Associations of Body Mass and Body Fat Distribution with Parity Among African-American and Caucasian Women: The CARDIA Study

Associations of parity with body fat and its distribution are poorly understood; therefore, we examined the relationships between parity and obesity in young adult women. Body mass index (BMI), skin folds, and waist-hip ratio were compared in 1452 African-American and 1268 Caucasian nonpregnant women aged 18 to 30, adjusting for age (where no age-parity interactions were present), education, physical activity (assessed by questionnaire) and fitness (assessed by graded exercise test), dietary fat intake, alcohol and smoking. Adjusted mean BMI was significantly higher in African-American women aged 25–30 years with three or more children (28.5 kg/m²) than in those with two (27.0 kg/m²), one (26.2 kg/m²), or no children (26.3 kg/m²). Similar trends were found in Caucasians (BMI = 23.3, 23.4, 23.7, 25.0 kg/m² for parity = 0,1, 2, ≥ 3, respectively), but the mean BMI was significantly higher in African Americans in each parity group. The association between BMI and parity was not present among women 18–24 years of age. Skinfolds were directly associated with parity in African Americans only. Waist-hip ratios were generally lower among nulliparous than parous women in both ethnic groups; race differences were present only among nulliparas. In conclusion, parity was associated with BMI in women aged 25 to 30 years but did not explain ethnicity-related differences in body mass.     

Body Mass Index and Coronary Artery Disease in African-Americans

There are limited data available concerning the influence of obesity, a major cardiovascular disease risk factor, in relationship to coronary artery disease (CAD). This is of considerable importance to African-Americans since African-Americans have one of the world's highest CAD mortality rates coupled with the fact that obesity is extremely prevalent in this population. The present study assessed the relationship between body mass index and CAD in African-Americans undergoing coronary angiography. Eight hundred sixty-six available cardiac catheterization reports between the years 1983 through 1990 were retrospectively reviewed at Howard University Hospital in Washington, D.C. CAD was prevalent in 59.6% and 41.2%, males and females, respectively. Among the males overweight and obesity were found in 22.4% and 20.9%, respectively, compared to 39.6% and 30.6% for females. An upside-down U-shaped relationship between BMI and CAD was found. The interpretation of this finding is that being overweight is associated with increased risk of CAD compared to the lean and obese.     

Comparisons for Body Mass Index and Body Fat Percent Among Puerto Ricans,Blacks, Whites and Asians Living in the New York City Area

The latest data (NHANES III) from the National Center for Health Statistics (NCHS) show that the black population has the highest proportion of overweight among all adult populations in the United States. The present study compared the body mass index (BMI) and body fat percent from dual-photon absorptiometry in 1,324 healthy adults aged 18 to 107 years recruited from four ethnic groups in the New York City area; 523 whites, 280 blacks, 267 Asians and 254 Puerto Ricans. Puerto Ricans had the largest BMI and the largest percent of subjects with body weight more than 120% of their ideal weight, and the largest fat percent of the four ethnic groups: 76% of Puerto Rican males had fat percent above the median value for white males (fat percent = 19.6%) and 95% of Puerto Rican females had fat percent above the median for white females (fat percent = 30.8%). Asians had the smallest BMI, but 63% of them had fat percent above the median values for whites in each gender. Puerto Ricans also had the largest waist-to-hip ratios among the four ethnic groups. In blacks, the percent of subjects with fat percent larger than the median for whites was slightly smaller than that for Puerto Ricans, 64% and 82% of males and females respectively. These results differ from the latest NCHS data and show that Puerto Ricans in this sample are heavier and fatter than blacks.     

