHg in systolic blood pressure and of 1.5 mmHg in diastolic blood pressure. Taking into account self-reported dieting did not modify these associations.

CONCLUSIONS

In both genders, systolic and diastolic blood pressure and serum cholesterol increased with weight gain and decreased with weight loss, independently of the intentionality to lose weight. At the population level, modest weight loss may have a substantial impact on cardiovascular risk, and preventing even modest weight gain in adults is an important goal in terms of public health.

5-HT2A receptor gene promoter polymorphism in relation to abdominal obesity and cortisol

OBJECTIVE

There is considerable evidence that cortisol secretion is associated with obesity. The regulation of the 5-hydroxytryptamine receptor 2A (5-HT2A) gene might play an essential role because it is involved in the control of cortisol secretion. Therefore, we examined the potential impact of the 5-HT2A -1438G/A promoter polymorphism on obesity and estimates of insulin, glucose, and lipid metabolism as well as circulating hormones, including salivary cortisol, in 284 unrelated Swedish men born in 1944.

RESEARCH METHODS AND PROCEDURES

The subjects were genotyped by using polymerase chain reaction amplification of the promoter region of the gene for 5-HT2A followed by digestion of the reaction product with the restriction enzyme MspI.

RESULTS

The frequencies were 0.39 for allele -1438A and 0.61 for allele -1438G. Homozygotes for the -1438G allele had, in comparison with -1438A/A subjects, higher body mass index, waist-to-hip ratio, and abdominal sagittal diameter. Moreover, cortisol escape from 0.25-mg dexamethasone suppression was found in subjects with the -1438A/G genotype. Serum leptin, fasting insulin, and glucose, as well as serum lipids, were not different across the -1438G/A genotype groups.

DISCUSSION

From these results, we suggest the possibility that an abnormal production rate of the 5-HT2A gene product might lead to the development of abdominal obesity. The pathophysiology could involve stress factors that destabilize the serotonin-hypothalamic-pituitary-adrenal system in those with genetic vulnerability in the serotonin receptor gene.

Anthropometric estimates of muscle and fat mass in relation to cardiac and cancer mortality in men: the Paris Prospective Study

BACKGROUND

The associations of different components of body mass with disease outcomes are not well defined.

OBJECTIVE

We investigated the effects of body composition on risk of death from cardiac causes and cancer in adult men.

DESIGN

Middle-aged men (n = 7608) in the Paris Prospective Study were followed up for 15 y. At study entry, the following measurements were obtained: sagittal diameter, sum of midarm and midthigh circumferences, sum of 3 trunk skinfold thicknesses (estimate of trunk subcutaneous fat), and sum of 3 extremity skinfold thicknesses (estimate of extremity subcutaneous fat). To assess their relative contributions to cardiac and cancer mortality, we used multivariate Cox models in which the sagittal diameter adjusted for trunk skinfold thicknesses was used as an estimate of intraabdominal fat and the sum of midarm and midthigh circumferences adjusted for extremity skinfold thicknesses was used as an estimate of muscle mass.

RESULTS

In multivariate analyses in both smokers and nonsmokers, the sagittal diameter was the only significant predictor of cardiac death. The sum of midarm and midthigh circumferences was negatively associated and sagittal diameter was positively associated with cancer death, whereas extremity skinfold thicknesses exhibited a U-shape relation. Exclusion of subjects who died from cancer in the first 5 y of follow-up did not change these results.

CONCLUSIONS

Intraabdominal fat appears to be the main body compartment involved in risk of cardiac death, whereas increased risk of cancer death is associated with lower muscle mass and lower subcutaneous fat, independent of smoking and after the exclusion of early mortality. Increased central fat distribution may confer additional risk of death from cancer.

Glucocorticoid receptor variants: clinical implications

Following exposure to stress, cortisol is secreted from the adrenal cortex under the control of the hypothalamic-pituitary-adrenal axis (HPA-axis). Central in the regulation of the HPA-axis is a two tied corticosteroid-receptor system, comprised of high and low affinity receptors, the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR), respectively. In addition, these corticosteroid receptors mediate the effects of cortisol during stress on both central and peripheral targets. Cortisol modulates gene-expression of corticosteroid-responsive genes, with the effect lasting from hours to days. Mutations in the GR-gene are being associated with corticosteroid resistance and haematological malignancies, although these mutations are relatively rare and probably not a common cause of these diseases. However, several GR-gene variants and single nucleotide polymorphisms (SNP) in the GR-gene have been identified which are relatively common in the human population. The GRbeta-variant, for example, has been proposed to influence corticosteroid-sensitivity and most evidence has been derived from the immune system and in particular asthma. With respect to polymorphisms, a BclI restriction fragment polymorphism and a Asp363Ser have been described, which not only influence the regulation of the HPA-axis, but are also associated with changes in metabolism and cardiovascular control. These associations of a GR-gene polymorphism with metabolism and cardivascular control, and also with the regulation of the HPA-axis, indicates an important underlying role of cortisol in the etiology of these complex disorders. Therefore, we propose that a common underlying defect in these complex disorders is a disregulation of the HPA-axis, especially during stress. The clinical implication is that the regulation of the HPA-axis should be envisioned as a primary target of new drugs for the treatment of stress-related disorders.

Obesity and health risks

Childhood obesity is multi-factorial in etiology. Several factors contribute to the etiology of childhood obesity, and childhood obesity is itself associated with significant morbidity. This article focuses on the health risks of childhood obesity and on the prenatal and childhood influences that contribute to the genesis of childhood obesity.

Hypercortisolemic depression is associated with increased intra-abdominal fat

OBJECTIVE

Similar to patients with a metabolic syndrome, patients with major depression are at increased risk of developing cardiovascular disorders. Interestingly, both disorders share a specific endocrine syndrome that promotes the accumulation of visceral fat, which again is considered a marker of increased cardiovascular morbidity and mortality.

METHODS

Intra-abdominal fat was measured in 22 postmenopausal depressed women and 23 age-matched healthy women by computer tomography at the level of lumbar vertebrae 1 (L1) and 4 (L4). Saliva was taken in patients and control subjects at 08:00 hours over a period of 7 drug-free days for the measurement of free cortisol. In patients only we performed an oral glucose tolerance test.

RESULTS

Compared with control subjects, depressed patients with elevated free cortisol concentrations showed similar visceral fat depots at L1 (113.0 +/- 41.6 vs. 94.3 +/- 53.2 cm(2)). Hypercortisolemic depressed patients also showed greater fat depots in this area (74.5 +/- 55.5 cm(2), p =.04) than the normocortisolemic patients. However, a comparison of all patients with control subjects revealed no difference in fat accumulation at either L1 or L4. Finally, glucose concentrations during the glucose tolerance test were higher in hypercortisolemic than in normocortisolemic patients, whereas their insulin levels showed only a tendency toward being increased.

