Relationship of Leptin Concentration to Gender,Menopause, Age,Diabetes, and Fat Mass in African Americans

This investigation was designed to determine the relationship of leptin concentration to gender, sex hormones, menopause, age, diabetes, and fat mass in African Americans. Participants included 101 African Americans, 38 men (mean age, 34. 2 ± 7. 4 years), 29 age-matched premenopausal women (mean age, 32. 6 ± 3. 7 years), and 36 postmenopausal women (mean age, 57. 8 ± 5. 9 years). The women were not taking exogenous sex hormones, and 12 subjects were diabetic. Percent body fat was calculated with the Siri formula, fat mass (FM) was calculated as weight x percent body fat, and Fat-free mass (FFM) was calculated as weight minus FM. Fasting plasma was assayed for leptin, estradiol, free testosterone, glucose, and insulin concentrations. The nondiabetics had an oral glucose tolerance test (OGTT). The diabetics compared with the non-diabetics had a higher central fat index (^P=0. 04) but otherwise were similar to nondiabetics in all parameters measured. Body mass index, percent body fat, and FM were greater in women than men (p<0. 001). Leptin concentrations in men, premenopausal, and postmenopausal women were: 7. 51 ± 8. 5, 33. 9 ± 17. 3, 31. 4 ± 22. 3 ng/mL. Leptin/FM x 100 in the three groups were: 28. 9 ± 16. 1, 98. 65 ± 44. 9, 77. 1 ± 44. 5 ng/mL/kg. The gender difference in leptin concentration and leptin/FM was significant (p<0. 001), but the difference between premenopausal and postmenopausal women was not. In each group, weight, percent body fat, and FM were highly correlated with leptin concentration. Multiple regression analyses with leptin concentration as the dependent variable and age, diabetic status, percent body fat, weight, FM, FFM, estradiol, and free testosterone concentrations as independent variables demonstrated that the determinants of leptin concentration in men was weight only (R=0. 83,p<0. 001), in premenopausal women it was FM only (R=0. 57,P<0. 001), and in postmenopausal women it was weight only (R=0. 67, p<0. 001). With diabetics excluded, the multiple regression analysis was repeated with fasting insulin concentration and the area under the insulin curve during the OGTT included as independent variables. The results for this multiple regression analyses were the same as the first. Therefore, leptin concentration in African Americans is determined by gender and fat mass. Menopause, age, and diabetes do not affect leptin concentration.     

Relationships between anthropometric, body composition and bone mineral parameters in 7-8-year-old rhythmic gymnasts compared with controls

The aim of the study was to investigate the relationships between specific anthropometric (9 skinfolds, 13 girths, 8 lengths and 8 breadths), body composition (body fat %, fat free mass [FFM], fat mass [FM]) parameters and bone mineral parameters (bone mineral density [BMD], bone mineral content [BMC) in young rhythmic gymnasts and same age controls. Eighty nine 7-8-year-old girls participated in this study and were divided to the rhythmic gymnast's (n = 46) and control (n = 43) groups. Body composition was determined by dual energy X-ray absorptiometry (FFM, FM, body fat %, BMD and BMC). Body fat % and FM were lower and BMD and BMC values at lumbar spine (L2-L4) and femoral neck were higher in rhythmic gymnasts compared with controls. All measured skinfold thicknesses were thicker in controls. In girths, lengths and widths there were only few significant differences between the groups. Stepwise multiple regression analysis indicated that skinfold thicknesses (supraspinale and medial calf) influenced L2-L4 BMD only in controls 38.2% (R2x100). Supraspinale and iliac crest skinfold thicknesses characterised L2-L4 BMC 43.9% (R2x100). Calf girths influenced BMD in L2-L4 52.3% (R2x100) in controls. BMC in L2-L4 was dependent only on mid-thigh girths 35.9% (R2x100). BMD in L2-L4 was dependent on tibiale-laterale height 30.0% (R2x100). Biiliocristal breadths together with sitting height characterised BMC in L2-L4 BMD 62.3% (R2x100). In conclusion, we found that the relationships between anthropometry, body composition and bone parameters in young rhythmic gymnasts are weak. In control group first of all lower body anthropometric parameters significantly correlated with BMD and BMC in spine.     

