Serum leptin in elderly people: associations with sex hormones, insulin, and adipose tissue volumes

OBJECTIVE: There are few data for associations of serum leptin with body fat, fat distribution, sex hormones, or fasting insulin in elderly adults. We hypothesized that the sex difference in serum leptin concentrations would disappear after adjustment for subcutaneous, but not visceral body fat. Serum leptin would not be associated with sex hormone concentrations or serum fasting insulin after adjusting for body fat and fat distribution. RESEARCH METHODS AND PROCEDURES: Subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) volumes were measured using magnetic resonance imaging in a cross-sectional sample of 56 nondiabetic, elderly men and women aged 64 years to 94 years. Serum leptin, sex hormones (testosterone and estrone), sex hormone-binding globulin, and fasting insulin were also measured. Nine women were taking hormone replacement, and five men were clinically hypogonadal. RESULTS: Leptin was significantly associated with both SAT and VAT in each sex. Adjustment for SAT reduced the sex difference in leptin by 56%, but adjustment for VAT increased the difference by 25%. Leptin was not associated with serum estrone or hormone replacement therapy in the women, but had a significant, negative association with testosterone in the men that was independent of SAT, but not VAT. Leptin was significantly associated with fasting insulin in both sexes independent of age, sex hormones, sex hormone-binding globulin, VAT and SAT. DISCUSSION: Sex difference in serum leptin is partly explained by different amounts of SAT. Studies including both men and women should adjust for SAT rather than total body fat that includes VAT. The sex difference in serum leptin is not due to estrogen, but may be partly explained by testosterone. Testosterone is negatively associated with leptin in men, but the association is confounded with VAT. Leptin is associated with fasting insulin in nondiabetic elderly men and women independent of body fat, fat distribution, or sex hormones.     

Leptin and body composition in healthy postmenopausal women

BACKGROUND: Leptin has been proposed to be involved in central control of adiposity and fat distribution but the role of this peptide is controversial. The aim of our study was to test the relationship between serum leptin and body composition, fat distribution, and some biochemical markers such as fasting insulinemia and lipoproteins in a population of healthy Italian postmenopausal women. METHODS: One hundred and twenty-three postmenopausal women (62.1+/-8.7 years) were evaluated. Body composition (fat and lean mass) was assessed by dual-energy X-ray absorptiometry (DXA). Two regions of interest were determined for regional fat analysis. Serum leptin and insulinemia were measured by radioimmunoassay, lipoproteins with colorimetric methods and apolipoproteins nephelometrically. RESULTS: Plasma leptin levels are strongly related to total fat mass, in grams (r=0.73, p<0.001) or as a percentage of soft tissue (r=0.75, p<0.001), and to adiposity, calculated as ratio between lean and fat mass (r=0.76, p<0.001). A significant correlation was also found between serum leptin and central fat distribution (r=0.29, p<0.01). As concerns biochemical markers, serum leptin was significantly related to fasting insulin (r=0.38, p<0.001), total cholesterol (r=0.29, p<0.01), Apolipoprotein-B (r=0.35, p<0.001), and triglycerides (r=0.22, p<0.05). When corrected for total fat mass, the partial correlation coefficients remain significant for percentage of total body fat (r=0.27, p<0.01), adiposity (r=0.23, p<0.01), and fat proportion in android region (r=0.18, p<0.05). CONCLUSIONS: These data indicate that leptin levels are related to adiposity and fasting insulin levels; indeed fast insulin mantains significant correlation with leptin (r=0.23, p<0.01) after controlling for fat mass. Android distribution of fat mass in elderly women is associated with leptin concentration.     