CONCLUSIONS

Hypercortisolemic depressed patients suffer from resistance to insulin and increased visceral fat. The fact that hypercortisolemia reverses depression-related fat loss, particularly in the visceral area, might partially explain why major depression can be considered a risk factor for cardiovascular disorders.

Assessment of dietary and genetic factors influencing serum and adipose fatty acid composition in obese female identical twins

Fourteen pairs of obese female monozygotic twins were recruited for a study of genetic influences on serum and adipose fatty acid (FA) composition. Following 1 wk of inpatient stabilization, fasting serum and adipose tissue obtained by surgical excision were analyzed by thin-layer and gas chromatography. Intrapair resemblances (IPR) for individual FA were assessed by Spearman rank correlation and by analysis of variance and were found in serum cholesteryl esters (CF), triglycerides (TG), and adipose TG. With two exceptions (CE linoleate and adipose eicosapentaenoate), these IPR were limited to the nonessential FA. Palmitate had significant IPR in four lipid fractions; in serum CE and adipose TG palmitate was strongly correlated with multiple measures of adiposity. In contrast to other lipid fractions, serum phosphatidylcholine (PC) FA had 12 [PR, of which 6 were essential FA including arachidonate (r = 0.76, P < 0.0005), eicosapentaenoate (r = 0.78, P < 0.0005), and docosahexaenoate (r = 0.86, P< 0.0001). The PC [PR could not be explained by analysis of preadmission 7-d food records. After dividing the pairs into two groups differing and nondiffering according to fat intake of individuals in the pair, there was no evidence of a gene-environment interaction between fat intake and FA composition. The IPR for nonessential FA indicate that there is active genetic control of either food choices or postabsorptive metabolic processing. The high level of IPR in the PC fraction in contrast to the other lipid fractions suggests strong genetic influence over selection of specific FA for this membrane fraction independent of diet.

Food patterns and components of the metabolic syndrome in men and women: a cross-sectional study within the Malmö Diet and Cancer cohort

This study examined the relations between food patterns and five components of the metabolic syndrome in a sample of Swedish men (n = 2,040) and women (n = 2,959) aged 45-68 years who joined the Malmö Diet and Cancer study from November 1991 to February 1994. Baseline examinations included an interview-administered diet history, a self-administered questionnaire, blood pressure and anthropologic measurements, and blood samples donated after an overnight fast. Cluster analysis identified six food patterns for which 43 food group variables were used. Logistic regression analysis was used to examine the risk of each component (hyperinsulinemia, hyperglycemia, hypertension, dyslipidemia, and central obesity) and food patterns, controlling for potential confounders. The study demonstrated relations, independent of specific nutrients, between food patterns and hyperglycemia and central obesity in men and hyperinsulinemia in women. Food patterns dominated by fiber bread provided favorable effects, while food patterns high in refined bread or in cheese, cake, and alcoholic beverages contributed adverse effects. In women, food patterns dominated by milk-fat-based spread showed protective relations with hyperinsulinemia. Relations between risk factors and food patterns may partly depend on gender differences in metabolism or food consumption and on variations in confounders across food patterns.

Relationship between socio-economic and cultural status, psychological factors and body fat distribution in middle-aged women living in Northern Italy

This study analyses the relationships between body fat distribution and socioeconomic and psychological factors in a cohort of 426 healthy middle-aged women living in Virgilio, Mantua (Northern Italy). The information concerning their occupational, social and psychological conditions and smoking habits were obtained by means of questionnaires. Psychological factors were investigated using the Italian version of the Illness Behaviour Questionnaire and the Symptom Questionnaire. Anthropometric measurements, body mass index (BMI) (kg/m2), waist/hip ratio (WHR) and clinical/hormonal menopausal status were also collected for each subject. The women reported significantly higher or lower psychological factor scores (symptoms of conversion: p=0.005; perception of disease: p=-0.018; denial: p=0.021; hostility: p=0.57; and laxity: p=0.047) as their WHR increased, thus indicating some concern about their health. In a multiple regression model, their WHR and waist circumference (W) significantly correlated with symptoms of conversion (p=0.005 and p=0.029), and W was also significantly related to the perception of disease (p=0.043). There was a significant inverse correlation between the WHR and educational level (p<0.001). The prevalence of partners who were entrepreneurs or self-employed also decreased as WHR increased (p<0.001). Furthermore, the number of women living in the centre of town significantly diminished, whereas those living in the suburbs or in the country significantly increased (p=0.005). However, using age, BMI and menopausal status as covariates, only the partner's work significantly and negatively correlated with the WHR (p=0.029). These results are consistent with the hypothesis that psychological and socio-economic handicaps are associated with a higher prevalence of abdominal fatness in middle-aged women living in Northern Italy

Is the somatotropic axis related to sympathetic nerve activity in healthy ageing men?

OBJECTIVE

The mechanisms underlying the age-related increase in blood pressure and sympathetic nerve activity remain largely unknown. The decline in growth hormone (GH) secretion and insulin-like growth factor-I (IGF-I) with age has been related to several cardiovascular risk factors. Low serum IGF-I levels in severe adult GH deficiency is associated with markedly increased sympathetic nerve activity. This study evaluates whether a relationship between serum IGF-I and sympathetic nerve traffic exists in healthy aging men.

DESIGN AND METHODS

Sympathetic nerve activity to the muscle vascular bed (MSA) was recorded in 56 healthy normotensive males, and related to age (range 21-71 years), body mass index (BMI, range 18.4-32.2), serum IGF-I and plasma nitrate levels. Blood pressure, BMI and MSA increased with age, whereas IGF-I and plasma nitrate decreased. In a forward stepwise multiple regression analysis, age explained 40% of the variability in MSA and excluded other variables. Omitting age, IGF-I became the strongest independent predictor, explaining 23% of the variability in MSA. MSA was an independent predictor of diastolic blood pressure, but its influence (10%) was less than that of BMI (28%). BMI was not related to MSA or IGF-I.

CONCLUSIONS

Decreased serum IGF-I levels are coupled to increased MSA during ageing, an effect independent from the impact of increased body weight. Although MSA is a weak predictor of rising blood pressure with age, it constitutes one possible pathway for the somatotropic axis to affect cardiovascular function in ageing.

Secular changes in body fat patterning in children and adolescents of Zaragoza (Spain), 1980-1995

OBJECTIVE

To examine whether children and adolescents of Zaragoza (Spain) are becoming centrally obese to a greater extent than would be predicted by their relative body weights.

DESIGN

Two cross-sectional surveys conducted in 1980 and 1995.

SUBJECTS

The samples selected for the 1980 and 1995 surveys comprised 1553 and 701 male children, and 1311 and 659 female children, respectively, with ages ranging from 6.0 to 14.9 y.