Body Composition Changes in Caucasian and African American Children and Adolescents with Obesity Using Dual-Energy X-ray Absorptiometry Measurements after a 10-Week Weight Loss Program

Objective : Changes in body composition during a weight loss program have not been described in children. We wanted to test the hypothesis that weight loss can be achieved while maintaining total body fat-free mass. Research Methods and Procedures : We determined body composition changes by using dual-energy X-ray absorptiometry measured at baseline and after the first 10 weeks of a multidisciphnary weight loss program. The program consisted of 10 weekly group sessions where the children were provided instruction in lifestyle modification, including diet and exercise. Program leaders included a pediatrician, psychologist, registered dietitian, and exercise instructor. Results : We studied 59 obese children, mean (± SD) age 12.8 ± 2.6 years, 29% boys and 71% girls, 49% Caucasian, and 51% African American. At enrollment, the children's mean height and body mass index were 157 cm and 38.9 kg/m², respectively. The children's dual-energy X-ray absorptiometry-derived mean at baseline and at 10 weeks and corresponding p values were: weight (94.6 kg vs. 92.3 kg, p<0.0001), total body fat mass (46.9 kg vs. 44.3 kg, p<0.0001), percentage total body fat (49.2% vs. 47.5%, p<0.0001), total trunk mass (43.0 kg vs. 41.5 kg,p<0.0001), total trunk fat (21.2 kg vs. 20.0 kg, p<0.0001), total body fat-free mass (47.6 kg vs. 47.9 kg, p = 0.33), total body bone mass (2.7 kg vs. 2.7 kg, p = 0.99), and total body bone mineral density (1.14 g/cm² vs. 1.15 g/cm², p = 0.0119). The children's race, gender, or Tanner stage did not affect these changes. Discussion : Decreases in total body fat mass was achieved, and total body fat-free mass was maintained among boy and girl Caucasian and African American children participating in this lifestyle modification weight loss program.     

Genetic and Behavioral Determinants of Waist-Hip Ratio and Waist Circumference in Women Twins

ROSE, KATHRYN M, BETH NEWMAN, ELIZABETH J. MAYER-DAVIS, JOSEPH V. SELBY. Genetic and behavioral determinants of waist-hip ratio and waist circumference in women twins. Obes Res. 1998;6:383–392. Objectives : This study examines genetic and behavioral determinants of waist-hip ratio (WHR) and waist circumference among women twins. Research Methods and Procedures : Six hundred eighty participants from the second examination of the Kaiser-Permanente Women Twins Study (1989 to 1990) were included. Women ranged in age from 31 to 90 years, and included 59% monozygotic and 41% dizygotic twins. Heritabilities of WHR and waist circumference were estimated (range = 0 to 1) using three different statistical methods. Linear regression models that adjusted for the lack of independence within twin pairs were used to assess associations between behavioral variables, WHR, and waist circumference. Results : Age and body mass index-adjusted heritability estimates ranged from 0.36 to 0.61 for WHR and 0.72 to 0.82 for waist circumference. When considered individually, after adjusting for age and body mass index, all behavioral characteristics, except calorie-adjusted fat intake, were significantly (p<0.10) associated with waist circumference and WHR. Greater central adiposity was associated with lower education, higher alcohol consumption, lower physical activity, current cigarette smoking, higher parity, and postmenopausal status without hormone replacement therapy. In multivariate models, these associations persisted, except neither educational attainment nor alcohol intake was significantly associated with waist circumference. In longitudinal analyses, both measures were positively associated with current or recent-past smoking; infrequent or inconsistent physical activity; and long-term, daily consumption of alcohol. Discussion : These cross-sectional and longitudinal associations are consistent with genetic and behavioral predictors of waist circumference and WHR. Whereas the evidence for genetic influences is stronger for waist circumference, both body fat measures may be similarly influenced by the behavioral factors considered.     