Cigarette smoking and fat distribution in 21,828 British men and women: a population-based study

OBJECTIVE: To examine the relationship between cigarette smoking habits and fat distribution in a population-based cohort of men and women. RESEARCH METHODS AND PROCEDURES: We analyzed cross-sectional data from 21,828 men and women who were 45 to 79 years of age, residents in Norfolk, United Kingdom, and were recruited between 1993 and 1997. Cigarette smoking habits and other lifestyle factors were assessed using self-reported questionnaires. Anthropometric measures were obtained during a health examination. RESULTS: Waist-hip ratio was highest among current smokers and least among never smokers after adjusting for age, BMI, alcohol intake, total energy intake, physical activity, and education. Higher waist-hip ratio was directly associated with higher smoking pack-years in current and former smokers and inversely with duration since quitting smoking in former smokers. Adjusting for age, BMI, and other covariates, current smokers had higher waist circumference but lower hip circumference compared with former or never smokers. DISCUSSION: Cigarette smoking habits seem to influence fat distribution patterns. Although smokers have lower mean BMI compared with nonsmokers, they have a more metabolically adverse fat distribution profile, with higher central adiposity. The explanation for this association may help elucidate the mechanisms underlying the adverse health consequences of cigarette smoking and abdominal obesity.     

Impact of age on leptin and adiponectin independent of adiposity

Age-related changes in leptin and adiponectin levels remain controversial, being affected by inconsistent normalisation for adiposity and body fat distribution in the literature. In a cross-sectional study on 210 Caucasians (127 women, eighty-three men, 18-78 years, BMI 16.8-46.8 kg/m2), we investigated the effect of age on adipokine levels independent of fat mass (FM measured by densitometry), visceral and subcutaneous adipose tissue volumes (VAT and SAT assessed by whole-body MRI). Adiponectin levels increased with age in both sexes, whereas leptin levels decreased with age in women only. There was an age-related increase in VAT (as a percentage of total adipose tissue, VAT%TAT), associated with a decrease in SAT(legs)%TAT. Adiposity was the main predictor of leptin levels, with 75.1 % of the variance explained by %FM in women and 76.6 % in men. Independent of adiposity, age had a minor contribution to the variance in leptin levels (5.2 % in women only). The variance in adiponectin levels explained by age was 14.1 % in women and 5.1 % in men. In addition, independent and inverse contributions to the variance in adiponectin levels were found for truncal SAT (explaining additional 3.0 % in women and 9.1 % in men) and VAT%TAT (explaining additional 13.0 % in men). In conclusion, age-related changes in leptin and adiponectin levels are opposite to each other and partly independent of adiposity and body fat distribution. Normalisation for adiposity but not for body fat distribution is required for leptin. Adiponectin levels are adversely affected by subcutaneous and visceral trunk fat.     

Body fat, caloric intake, and plasma leptin levels in women with anorexia nervosa.

OBJECTIVE: To measure serum leptin concentrations in women with anorexia nervosa (AN) and to identify independent predictors of leptin levels, thereby allowing hormone levels to be modeled using regression analysis. METHODS: A cross-sectional study of 15 AN inpatients and 16 healthy control subjects. Age, height, weight, percent body fat, total caloric intake, fat intake, and fasting plasma leptin levels were recorded. Stepwise forward regression analysis was carried out to identify predictors of leptin levels. RESULTS: Circulating leptin concentrations in AN were 3.5+/-0.5 versus 7.6+/-1.2 ng/ml in control subjects. Percent body fat correlated best with leptin levels in anorexic and control subjects (r =.63; p =.0002), with caloric intake showing only a moderate correlation (r = .47; p = .008). Only percent body fat was a significant predictor of plasma leptin levels in our regression model. DISCUSSION: Leptin levels are proportionately lower in AN as compared to healthy controls. It appears that physiological regulation of plasma levels with respect to percent body fat is maintained in individuals with little body fat.     

Association of total and central adiposity measures with fasting insulin in a biracial population of young adults with normal glucose tolerance: the CARDIA study.

OBJECTIVE: To determine the association of computed tomography (CT)-measured visceral adipose tissue (AT) and other measures of adiposity with fasting insulin in a biracial (African American and Caucasian) study population of young adults. RESEARCH METHODS AND PROCEDURES: The study population consisted of 251 young adults with normal glucose tolerance (NGT), ages 28-40 years, who were volunteers from the Birmingham, Alabama, and Oakland, California centers of the Coronary Artery Risk Development in Young Adults (CARDIA) study. RESULTS: In regression models with total adiposity measures (body mass index or dual-energy X-ray absorptiometry-measured percent fat), visceral AT (measured as a cross-sectional area in cm2) was generally a stronger predictor of insulin than overall adiposity in all race/gender groups (partial correlation coefficients ranging from 0.31 to 0.47) except for black men, in whom the associations were nonsignificant. Partial correlation coefficients between waist circumference and insulin, controlling for percent fat, were nearly identical to those between visceral AT and insulin in women and in white men. Analyses performed on 2060 NGT CARDIA subjects who were not in this study of visceral AT showed significant correlations of waist circumference with insulin in all race/gender groups, including black men, and that black men in the visceral AT study group were significantly leaner than other black male CARDIA subjects. DISCUSSION: We conclude that visceral AT was associated with fasting insulin in NGT participants in three of the four race/gender groups (black men excepted) and that waist circumference was a good surrogate for visceral AT in examining associations of central adiposity with fasting insulin.     