Aged-Related Changes in Body Composition and Association between Body Composition with Bone Mass Density by Body Mass Index in Chinese Han Men over 50-year-old

Objectives

Aging, body composition, and body mass index (BMI) are important factors in bone mineral density (BMD). Although several studies have investigated the various parameters and factors that differentially influence BMD, the results have been inconsistent. Thus, the primary goal of the present study was to further characterize the relationships of aging, body composition parameters, and BMI with BMD in Chinese Han males older than 50 years.

Methods

The present study was a retrospective analysis of the body composition, BMI, and BMD of 358 Chinese male outpatients between 50 and 89 years of age that were recruited from our hospital between 2009 and 2011. Qualified subjects were stratified according to age and BMI as follows: 50–59 (n = 35), 60–69 (n = 123), 70–79 (n = 93), and 80–89 (n = 107) years of age and low weight (BMI: < 20 kg/m²; n = 21), medium weight (20 ≤ BMI < 24 kg/m²; n = 118), overweight (24 ≤ BMI < 28 kg/m²; n = 178), and obese (BMI ≥ 28 kg/m²; n = 41). Dual-energy X-ray absorptiometry (DEXA) was used to assess bone mineral content (BMC), lean mass (LM), fat mass (FM), fat-free mass (FFM), lumbar spine (L1-L4) BMD, femoral neck BMD, and total hip BMD. Additionally, the FM index (FMI; FM/height²), LM index (LMI; LM/height²), FFM index (FFMI; [BMC+LM]/height²), percentage of BMC (%BMC; BMC/[BMC+FM+LM] × 100%), percentage of FM (%FM; FM/[BMC+FM+LM] × 100%), and percentage of LM (%LM; LM/(BMC+FM+LM) × 100%) were calculated. Osteopenia or osteoporosis was identified using the criteria and T-score of the World Health Organization.

Results

Although there were no significant differences in BMI among the age groups, there was a significant decline in height and weight according to age (p < 0.0001 and p = 0.0002, respectively). The LMI and FFMI also declined with age (both p < 0.0001) whereas the FMI exhibited a significant increase that peaked in the 80-89-years group (p = 0.0145). Although the absolute values of BMC and LM declined with age (p = 0.0031 and p < 0.0001, respectively), there was no significant difference in FM. In terms of body composition, there were no significant differences in %BMC but there was an increase in %FM (p < 0.0001) and a decrease in %LM (p < 0.0001) with age. The femoral neck and total hip BMD significantly declined with age (p < 0.0001 and p = 0.0027, respectively) but there were no differences in L1-L4. BMD increased at all sites (all p < 0.01) as BMI increased but there were declines in the detection rates of osteoporosis and osteopenia (both p < 0.001). A logistic regression revealed that when the medium weight group was given a BMI value of 1, a decline in BMI was an independent risk factor of osteoporosis or osteopenia, while an increase in BMI was a protective factor for BMD. At the same time, BMD in L1-L4 exhibited a significant positive association with FMI (p = 0.0003) and the femoral neck and total hip BMDs had significant positive associations with FFMI and LMI, respectively (both p < 0.0001).

Conclusions

These data indicate that LMI and FFMI exhibited significant negative associations with aging in Chinese Han males older than 50 years, whereas FMI had a positive association. BMD in the femoral neck and total hip declined with age but an increased BMI was protective for BMD. LMI and FFMI were protective for BMD in the femoral neck and total hip.     