The Response to Exercise with Constant Energy Intake in Identical Twins

Seven pairs of young adult male identical twins completed a negative energy balance protocol during which they exercised on cycle ergometers twice a day, 9 out of 10 days, over a period of 93 days while being kept on a constant daily energy and nutrient intake. The total energy deficit caused by exercise above the estimated energy cost of body weight maintenance reached 244 ± 9.8 MJ (Mean ± SEM). Baseline energy intake was estimated over a period of 17 days preceding the negative energy balance protocol. Mean body weight loss was 5.0 kg (SEM = 0.6) (p <0.001) and it was entirely accounted for by the loss of fat mass (p <0.001). Fat-free mass was unchanged. Body energy losses reached 191 MJ (SEM = 24) (p <0.001) which represented about 78% of the estimated energy deficit. Subcutaneous fat loss was slightly more pronounced on the trunk than on the limbs as estimated from skinfolds, circumferences, and computed tomography (CT). The reduction in CT-assessed abdominal visceral fat was quite striking, from 81 cm² (SEM = 5) to 52 cm² (SEM = 6) (p <0.001). At the same submaximal power output level, subjects oxidized more lipids than carbohydrates after the program as indicated by the changes in the respiratory exchange ratio (p <0.05). Intrapair resemblance was observed for the changes in body weight (p <0.05), fat mass (P <0.01), percent fat (p <0.01), body energy content (p <0.01), sum of 10 skinfolds (p <0.01), abdominal visceral fat (p <0.01), fasting plasma triglycerides (p <0.05) and cholesterol (p <0.05), maximal oxygen uptake (p <0.05), and respiratory exchange ratio during submaximal work (p <0.01). We conclude that even though there were large individual differences in response to the negative energy balance and exercise protocol, subjects with the same genotype were more alike in responses than subjects with different genotypes particularly for body fat, body energy, and abdominal visceral fat changes. High lipid oxidizers and low lipid oxidizers during sub-maximal exercise were also seen despite the fact that all subjects had experienced the same exercise and nutritional conditions for about three months.     

Alternative Methods for Measuring Obesity in African American Women

The use of body mass index (BMI) may not be the most appropriate measurement toolin determining obesity in diverse populations. We studied a convenience sampleof 108 African American (AA) women to determine the best method for measuringobesity in this at-risk population. The purpose of this study was to determineif percent body fat (PBF) and percent body water (PBW) could be used asalternatives to BMI in predicting obesity and risk for hypertension (HTN) amongAA women.After accounting for age, BMI, and the use of anti-hypertensive medication, PBF(p = 0.0125) and PBW (p = 0.0297) were significantly associated with systolicblood pressure, while BMI was not. Likewise, PBF (p = 0.0316) was significantlyassociated with diastolic blood pressure, while PBW and BMI were not. Thus,health care practitioners should consider alternative anthropometricmeasurements such as PBF when assessing obesity in AA women.     

Biracial Differences in Physical Activity and Body Composition Among Women

Overweight among black females is almost two times as frequent as among white females. Genetics, caloric intake, and physical activity have been identified as possible explanatory factors. This study assessed the differences in physical activity and body composition in 76 white and 66 black adult females. Black women had significantly higher (p=.0001) percent body fat (32.2 ± 7.1) than white women (27.7 ± 6.5) with a similar difference in weight (4.4 kg) approaching significance (p=.055). Physical activity was assessed using a structured 24-hour recall instrument. A purposive sampling design was implemented to control for age, education and occupation. A summary physical activity value unit for the 24-hour period revealed a significantly greater mean value for white females (41.93 + 4.7) than for black females (40.01 ± 3.9) suggesting white females were more physically active (p=.02) although this was not a function of biracial differences in play/recreation and exercise/sport type of activities. Although both black and white females were found to be sedentary (MET value ± 2) over 90 percent of the time, black women were significantly more sedentary (p=.03). Biracial differences in discretionary non-exercise oriented activities may contribute to different rates of overweight observed between black and white women.     