MEASUREMENTS

We measured four skinfold thicknesses (biceps, triceps, subscapular, suprailiac) and calculated some indices of fat patterning: triceps/subscapular skinfolds (T/SS), biceps+triceps/subscapular+suprailiac skinfolds (B+T/SS+SI), and (subscapular+suprailiac/biceps+triceps+subscapular+suprailiac skinfolds)x100 (trunk-to-total skinfolds %).

RESULTS

In males, B+T/SS+SI, and trunk-to-total skinfolds % showed a significant trend to a central pattern of fat distribution from 1980 to 1995, at the ages of 6.5-11.5 y. In females, B+T/SS+SI and trunk-to-total skinfolds % showed a significant trend to a central pattern of fat distribution from 1980 to 1995, at the ages of 6.5 and 7.5 y. Similar results were obtained when we adjusted for BMI values.

CONCLUSION

We have observed a trend to a central pattern of adipose tissue distribution, especially in males and at the youngest ages studied (6-11 y in males, and 6-7 y in females). These observations were independent of trends in BMI.

Treatment of abdominally obese men with a serotonin reuptake inhibitor: a pilot study

OBJECTIVE

To investigate the effects of a selective serotonin reuptake inhibitor (SSRI) on the neuroendocrine and autonomic nervous system perturbations found in abdominal obesity.

DESIGN

Treatment for 6 months with citalopram and for 6 months with placebo using a double-blind, cross-over design, with a 2-month wash-out period between treatment periods.

SUBJECTS

Sixteen healthy men, 45-60 years, moderately obese and with an abdominal fat distribution.

MEASUREMENTS

Anthropometry, three different depression rating scales, serum lipids, testosterone, IGF-I, oral glucose tolerance test (OGTT), pituitary stimulation with corticotropin releasing hormone (CRH), arithmetic stress test, and excretion of cortisol and metoxycatecholamines in urine, collected during 24 h.

RESULTS

Cortisol concentrations in the morning were low before treatment, indicating a perturbed function of the hypothalamic-pituitary-adrenal (HPA) axis. After treatment with citalopram morning cortisol concentrations rose to normal. Cortisol concentrations after stimulation with CRH or stress were elevated by citalopram treatment, but urinary cortisol excretion was unchanged. The glucose concentrations after OGTT (120 min) tended to be reduced, with unchanged insulin concentrations, whilst other metabolic values did not change during treatment. Heart rate after administration of CRH, and during laboratory stress test, decreased by treatment with citalopram. Diurnal urinary excretion of metoxycatecholamines tended to decrease. Neither body mass index nor waist/hip circumference ratio decreased. Depression scores were within normal limits before treatment and did not change.

CONCLUSION

The results of this pilot study indicate improvements in the regulation of neuroendocrine-autonomic systems as well as metabolism in abdominal obesity during treatment with an SSRI.

Conjugated linoleic acid (CLA) reduced abdominal adipose tissue in obese middle-aged men with signs of the metabolic syndrome: a randomised controlled trial

BACKGROUND

Abdominal obesity is strongly related to metabolic disorders. Recent research suggests that dietary conjugated linoleic acid (CLA) reduces body fat and may improve metabolic variables in animals. The metabolic effects of CLA in abdominally obese humans have not yet been tested.

OBJECTIVE

To investigate the short-term effect of CLA on abdominal fat and cardiovascular risk factors in middle-aged men with metabolic disorders.

METHODS

Twenty-five abdominally obese men (waist-to-hip ratio (WHR), 1.05+/-0.05; body mass index (BMI), 32+/-2.7 kg/m(2) (mean+/-s.d.)) who were between 39 and 64-y-old participated in a double-blind randomised controlled trial for 4 weeks. Fourteen men received 4.2 g CLA/day and 10 men received a placebo. The main endpoints were differences between the two groups in sagittal abdominal diameter (SAD), serum cholesterol, low-density lipoprotein, high-density lipoprotein, triglycerides, free fatty acids, glucose and insulin.

RESULTS

At baseline, there were no significant differences between groups in anthropometric or metabolic variables. After 4 weeks there was a significant decrease in SAD (cm) in the CLA group compared to placebo (P=0.04, 95% CI; -1.12, -0.02). Other measurements of anthropometry or metabolism showed no significant differences between the groups.

CONCLUSIONS

These results indicate that CLA supplementation for 4 weeks in obese men with the metabolic syndrome may decrease abdominal fat, without concomitant effects on overall obesity or other cardiovascular risk factors. Because of the limited sample size, the effects of CLA in abdominal obesity need to be further investigated in larger trials with longer duration.

BMI does not accurately predict overweight in Asian Indians in northern India

Asian Indians are at high risk for the development of atherosclerosis and related complications, possibly initiated by higher body fat (BF). The present study attempted to establish appropriate cut-off levels of the BMI for defining overweight, considering percentage BF in healthy Asian Indians in northern India as the standard. A total of 123 healthy volunteers (eighty-six males aged 18--75 years and thirty-seven females aged 20--69 years) participated in the study. Clinical examination and anthropometric measurements were performed, and percentage BF was calculated. BMI for males was 21.4 (sd 3.7) kg/m(2) and for females was 23.3 (sd 5.5) kg/m(2). Percentage BF was 21.3 (sd 7.6) in males and 35.4 (sd 5.0) in females. A comparison of BF data among Caucasians, Blacks, Polynesians and Asian ethnic groups (e.g. immigrant Chinese) revealed conspicuous differences. Receiver operating characteristic (ROC) curve analysis showed a low sensitivity and negative predictive value of the conventional cut-off value of the BMI (25 kg/m(2)) in identifying subjects with overweight as compared to the cut-off value based on percentage BF (males >25, females >30). This observation is particularly obvious in females, resulting in substantial misclassification. Based on the ROC curve, a lower cut-off value of the BMI (21.5 kg/m(2) for males and 19.0 kg/m(2) for females) displayed the optimal sensitivity and specificity, and less misclassification in identification of subjects with high percentage BF. Furthermore, a novel obesity variable, BF:BMI, was tested and should prove useful for interethnic comparison of body composition. In the northern Indian population, the conventional cut-off level of the BMI underestimates overweight and obesity when percentage BF is used as the standard to define overweight. These preliminary findings, if confirmed in a larger number of subjects and with the use of instruments having a higher accuracy of BF assessment, would be crucial for planning and the prevention and treatment of various obesity-related metabolic diseases in the Asian Indian population.