Relationship of fat mass and serum estradiol with lower extremity bone in persons with chronic spinal cord injury

In the spinal cord injury (SCI) population, a relationship between adiposity and leg bone has not been reported, nor one between serum estradiol and leg bone mass. A cross-sectional, comparative study of 10 male pairs of monozygotic twins discordant for SCI was performed. Relationships were determined among bone mineral density (BMD), bone mineral content (BMC), lean mass, fat mass, and serum sex steroids. In the twins with SCI, significant relationships were evident between leg BMD or BMC with total body percent fat (r2= 0.49, P < 0.05; r2= 0.45, P = 0.05), leg fat mass (r2 = 0.76, P < 0.0005; r2= 0.69, P = 0.005), and serum estradiol (r2= 0.40, P = 0.05; r2= 0.37, P = 0.05). By stepwise regression analysis, in the twins with SCI, leg fat mass was found to be the single most significant predictor of leg BMD or BMC (F = 12.01, r2= 0.76, P = 0.008; F = 50.87, r2= 0.86, P < 0.0001). In the able-bodied twins, leg lean mass correlated with leg BMD and BMC (r2= 0.58, P = 0.01; r2= 0.87, P = 0.0001). By use of within-pair differences, significant correlations were found for leg lean mass loss with leg BMD loss (r2= 0.56, P = 0.01) or leg BMC loss (r2= 0.64, P = 0.0005). In conclusion, in twins with SCI, significant correlations were observed between fat mass and leg BMD or BMC as well as between serum estradiol values and leg BMD. The magnitude of the leg muscle mass loss was correlated with the magnitude of bone loss.     

Relation of bone mineral density and content to mineral content and density of the fat-free mass.

Differences in the mineral fraction of the fat-free mass (M(FFM)) and in the density of the FFM (D(FFM)) are often inferred from measures of bone mineral content (BMC) or bone mineral density (BMD). We studied the relation of BMC and BMD to the M(FFM) and D(FFM) in a heterogeneous sample of 216 young men (n = 115) and women (n = 101), which included whites (n = 155) and blacks (n = 61) and collegiate athletes ( n = 132) and nonathletes (n = 84). Whole body BMC and BMD were determined by dual-energy X-ray absorptiometry (DXA; Hologic QDR-1000W, enhanced whole body analysis software, version 5.71). FFM was estimated using a four-component model from measures of body density by hydrostatic weighing, body water by deuterium dilution, and bone mineral by DXA. There was no significant relation of BMD to M(FFM) (r = 0.01) or D(FFM) (r = -0.06) or of BMC to M(FFM) (r = -0.11) and a significant, weak negative relation of BMC to D(FFM) (r = -0.14, P = 0.04) in all subjects. Significant low to moderate relationships of BMD or BMC to M(FFM) or D(FFM) were found within some gender-race-athletic status subgroups or when the effects of gender, race, and athletic status were held constant using multiple regression, but BMD and BMC explained only 10-17% of the variance in M(FFM) and 0-2% of the variance in D(FFM) in addition to that explained by the demographic variables. We conclude that there is not a significant positive relation of BMD and BMC to M(FFM) or D(FFM) in young adults and that BMC and BMD should not be used to infer differences in M(FFM) or D(FFM).     

Adiponectin is associated with bone mineral density in perimenopausal women.

The aim of the current investigation was to investigate any potential effect of fasting plasma adiponectin concentration on bone tissue, and to find possible relationships of fasting plasma adiponectin level with different body composition, insulin sensitivity and physical performance parameters in a group of healthy perimenopausal women. Twenty-one premenopausal and 17 early postmenopausal women participated in this study. The women were matched for body mass index (BMI) and level of mean daily energy expenditure. Women had similar adiponectin (8.4 +/- 3.9 vs. 9.9 +/- 5.4 microg/ml) and leptin values (12.0 +/- 7.7 vs. 14.0 +/- 8.2 ng/ml) before and after menopause. Significant relationships were observed between plasma adiponectin and bone mineral content, total bone mineral density (BMD) and lumbar spine BMD values (r > - 0.36; p < 0.05). Furthermore, adiponectin had a significant negative association with total BMD (beta = - 1.228; p = 0.004) and lumbar spine BMD (beta = - 0.312; p = 0.005) independent of the influence that other measured body compositional, hormonal or physical performance factors may exert on BMD. Adiponectin was also significantly related to waist-to-hip ratio (WHR) (beta = - 2.300; p = 0.002) and fasting insulin resistance index (FIRI) (beta = - 0.006; p = 0.007) in separate regression models. No relationship was observed between leptin and measured bone, physical performance and insulin resistance values. Leptin significantly correlated to BMI (beta = 0.018; p = 0.034), lean body mass (beta = 0.025; p = 0.024) and fat mass (beta = 0.019; p = 0.001) in separate regression models. In conclusion, the results of present study show that circulating adiponectin appears to exert an independent effect on BMD in perimenopausal women and may represent a link between adipose tissue and bone mineral density.     

