Body Composition Measured by Dual‐energy X‐ray Absorptiometry Half‐body Scans in Obese Adults

Dual‐energy X‐ray absorptiometry (DXA) has become a common measurement of human body composition. However, obese subjects have been understudied largely due to weight and scan area restrictions. Newer DXA instruments allow for heavier subjects to be supported by the DXA scanner, but the imaging area is still smaller than the body size of some obese subjects. In this study, we determined the validity of an automated half‐scan methodology by comparing to the standard whole‐body scans in a cohort of obese volunteers. Fifty‐two subjects whose BMI >30 kg/m² completed whole‐body iDXA (GE Lunar) scans. The resulting scans were analyzed in three ways: the standard whole‐body scan, total body estimated from the left side, and from the right side. Fat mass, nonbone lean mass, bone mineral content (BMC), and percent fat derived from each half scan were compared to the whole‐body scans. Total fat mass, nonbone lean mass, or percent fat was comparable for the whole‐body scans, left, and right side scans (>97% within individuals and >99.9% for the group). The BMC estimate using the right side scan was slightly but statistically higher than the whole‐body BMC (～30 g or 1%, P < 0.001), while the left side scan BMC estimate was lower than the whole‐body BMC by the same magnitude. No significant magnitude bias was found for any of the composition variables. We conclude that the new iDXA half‐body analysis in obese subjects appears to be closely comparable to whole‐body analysis for fat mass, nonbone lean mass, and percent fat.     

Long-term effects of aging and orchidectomy on bone and body composition in rapidly growing male rats

The purpose of this study was to assess the long-term effects of aging and sex hormone deficiency on skeletal metabolism and body composition in rapidly growing male rats. Sprague-Dawley male rats were sham-operated (sham) or orchidectomized (ORX) at 3 months of age. Eight sham rats and eight ORX rats at each time point were serially sacrificed at 3, 4, 8, 12, 15, and 23 months of age. Bone mass in sham rats rapidly increased until 8 months of age, then slightly increased between 8 to 12 months of age; thereafter, an age-related decrease in bone mass was found between 12 to 23 months of age. In sham rats, bone formation parameters decreased between 3 and 8 months, and maintained at the lower level between 8 and 23 months of age, while bone resorption parameters decreased between 3 and 12 months, and thereafter, increased with age between 12 and 23 months of age. ORX significantly inhibited age-related gain in body weight, lean body mass, and cancellous and cortical bone mass and decreased peak bone mass (approximately 20% less versus sham). Further, we found that the lower bone and lean body mass in ORX rats was due to the lack of age-related gain rather than the net loss from basal controls. These data suggest that sex hormones are important factors for the accumulation of peak bone and lean body mass in male rats.     

Body Composition in a Seasonal Model of Obesity: Longitudinal Measures and Validation of DXA

Objective: Collared lemmings, Dicrostonyx groenlandicus, show rapid changes in body mass on a seasonal basis. The objective of this study was to measure longitudinal changes in body composition in animals undergoing photoperiod-induced weight gain and loss using DXA. Research Methods and Procedures: Adult, female collared lemmings exposed to either long (LD; 22 hours light/2 hours dark) or short (SD; 8 hours light/16 hours dark) photoperiods were anesthetized, and DXA was used to determine fat mass, lean tissue mass (LTM), total-body bone mineral content, and total-bone mineral density. After a baseline scan, one-half of the animals were transferred to the alternate photoperiod (SD-LD, weight loss; LD-SD, weight gain) and one-half remained on the same photoperiod (controls; SD-SD, LD-LD). Body composition was determined by DXA after 4 and 8 weeks. Animals were killed, and body composition was determined by carcass analysis. DXA-derived data were validated by comparing with carcass analysis. Results: Body composition by DXA was highly related to body composition measured by chemical analysis, thereby justifying the use of DXA. Lemmings in the SD-LD group lost weight, and this was reflected in measurable losses of fat and LTM. Lemmings in the LD-SD group gained weight, which was shown by measurable increases in fat, LTM and total-body bone mineral content. Discussion: Comparison of body composition determined by DXA to that by chemical extraction revealed that DXA is useful for measuring body composition. The longitudinal analysis revealed that collared lemmings undergo rapid changes in body composition when exposed to changes in photoperiod.     