Heritability of Longitudinal Changes in Coronary-Heart-Disease Risk Factors in Women Twins

Numerous studies have demonstrated genetic influences on levels of coronary heart disease (CHD) risk factors, but there also may be genetic effects on the intraindividual variation in these risk factors over time. Changes in risk factors are likely to reflect genetic-environmental interactions and may have important implications for understanding CHD risk. The present study examines the heritability of changes in CHD risk factors, using data from the two examinations by the Kaiser Permanente Women Twins Study, performed a decade apart. The sample consisted of 348 pairs of women twins who participated in both examinations, including 203 MZ pairs and 145 DZ pairs. Average ages at the two examinations were 41 and 51 years, respectively. By means of three different statistical analytic approaches, moderate heritability estimates were demonstrated for changes in LDL cholesterol (h2 = .25-.36) and in HDL cholesterol (h2 = .23-.58), some of which were statistically significant. Although small to moderate heritability estimates were found for systolic blood pressure (.18-.37; P < .05 for some estimates), no genetic influence on changes in diastolic blood pressure was detected. Based on longitudinal twin data in women, this study demonstrates a genetic influence on changes in both lipoprotein risk factors and systolic blood pressure over a decade. In addition to environmental factors, which clearly are operating, the effect of various "variability genes" may be acting independently of the genetic influences on the absolute levels of these risk factors. Both mapping the gene(s) underlying intraindividual variations in these CHD risk factors and understanding their function(s) could lead to targeted intervention strategies to reduce CHD risk among genetically susceptible individuals.     

The Body Mass Index-Mortality Relationship in White and African American Women

Objective : To examine the association of body mass index to all-cause and cardiovascular disease (CVD) mortality in white and African American women. Research methods and procedures : Women who were members of the American Cancer Society Prevention Study I were examined in 1959 to 1960 and then followed 12 years for vital status. Data for this analysis were from 8,142 black and 100,000 white women. Body mass index (BMI) was calculated from reported height and weight. Associations were examined using Cox proportional hazards modeling with some analyses stratified by smoking (current or never) and educational status (less than complete high school or high school graduate). Results : There was a significant interaction between ethnicity and BMI for both all-cause (p<0.05) and CVD mortality (p<<0.001). BMI (as a continuous variable) was associated with all-dause mortality in white women in all four groups defined by smoking and education. In black women with less than a high school education, there were no significant associations between BMI mortality. For high school-educated black women, there was a significant association between BMI and all-cause mortality. Among never smoking women with at least a high school education, models using the lowest BMI as the reference indicated a 40% higher risk of all-cause mortality at a BMI of 35.9 in black women vs. 27.3 in white women. Discussion : The impact of BMI on mortality was modified by educational level in black women; however, BMI was a less potent risk factor in black women than in white women in the same category of educational status.     

A Major Gene for Resting Metabolic Rate Unassociated with Body Composition: Results from the Québec Family Study

A major gene hypothesis for resting metabolic rate (RMR) was investigated using segregation analysis (POINTER) of data on families participating in Phase 2 of the Québec Family Study. Complete analyses were conducted on RMR adjusted for age, and also on RMR adjusted for age and other covariates, primarily fat mass (FM) and fat-free mass (FFM). Prior to adjustment for covariates, support for a major gene hypothesis was equivocal — i.e., there was evidence for either a major gene or a multifactorial component (i.e., polygenic and/or familial environment). The multifactorial model was preferred over the major gene model, although the latter did segregate according to Mendelian expectations. However, after the effects of FM and FFM were accounted for, a major gene effect was unambiguous and compelling. The putative locus accounted for 57% of the variance, affected 7% of the sample, and led to high values of RMR. The lack of a significant multifactorial effect suggested that the familial etiology of RMR adjusted for FM and FFM was likely to be entirely a function of the major locus. Comparing the RMR results from pre- and post-adjustment for FM and FFM suggests a plausible hypothesis. We know from earlier studies in this sample that there is a putative major gene for FM and a major non-Mendelian effect for FFM. The current study leads us to speculate that: (1) the gene(s) affecting body size and body composition also may have an effect on RMR, and further (2) removal of the effect of the major gene(s) for body size and composition allowed for detection of an additional major gene affecting only the RMR. Thus, RMR appears to be an oligogenic trait.     