Basal and insulin-regulated free fatty acid and glucose metabolism in humans

These studies were done to examine the effects of body composition, resting energy expenditure (REE), sex, and fitness on basal and insulin-regulated FFA and glucose metabolism. We performed 137 experiments in 101 nondiabetic, premenopausal women and men, ranging from low normal weight to class III obese (BMI 18.0-40.5 kg/m2). Glucose flux was measured using [6-(2)H2]glucose and FFA kinetics with [9,10-(3)H]oleate under either basal (74 experiments) or euglycemic hyperinsulinemic (1.0 mU.kg FFM(-1).min(-1)) clamp conditions (63 experiments). Consistent with our previous findings, REE and sex independently predicted basal FFA flux, whereas fat-free mass was the best predictor of basal glucose flux; in addition, percent body fat was independently and positively associated with basal glucose flux (total r2 = 0.52, P < 0.0001). Insulin-suppressed lipolysis remained significantly associated with REE (r = 0.25, P < 0.05), but percent body fat also contributed (total adjusted r2 = 0.36, P < 0.0001), whereas sex was not significantly related to insulin-suppressed FFA flux. Glucose disposal during hyperinsulinemia was independently associated with peak VO2, percent body fat, and FFA concentrations (total r2 = 0.63, P < 0.0001) but not with sex. We conclude that basal glucose production is independently related to both FFM and body fatness. In addition, hyperinsulinemia obscures the sex differences in FFA release relative to REE, but brings out the effects of fatness on lipolysis.     

Age and sex variation in measures of body composition among the elderly Bengalee Hindus of Calcutta, India

In the present cross-sectional study we examined 332 (171 men and 161 women) elderly (60 years and above) urban Bengalee Hindu resident in south Calcutta, India. Individuals were selected by random sampling procedure using local voter's registration list. Skin folds measures were used to compute body composition measures among them. There existed significant sex differences in various anthropometric body composition measures. Age had significant (p < 0.001) negative association with all anthropometric body composition measures namely percentage of body fat (PBF), fat mass (FM), arm muscle circumference (AMC), arm muscle area (AMA) and arm fat area (AFA) in both sexes. Fat free mass (FFM) in contrast had negative but not significant age impact. Regression analyses demonstrated that age had explained substantial amount of variance of PBF (men = 32%; women = 18.2%), FM (men = 18.2%; women = 12.8%), AMC (men = 23.4%; women = 19.2%), AMA (men = 22.2%; women = 10.2%) and AFA (men = 34%; women = 31%) in both sexes. Two-way ANOVA revealed age-sex interaction only had significant effect on FFM. The present investigation vindicated that there is a significant inverse age trends in anthropometric body composition measures among the Bengalee Hindus. Moreover, there existed sexual dimorphism in the effect of age on various anthropometric body composition measures.     