Accuracy and precision of dual-energy X-ray absorptiometry for body composition measurements in rhesus monkeys

Accuracy of body composition measurements by dual-energy X-ray absorptiometry (DXA) was compared with direct chemical analysis in 10 adult rhesus monkeys. DXA was highly correlated (r-values > 0.95) with direct analyses of body fat mass (FM), lean mass (LM) and lumbar spine bone mineral content (BMC). DXA measurements of total body BMC were not as strongly correlated (r-value = 0.58) with total carcass ash content. DXA measurements of body FM, LM and lumbar spine BMC were not different from data obtained by direct analyses (P-values > 0.30). In contrast, DXA determinations of total BMC (TBMC) averaged 15%, less than total carcass ash measurements (P = 0.002). In conclusion, this study confirms the accurate measurement of fat and lean tissue mass by DXA in rhesus monkeys. DXA also accurately measured lumbar spine BMC but underestimated total body BMC as compared with carcass ash determinations.     

Dual Energy X-Ray Absorptiometry Body Composition Reference Values from NHANES

In 2008 the National Center for Health Statistics released a dual energy x-ray absorptiometry (DXA) whole body dataset from the NHANES population-based sample acquired with modern fan beam scanners in 15 counties across the United States from 1999 through 2004. The NHANES dataset was partitioned by gender and ethnicity and DXA whole body measures of %fat, fat mass/height², lean mass/height², appendicular lean mass/height², %fat trunk/%fat legs ratio, trunk/limb fat mass ratio of fat, bone mineral content (BMC) and bone mineral density (BMD) were analyzed to provide reference values for subjects 8 to 85 years old. DXA reference values for adults were normalized to age; reference values for children included total and sub-total whole body results and were normalized to age, height, or lean mass. We developed an obesity classification scheme by using estabbody mass index (BMI) classification thresholds and prevalences in young adults to generate matching classification thresholds for Fat Mass Index (FMI; fat mass/height²). These reference values should be helpful in the evaluation of a variety of adult and childhood abnormalities involving fat, lean, and bone, for establishing entry criteria into clinical trials, and for other medical, research, and epidemiological uses.     

Feeding flaxseed oil but not secoisolariciresinol diglucoside results in higher bone mass in healthy rats and rats with kidney disease

Flaxseed's oil and lignan, secoisolariciresinol diglucoside (SDG), are implicated in attainment of health and treatment of renal injury and osteoporosis. To test for these benefits, weanling Han:SPRD-cy rats (n=171) with or without kidney disease were randomized to diets made with either corn oil or flaxseed oil and with or without SDG for 12 weeks. In females, weight was lower with the SDG diet. In males fed flaxseed oil, lean mass was higher and fat % was lower. In both sexes, fat % was lower in diseased rats. Bone mineral content (BMC) and density were higher in rats fed flaxseed oil and lower in diseased rats, additionally; BMC was lower in SDG-supplemented females. The benefit of flaxseed oil on body composition is sex specific but the effect on bone mass is not. Lastly, reduced weight due to early rat kidney disease is not due to loss of lean body mass.     

Dietary conjugated linoleic acid does not adversely affect bone mass in obese fa/fa or lean Zucker rats

Conjugated linoleic acid (CLA) elevates body ash in healthy animals. The objective of the present study was to determine if single or mixed CLA isomers improve bone mass in an obese and hyperinsulinemic state. Male (n = 120) lean and obese fa/fa Zucker rats (age, 6 weeks) were randomized to 8 weeks on a control diet or to 0.4% (w/w) cis-9, trans-11 CLA (Group 1); 0.4% (w/w) trans-10, cis-12 CLA (Group 2); 0.4% (w/w) cis-9, trans-11 CLA and 0.4% (w/w) trans-10, cis-12 CLA (Group 3); 0.4% (w/w) cis-9, trans-11 CLA, 0.4% (w/w) trans-10, cis-12 CLA, and traces of other CLA isomers (Group 4); and 0.4% (w/w) cis-9, trans-11 CLA, 0.4% (w/w) trans-10, cis-12 CLA, and 0.3% (w/w) other CLA isomers (Group 5). Bone area (BA), bone mineral content (BMC), and bone mineral density (BMD) of the whole body, spine, and femur were measured at baseline (6 weeks) and at 14 weeks of age. Effects of genotype, diet, and genotype x diet interactions were assessed using factorial analysis of variance. At 6 and 14 weeks, whole-body BA and BMC were lower in lean rats compared with fa/fa rats. Similarly, at 14 weeks, fa/fa rats had a higher spine and femur BMD despite a lower femur weight. The fa/fa rats in Groups 4 and 5 had higher adjusted whole-body BMC compared with Group 3, but not with Group 1, Group 2, or the control. In lean rats, Group 3 had a greater adjusted whole-body BMC than Groups 1 and 2, but not Group 4, Group 5, or the control. Thus, commercially available CLA mixtures and single CLA isomers do not affect bone mass in a hyperinsulinemic, obese state.     