Visceral obesity and the role of the somatotropic axis in the development of metabolic complications

It is well recognized that aberrant fat localization such as visceral obesity rather than total body fat mass is a major risk factor for cardiovascular disease and type 2 diabetes mellitus. During recent decades, several studies have described a range of metabolic disturbances associated with abdominal obesity, including glucose intolerance, hyperinsulinaemia, insulin resistance, hypertension and dyslipoproteinaemia, now widely known as the metabolic syndrome. Several abnormalities in the hypothalamic-pituitary axis have been described associated with visceral obesity, suggesting a central neuroendocrine dysregulation including increased cortisol concentration and impaired gonadotropin and growth hormone (GH) secretion. Some steps in the chain of events in this theory still remain unclear, however, although these findings have introduced new therapeutic possibilities. These include therapy with sex steroids in both viscerally obese men and women, and several attempts to use GH to treat the endocrine abnormalities present in visceral obesity. The results of these studies are promising, but the therapies are still not recommended for general use.

Do stress reactions cause abdominal obesity and comorbidities?

'Stress' embraces the reaction to a multitude of poorly defined factors that disturb homeostasis or allostasis. In this overview, the activation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system have been utilized as objective measurements of stress reactions. Although long-term activation of the sympathetic nervous system is followed by primary hypertension, consequences of similar activation of the HPA axis have not been clearly defined. The focus of this overview is to examine whether or not repeated activation of these two stress centres may be involved in the pathogenesis of abdominal obesity and its comorbidities. In population studies adrenal hormones show strong statistical associations to centralization of body fat as well as to obesity. There is considerable evidence from clinical to cellular and molecular studies that elevated cortisol, particularly when combined with secondary inhibition of sex steroids and growth hormone secretions, is causing accumulation of fat in visceral adipose tissues as well as metabolic abnormalities (The Metabolic Syndrome). Hypertension is probably due to a parallel activation of the central sympathetic nervous system. Depression and 'the small baby syndrome' as well as stress exposure in men and non-human primates are followed with time by similar central and peripheral abnormalities. Glucocorticoid exposure is also followed by increased food intake and 'leptin resistant' obesity, perhaps disrupting the balance between leptin and neuropeptide Y to the advantage of the latter. The consequence might be 'stress-eating', which, however, is a poorly defined entity. Factors activating the stress centres in humans include psychosocial and socioeconomic handicaps, depressive and anxiety traits, alcohol and smoking, with some differences in profile between personalities and genders. Polymorphisms have been defined in several genes associated with the cascade of events along the stress axes. Based on this evidence it is suggested that environmental, perinatal and genetic factors induce neuroendocrine perturbations followed by abdominal obesity with its associated comorbidities.

Quality of life, overweight, and body fat distribution in middle-aged men

Measurements of obesity [body mass index (BMI)] and body fat distribution [waist-to-hip ratio (WHR)] were analyzed in 284 51-year-old men in relation to items about social, mental, and physical well-being from the Göteborg Quality of Life Instrument. Overweight participants (BMI > or = 25) reported a better home-family situation, appetite, and self-esteem, but decreased physical fitness and more pain in the legs compared with their leaner counterparts. Men with abdominal obesity (WHR > or = 1.0) experienced impaired health and physical fitness and lower self-esteem compared with those with WHR < 1.0. The abdominally obese participants were more often exhausted and experienced depressive symptoms. Abdominal pain was more frequent among those with WHR > or = 1.0. Overweight and abdominal obesity seem differently associated with social, mental, and physical well-being in men. Impaired quality of life may be causally related to the development of abdominal obesity; the mechanism involved might be increased cortisol secretion, which can redistribute body fat to central adipose tissue depots.

Obesity, body fat distribution, insulin sensitivity and Islet beta-cell function as explanations for metabolic diversity

Studies of metabolic processes have been enhanced by our understanding of the relationships among obesity, body fat distribution, insulin sensitivity and islet beta-cell function. Thus, we have learned that although insulin resistance is usually associated with obesity, even lean subjects can be insulin resistant due to the accumulation of visceral fat. Insulin sensitivity and beta-cell function are also intimately linked. The hyperbolic relationship between these two parameters explains why insulin-resistant individuals have markedly enhanced insulin responses, whereas subjects who are insulin sensitive exhibit very low responses. Failure to take into account this relationship will lead to erroneous conclusions. By accounting for this important interaction, it has been clearly demonstrated that subjects at high risk of developing type 2 diabetes (older individuals, women with a history of gestational diabetes or polycystic ovary syndrome, subjects with impaired glucose tolerance and first-degree relatives of individuals with type 2 diabetes) have impaired beta-cell function. Furthermore, the progression from normal glucose tolerance to impaired glucose tolerance and type 2 diabetes is associated with declining insulin secretion.

Endocrine, metabolic and nutritional factors in obesity and their relative significance as studied by factor analysis

OBJECTIVE

To evaluate different aspects of obesity, such as body fat distribution, plasma hormone and lipid profiles, adipose tissue composition and dietary intake in an obese population in order to identify the most important factors that contribute to obesity.

DESIGN

Eighty-five obese subjects, 30 men and 55 women (age, 30-70 y; body mass index (BMI), 27-35 kg/m2), were studied using anthropometric measurements, computed tomography, adipose tissue composition, serum hormone and lipid profiles and nutritional evaluations. To determine to what extent individual factors contributed to the general process of obesity, the data were subjected to a factor analysis.

RESULTS

Three patterns of anthropometric and computed tomography data emerged that accounted for 69% of the variance. Factor 1 defined abdominal obesity and explained 30% of the total variance, factor 2 (gynoid obesity) accounted for 26%; and factor 3 (subcutaneous fat) explained 13% of the total variance. When other factors associated with obesity, such as lipid profile, hormonal profile and fat composition, were introduced, obesity itself, especially abdominal obesity, remained the principal factor, accounting for 23% of total variability. All factors were of secondary importance when dietary characteristics were introduced. In the overall factor analysis, more than 40% of the variability in obesity was related to dietary habits, particularly fat intake, followed by energy and saturated fatty acids intake.

CONCLUSION

Even though obesity is a multifactorial phenomenon, the results suggest that dietary intake, especially fat intake, is the most important factor contributing to obesity. Secondary factors include endocrine and metabolic factors.

Lack of mutations of type 1 11beta-hydroxysteroid dehydrogenase gene in patients with abdominal obesity

There is increasing evidence that in human obesity, particularly the abdominal phenotype, the activity of the hypothalamic-pituitary-adrenal (HPA) axis is disregulated. At least two distinct alterations have been reported: one is characterized by several neuroendocrine abnormalities and hyperresponsiveness of the HPA axis to different neuropeptides, the other is characterized by elevated cortisol traffic and probably by supranormal cortisol production. The 11beta-hydroxysteroid dehydrogenase (11beta-HSD) enzymes interconvert cortisol and cortisone in human. Two different isoforms have been identified. A possible modification of the activity of the enzyme 11beta-HSD1 in subjects with abdominal obesity has been described in the literature. We decided to test the hypothesis that mutated isoforms of type 11beta-HSD1 protein could be responsible for alterations of cortisol metabolism in patients with abdominal obesity. A mutational screening of the whole coding sequence and exon-flanking regions of the 11B-HSD1 gene has been performed in 8 patients. The main results of our study are the exclusion of a common association of 11beta-HSD1 mutations to obesity and the identification of two novel allelic variants for the gene 11beta-HSD1 in the Italian population, not previously described in any database.