Anthropometric and leptin changes in women following different dietary approaches to weight loss

Leptin may favorably respond to fat mass (FM) losses induced by a low-carbohydrate (LC) diet, although this is unclear. We examined serum leptin concentrations in women in midlife undergoing different dietary approaches to body weight (BW) loss. Women followed either a LC, high-protein (LCHP; n = 13) or high-carbohydrate, low-fat (HCLF; n = 12) diet for 12 weeks. Changes in anthropometric and soft-tissue mass measurements and leptin concentrations were assessed. Women in both diet groups had reductions in BW, BMI, fat-free soft-tissue mass, FM, body fat percentage, and central abdominal fat (CAF) (P < 0.001 for all variables) over the 12-week intervention. These changes were not significantly different between diet groups. Serum leptin concentrations decreased by 41.8% (P < 0.001) in the LCHP group and by 44.3% (P < 0.001) in the HCLF group from baseline to week 12, with no significant difference between groups. The association of CAF (r = 0.73) and FM (r = 0.83) change with leptin change was strong in the HCLF group. Leptin change did not relate to change in any variable in the LCHP group. Both LCHP and HCLF diets favorably lower FM, CAF, and leptin in women, suggesting that beneficial changes in leptin can be similarly achieved through different dietary approaches to BW loss.     

Relation between fat distributions and several plasma adipocytokines after exercise training in premenopausal and postmenopausal women

Circulating concentrations of adipocytokines, such as leptin, tumor necrosis factor-alpha (TNF-alpha), and plasminogen activator inhibitor-1 (PAI-1), vary with exercise training, menopause, or regional variations in adipose tissues. In the present study, the relationships between body fat distributions and some adipocytokines were compared in premenopausal (N = 9) and postmenopausal women (N = 9), before and after exercise training. The training for 10 weeks (that is, 3 days/week) consisted of aqua exercise plus resistance exercise. The training reduced percent fat, body mass index, total fat mass (TFM), subcutaneous fat mass (SFM), and plasma levels of leptin and PAI-1 in both women. Mean value of plasma TNF-alpha tended to increase after training in both women. Plasma leptin levels were lower in postmenopausal than in premenopausal women, independently of training. In premenopausal women, plasma leptin levels correlated well with either TFM or SFM before and after training. Regression analysis of decreases in plasma leptin with a reduced amount of SFM revealed that decreases in plasma leptin depended to a greater extent on a loss of SFM. In postmenopausal women, no significant correlation was found between leptin levels and any of the fat depots. Plasma TNF-alpha levels correlated well with visceral fat mass (VFM) in premenopausal but not in postmenopausal women. Changes in TNF-alpha levels after training correlated well with reduced amount of VFM in premenopausal but not in postmenopausal women. Plasma PAI-1 levels were not different between groups. Moreover, no significant correlation was found between PAI-1 levels and any of the fat depots in both women. Thus, in premenopausal but not in postmenopausal women, changes in plasma concentrations of leptin and TNF-alpha correlate well with specific alterations in relative amount of SFM and VFM after training, respectively. However, no significant relationship between PAI-1 and any of the fat depots was found independently of either menopause or training.     

Ancestral proportions and their association with skin pigmentation and bone mineral density in Puerto Rican women from New York city

Hispanic and African American populations exhibit an increased risk of obesity compared with populations of European origin, a feature that may be related to inherited risk alleles from Native American and West African parental populations. However, a relationship between West African ancestry and obesity-related traits, such as body mass index (BMI), fat mass (FM), and fat-free mass (FFM), and with bone mineral density (BMD) in African American women has only recently been reported. In order to evaluate further the influence of ancestry on body composition phenotypes, we studied a Hispanic population with substantial European, West African, and Native American admixture. We ascertained a sample of Puerto Rican women living in New York (n=64), for whom we measured BMI and body composition variables, such as FM, FFM, percent body fat, and BMD. Additionally, skin pigmentation was measured as the melanin index by reflectance spectroscopy. We genotyped 35 autosomal ancestry informative markers and estimated population and individual ancestral proportions in terms of European, West African, and Native American contributions to this population. The ancestry proportions corresponding to the three parental populations are: 53.3±2.8% European, 29.1±2.3% West African, and 17.6±2.4% Native American. We detected significant genetic structure in this population with a number of different tests. A highly significant correlation was found between skin pigmentation and individual ancestry (R²=0.597, P<0.001) that was not attributable to differences in socioeconomic status. A significant association was also found between BMD and European admixture (R²=0.065, P=0.042), but no such correlation was evident with BMI or the remaining body composition measurements. We discuss the implications of our findings for the potential use of this Hispanic population for admixture mapping.     

