Resting metabolic rate in young Polynesian and Caucasian women

OBJECTIVE: To investigate whether resting metabolic rate (RMR) differs between Caucasian and Polynesian women. DESIGN: Cross-sectional comparison. SUBJECTS: Eighty-two (42 Caucasian, 40 Polynesian) healthy women aged between 18 and 27 y. MEASUREMENTS: RMR (indirect calorimetry) and body composition (fat-free mass and fat mass derived from oxygen-18 dilution measurement of total body water). RESULTS: RMR was similar in the Caucasian (6956 +/- 1291 (s.d.) kJ/d) and Polynesian (7125 +/- 1290 kJ/d) groups while fat-free mass was significantly lower in the Caucasian group (45.3 +/- 6.8 vs 51.0 +/- 6.4 kg, P < 0.002). After adjustment for fat-free mass and fat mass, RMR was lower in the Polynesian than the Caucasian groups (6783 +/- 904 vs 7281 +/- 901 kJ/d, P = 0.023). CONCLUSION: The significantly lower relative RMR observed in Polynesian compared to Caucasian women may predispose Polynesian women to eventual onset of obesity.     

Effects of strength training on total and regional body composition in older men

The effects of a 16-wk strength-training program on total and regional body composition were assessed by dual-energy X-ray absorptiometry (DEXA), magnetic resonance imaging (MRI), and hydrodensitometry in 13 untrained healthy men [60 +/- 4 (SD) yr]. Nine additional men (62 +/- 6 yr) served as inactive controls. The strength-training program resulted in substantial increases in both upper (39 +/- 8%; P < 0.001) and lower (42 +/- 14%; P < 0.001) body strength. Total fat-free mass (FFM) increased by 2 kg (62.0 +/- 7.1 to 64.0 +/- 7.2 kg; P < 0.001), and total fat mass decreased by the same amount (23.8 +/- 6.7 to 21.8 +/- 6.0 kg; P < 0.001) when measured by DEXA. When measured by hydrodensitometry, similar increases in FFM (61.3 +/- 7.8 to 63.0 +/- 7.6 kg; P < 0.01) and decreases in fat mass (23.8 +/- 7.9 to 22.1 +/- 7.7 kg; P < 0.001) were observed. When measured by DEXA, FFM was increased in the arms (6.045 +/- 0.860 to 6.418 +/- 0.803 kg; P < 0.01), legs (19.416 +/- 2.228 to 20.131 +/- 2.303 kg; P < 0.001), and trunk (29.229 +/- 4.108 to 30.134 +/- 4.184 kg; P < 0.01), whereas fat mass was reduced in the arms (2.383 +/- 0.830 to 2.128 +/- 0.714 kg; P < 0.01), legs (7.583 +/- 1.675 to 6.945 +/- 1.551 kg; P < 0.001), and trunk (12.216 +/- 4.143 to 11.281 +/- 3.653 kg; P < 0.01) as a result of training.(ABSTRACT TRUNCATED AT 250 WORDS)     

Body composition by X-ray absorptiometry and bioelectrical impedance in chronic respiratory insufficiency patients

Nutrition assessment is important during chronic respiratory insufficiency to evaluate the level of malnutrition or obesity and should include body composition measurements. The appreciation of fat-free and fat reserves in patients with chronic respiratory insufficiency can aid in designing an adapted nutritional support, e.g., nutritional support in malnutrition and food restriction in obesity. The purpose of the present study was to cross-validate fat-free and fat mass obtained by various bioelectric impedance (BIA) formulas with the fat-free and fat mass measured by dual-energy X-ray absorptiometry (DXA) and determine the formulas that are best suited to predict the fat-free and fat mass for a group of patients with severe chronic respiratory insufficiency. Seventy-five patients (15 women and 60 men) with chronic obstructive and restrictive respiratory insufficiency aged 45-86 y were included in this study. Body composition was calculated according to 13 different BIA formulas for women and 12 for men and compared with DXA. Because of the variability, calculated as 2 standard deviations, of +/- 5.0 kg fat-free mass for women and +/- 6.4 kg for men for the best predictive formula, the use of the various existing BIA formulas was considered not clinically relevant. Therefore disease-specific formulas for patients with chronic respiratory insufficiency should be developed to improve the prediction of fat-free and fat mass by BIA in these patients.     

Gender differences in body fat content are present well before puberty

To determine whether gender differences in body fat could be detected in prepubertal children using dual energy X-ray absorptiometry (DEXA), body composition was measured in 20 healthy boys aged 3-8 y matched for age, height and weight with 20 healthy girls. Although boys and girls did not differ in age, height, weight, body mass index (BMI) or bone mineral content, the boys had a lower percentage of body fat (13.5 +/- 5.1 vs 20.4 +/- 6.1%, P < 0.01), a lower fat mass (3.2 +/- 2.0 vs 4.9 +/- 3.1 kg, P < 0.01), and a higher bone-free lean tissue mass (18.6 +/- 4.3 vs 17.0 +/- 3.5 kg, P < 0.01) than the girls. Girls had approximately 50% more body fat than the boys. This is the first DEXA study to show that boys aged 3-8 y have less body fat than girls of similar age, height and weight. Thus, this technology demonstrates that significant gender differences in body composition are evident, well before the onset of puberty.     