Relationship of the metabolic syndrome and obesity to polycystic ovary syndrome: a controlled, population-based study

OBJECTIVE

Although hyperinsulinemia seems to be an essential feature of polycystic ovary syndrome, the frequency of gynecologic disorders related to polycystic ovary syndrome at a population level in women with evident metabolic syndrome is not known.

STUDY DESIGN

We conducted a cross-sectional, population-based study. Participants (N = 204) were recruited from a random sample of women in 5 age groups (range, 35-54 years) living in a defined area. Metabolic syndrome was considered to be present if 3 of the following 8 criteria were fulfilled: (1) first-degree relative with type II diabetes, (2) body mass index > or = 30 kg/m2, (3) waist/hip ratio > or = 0.88, (4) blood pressure > or = 160/95 mm Hg or drug treatment for hypertension, (5) fasting serum triglyceride level > or = 1.70 mmol/L, (6) high-density lipoprotein cholesterol value < 1.20 mmol/L, (7) abnormal glucose metabolism, and (8) fasting insulin value > or = 13.0 mU/L. The frequency of metabolic syndrome was 106 (19.5%) of 543 cases. The control group consisted of 62 overweight women without central obesity or metabolic syndrome and 53 healthy lean women (body mass index < 27 kg/m2.

RESULTS

The group with metabolic syndrome differed from the other women according to most of the selection criteria and also had the highest free testosterone concentration. However, there were no differences between the groups regarding parity, infertility problems, or obstetric outcome. However, oligomenorrhea appeared to be more common in women with metabolic syndrome, especially in those with more severe symptoms (46.2%), than in obese (25.4%) and lean (15.1%) control subjects. Polycystic-like ovaries were detected by vaginal ultrasonography with similar frequency (13.1%, 15.3%, and 13.2% in women with metabolic syndrome, obese women, and lean women, respectively).

CONCLUSIONS

Surprisingly few women with metabolic syndrome had symptoms suggestive of polycystic ovary syndrome, in comparison with obese and lean women. Our results suggest that at the population level polycystic ovary syndrome only accounts for a distinct subgroup of a much wider problem, metabolic syndrome.

Tissue specificity: the clinical importance of steroid metabolites in hormone replacement therapy

Metabolic activations or inactivations of estrogens, progesterone and androgens are important steps towards the understanding of the physiological and the pathological effects of these hormones in the female organism. Analysis of the tissue specific metabolic pathways of sex steroids will result in a better understanding of successful hormone replacement therapy on the one hand and of the occurrence of steroid hormone related side effects on the other hand. In this contribution we analyse the different mechanisms involved in the synthesis of tissue specific metabolites and discuss the therapeutical importance of these metabolites in hormone replacement therapy.

Magnitude of sustained multiple risk factors for ischemic heart disease in Japanese employees: a case-control study

A case-control study was performed to clarify the cause of ischemic heart disease (IHD), such as acute myocardial infarction and angina pectoris, in Japanese employees. Among 122,051 workers from 31 industries, 94 cases of IHD were the subjects of the study, and a total of 191 age-matched subjects from the same department, but who did not develop IHD, served as the controls. Compared with the control group, body mass index, blood pressure, fasting plasma glucose, serum total cholesterol and serum triglyceride were significantly higher, and cigarette consumption and serum uric acid also tended to be higher, in the patient group from at least 10 years prior to onset. The frequency of moderate-drinkers tended to be lower in the case group. Electrocardiograms showed that, compared with the control group, the frequency of myocardial ischemia was higher in the case group from 9 years prior to onset and further rapidly increased from 3 years prior. The frequency of subjects with arrhythmia was the same as the control group until 3 years before onset and increased rapidly from 2 years prior. The frequency of subjects with multiple risk factors, particularly obesity, hypertension, hyperlipidemia and hyperglycemia, was consistently higher in the case group compared with the control group from 10 years prior to onset. Conditional logistic regression analysis demonstrated that having more than one risk factor greatly increased the risk; in particular, the combination of 3 or more factors increased the relative risk to 10.56 (95% confidence interval: 3.30-33.78). These findings suggest that a long duration of multiple risks is involved in the onset of IHD in Japanese employees, and that annual ECG monitoring as part of the medical examination was important in the prognosis.

Comparison of regional fat distribution and health risk factors in middle-aged white and African American women: The Healthy Transitions Study

OBJECTIVE

Both ethnicity and menopause appear to influence intra-abdominal fat distribution. This study evaluated intra-abdominal fat distribution and obesity-related health risks in perimenopausal white and African American women.

RESEARCH METHODS AND PROCEDURES

Baseline data from a longitudinal study of changes in body composition and energy balance during menopause are reported. Healthy women (55 African Americans and 103 whites) who were on no medication and had at least five menstrual cycles in the previous 6 months were recruited. Body composition was assessed by DXA, and visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were assessed by computed tomography scan. SAT was divided into deep and superficial layers demarcated by the fascia superficialis.

RESULTS

African American women were slightly younger (46.7 +/- 0.2 vs. 47.7 +/- 0.2 years, p = 0.002) and fatter (42.4% +/- 1.0% vs. 39.4% +/- 0.8% body fat, p = 0.02) than white women. In unadjusted data, African Americans had significantly more total abdominal fat and total, deep, and superficial SAT than whites. After adjustment for percent body fat and age, only total and superficial SAT remained significantly higher in African Americans. VAT, although slightly less in African American women, did not differ significantly by race. In multiple regression analysis, VAT was the strongest predictor of serum lipids, glucose, and insulin in women of both races, although superficial SAT was significantly associated with fasting glucose in whites.

CONCLUSIONS

Middle-aged African American women have larger SAT depots, adjusted for total body fatness, but do not differ from white women with regard to VAT. The complexity of the relationship between abdominal fat and metabolic risk is increased by ethnic differences in such associations.

Body mass index and the prevalence of hypertension and dyslipidemia

OBJECTIVE

To describe and evaluate relationships between body mass index (BMI) and blood pressure, cholesterol, high-density lipoprotein-cholesterol (HDL-C), and hypertension and dyslipidemia.

RESEARCH METHODS AND PROCEDURES

A national survey of adults in the United States that included measurement of height, weight, blood pressure, and lipids (National Health and Nutrition Examination Survey III 1988-1994). Crude age-adjusted, age-specific means and proportions, and multivariate odds ratios that quantify the association between hypertension or dyslipidemia and BMI, controlling for race/ethnicity, education, and smoking habits are presented.