Genomic scan for genes affecting body composition before and after training in Caucasians from HERITAGE.

An autosomal genomewide search for genes related to body composition and its changes after a 20-wk endurance-exercise training program has been completed in the HERITAGE Family Study. Phenotypes included body mass index (BMI), sum of eight skinfold thicknesses, fat mass (FM), fat-free mass, percent body fat (%Fat), and plasma leptin levels. A maximum of 364 sib-pairs from 99 Caucasian families was studied with the use of 344 markers with single-point and multipoint linkage analyses. Evidence of significant linkage was observed for changes in fat-free mass with the S100A and the insulin-like growth factor I genes (P = 0.0001). Suggestive evidence (2.0 < or = Lod < 3.0; 0.0001 < P < or = 0.001) was also observed for the changes in FM and %Fat at 1q31 and 18q21-q23, in %Fat with the uncoupling protein 2 and 3 genes, and in BMI at 5q14-q21. At baseline, suggestive evidence was observed for BMI at 8q23-q24, 10p15, and 14q11; for FM at 14q11; and for plasma leptin levels with the low-density lipoprotein receptor gene. This is the first genomic scan on genes involved in exercise-training-induced changes in body composition that could provide information on the determinants of weight loss.     

Relationship between fat-to-fat-free mass ratio and decrements in leg strength after downhill running.

The purpose of this study was to determine whether greater body fat mass (FM) relative to lean mass would result in more severe muscle damage and greater decrements in leg strength after downhill running. The relationship between the FM-to-fat-free mass ratio (FM/FFM) and the strength decline resulting from downhill running (-11% grade) was investigated in 24 male runners [age 23.4 +/- 0.7 (SE) yr]. The runners were divided into two groups on the basis of FM/FFM: low fat (FM/FFM = 0.100 +/- 0.008, body mass = 68.4 +/- 1.3 kg) and normal fat (FM/FFM = 0.233 +/- 0.020, body mass = 76.5 +/- 3.3 kg, P < 0.05). Leg strength was reduced less in the low-fat (-0.7 +/- 1.3%) than in the normal-fat individuals (-10.3 +/- 1.5%) 48 h after, compared with before, downhill running (P < 0.01). Multiple linear regression analysis revealed that the decline in strength could be predicted best by FM/FFM (r2 = 0.44, P < 0.05) and FM-to-thigh lean tissue cross-sectional area ratio (r2 = 0.53, P < 0.05), with no additional variables enhancing the prediction equation. There were no differences in muscle glycogen, creatine phosphate, ATP, or total creatine 48 h after, compared with before, downhill running; however, the change in muscle glycogen after downhill running was associated with a higher FM/FFM (r = -0.56, P < 0.05). These data suggest that FM/FFM is a major determinant of losses in muscle strength after downhill running.     

Anthropometric and body composition characteristics in pre- and postmenopausal Asian Indian women: Santiniketan women study