Effect of Group vs. Single Housing on Phenotypic Variance in C57BL/6J Mice

Objective: To determine if group housing affects the variance of body composition parameters in a highly inbred mouse strain. Research Methods and Procedures: Thirty 3‐week‐old male C57BL/6J mice were obtained from the Jackson Laboratory. Fifteen mice were housed individually, and 15 mice were housed in groups of 5/cage. Animals were fed ad libitum and maintained in the same room under a 12:12‐hour light/dark photoperiod at 22 °C for 9 weeks. Animals were killed, and fat mass, soft‐lean tissue mass, bone mineral density (BMD), and bone mineral content (BMC) were determined by DXA. At necropsy, weights of the paired epididymal fat pads, paired retroperitoneal fat pads, right inguinal fat pad, liver, kidneys, paired testes, and seminal vesicles were obtained. Results: Relative to mice housed singly, group‐housed mice showed significantly greater variance in percentage of body fat, testes weight, and BMC. Group‐housed mice tended to show greater variance in liver weights and BMD. Mice housed singly were smaller, had less soft‐lean tissue mass and BMC, and lower BMD when compared with group‐housed mice. Discussion: These results suggest that with respect to body composition parameters, mice housed singly are more similar to one another than are group‐housed mice, most likely because of a reduction in environmental (predominately behavioral/social) effects. Thus, mice housed singly may be more representative of genotypic effects on body composition than group‐housed mice. Whether other inbred strains of mice show similar responses to housing condition is unknown.     

Testosterone alters duodenal calcium transport and longitudinal bone growth rate in parallel in the male rat.

Duodenal active calcium transport and longitudinal bone growth rate have been shown previously to be regulated in parallel by alteration of gonadal hormone status in sexually maturing female rats. The present study was designed to extend these observations to the sexually maturing male rat. Male rats were orchidectomized (ORX) and given Silastic implants containing either testosterone or estradiol at 6 weeks of age. At 9 weeks of age, duodenal active calcium transport was measured by the everted gut sac method and longitudinal bone growth rate was determined by tetracycline labeling. Decreases in body weight, longitudinal bone growth rate, duodenal calcium transport, and serum Ca and P were exhibited by ORX animals as compared with age-matched control animals. Testosterone administration to ORX animals resulted in an increase in body weight, longitudinal bone growth rate, duodenal calcium transport, and serum Ca and P as compared with ORX animals to a level not significantly different from that of age-matched control animals. Estradiol administration to ORX animals resulted in an additional decrease in body weight, although no significant effect on duodenal calcium transport, serum Ca, or P was noted as compared with ORX animals. There were no statistically significant alterations in the circulating levels of 1,25-dihydroxyvitamin D, parathyroid hormone, or osteocalcin in response to any of the experimental manipulations of gonadal status. These results indicate that, as in the female, gonadal hormone status affects intestinal calcium transport in sexually maturing male rats in parallel with changes in bone growth rate by mechanisms that are independent of circulating levels of 1,25-dihydroxyvitamin D.     