Serum leptin concentrations and body adipose measures in older black and white adults

BACKGROUND: Among US adults, serum leptin concentrations are higher in women than in men and are higher in blacks than in whites independent of anthropometric measures of body fatness. OBJECTIVE: Using radiographic measures of body fat, we determined the best correlates of leptin and whether adiposity can explain sex and race differences in leptin concentrations in older adults. DESIGN: This was a cross-sectional analysis of fasting serum leptin concentrations and body fat measured by dual-energy X-ray absorptiometry (DXA), abdominal computed tomography, and standard anthropometry in 3026 well-functioning 70-79-y-old participants (42% black, 51% women) of the Health, Aging, and Body Composition Study. RESULTS: Geometric mean (+/-SE) leptin concentrations (ng/mL) were higher in the women than in the men (16.5 +/- 0.3 and 5.7 +/- 0.1, respectively) and in the black women than in the white women (20.2 +/- 0.6 and 13.9 +/- 0.4, respectively), but did not differ significantly between the white and black men (5.8 +/- 0.2 and 5.5 +/- 0.2, respectively). Percentage fat estimated from DXA showed the highest correlation with leptin (R(2) = 0.56 for both sexes). Addition of abdominal visceral fat minimally increased the correlation. In the multivariate analysis, the association with sex was eliminated after adjustment for percentage fat and visceral fat in both whites (P = 0.051) and blacks (P = 0.34). Among women, higher leptin concentrations in blacks remained after adjustment for percentage fat and visceral fat (mean race difference = 4.95 ng/mL; P < 0.001). Among men, an association with black race emerged after adjustment for these factors (mean race difference = 1.42 ng/mL; P < 0.001). CONCLUSIONS: Among older adults, higher serum leptin concentrations in women are explained by a greater percentage of body fat. Higher leptin concentrations in blacks are not explained by percentage of body fat.     

Collection and interpretation of plasma leptin concentration data in humans.

OBJECTIVE: To reassess the relationship between body fat and plasma leptin concentrations when a) replicate measures of leptin are made; b) energy intake is controlled at isoenergetic levels before the study; and c) body fat and percent body fat are measured with dual energy X-ray absorptiometry (DXA). RESEARCH METHODS AND PROCEDURES: Two separate studies were conducted. In the first study, four plasma samples were collected for measurement of leptin over 30 minutes on a single day in 43 lean and obese men and women. For the second study, plasma samples were collected on four consecutive days from a group of 50 lean and obese men and women. Percent body fat (and body fat mass) was related to log-transformed mean plasma leptin concentrations using linear regression analysis; multiple linear regression analysis was used to determine whether there was an effect of gender on this relationship, and the analysis of Choi was used to examine whether percent body fat or body fat mass better predicts plasma leptin concentrations. RESULTS: For the first study, percent body fat was highly correlated (r=0.96, p<0.0001) with log-transformed mean leptin concentrations. No difference in the relationship between leptin and percent body fat in men and women was detected. The second study confirmed this observation; the relationship between ln leptin and percent body fat was virtually identical (r=0.93, p<0.001). Analysis of the pooled data suggests that percent body fat is a better predictor of plasma leptin concentration than body fat mass. The use of multiple (as opposed to a single) leptin measurements did not significantly improve the leptin/body fat relationship. DISCUSSION: When robust body composition techniques and diet control measures are taken into consideration, the relationship between ln plasma leptin concentrations and percent body fat is not different in men and women.     