The present cross-sectional study was aimed to investigate anthropometric and body composition characteristics in pre- and postmenopausal Asian Indian women. A total of 245 healthy women aged 25 to 65 years took part in the study. A random sampling procedure using a local voters' registration list was followed to select the participants. All participants belonged to the Bengalee population and were inhabitants of the Bolpur-Santiniketan area (lying in between 23 degrees 40' north latitude and 87degrees 43' east longitude) West Bengal, India. Before the actual commencement of the study, written information was communicated to select individuals, and an appointment was requested at their respective houses. Anthropometric measures, namely height, weight etc., were collected using standard techniques. Percentages of body fat (%BF) and body mass index (BMI) were measured using an Omron body fat analyser. All subjects were categorized into two groups: premenopausal (Group I; n = 145, mean age = 32.66 +/- 5.75 years) and postmenopausal (Group II; n = 100, mean age = 52.72 +/- 5.62 years). It was observed that 80.00% women were cohabited and 80.82% were housewife with 44.08% of them having an education up to secondary level. Furthermore, 62.45% subjects had monthly family expenditure of > or = 5000 Indian Rupees. One way ANOVA revealed that there was significant group difference for age, age at menarche, MWC, WHR, FM, FFM and %BF across the groups. Intercorrelation matrix (Pearson's correlation) showed that age had significantly positive association with MWC (p < 0.01), MHC (p < 0.05), WHR (p < 0.01), FM (p < 0.01), and %BF (p < 0.01), whereas FFM has had negative association with age. Most interestingly, it was observed that there was significant difference [chi2 (1) = 9.73] for central obesity status across the groups. It seems reasonable to argue that onset of menopause does play a vital role to alter body composition and in turn CVD risk factors.     

Validation of a dual energy X-ray absorptiometer: measurement of bone mass and soft tissue composition

We investigated the reproducibility of total and regional body composition measurements performed on a dual energy X-ray absorptiometer (DXA). A group of 38 women aged 21–81 (mean 52. 4) years was scanned twice with repositioning to determine intra-observer reproducibility of measurements of bone mineral density (BMD, g · cm⁻²), bone mineral content (BMC, g), lean mass (LM, kg) and fat mass (FM, kg) of the total body and of the major subregions of the body. In addition, the ability of the DXA machine to detect changes in LM and FM (simulated by placing 11.1 and 22.3 kg porcine lard on the body of 11 subjects) was examined. Coefficients of variations calculated from the root mean square averages of individual standard deviations were as follows (BMD, BMC, FM, LM): 1.4%, 1.1%, 1.4%, 1.7% (total body), 2.2%, 2.1%,-,- (head), 2.8%, 2.8%, 2.0%, 2.2% (trunk), 3.6%, 3.9%, 4.0%, 4.9% (arms), 2.7%, 1.3%, 2.6%, 2.8% (legs). Percentage fat (%fat) of exogenous lard was 81.3 (SD 3.5)% as assessed by the absorptiometer which corresponded well with the result of chemical analysis (82.8%). Estimated %fat of exogenous lard was not influenced by initial body mass or percentage body fat. Percentages of expected mean values with 11.1 kg lard placed on the body were 99.9 (SD 0.3) for body mass, 100.5 (SD 2.1) for LM, and 99.5 (SD 3.5) for FM. BMD was overestimated by 3.2% (P < 0.005) with 11.1 kg lard on the body. BMD as well as BMC increased significantly with 22.3␣kg lard on the body (P < 0.005). The results showed that BMD, BMC, LM, and FM of the total body were precisely estimated by the DXA machine used. Regional measurements were less precise. Changes in total body soft tissue composition were precisely and accurately estimated. The lard placed on the body falsely affected BMD and BMC measurements. Changes in body mass could have a similar effect. Accepted: 6 January 1997     

The different correlations between obesity and osteoporosis after adjustment of static mechanical loading from weight and fat free mass

Objectives:To explore complex correlations between obesity (OB) and osteoporosis (OP) after adjustment of static mechanical loading from weight and fat free mass (FFM).Methods:A total of 3749 Chinese aged ≥65 years were selected from our ongoing cohort study. OB indices and bone mineral density (BMD) were measured for each subject. Linear regression analyses were performed to explore the correlations between OB indices and OP under three adjustment models (unadjusted, adjusted with weight and adjusted with FFM).Results:Under no adjustment, three general obesity indices (body mass index: BMI, fat mass: FM, and percentage FM: PFM) were positively associated with BMD at three skeletal sites (P<0.001) in the regression analyses. However, after the adjustment with weight, these associations were mostly significant but reverse i.e., negatively in direction. After adjustment with FFM, the three indices were still positively and significantly (P<0.001) associated with BMD but regression coefficients were smaller compared to the unadjusted associations. Similar associations were observed for central adiposity and lower limb adiposity indices.Conclusions:The combined relation of OB to OP due to the physiological factors secreted from adipose tissues and the static mechanical loading from FM is positive in direction.     