RESULTS

More than one-half of the adult population is overweight (BMI of 25 to 29.9) or obese (BMI of > or =30). The prevalence of high blood pressure and mean levels of systolic and diastolic blood pressure increased as BMI increased at ages younger than 60 years. The prevalence of high blood cholesterol and mean levels of cholesterol were higher at BMI levels over 25 rather than below 25 but did not increase consistently with increasing BMI above 25. Rates of low HDL-C increased and mean levels of HDL-C decreased as levels of BMI increased. The associations of BMI with high blood pressure and abnormal lipids were statistically significant after controlling for age, race or ethnicity, education, and smoking; odds ratios were highest at ages 20 to 39 but most trends were apparent at older ages. Within BMI categories, hypertension was more prevalent and HDL-C levels were higher in black than white or Mexican American men and women.

DISCUSSION

These data quantify the strong associations of BMI with hypertension and abnormal lipids. They are consistent with the national emphasis on prevention and control of overweight and obesity and indicate that blood pressure and cholesterol measurement and control are especially important for overweight and obese people.

Trends in waist-to-hip ratio and its determinants in adults in Finland from 1987 to 1997

BACKGROUND

Although abdominal obesity has been shown to be an important risk factor for cardiovascular disease and a variety of other diseases, secular changes in fat distribution in populations have rarely been documented.

OBJECTIVE

Our objective was to assess trends in waist-to-hip ratio (WHR) in the Finnish population during a 10-y period. In addition, we investigated the associations of WHR with body mass index (BMI), age, education, and lifestyle factors.

DESIGN

Three independent cross-sectional surveys were carried out at 5-y intervals between 1987 and 1997. Altogether, 15096 randomly selected men and women aged 25-64 y participated in these surveys.

RESULTS

The WHR increased in both men and women during the 10-y period (P: < 0.0001). In men, the strongest upward trend took place in the first 5-y period and then seemed to plateau; in women, the WHR continued to increase into the 1990s. In both sexes, the most prominent increase was observed in subjects aged >/=45 y. The WHR increased in all education-level groups, the lowest WHR being among those with the highest education. Age (18% in men, 12% in women) and BMI (33% in men, 25% in women) accounted for most of the variation in WHR, whereas only 3% was explained by education and lifestyle factors.

CONCLUSIONS

Abdominal obesity is a growing problem in Finland, especially in persons aged >/=45 y. These adverse changes in body shape continued to take place, particularly in women, in the 1990s.

Obesity: criteria and classification

Obesity is defined as an excess accumulation of body fat. To measure fat in the body accurately is difficult, and no method is easily available for routine clinical use. Traditionally, overweight and obesity have been evaluated by anthropometric measurement of weight-for-height. More recently, BMI has been used. The normal range is 19-24.9 kg/m2, overweight is 25-29.9 kg/m2, and obesity >/= 30 kg/m2. Not only is the total amount of fat an individual carries important, but also where the fat is distributed in the body. Fat in a central or upper body (android) distribution is most related to health risk. The most accurate way to measure central obesity is by magnetic resonance imaging or computer-assisted tomography scanning, but this approach is too expensive for routine use. Simple anthropometric measurements can be used, such as waist circumference. A waist circumference of greater than 1020 mm in men and 880 mm in women is a risk factor for insulin resistance, diabetes mellitus and cardiovascular disease. There is a clear genetic predisposition for obesity. The genetic contribution to obesity is between 25 and 40 % of the individual differences in BMI. For the overwhelming majority of individuals, the genetic predisposition will not be defined by one gene, but by multiple genes. Eventually, classification of obesity may be done by genetic means, but this approach will require more knowledge.

The activity of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system in relation to waist/hip circumference ratio in men

OBJECTIVE

To investigate possible differences, between generally and abdominally obese men, in activity and regulation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system.

RESEARCH METHODS AND PROCEDURES

Fifty non-diabetic, middle-aged men were selected to obtain two groups with similar body mass index (BMI) but different waist/hip circumference ratio (WHR). Measurements were performed of the activity of the HPA axis and the sympathetic nervous system, as well as metabolic and endocrine variables.

RESULTS

Men with a high WHR, in comparisons with men with a low WHR, had higher insulin, glucose, and triglyceride values in the basal state and higher glucose and insulin after an oral glucose tolerance test. Men with high WHR had elevated diurnal adrenocorticotropic hormone (ACTH) values but similar cortisol values, except lower cortisol values in the morning. Diurnal growth hormone concentrations showed reduced peak size. Stimulation of the HPA axis with corticotropin-releasing hormone (CRH) and laboratory stress showed no difference in ACTH values between groups, but cortisol values were lower in men with high WHR. In comparison with men with a low WHR, men with a high WHR had elevated pulse pressure and heart rate in the basal state and after challenges by CRH and laboratory stress. They also had increased urinary excretion of catecholamine metabolites.

DISCUSSION

These results suggest a mild dysregulation of the HPA axis, occurring with elevated WHR independent of the BMI. The results also indicate a central activation of the sympathetic nervous system, such as in the early phases of hypertension, correlating with insulin resistance.

Obesity and cortisol

Cortisol in obesity is a much-studied problem. Previous information indicates that cortisol secretion is elevated but that circulatory concentrations are normal or low, suggesting that peripheral disappearance rate is elevated. These studies have usually not taken into account the difference between central and peripheral types of obesity. Recent studies using saliva cortisol have indicated that the problem is complex with both high and low secretion of cortisol, perhaps depending on the status of the function of the hypothalamic-pituitary-adrenal gland axis. A significant background factor seems to be environmental stress. The results also suggest that the pattern of cortisol secretion may be important. Other neuroendocrine pathways are also involved, including the central sympathetic nervous system, the gonadal and growth hormone axes, and the leptin system. In concert, these abnormalities seem to be responsible for the abnormal metabolism often seen in central obesity. Several associated polymorphisms of candidate genes may provide a genetic background. Cortisol conversion to inactive metabolites may be a factor increasing central signals to secretion and may add to the increased secretion of cortisol induced by centrally acting factors. Perinatal factors have been found to be involved in the pathogenesis of obesity and its complications. The mechanism involved is not known, but available information suggests that programming of the hypothalamic-pituitary-adrenal axis may be responsible.

Hypertension and the metabolic syndrome: closely related central origin?