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

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

Dietary fiber and associations with adiposity and fasting insulin among college students with plausible dietary reports

ObjectiveWe examined dietary fiber intake, food sources of dietary fiber, and relation of dietary fiber to body composition and metabolic parameters in college students with plausible dietary reports.MethodsStudents (18–24 y of age) provided data on anthropometry, fasting blood chemistries, and body composition (bioelectric impedance). Diet and physical activity were assessed with the Diet History Questionnaire and the International Physical Activity Questionnaire. Plausible dietary reporters were identified (±1 SD cutoffs for reported energy intake as a percentage of predicted energy requirement). Multiple regression analyses were conducted with the total (n = 298) and plausible (n = 123) samples, adjusting for age, race, sex, smoking status, physical activity, energy intake, and fat-free mass (where applicable).ResultsFood sources of dietary fiber were similar in men and women. In the plausible sample compared with the total sample, dietary fiber was more strongly associated with fat mass (β = ?0.24, P < 0.001), percentage of body fat (β = ?0.23, P < 0.001), body mass index (β = ?0.11, P < 0.01), waist circumference (β = ?0.67, P < 0.05), and fasting insulin (β = ?0.15, P < 0.001). When the effect of sex was investigated, dietary fiber was inversely related to fasting insulin and fat mass in men and women and inversely related to percentage of body fat, body mass index, and waist circumference in men only (P < 0.05).ConclusionInclusion of implausible dietary reports may result in spurious or weakened diet–health associations. Dietary fiber is negatively associated with fasting insulin levels in men and women and consistently associated with adiposity measurements in men.     

Obesity and body fat distribution in relation to the incidence of non-insulin-dependent diabetes mellitus. A prospective cohort study of men in the normative aging study.

The relation between the abdominal accumulation of body fat, total-body adiposity, and blood glucose level and the risk of non-insulin-dependent diabetes mellitus was evaluated prospectively among 1,972 male participants in the Department of Veterans Affairs Normative Aging Study cohort. The risk of non-insulin-dependent diabetes mellitus was assessed by means of the proportional hazards model; 226 cases of diabetes occurred among the 1,972 men (mean age at entry, 41.9 years; range, 22-80 years) over 35,496 person-years of observation. The relation of body mass index to diabetes risk was partly explained by body fat distribution; after adjusting for age, the ratio of abdominal circumference to hip breadth, and cigarette smoking, men in the top tertile for body mass index had a 1.3-fold greater risk of diabetes than did men in the lowest tertile (95% confidence interval 0.9-1.8). Moreover, after adjusting for age, body mass index, and cigarette smoking, men in the top tertile for the ratio of abdominal circumference to hip breadth had a 2.4-fold greater risk of diabetes than did men in the lowest tertile (95% confidence interval 1.7-3.7). When blood glucose was analyzed as a continuous outcome variable, the findings were consistent, i.e., a positive association with abdominal fat independent of total-body adiposity. These results confirm previous reports of a prospective relation between abdominal adiposity and the risk of diabetes and provide prospective evidence of a relation between blood glucose levels and both body fat distribution and obesity.     

Association of sex, adiposity, and diet with HDL subclasses in middle-aged Chinese.

BACKGROUND: There is limited information regarding the associations of lifestyle factors and sex with HDL subclasses containing apolipoprotein (apo) A-I (Lp A-I) and both apo A-I and apo A-II (Lp A-I:A-II). OBJECTIVE: We sought to examine the relations between 2 major HDL subclasses and sex, menopausal status, nutrient intakes, and adiposity. DESIGN: We conducted interviews and measured blood variables in 409 government employees aged 40-59 y in Taiwan. RESULTS: Women (n = 203) had significantly higher concentrations of HDL cholesterol, Lp A-I, and Lp A-I:A-II than did men (n = 206). Postmenopausal women (n = 72) had higher concentrations of HDL cholesterol, Lp A-I, and Lp A-I:A-II than did premenopausal women (n = 131). Body mass index and waist-to-hip ratio were strong predictors of and exerted an independent additive effect on Lp A-I concentrations in both men and women. However, body adiposity was associated with Lp A-I:A-II concentrations only in men. Waist-to-hip ratio was an independent determinant of Lp A-I but not of Lp A-I:A-II in men and postmenopausal women after adjustment for age, body mass index, smoking, and diet. Although there were relatively weak associations between dietary factors and both HDL subclasses (r = 0.01-0.26) in men and women according to bivariate analyses, multiple regression models showed that total fat, saturated fat, and cholesterol intakes were significantly correlated with HDL cholesterol and both Lp A-I and Lp A-I:A-II in men, but not in women. CONCLUSION: Our data suggest that body adiposity and dietary fat consumption affect 2 major HDL subclasses differently depending on subject sex and menopausal status.     