Effect of intense military training on body composition

Individuals in a structural physical training program can show beneficial changes in body composition, such as body fat reduction and muscle mass increase. This study measured body composition changes by using 3 different techniques-skinfold thickness (SF) measurements, air displacement plethysmography (BOD-POD), and dual-energy x-ray absorptiometry (DXA)-during 9 months of intense training in healthy young men engaged in military training. Twenty-seven young men were recruited from a special faction of the Italian Navy. The program previewed three phases: ground combat, sea combat, and amphibious combat. Body composition was estimated at the beginning, in the middle, and at the end of the training. After the subjects performed the ground combat phase, body composition variables significantly decreased: body weight (P < 0.05), fat-free mass (FFM) (P < 0.001), and fat mass (FM) (P < 0.03). During the amphibious combat phase, body weight increased significantly (P < 0.01), mainly because of an increase in FFM (P < 0.001) and a smaller mean decrease in FM. There was a significant difference (P < 0.05) in circumferences and SF at various sites after starting the training course. Bland-Altman analysis did not show any systematic difference between FM and FFM measured with the 3 different techniques on any occasion. On any visit, FFM and FM correlation measured by BOD-POD (P = 0.90) and DXA was significantly greater than measured by SF. A significant difference was found in body mass index (BMI) measured during the study. BOD-POD and SF, compared with DXA, provide valid and reliable measurement of changes in body composition in healthy young men engaged in military training. In conclusion, the findings suggest that for young men of normal weight, changes in body weight alone and in BMI are not a good measure to assess the effectiveness of intense physical training programs, because lean mass gain can masquerade fat weight loss.     

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.     

Association between VDR ApaI 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 to be 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 extensive 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 VDR ApaI locus using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Raw hip 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). In addition, 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 correlated with BMI (r=0.517, P=0.0001), with BMI explaining 26.35% of the variation of hip BMD. All of these facts prompt us to conclude that the significant association between the VDR ApaI genotype and hip BMD may be modified by BMI in postmenopausal Chinese women. Our findings may partially explain the earlier inconsistent association results concerning the VDR gene and BMD, and highlight the importance of incorporating covariates such as BMI into osteoporosis association studies.     

Body Fat and Fat‐Free Mass and All‐Cause Mortality

Objective: To investigate whether the association between BMI and all‐cause mortality could be disentangled into opposite effects of body fat and fat‐free mass (FFM). Research Methods and Procedures: All‐cause mortality was studied in the Danish follow‐up study “Diet, Cancer and Health” with 27, 178 men and 29, 875 women 50 to 64 years old recruited from 1993 to 1997. By the end of year 2001, the median follow‐up was 5.8 years, and 1851 had died. Body composition was assessed by bioelectrical impedance. Cox regression models were used to estimate the relationships among body fat mass index (body fat mass divided by height squared), FFM index (FFM divided by height squared), and mortality. All analyses were adjusted for smoking habits. Results: Men and women showed similar associations. J‐shaped associations were found between body fat mass index and mortality adjusted for FFM and smoking. The mortality rate ratios in the upper part of body fat mass were 1.12 per kg/m² (95% confidence interval: 1.07, 1.18) in men and 1.06 per kg/m² (95% confidence interval: 1.02, 1.10) in women. Reversed J‐shaped associations were found between FFM index and mortality with a tendency to level off for high values of FFM. Discussion: Our findings suggest that BMI represents joint but opposite associations of body fat and FFM with mortality. Both high body fat and low FFM are independent predictors of all‐cause mortality.