Sex hormones, body fat distribution, resting metabolic rate and glucose-induced thermogenesis in premenopausal obese women

The topographic specificity of upper body obesity is known to be at the origin of a series of metabolic complications. In contrast to this negative effect, women with abdominal obesity usually can lose more body weight than women with gluteal-femoral obesity. In order to find some contributive explanations for this effect, we studied resting metabolic rate (RMR) and glucose-induced thermogenesis (GIT) in both types of obesity. Since upper body obesity is characterized by androgen excess, a relationship between body fat distribution, sex hormones, RMR and indices of thermogenesis was studied. Of 39 obese women who were recruited (mean age: 32.4 +/- 9.3 years), 30 were compared for analysis. Upper body obesity (waist-to-hip ratio (WHR): 0.84 +/- 0.02; body mass index (BMI) 36.2: 36.2 +/- 6.0) is not characterized by differences in RMR, whereas glucose-induced thermogenesis is significantly higher in this subgroup (P < 0.008), expressed as percentage increase above RMR (18.3 +/- 8.5 vs. 11.9 +/- 3.6%) or as percentage of metabolisable energy intake (8.2 +/- 3.3 vs. 5.8 +/- 2.3%). Correlation coefficient data show that GIT determinants are closely related to WHR (r = 0.43; P < 0.01) and not to BMI. Resting metabolic rate, both in absolute terms and corrected for fat-free mass (FFM), is not related to indices of androgenicity, but is negatively related to serum oestradiol levels; this negative relationship with oestradiol disappears when RMR is corrected for both fat mass (FM) and FFM. GIT parameters are not related to free testosterone or oestradiol, regardless of the phase of the menstrual cycle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Central markers of body fat distribution are important predictors of plasma lipids in elderly men and women

We determined the contribution of body fat distribution, peak VO2, fat mass, and dietary intake to variation in plasma lipids in elderly individuals. Volunteers were a healthy cohort of older Caucasian women (n = 75, mean age +/- SD, 72 +/- 5 years) and older men (n = 101, 72 +/- 5 years). We determined fat mass from underwater weighing, fat patterning from waist circumference, as well as peripheral and truncal skinfolds, exercise capacity from peak VO2, and dietary intake from three-day food diaries. Plasma lipid levels were measured in the fasting state and included total cholesterol, high density lipoprotein (HDL-C), low density lipoprotein (LDL-C), and fasting triglycerides. Older women weighted less than older men, but had higher fat mass, truncal, and peripheral skinfolds. Waist circumference and peak VO2 were lower in older women than older men. Older women had higher total cholesterol (217 +/- 31 vs. 197 +/- 30; p < 0.01), HDL-C (54 +/- 12 vs. 49 +/- 14; p < 0.05), and LDL-C (133 +/- 26 vs. 121 +/- 27; p < 0.01) when compared with older men. No gender differences were noted in fasting triglycerides. Truncal skinfolds were the best predictor of plasma lipids in older men, accounting for between 9% and 30% (r2) of the variation in plasma lipids. Similarly, in older women, central markers of fatness (i.e., waist circumference and truncal skinfolds) were the best predictors of plasma lipids (r2 = 3% to 24%). Total fat mass, peak VO2 and dietary intake were not independent predictors of plasma lipids in older men and women. Indices of central body fatness, rather than total fat mass, peak VO2 or dietary intake are stronger predictors of plasma lipids in healthy older men and women.     

Assessment of fat-mass loss during weight reduction in obese women

Methods for assessing body fat mass (FM) loss were compared in 32 obese (body mass index [BMI], 29 to 41 kg/m2) premenopausal women before and after a weight loss of 13.0 +/- 3.4 kg (mean +/- SD). A four-component (4C) model was used as the criterion. The other methods were as follows: three-component models (body density with total body water [3W] or bone minerals [3M]), underwater weighing, dual-energy x-ray absorptiometry ([DXA] XR-26, software 2.5.2; Norland, Ft Atkinson, WI), bioelectric impedance analysis (BIA) with an obese-specific equation [Segal et al), skinfolds (Durnin and Womersley), and an equation with BMI (Deurenberg et al). The 3W model (bias +/- SD, 0.5 +/- 0.4 kg), XR-26 (0.6 +/- 2.1 kg), and BMI equation (-0.3 +/- 2.1 kg) gave practically unbiased mean estimations of fat loss. All other methods underestimated fat loss by at least 1.6 kg (range of bias, -2.7 to -1.6 kg). The small bias (0.7 +/- 1.0 kg) between underwater weighing and model 4C before weight reduction indicates that the two-component assumptions were valid in premenopausal, weight-stable obese women. However, particularly the water fraction of the fat-free body component (4C model) was increased after weight reduction (before, 72.9% +/- 1.4%; after, 75.7% +/- 2.2%), making both underwater weighing and the 3M model uncertain for assessment of body composition changes. A general tendency for overestimating FM was seen before and more clearly after weight reduction. However, most methods underestimated fat loss, apparently because of unexpected changes in hydration of the fat-free body component.     