Cross-Validation of Fat-Free Mass Estimated From Body Density Against Bioelectrical Resistance: Effects of Obesity and Gender

GORAN, MICHAEL I AND M ABU KHALED. Cross-validation of fat-free mass estimated from body density against bioelectrical resistance: effects of obesity and gender. Obes Res. The major purpose of this study was to examine whether estimates of body composition from bioelectrical resistance were systematically biased by obesity and/or gender (using hydrodensitometry as a comparison method). We compared fat-free mass (FFM) by bioelectrical resistance (BR) using 5 equations (Lukaski, Kushner, Rising, Khaled, and Segal) to FFM by hydrodensitometry (HD) in 20 lean men, 30 lean women, 33 obese men and 22 obese women. None of the BR equations was successfully cross-validated against FFM by HD in all 4 sub-groups. The Lukaski equation significantly underestimated FFM in all 4 groups by 2.7 to 4.7 kg; the Kushner equation significantly underestimated FFM by 2.0 to 2.9 kg except in obese women; the Rising equation significantly overestimated FFM in obese women (5.3 kg) and men (2.9 kg); the Khaled equation successfully predicted FFM in all groups except obese men; and the Segal equation successfully predicted FFM in all groups except lean men. In some groups, a portion of the discrepancy could be explained by bias originating from body fat. Analysis of our data by forward regression analysis demonstrated that height²/resistance, body weight, gender and suprailiac skinfold thickness provide the most accurate estimates of FFM (R²=0.92; SEE = 3.58kg) that are free of bias originating from gender and body fat. We conclude that the estimation of fat-free mass by BR is significantly influenced by gender and obesity. An alternative equation is proposed for estimating fat-free mass based on measurement of height²/resistance, body weight, gender and suprailiac skinfold thickness.     

青少年双生子体型指征相关指标的遗传度研究(英文)

目的:用经典的双生子设计探讨遗传因素对青少年身高、体重、体质指数(BMI)等体型指征的影响程度。方法:从青岛市双生子库中选择自愿参加本研究的362对11-19岁双生子,测量身高、体重。同性别的双生子通过16个多态标记进行卵型鉴定,在此基础上,应用Mx软件构建结构方程模型分析计算遗传度。结果:对362对有效双生子数据进行分析,其中同卵双生子194对,异卵双生子168对,身高的最佳拟合模型ACE模型,体重和BMI的最佳拟合模型为AE模型。调整年龄性别后,身高的遗传度为66%,体重的遗传度为84%,体质指数的遗传度为75%。结论:在青少年体型指征的相关指标中,身高、体重、BMI受遗传因素影响都较大。     

Prediction Equations Do Not Eliminate Systematic Error in Self-Reported Body Mass Index

PLANKEY MICHAEL W, JUNE STEVENS, KATHERINE M FLEGAL, PHILIP F RUST. Prediction equations do not eliminate systematic error in self-reported body mass index. Epidemiological studies of the risks of obesity often use body mass index (BMI) calculated from self-reported height and weight. The purpose of this study was to examine the pattern of reporting error associated with self-reported values of BMI and to evaluate the extent to which linear regression models predict measured BMI from self-reported data and whether these models could compensate for this reporting error. We examined measured and self-reported weight and height on 5079 adults aged 30 years to 64 years from the second National Health and Nutrition Examination Survey. Measured and self-reported BMI (kg/m2) was calculated, and multiple linear regression techniques were used to predict measured BMI from self-reported BMI. The error in self-reported BMI (self-reported BMI minus measured BMI) was not constant but varied systematically with BMI. The correlation between measured BMI and the error in self-reported BMI was ?0.37 for men and ?0.38 for women. The pattern of reporting error was only weakly associated with self-reported BMI, with the correlation being 0.05 for men and ?0.001 for women. Error in predicted BMI (predicted BMI minus measured BMI) also varied systematically with measured BMI, but less consistently with self-reported BMI. More complex models only slightly improved the ability to predict measured BMI compared with self-reported BMI alone. None of the equations were able to eliminate the systematic reporting error in determining measured BMI values from self-reported data. The characteristic pattern of error associated with self-reported BMI is difficult or impossible to correct by the use of linear regression models.     