In primary hypertension a mild hyperresponsiveness of hypothalamic, sympatho-hormonal centres to psychosocial stimuli forms a major pathogenetic element, although high salt intake in some subjects may contribute via volume expansion. Hypertension is often associated with another "civilisation" disorder, the metabolic syndrome, defined as abdominal obesity, insulin resistance and dyslipidaemia. According to recent research, the metabolic syndrome has in all likelihood a central neuroendocrine origin in the form of enhanced engagement of the hypothalamic-pituitary-adrenal (HPA) axis. Here the peripheral endocrine perturbations act as triggers for both central obesity and the metabolic abnormalities. The reaction pattern characterising early primary hypertension is identical with, or closely related to, the "defence reaction", while that leading to the metabolic syndrome is similar to that of the "defeat reaction". Both belong to the primitive survival reactions, common to all mammals, though man can control, or at least mask, his outward-behavioural part but not the neuro-hormonal expressions. Animal experiments show how frequent or chronic mental challenges are capable of engaging these limbic-hypothalamic centres, affecting blood pressure regulation as well as endocrine-metabolic regulation. Furthermore, these centres are tightly coupled functionally, and their signals to the periphery often combined. On a long-term basis their engagements appear to be decisive for the development of both primary hypertension and the metabolic syndrome, as suggested by intervention studies. In both these "disorders of civilisation", observations strongly indicate that psychosocial stress, socioeconomic handicaps, lack of exercise, abuse and also psychiatric traits are involved. Such factors, characteristic of current competitive society, probably cause mixed engagements of the two above-mentioned neuro-hormonal patterns, and thereby, with time, primary hypertension and the metabolic syndrome, with end-points such as coronary artery disease, diabetes mellitus type2 and stroke. Susceptibility to such developments is probably enhanced by genetic factors. This overview of recent developments therefore serves to emphasise how both primary hypertension and the metabolic syndrome seem to have a common central origin. Central regulatory factors are often overlooked, partly because it is not realised that limbic-hypothalamic centres are the major regulators of both circulatory and metabolic events, and partly because of the long period of time required before these disease end-points are reached.

Visceral adipose tissue is an independent correlate of glucose disposal in older obese postmenopausal women

Older obese postmenopausal women have an increased risk for type 2 diabetes and cardiovascular disease. Increased abdominal obesity may contribute to these comorbidities. There is considerable controversy, however, regarding the effects of visceral adipose tissue as a singular predictor of insulin resistance compared to the other constituents of adiposity. To address this issue, we examined the independent association of regional adiposity and total fat mass with glucose disposal in obese older postmenopausal women. A secondary objective examined the association between glucose disposal with markers of skeletal muscle fat content (muscle attenuation) and physical activity levels. We studied 44 healthy obese postmenopausal women between 50 and 71 yr of age (mean +/- SD, 56.5 +/- 5.3 yr). The rate of glucose disposal was measured using the euglycemic/hyperinsulinemic clamp technique. Visceral and sc adipose tissue areas and midthigh muscle attenuation were measured from computed tomography. Fat mass and lean body mass were estimated from dual energy x-ray absorptiometry. Peak VO2 was measured from a treadmill test to volitional fatigue. Physical activity energy expenditure was measured from indirect calorimetry and doubly labeled water. Pearson correlations indicated that glucose disposal was inversely related to visceral adipose tissue area (r = -0.40; P < 0.01), but not to sc adipose tissue area (r = 0.17), total fat mass (r = 0.05), midthigh muscle attenuation (r = 0.01), peak VO2 (r = -0.22), or physical activity energy expenditure (r = -0.01). The significant association persisted after adjusting visceral adipose tissue for fat mass and abdominal sc adipose tissue levels (r = -0.45; P < 0.005; in both cases). Additional analyses matched two groups of women for fat mass, but with different visceral adipose tissue levels. Results showed that obese women with high visceral adipose tissue levels (283 +/- 59 vs. 137 +/- 24 cm2; P < 0.0001) had a lower glucose disposal per kg lean body mass compared to those with low visceral adipose tissue levels (0.44 +/- 0.14 vs. 0.66 +/- 0.28 mmol/kg x min; P < 0.05). Visceral adipose tissue is an important and independent predictor of glucose disposal, whereas markers of skeletal muscle fat content or physical activity exhibit little association in obese postmenopausal women.

Measures of body composition in blacks and whites: a comparative review

Biological differences exist in the body composition of blacks and whites. We reviewed literature on the differences and similarities between the 2 races relative to fat-free body mass (water, mineral, and protein), fat patterning, and body dimensions and proportions. In general, blacks have a greater bone mineral density and body protein content than do whites, resulting in a greater fat-free body density. Additionally, there are racial differences in the distribution of subcutaneous fat and the length of the limbs relative to the trunk. The possibility that these differences are a result of ethnicity rather than of race is also examined. Because most equations that predict relative body fat were derived from predominantly white samples, biological variation between the races in these body-composition indexes has practical significance. Systematic error can result in the inaccurate estimation of the relative body fat of blacks, and therefore of definitions of obesity, if these inherent differences are ignored.

A nine-month, placebo-controlled study of the effects of growth hormone treatment on lipoproteins and LDL size in abdominally obese men

Abdominal/visceral obesity is associated with blunted growth hormone (GH) secretion and an unfavourable lipoprotein pattern. In this study, the effect of GH treatment on LDL size and on serum lipoprotein concentrations was determined in abdominally obese men. Thirty men, aged 48-66 years, with a body mass index (BMI) of 25-35 kg/m(2)and a waist:hip ratio of >0.95, received treatment with GH (9. 5 microg/kg/day) or placebo for 9 months. Serum concentrations of total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C) and apolipoprotein B (apoB) were reduced (P<0.05, P<0.05 and P<0.001 vs placebo, respectively). Serum lipoprotein(a) [Lp(a)] concentration increased (P<0.05 vs. placebo). Mean low density lipoprotein (LDL) particle diameter was marginally increased by active treatment as compared with placebo (P =0.08). No changes were observed in the serum concentrations of high density lipoprotein-cholesterol (HDL-C), apolipoprotein A-I (apoA-I) and apolipoprotein E (apoE). In conclusion, 9 months of GH treatment in abdominally obese men beneficially reduced serum concentrations of TC, LDL-C and apoB, and marginally increased mean LDL diameter, while serum Lp(a) increased. The ultimate effect of GH therapy on the cardiovascular risk remains, however, to be determined.

A glucocorticoid receptor gene marker is associated with abdominal obesity, leptin, and dysregulation of the hypothalamic-pituitary-adrenal axis

OBJECTIVE

Abdominal obesity has a key role in the pathogenesis of prevalent and serious diseases and has been shown to be associated with an altered hypothalamic-pituitary-adrenal (HPA) axis function, which is regulated by endocrine feedback mediated via hippocampal glucocorticoid receptors (GR).

RESEARCH METHODS AND PROCEDURES

We examined the HPA axis function by repeated salivary samples for the assessment of cortisol, as well as other endocrine, anthropometric, metabolic, and circulatory variables in middle-aged Swedish men (n = 284). With the restriction enzyme BclI, variants of the GR gene (GRL) locus were identified and two alleles with fragment lengths of 4.5 and 2.3 kilobases (kb) were detected.