Relation of plasma leptin concentrations to sex, body fat, dietary intake, and peak oxygen uptake in young adult women and men

The purpose of this study was to examine the relation of leptin to metabolic and dietary factors in college-age adults. Young adult women and men (n = 32) were recruited and underwent testing for measurement of body mass index, body composition, peak oxygen consumption (VO2peak), dietary intake, and plasma levels of leptin and insulin. Ln leptin was significantly greater for women than for men (2.1 versus 1.2 ng/mL, respectively). This difference remained significant even after adjusting ln leptin for fat mass and fat-free mass as covariates in separate analyses. VO2peak was higher for men than for women and this remained significant after adjustment for differences in fat-free mass and total body mass. Significant correlations were found between ln leptin and indicators of fat mass in women and men, with higher correlations for similar variables observed in men (r = 0.548, 0.674, and 0.732 for body mass index, percentage of body fat, and fat mass [kg] for women, respectively, and r = 0.740, 0.888, 0.858 for body mass index, percentage of body fat, and fat mass [kg] for men, respectively). Ln leptin showed a significant inverse relationship with VO2peak (r = -0.751) in men only. After adjusting ln leptin for body fat mass using partial correlations, ln leptin was not significantly associated with any of the measured variables. Alternatively, after normalization of ln leptin using fat mass as the divisor, a less adequate statistical analysis method, men showed statistical significant correlations between ln leptin and dietary intake and VO2peak. Although plasma leptin values were higher in women, stronger associations were evident for men than for women between leptin and metabolic and dietary factors.     

Percent body fat and lean mass explain the gender difference in leptin: analysis and interpretation of leptin in Hispanic and non-Hispanic white adults

OBJECTIVE: To reassess the relationship between body fat and fasting leptin concentrations comparing plasma vs. serum assessments of leptin; ratios vs. regression adjustment for body composition; fat and lean mass vs. percent body fat; and gender-, ethnic-, and age-related variations. RESEARCH METHODS AND PROCEDURES: Subjects included 766 adults from the nondiabetic cohort of the San Luis Valley Diabetes Study examined at follow up (1997 to 1998). Body composition was determined by dual energy X-ray absorptiometry. Leptin concentrations were determined after an overnight fast. RESULTS: Fasting serum and plasma assessments of leptin were correlated with percent body fat to the same degree. Women had significantly higher serum leptin concentrations than men when leptin concentrations were divided by body mass index, fat mass in kilograms or percent body fat. The methodological problem inherent in interpreting these ratio measures is pictorially demonstrated. In regression analysis, fat mass alone did not explain the gender difference. However, lean body mass was inversely related to leptin concentrations (p < 0.0001) and explained 71% of the gender difference at a given fat mass. Percent body fat explained all of the gender difference in leptin concentrations in both Hispanics and non-Hispanic whites. Similar to findings about gender differences, ethnic- and age-related variations in the leptin-body fat association were minimized when percent body fat was employed as the body fat measure. DISCUSSION: Regression analysis and percent body fat measured with dual energy X-ray absorptiometry are recommended when assessing the relationship between leptin and body fat. Gender differences in leptin concentrations were accounted for by percent body fat in free living (no diet control), Hispanic and non-Hispanic white adults.     

Dietary glycemic index and load, measures of glucose metabolism, and body fat distribution in older adults