Regional Body Composition: Cross‐calibration of DXA Scanners—QDR4500W and Discovery Wi

Differences exist in body composition assessed by dual‐energy X‐ray absorptiometers (DXAs) between devices produced by different manufacturers and different models from the same manufacturer. Cross‐calibration is needed to allow body composition results to be compared in multicenter trials or when scanners are replaced. The aim was to determine reproducibility and extent of agreement between two fan‐beam DXA scanners (QDR4500W, Discovery Wi) for body composition of regional sites. The sample was: 39 women 50.6 ± 9.6 years old with BMI 26.8 ± 5.5 kg/m², body fat 33 ± 7%. Four whole body scans (two on each device) were performed over 3 weeks. Major variables were fat mass, nonosseous lean mass, and bone mineral content (BMC) for the truncal and appendicular regions. Extent of agreement was assessed using Bland and Altman plots. Both devices demonstrated good precision with mean test–retest differences close to zero for fat mass, nonosseous lean mass, and BMC of the truncal and appendicular regions. Evaluation of interdevice agreement revealed significant differences for truncal and appendicular BMC, nonosseous lean mass, and fat mass. The greatest interdevice difference was for truncal fat mass (0.69 ± 0.60 kg). Differences in truncal and appendicular fat mass increased in magnitude at higher mean values. Furthermore, differences in truncal and appendicular fat mass were strongly related to BMI (R = ?0.61, R = ?0.55, respectively). In conclusion, in vivo cross‐calibration is important to ensure comparability of regional body composition data between scanners, especially for truncal fat mass and for subjects with higher BMI.     

In vivo whole body and appendicular bone mineral density in rats: a dual energy X-ray absorptiometry study

Bone mineral density (BMD) of the whole body and hind limb of young adult rats, with and without a sham-operated stifle joint was studied, using dual energy x-ray absorptiometry (DEXA) at three time points. Data from the whole body scan were used for analyses of BMD, bone mineral content (BMC), fat, lean, body weight (BW), percentage of BMC (%BMC), percentage of fat (%fat), and percentage of lean (%lean), none of which were significantly different between the groups at any time point. Significant (P < 0.05) differences in BMD, BMC, %BMC, BW, fat, %fat, and %lean were apparent at the second and third scans, compared with the initial scan, within both groups. Changes in whole body BMD, BMC, and %BMC as well as BW were highly correlated with time in both groups. In the hind limb scans, regions of interest (ROIs) were created to obtain values of BMD and BMC from the whole femur, whole tibia including the fibula, distal portion of the femur, and proximal portion of the tibia. Significant differences were not found between the groups for any ROIs. However, significant BMD and BMC increases were evident in all ROIs at the second and third scans, compared with the initial scan. Similar to those in the whole body scan, BMD and BMC obtained from ROIs were highly correlated with time. The positioning technique for the whole body and appendicular scans was analyzed by calculating percentage of the coefficient of variation (%CV) at the beginning of the study. The %CV was low and acceptable in ROIs for the hind limb and for all parameters of the whole body scan, except fat. The results suggest that in vivo DEXA scanning of the rat whole body and appendicular skeleton is highly reproducible and useful to study the whole skeleton, as well as a region of a long bone of the rat. Values for the sham-operated rats were not significantly different from those for the untreated controls, which suggests that soft tissue damage around the stifle joint did not alter BMD in the subchondral bone of the distal portion of the femur and proximal portion of the tibia.     

Orchiectomized Fischer 344 male rat models body composition in hypogonadal state

The hypogonadal state in men is accompanied by substantial decreases in muscle and bone mass and by an increase in adiposity. Most of the strains of orchiectomized (ORX) rat that have been used to model this state display substantial losses in bone, but only subtle changes in adiposity and muscle mass. In order to identify a rat model displaying a robust catabolic response to ORX, we studied three strains: Fischer 344 (F344), Brown Norway and Wistar. ORX caused a significant and sustained decrease in weight gained by F344, but only a trend toward reduced weight gain in Brown Norway rats and a modest reduction weight gain in Wistar rats that was significant only after 56days. ORX suppressed food intake in F344 rats, and to a lesser degree in Brown Norway and Wistar rats. ORX reduced muscle mass significantly in F344 rats, but not in Brown Norway or Wistar rats. ORX increased adiposity moderately in F344 rats and substantially in Wistar rats. ORX caused a marked reduction in prostate mass and increase in bone resorption in all three strains. Thus, F344 was the only strain in which ORX produced substantial decreases in food intake, body weight and muscle mass with increased adiposity and increased bone resorption. We conclude that the F344 rat displays a broad range of catabolic effects following ORX and is the best rat model for studying the androgenic pathway and strategies for reversing catabolic changes induced by hypogonadism.     