RESULTS

The observed frequencies were 40.1% for the 2.3- and 2.3-kb, 46.2% for the 4.5- and 2.3-kb, and 13.7% for the 4.5- and 4.5-kb genotypes. The larger allele (4.5 and 4.5 kb) was associated with elevated body mass index (BMI; p < 0.001), waist-to-hip circumference ratio (p = 0.015), abdominal sagittal diameter (p = 0.002), leptin (p < 0.001), and systolic blood pressure (borderline, p = 0.058). The 4.5- and 4.5-kb allele was associated with leptin after adjustment for BMI. Moreover, salivary cortisol values, particularly after stimulation by a standardized lunch (p = 0.040 to 0.086), were elevated in the men with the larger allele.

DISCUSSION

These results indicate that there is an association between a deficient GR function, defined as a poor feedback regulation of the HPA axis activity, and a polymorphic restriction site at the GR gene locus. An abnormal control of HPA axis function due to genetic alterations may contribute to the pathogenesis of abdominal obesity.

Gender-related behavior during childhood and associations with adult abdominal obesity: a nested case-control study in women

Abdominal obesity affects many aspects of women's health, and recent studies indicate that hyperandrogenicity (HA) may contribute to the excess of body fat in women. As hormone behavior research attributes male-like play patterns in childhood to the effects of androgens, the aim of the present study was to assess the potential association of such behavior with obesity in adult women. In a randomly selected sample of 40-year-old women (n = 1464), 78% volunteered to respond to a questionnaire collecting information on the effect of other variables on childhood behavior. Self-reported body weight, height, and waist and hip circumferences were used to calculate body mass index (BMI) and waist/hip ratio (WHR). Age at menarche showed an inverse association with overweight (BMI > or = 25) (odds ratio [OR] = 0.82). Reports of gender-related behavior as a child showed that playing with girls and girl toys was negatively related to both overweight and abdominal obesity (WHR > or = 0.85). Among respondents who were overweight, relationships were found for playing with boys (OR = 0.90) and fighting (OR = 1.70). The OR of playing with boy toys and fighting among respondents with abdominal obesity were increased 1.12 and 1.65, respectively. Interests in athletics as a child seemed to decrease the risk for overweight (OR = 0.89) and abdominal obesity (OR = 0.91). Furthermore, dose-response analysis between the individual exposure levels and the OR for overweight showed a negative trend for playing with girls (p = 0.002) and girl toys (p = 0.017) and a positive trend for playing with boys (p = 0.011) and fighting (p = 0.031). Among respondents with abdominal obesity, positive dose-response effects were found for playing with boys (p = 0.026) and boy toys (p = 0.036) and fighting (p = 0.008). Thus, women with an elevated WHR showed a preference to play with boys and boy toys and also fought frequently as children. This might be a sign of a relative HA in childhood ("tomboyism"). These preliminary observations suggest that HA may originate in childhood.

New developments in obesity

Obesity is an important health problem. Worldwide epidemiological data show that its frequency is rising steeply, probably because of a reduction in physical activity and bad eating habits. Health risks are most prominent in the central type of obesity, due to the relatively increased lipolytic activity, which leads to a series of events. The overall results of treatment are not satisfactory. Drugs, such as orlistat, fluoxetine, and ephedrine/caffeine, may be useful. The first results with leptin treatment are encouraging, but not yet optimal. Research on various neuropeptides and beta3-agonists is promising. Prevention of obesity is extremely important but difficult.

Food-induced cortisol secretion in relation to anthropometric, metabolic and haemodynamic variables in men

OBJECTIVE

To assess the relationships between the regulation of diurnal and food-induced cortisol secretion and anthropometric, metabolic and haemodynamic variables in middle-aged men.

SUBJECTS AND METHOD

Salivary cortisols were collected repeatedly (n = 7) over an ordinary working day (8a.m. to 11 p.m.) in a randomly selected population of 284 men, aged 51 y. A standardized lunch was provided, and an overnight low-dose dexamethasone suppression test was performed. These measurements were correlate with the anthropometric factors-body mass index, BMI, (kg/m2), waist-to-hip ratio (WHR) and abdominal sagittal diameter; the metabolic factors-fasting insulin and glucose as well as their ratio, and triglycerides; and the haemodynamic factors-systolic and diastolic blood pressures and heart rate.

RESULTS

As reported previously two principal types of salivary cortisol secretory patterns can be singled out, one characterized by high morning cortisol levels, a normal circadian rhythm and feedback regulation (dexamethasone) along with a brisk cortisol response to lunch, and another, found in a limited number of men, characterized by low morning cortisols, the absence of a circadian rhythm, a relative resistance to dexamethasone inhibition and a poor lunch-induced cortisol response. The normal cortisol secretory pattern showed negative associations with BMI (P< 0.05), WHR (P< 0.01), and blood pressures (P< 0.001). After stimulation by food intake, negative relationships were found with all obesity measurements, insulin, insulin/glucose ratio, triglycerides, blood pressures and heart rate (all P < 0.001). These results suggest that normally regulated cortisol is associated with a favourable somatic health. In contrast, after food intake cortisol secretion, based on an abnormal cortisol secretory pattern, showed consistent positive associations with obesity measurements, insulin, glucose and insulin/glucose ratio, triglycerides, blood pressures and heart rate (all P < 0.001).

CONCLUSIONS

A normal HPA axis regulation is associated with excellent health anthropometric, metabolic and haemodynamic variables, particularly visible after the physiological stimulus of food intake. This is, however, not the case in men with perturbed HPA axis function where associations in these somatic variables become exaggerated by food intake. We have previously reported that perceived stress-related cortisol is associated with abnormalities in the variables mentioned above, both with a normal and, particularly, with an abnormal function of the HPA axis. It is thus apparent that perceived stress and food intake show separate associations to somatic variables with a normally functioning HPA axis, while with an abnormal regulation of this axis both perceived stress and food intake exaggerate associations to abnormal somatic variables.

Obesity, body fat distribution, and coronary artery disease

Obesity is an independent risk factor for the development of coronary artery disease (CAD). Obesity also increases risk for CAD indirectly through its association with insulin resistance, hyperlipidemia, and hypertension. An increased accumulation of fat in the intraabdominal cavity, termed visceral adiposity, is highly correlated with an adverse coronary risk profile. In patients at risk for coronary artery disease, the treatment of obesity results in an improved coronary risk profile. The prevalence of obesity is extremely high in coronary populations, yet the effect of weight loss on cardiovascular outcomes in CAD patients has received relatively little attention. Observational studies in the cardiac rehabilitation setting showed that patients who lose weight and exercise show an improvement in coronary risk profile. Further research is needed to better define the clinical effectiveness of weight loss programs and their benefits in coronary patients.