BACKGROUND: Recent evidence suggests that the rate of carbohydrate digestion and absorption may influence the development of type 2 diabetes. OBJECTIVE: The aim of this study was to examine associations of dietary glycemic index and glycemic load with predictors of type 2 diabetes in older adults. DESIGN: This study evaluated cross-sectional relations of dietary glycemic index and glycemic load with measures of glucose metabolism and body fat distribution in participants of the Health, Aging and Body Composition Study, a prospective cohort study of adults aged 70-80 y (n = 2248). RESULTS: In men, dietary glycemic index was positively associated with 2-h glucose (P for trend = 0.04) and fasting insulin (P for trend = 0.004), inversely associated with thigh intramuscular fat (P for trend = 0.02), and not significantly associated with fasting glucose, glycated hemoglobin, or visceral abdominal fat. Dietary glycemic load was inversely associated in men with visceral abdominal fat (P for trend = 0.02) and not significantly associated with fasting glucose, 2-h glucose, glycated hemoglobin, fasting insulin, or thigh intramuscular fat. In women, although dietary glycemic index and load were not significantly related to any measures of glucose metabolism or body fat distribution, the association between dietary glycemic index and 2-h glucose was nearly significant (P for trend = 0.06). CONCLUSION: The findings of this cross-sectional study indicate an association between dietary glycemic index and selected predictors of type 2 diabetes in older adults, particularly in men.     

Role of leptin in women with eating disorders.

OBJECTIVE: This study investigated the role of leptin on eating behavior and reproductive function in eating disorders. METHOD: The subjects included 80 eating-disordered women, having different fat mass, eating behavior, and endocrine abnormalities, and 26 control women. Plasma leptin, insulin, luteinizing hormone (LH), follicle-stimulating hormone (FSH), cortisol, insulin growth factor-1 (IGF-1), free T4 levels, percent body fat, eating behavior score, and menstrual status score were evaluated for each subject. RESULTS: In eating-disordered patients, log of leptin levels were significantly correlated with body fat mass, eating behavior score, menstrual status score, and insulin, LH, and FSH levels. Stepwise regression analysis showed that fat mass and eating behavior score were significant determinants of leptin levels. Furthermore, in patients undergoing recovery, leptin levels were determined by fat mass and/or eating behavior. DISCUSSION: These results suggest that leptin may play some role in counteracting the abnormal eating behavior, reproductive function, and fat mass in these disorders.     

Serum concentrations of beta-carotene and alpha-tocopherol are associated with diet, smoking, and general and central adiposity

BACKGROUND: Previous studies of associations between diet, obesity, and blood concentrations of alpha-tocopherol and beta-carotene have been equivocal. Furthermore, most studies used only body mass index (BMI) as an obesity measure. OBJECTIVES: Our objectives were to examine the associations between energy and nutrient intakes, alcohol consumption, tobacco use, and serum cholesterol and serum concentrations of alpha-tocopherol and beta-carotene, and to examine the associations between different measures of general and central adiposity and serum concentrations of alpha-tocopherol and beta-carotene. DESIGN: This was a cross-sectional, population-based study of 253 men and 276 women aged 46-67 y. Nutrient data were collected by a modified diet history method. Measures of obesity included BMI, percentage of body fat (impedance analysis), waist-to-hip ratio, and waist circumference. The associations between serum nutrient concentrations and the other factors were examined by multiple linear regression. RESULTS: Twenty-one percent of men and 34% of women used antioxidant supplements. The mean BMI was 26.1 in men and 25.4 in women. Serum beta-carotene concentration was positively associated with serum cholesterol concentration, fiber intake, and beta-carotene intake, and negatively associated with smoking and all measures of obesity. In men, serum beta-carotene concentration was not significantly associated with central adiposity after adjustment for body fat. Serum alpha-tocopherol concentration was positively correlated with serum cholesterol, obesity, and vitamin E intake. In women, serum alpha-tocopherol concentration was also positively associated with intakes of ascorbic acid and selenium. Serum alpha-tocopherol concentration was associated with central adiposity after adjustment for body fat. CONCLUSION: Serum beta-carotene and alpha-tocopherol concentrations have different associations with diet, smoking, general adiposity, and central adiposity.     