跑台运动训练和停训对去卵巢大鼠体成分和骨密度的影响

目的:研究中等强度跑台运动训练和停训对去卵巢大鼠骨密度和体成分的影响。方法:将60只成年雌性SD大鼠按体重分层后随机分为假手术组、去卵巢静止组和去卵巢运动组,每组20只。去卵巢运动组大鼠每周进行4次时间45min、速度18m/min、跑道倾角5℃的跑台训练,持续训练14周时,将各组大鼠又随机分为两个亚组,即:假手术-16周(Sham-16)和假手术32周(Sham-32)组、去卵巢-16周(OVX-16)和去卵巢-32周(OVX-32)组以及去卵巢运动(EX)和停训组(DEX)。分别在末次训练结束36-48小时内或停训16周时,用双能X线骨密度仪检测各组大鼠体成分和骨密度的变化。结果:(1)训练结束时,OVX-16组大鼠体脂重量和含量显著高于Sham-16和EX组,而瘦体含量、全身骨密度和腰椎骨密度显著低于Sham-16和EX组,各组其他检测指标无显著变化。(2)停训16周时,OVX-32组大鼠体重、脂肪重量和体脂含量显著高于Sham-32组,而全身、腰椎和左右股骨骨密度以及瘦体含量显著低于Sham-32组;DEX组大鼠脂肪重量和体脂含量显著高于OVX-32组,而瘦体含量显著低于OVX-32组。结论:跑台运动对去卵巢大鼠体成分和骨密度的改善效应在停训16周时均未能被保持。     

Effects of dietary phytase on body weight gain, body composition and bone strength in growing rats fed a low-zinc diet

Phytic acid, a major phosphorous storage compound found in foodstuffs, is known to form insoluble complexes with nutritionally essential minerals, including zinc (Zn). Phytases are enzymes that catalyze the removal of these minerals from phytic acid, improving their bioavailability. The objective of the present study was to determine the ability of dietary phytase to affect body weight, body composition, and bone strength in growing rats fed a high phytic acid, low Zn diet. Rats (n = 20) were fed either a control (AIN-93) or phytase supplemented (Natuphos, BASF, 1,500 phytase units (FTU)/kg) diet for a period of 8 weeks. Phytase supplementation resulted in increased (P<.05) bone and plasma Zn, but no change in plasma inorganic phosphorous or bone levels of Ca, Fe, or Mg. The addition of phytase to the diets resulted in a 22.4% increase (P<.05) in body weight at the end of the study as compared with rats fed a control diet. Dual x-ray absorptiometry (DXA) revealed that phytase supplementation resulted in increase lean body mass (LBM, P<.001) and increased bone mineral content (BMC, P<.001) as compared with feeding the control diet. Bone studies indicated that femurs and tibias from phytase supplemented rats had greater mass (P<.05) and were stronger (P<.05) than rats fed the control diet. This data suggest that the addition of phytase to low Zn diets results in improved Zn status, which may be responsible for beneficial effects on growth, body composition, and bone strength.     

Are bone and muscle changes from POWER PE, an 8-month in-school jumping intervention, maintained at three years?

Our aim was to determine if the musculoskeletal benefits of a twice-weekly, school-based, jumping regime in healthy adolescent boys and girls were maintained three years later. Subjects of the original POWER PE trial (n = 99) were contacted and asked to undergo retesting three years after cessation of the intervention. All original measures were completed including: sitting height, standing height, weight, calcaneal broadband ultrasound attenuation (BUA), whole body, hip and spine bone mineral content (BMC), lean tissue mass, and fat mass. Physical activity was recorded with the bone-specific physical activity questionnaire (BPAQ) and calcium intake was estimated with a calcium-focussed food questionnaire. Maturity was determined by Tanner staging and estimation of the age of peak height velocity (PHV). Twenty-nine adolescents aged 17.3 ± 0.4 years agreed to participate. Three years after the intervention, there were no differences in subject characteristics between control and intervention groups (p>0.05). Three-year change in weight, lean mass, and fat mass were similar between groups (p>0.05). There were no significant group differences in three-year change in BUA or BMC at any site (p>0.05), although the between-group difference in femoral neck BMC at follow-up exceeded the least significant change. While significant group differences were not observed three years after cessation of the intervention, changes in bone parameters occurred in parallel for intervention and control groups such that the original benefits of the intervention observed within the treatment group were sustained.     