Effect of Regain of Body Weight on Regional Body Fat Distribution: Comparison Between Pre- and Postmenopausal Obese Women

The aim of our study was to determine if regain of body weight increases visceral fat in obese women and if regain of weight has a different effect upon pre- and postmenopausal women. Twenty obese women (11 pre- and 9 postmenopausal) underwent a very low energy diet (VLED) for 2 weeks to lose weight. They then regained body weight in spite of the recommended hypocaloric diet. No significant modifications in body fat distribution indexes were found by computed tomography between VLED and after regain of weight. No significant changes were found in metabolic variables. No interactions between menopausal status and regain of body weight were observed. In conclusion, regain of weight does not seem to cause an increase in visceral fat; both pre- and postmenopausal women showed the same body fat distribution before weight loss and after regain of weight.     

Association between VDR Apal Polymorphism and Hip Bone Mineral Density Can Be Modified by Body Mass Index:A Study on Postmenopausal Chinese Women

Osteoporosis is a major public health problem for old people.Genetic factors are considered tobe major contributors to the pathogenesis of postmenopausal osteoporosis.The vitamin D receptor(VDR)gene is a prominent candidate gene for the regulation of postmenopausal bone mass;however,despite exten-sive studies,controversy remains regarding its association with postmenopausal body mineral density(BMD)variation.In this study,a total of 260 healthy postmenopausal Chinese women were genotyped at the VDRApaI locus using polymerase chain reaction(PCR)-restriction fragment length polymorphism (RFLP).Rawhip BMD was significantly associated with VDR ApaI polymorphism with and without adjusting for age(P=0.015 and 0.040,respectively).This genetic effect can explain 3.32% of hip BMD variation.However,the significant association vanished after correcting for both age and body mass index(BMI)(P=0.169).Inaddition,we observed a significant association between VDR ApaI polymorphism with unadjusted BMI(P=0.042)or BMI adjusted for age(P=0.049).The raw hip BMD was also found to be significantly corre-lated with BMI(r=0.517,P=0.0001),with BMI explaining 26.35% of the variation of hip BMD.All of thesefacts prompt us to conclude that the significant association between the VDR ApaI genotype and hip BMDmay be modified by BMI in postmenopausal Chinese women.Our findings may partially explain the earlierinconsistent association results concerning the VDR gene and BMD,and highlight the importance of incorpo-rating covariates such as BMI into osteoporosis association studies.     

A Role for Testosterone in the Maintenance of Seasonally Appropriate Body Mass but not in Lipectomy-Induced Body Fat Compensation in Siberian Hamsters

The purpose of this study was to test whether serum testosterone (T) concentrations characteristic of reproductively active, long-day-housed Siberian hamsters are necessary for compensatory increases in nonexcised fat pads following removal of epididy-mal white adipose tissue (EWAT) and/or for the maintenance of seasonally appropriate body weights in these hamsters. Long-day-housed hamsters were castrated or left intact, sham or EWAT lipectomized, and given T or cholesterol (C) implants. All groups had ad libitum food access except for two castrated T-treated groups that were pair-fed to their C-treat-ed counterparts to control for effects of T on food intake. C-treated castrates had decreased body weights compared with all other groups, suggesting a role of T in the maintenance of seasonally appropriate body mass. Since the T-treated hamsters pair-fed to these T-deficient animals exhibited seasonally appropriate body weights and fat pad masses, T does not appear to affect these parameters through the modulation of food intake. All fat pads of C-treated animals were smaller than those of ad libitum- or pair-fed, T-treated castrates; however, EWAT was the only fat pad that was smaller in the C-treated sham-lipectomized group than in gonad-intact sham-lipectomized hamsters. This result may indicate an enhanced sensitivity of EWAT to T. The effects of T on fat pad mass were not associated with proportionate changes in lipoprotein lipase activity, suggesting that the major effect of T on fat accumulation occurs through other mechanisms in this species. C-treated lipectomized hamsters compensated for the body fat deficit 8 weeks after lipectomy via statistically nonsignificant increases in retroperitoneal and inguinal WAT mass. This finding suggests that, whereas T is necessary for maintenance of seasonally-appropriate body weight, it is not necessary for fat pad compensation after EWAT lipectomy.     