Elevated atopy in healthy obese women

BACKGROUND: Allergic disorders, including asthma, have increased dramatically in the United States in the past 20 y. Epidemiologic studies have found body mass index (body weight in kg/height squared in m) to be a positive independent correlate of atopy in women but not in men. OBJECTIVE: We investigated the prevalence of atopy among healthy obese and nonobese women and its relation to fat mass (FM), insulin resistance, and plasma concentrations of 17beta-estradiol, interleukin 4 (IL-4), and leptin. DESIGN: A cross-sectional study of 21 obese (> or = 30% body fat) and 22 nonobese (< 30% body fat) women (18-41 y of age) was performed. The following measurements were taken: FM by plethysmography, total and specific immunoglobulin E (IgE) by automated immunosorbent analysis, and blood glucose, insulin, C-peptide, 17beta-estradiol, sex hormone-binding globulin, and IL-4. Insulin sensitivity was determined on the basis of the fasting insulin resistance index and with an oral-glucose-tolerance test. RESULTS: The frequency of specific IgE in the obese group was almost 3 times that in the nonobese group (P = 0.008). The total IgE concentration was not significantly different between groups. Plasma concentrations of 17beta-estradiol, the ratio of 17beta-estradiol to sex hormone-binding globulin, the fasting insulin resistance index, and C-peptide and leptin concentrations were higher in the obese than in the nonobese group (P < 0.05) after adjustment for oral contraceptive use. All factors correlated positively with FM. Logistic regression showed FM to be the only positive predictor of specific IgE (P = 0.01). CONCLUSION: The findings confirm a direct relation between obesity and a T helper 2 cell immune response in women.     

Body fat distribution, body composition, and respiratory function in elderly men

BACKGROUND: Most population studies have reported weak or nonsignificant associations between body mass index (BMI; in kg/m2) and lung function. OBJECTIVE: This study focused on the distinct effects of fat distribution and body composition on lung function and examined these relations in elderly men. DESIGN: The study was a cross-sectional evaluation of 2744 men aged 60-79 y who were free of cardiovascular disease and cancer and were drawn from general practices in 24 British towns. Anthropometric and body-composition [including fat mass (FM), fat-free mass (FFM), and percentage body fat (%BF) evaluated with bioelectric impedance] measurements were made, and lung function was examined by using spirometry. RESULTS: Height-standardized forced expiratory volume in 1 s (FEV1) was diminished only in lean (BMI < 22.5) and obese (BMI > or = 30) men, but forced vital capacity (FVC) tended to decrease with increasing BMI (P < 0.01). All other measures of adiposity [ie, waist circumference (WC), waist-hip ratio (WHR), FM, and %BF] were significantly and inversely related to FEV1 and FVC after adjustment for confounders, including age and cigarette smoking (all: P < 0.05). This was seen both in nonobese (BMI < 30) and obese men. FFM was positively associated with FEV1 (P = 0.03) and to a lesser extent with FVC. Higher BMI and FFM were both associated with reduced odds of a low FEV1-FVC ratio (ie, <70%). CONCLUSION: Total body fat and central adiposity are inversely associated with lung function, but increased FFM reflecting increases in muscle mass is associated with increased lung function and lower odds of low FEV1:FVC in the elderly.     

Adipose tissue resistin levels in patients with anorexia nervosa

OBJECTIVE: Resistin is a specific fat-derived hormone that affects fuel homeostasis and insulin action in rodents. However, its role in human physiology and pathophysiologic conditions, such as malnutrition, remains uncertain. METHODS: To enhance understanding of the role of resistin in the pathophysiology of anorexia nervosa (AN), we measured plasma resistin levels in 13 women with a restrictive type of AN and in 16 healthy age-matched women (control). Further, we measured resistin levels in the subcutaneous adipose tissue of eight women from the AN group and eight women from the control group with an in vivo microdialysis technique (CMA/107 pump, CMA/60 catheters, CMA Microdialysis AB, Solna, Sweden). RESULTS: Body mass index, percentage of body fat, fasting plasma leptin and insulin, and homeostasis model assessment index for insulin resistance were severely decreased in patients with AN compared with the control group. Plasma resistin levels were significantly decreased in patients with AN (P < 0.05), whereas subcutaneous adipose tissue resistin levels were significantly increased in patients with AN compared with the control group (P < 0.05). In both groups, plasma resistin levels showed no significant relation to resistin in dialysate, percentage of body fat, body mass index, homeostasis model assessment index for insulin resistance, and fasting plasma leptin levels. CONCLUSION: We demonstrated that AN is associated with decreased plasma resistin levels and increased resistin levels in extracellular space of the abdominal adipose tissue. Plasma resistin levels in patients with AN or in healthy normal-weight women were not directly related to body mass index, percentage of body fat, plasma leptin levels, and insulin sensitivity.