Effect of Protein Intake on Bone Mineralization during Weight Loss: A 6‐Month Trial

Objective: The long‐term effect of dietary protein on bone mineralization is not well understood. Research Methods and Procedures: Sixty‐five overweight (body mass index, 25 to 29.9 kg/m²) or obese (≥30 kg/m²) subjects were enrolled in a randomized, placebo‐controlled, 6‐month dietary‐intervention study comparing two controlled ad libitum diets with matched fat contents: high protein (HP) or low protein (LP). Body composition was assessed by DXA. Results: In the HP group, dietary‐protein intake increased from 91.4 g/d to a 6‐month intervention mean of 107.8 g/d (p < 0.05) and decreased in the LP group from 91.1 g/d to 70.4 g/d (p < 0.05). Total weight loss after 6 months was 8.9 kg in the HP group, 5.1 kg in the LP group, and none in the control group. After 6 months, bone mineral content (BMC) had declined by 111 ± 13 g (4%) in the HP group and by 85 ± 13 g (3%) in the LP group (not significant). Loss of BMC was more positively correlated with loss of body fat mass (r = 0.83; p < 0.0001) than with loss of body weight. Six‐month BMC loss, adjusted for differences in fat loss, was greater in the LP group than in the HP group [difference in LP vs. HP, 44.8 g (95% confidence interval, 16 to 73.8 g); p < 0.05]. Independent of change in body weight and composition during the intervention, highprotein intake was associated with a diminished loss of BMC (p < 0.01). Discussion: Body‐fat loss was the major determinant of loss of BMC, and we found no adverse effects of 6 months of high‐protein intake on BMC.     

Chronic injection of pansomatostatin agonist ODT8-SST differentially modulates food intake and decreases body weight gain in lean and diet-induced obese rats

The aim of this study was to investigate the central actions of the stable pansomatostatin peptide agonist, ODT8-SST on body weight. ODT8-SST or vehicle was acutely (1μg/rat) injected or chronically infused (5μg/rat/d, 14d) intracerebroventricularly and daily food intake, body weight and composition were monitored. In lean rats, neither acute nor chronic ODT8-SST influenced daily food intake while body weight was reduced by 2.2% after acute injection and there was a 14g reduction of body weight gain after 14d compared to vehicle (p<0.01). In diet-induced obese (DIO) rats, chronic ODT8-SST increased cumulative 2-week food intake compared to vehicle (+14%, p<0.05) and also blunted body weight change (-11g, p<0.05). ODT8-SST for 14d reduced lean mass (-22g and -25g respectively, p<0.001) and total water (-19g and -22g respectively, p<0.001) in lean and DIO rats and increased fat mass in DIO (+16g, p<0.001) but not lean rats (+1g, p>0.05) compared to vehicle. In DIO rats, ODT8-SST reduced ambulatory (-27%/24h, p<0.05) and fine movements (-38%, p<0.01) which was associated with an increased positive energy balance compared to vehicle (+50g, p<0.01). Chronic central somatostatin receptor activation in lean rats reduces body weight gain and lean mass independently of food intake which is likely related to growth hormone inhibition. In DIO rats, ODT8-SST reduces lean mass but promotes food intake and fat mass, indicating differential responsiveness to somatostatin under obese conditions.     

跑台运动训练和停训对去卵巢大鼠体成分和骨密度的影响

目的：研究中等强度跑台运动训练和停训对去卵巢大鼠骨密度和体成分的影响。方法：将60只成年雌性SD大鼠按体重分层后随机分为假手术组、去卵巢静止组和去卵巢运动组,每组20只。去卵巢运动组大鼠每周进行4次时间45min、速度18m／rain、跑道倾角5℃的跑台训练,持续训练14周时,将各组大鼠又随机分为两个亚组,即：假手术-16周（Sham．16）和假手术32周（Sham-32）组、去卵巢-16周（OVX-16）和去卵巢-32周（OVX-32）组以及去卵巢运动（EX）和停训组（DEX）。分别在末次训练结束36—48小时内或停训16周时,用双能X线骨密度仪检测各组大鼠体成分和骨密度的变化。结果：（1）训练结束时,OVX-16组大鼠体脂重量和含量显著高于Sham-16和EX组,而瘦体含量、全身骨密度和腰椎骨密度显著低于Sham-16和EX组,各组其他检测指标无显著变化。（2）停训16周时,OVX-32组大鼠体重、脂肪重量和体脂含量显著高于Sham-32组,而全身、腰椎和左右股骨骨密度以及瘦体含量显著低于Sham．32组;DEX组大鼠脂肪重量和体脂含量显著高于OVX-32组,而瘦体含量显著低于OVX-32组。结论：跑台运动对去卵巢大鼠体成分和骨密度的改善效应在停训16周时均未能被保持。     