COPD患者改善体质量指数与肺功能变化的相关性

目的:探讨COPD患者改善体质量指数(BMD与肺功能变化的相关性.方法:经加强营养达正常BMI的患者(A组)与低BMI的COPD患者(B组),比较2组肺功能指标、6min步行距离、呼吸困难评分.结果:与B组相比,A组FEV1％、FEV1/FVC、SVC、MVV、IC均明显升高(P＜0.01),RV/TLC明显上升(P＜0.01),6min步行距离延长(P＜0.01)、呼吸困难评分明显降低(P＜0.01).Pearson 相关性分析显示,FEV1％、FEV1/FVC、SVC、MVV、IC、RV/TIC与BMI相关,6min步行距离与BMI呈正相关,呼吸困难评分与BMI呈负相关.结论:改善BMI可明显改善COPD患者的肺功能指标,减轻临床症状.     

Relationship of a Novel Polymorphic Marker Near the Human Obese (OB) Gene to Fat Mass in Healthy Women

LAPSYS, NM, SM FURLER, KR MOORE, TV NGUYEN, H HERZOG, G HOWARD, K SAMARAS, DG CAREY, NA MORRISON, JA EISMAN, DJ CHISHOLM. Relationship of a novel polymorphic marker near the human obese (OB) gene to fat mass in healthy women. The cloning of the murine obese (ob)gene and its human homologue has recently been reported. Mutations in the mouse obgene result in hereditary obesity; however, the role of variations of OBin the regulation of bodyweight in humans has yet to be determined. The contribution of putative genetic variations in the human OBgene to total and regional fat mass in a normal twin population has been analyzed through linkage and association with a novel polymorphic marker, located in proximity to this gene. The polymorphic dinucleotide repeat, isolated from a PI clone containing the human OB gene, was physically localized by long-range restriction mapping to within 30 kilobases of the OB locus. The marker was genotyped in a population of 47 healthy female/female dizygotic (DZ) twin pairs for which direct measures of central abdominal and whole body fat had been obtained by dual X-ray absorbtiometry. Possible linkage between the microsatellite marker and whole-body (p=0.008), but not central abdominal (p=0.09), fat deposits was indicated. No association between fat depot phenotype and marker genotype was detected. These results suggest that genetic variation in or close to the human OB gene may play a role in the size of body fat stores in healthy women.     

The Relationship of Body Mass Index to Reproductive Factors in Pre- and Postmenopausal African-American Women With and Without Breast Cancer

To date, there are virtually no existing data on the relationship between obesity, menopausal status, and breast cancer in African-Americans. Therefore, the present study was designed to test the following hypotheses in an African-American population: (1) there exists a positive association between BMI and breast cancer among postmenopausal women; (2) there exists an inverse association between BMI and breast cancer among premenopausal women; and (3) similar associations between BMI and reproductive factors exist for both pre- and postmenopausal breast cancer cases. The study population comprised 357 African-American women (n=193 breast cancer cases; n=164 controls). No significant differences were observed between premenopausal cases and controls for BMI, obesity categories, and reproductive factors. Among the postmenopausal women, the cases had significantly lower weight and BMI levels than the controls. Age at first pregnancy and parity were significantly lower among postmenopausal cases than their controls. No significant associations were revealed between body mass index and breast cancer for pre- and postmenopausal women. In the present study, early age at menarche was the only reproductive factor that was an independent predictor of BMI for both pre- and postmenopausal women, irrespective of breast cancer status. Also, these findings strongly suggest the need to consider reproductive factors, particularly age at menarche, as a covariate of BMI and other obesity-related diseases.