Effects of chronic spinal cord injury on body weight and body composition in rats fed a standard chow diet

The inability to maintain body weight within prescribed ranges occurs in a significant portion of the human spinal cord injury (SCI) population. Using a rodent model of long-term high thoracic (spinal level T3) spinal cord transection (TX), we aimed to identify derangements in body weight, body composition, plasma insulin, glucose tolerance, and metabolic function, as measured by uncoupling protein 1 (UCP1) expression in interscapular brown adipose tissue (IBAT). Sixteen weeks after SCI, body weights of injured female rats stabilized and were significantly lower than surgical control animals. At the same time point, SCI rats had a significantly lower whole body fat:lean tissue mass ratio than controls, as measured indirectly by NMR. Despite lower body weight and fat mass, the cumulative consumption of standard laboratory chow (4.0 kcal/g) and mean energy intake (kcal.day(-1).100 g body wt(-1)) of chronic SCI rats was significantly more than controls. Glucose tolerance tests indicated a significant enhancement in glucose handling in 16-wk SCI rats, which were coupled with lower serum insulin levels. The post mortem weight of gonadal and retroperitoneal fat pads was significantly reduced after SCI and IBAT displayed significantly lower real-time PCR expression of UCP1 mRNA. The reduced fat mass and IBAT UCP1 mRNA expression are contraindicative of the cumulative caloric intake by the SCI rats. The prolonged postinjury loss of body weight, including fat mass, is not due to hypophagia but possibly to permanent changes in gastrointestinal transit and absorption, as well as whole body homeostatic mechanisms.     

Improvements in cardiovascular risk profile with large-volume liposuction: a pilot study

In this study, the authors investigated the physiologic effects of the altered body composition that results from surgical removal of large amounts of subcutaneous adipose tissue. Fourteen women with body mass indexes of greater than > 27 kg/m2 underwent measurements of fasting plasma insulin, triglycerides, cholesterol, body composition by dual-energy x-ray absorptiometry (DXA), resting energy expenditure, and blood pressure before and after undergoing large-volume ultrasound-assisted liposuction.There were no significant intraoperative complications. Body weight had decreased by 5.1 kg (p < 0.0001) by 6 weeks after liposuction, with an additional 1.3-kg weight loss (p < 0.05) observed between 6 weeks and 4 months after surgery, for a total weight loss of 6.5 kg (p < 0.00006). Body mass index decreased from (mean +/- SEM) 28.8 +/- 2.3 to 26.8 +/- 1.5 kg/m2 (p < 0.0001). This change in body weight was primarily the result of decreases in body fat mass: as assessed by DXA, lean body mass did not change (43.8 +/- 3.1 kg to 43.4 +/- 3.6 kg, p = 0.80), whereas DXA total body fat mass decreased from 35.7 +/- 6.3 to 30.1 +/- 6.5 kg (p < 0.0001). There were significant decreases in fasting plasma insulin levels (14.9 +/- 6.5 mIU/ml before liposuction versus 7.2 +/- 3.2 mIU/ml 4 months after liposuction, p < 0.007), and systolic blood pressure (132.1 +/- 7.2 versus 120.5 +/- 7.8 mmHg, p < 0.0002). Total cholesterol, high-density lipoprotein cholesterol, plasma triglycerides, and resting energy expenditure values were not significantly altered after liposuction.In conclusion, over a 4-month period, large-volume liposuction decreased weight, body fat mass, systolic blood pressure, and fasting insulin levels without detrimental effects on lean body mass, bone mass, resting energy expenditure, or lipid profiles. Should these improvements be maintained over time, liposuction may prove to be a valuable tool for reducing the comorbid conditions associated with obesity.