High body fatness, but not low fat-free mass, predicts disability in older men and women: the Cardiovascular Health Study

Using data from the Cardiovascular Health Study, we studied the relation between body composition (fat mass and fat-free mass, assessed by bioelectrical impedance) and self-reported, mobility-related disability (difficulty walking or stair climbing) in 2714 women and 2095 men aged 65-100 y. In a cross-sectional analysis at baseline (1989-1990), disability was reported by 26.5% of the women and 16.9% of the men. A positive association was observed between fat mass and disability. The odds ratio for disability in the highest quintile of fat mass was 3.04 (95% CI: 2.18, 4.25) for women and 2.77 (95% CI: 1.82, 4.23) for men compared with those in the lowest quintile. Low fat-free mass was not associated with a higher prevalence of disability. In a longitudinal analysis among persons not reporting disability at baseline, 20.3% of the women and 14.8% of the men reported disability 3 y later. Fat mass at baseline was predictive of disability 3 y later, with odds ratios of 2.83 (95% CI: 1.80, 4.46) for women and 1.72 (95% CI: 1.03, 2.85) for men in the highest quintile of fat. The increased risk was not explained by age, physical activity, chronic disease, or other potential confounders. Low fat-free mass was not predictive of disability. The results showed that high body fatness is an independent predictor of mobility-related disability in older men and women. These findings suggest that high body fatness in old age should be avoided to decrease the risk of disability.     

Cross-validation of fat-free mass estimated from body density against bioelectrical resistance: effects of obesity and gender

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 = 3.58 kg) 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.     

Energy requirements and physical activity in free-living older women and men: a doubly labeled water study

Determinants of daily energy needs and physical activity are unknown in free-living elderly. This study examined determinants of daily total energy expenditure (TEE) and free-living physical activity in older women (n = 51; age = 67 +/- 6 yr) and men (n = 48; age = 70 +/- 7 yr) by using doubly labeled water and indirect calorimetry. Using multiple-regression analyses, we predicted TEE by using anthropometric, physiological, and physical activity indexes. Data were collected on resting metabolic rate (RMR), body composition, peak oxygen consumption (VO2 peak), leisure time activity, and plasma thyroid hormone. Data adjusted for body composition were not different between older women and men, respectively (in kcal/day): TEE, 2,306 +/- 647 vs. 2,456 +/- 666; RMR, 1,463 +/- 244 vs. 1,378 +/- 249; and physical activity energy expenditure, 612 +/- 570 vs. 832 +/- 581. In a subgroup of 70 women and men, RMR and VO2 peak explained approximately two-thirds of the variance in TEE (R2 = 0.62; standard error of the estimate = +/-348 kcal/day). Crossvalidation of this equation in the remaining 29 women and men was successful, with no difference between predicted and measured TEE (2,364 +/- 398 and 2,406 +/- 571 kcal/day, respectively). The strongest predictors of physical activity energy expenditure (P < 0.05) for women and men were VO2 peak (r = 0.43), fat-free mass (r = 0.39), and body mass (r = 0.34). In summary, RMR and VO2 peak are important independent predictors of energy requirements in the elderly. Furthermore, cardiovascular fitness and fat-free mass are moderate predictors of physical activity in free-living elderly.     

Detection of small changes in body composition by dual-energy x-ray absorptiometry

The ability of dual-energy x-ray absorptiometry (DEXA) to detect small changes in body composition was studied in 17 men and women during a dehydration-rehydration protocol. Scale weight (BW) and total mass (TM) from DEXA were highly related (r > 0.99) as were estimates of fat-free mass (r = 0.99) and percent fat (r = 0.97) from DEXA and densitometry. Changes in BW of approximately 1.5 kg due to fluid loss and gain were highly correlated (r = 0.90) with both changes in TM and soft-tissue mass (STM) by DEXA but less so (r = 0.67) with changes in lean-tissue mass (LTM). Mean changes in TM, STM, and LTM were not different (P > 0.05) from changes in BW. Estimates of bone mass and fat were unaffected by changes in hydration. We conclude that DEXA is able to detect small individual changes in TM and STM and is also useful for detecting group changes in LTM.     

Reduction in intra-abdominal adipose tissue after strength training in older women

The purpose of this study was to examine the effects of a total body strength-training program on changes in total and regional body composition, in particular intra-abdominal adipose tissue (IAAT), in older women. Fourteen healthy older women (mean age 67 +/- 1 yr) exercised 3 times/wk for 16 wk. Strength was assessed by one-repetition maximum tests, with training intensity gradually increased to approximately 67% of one repetition maximum. Body composition was measured by hydrodensitometry and regional body composition was measured by computed tomography. Strength was significantly increased in the upper (51%) and lower body (65%). There was no significant change in body weight (64.4 +/- 2.7 vs. 64.2 +/- 2.7 kg), total body fat (38.7 +/- 1.4 vs. 38.0 +/- 1.6%) or fat-free mass (39.7 +/- 1.0 vs. 40.0 +/- 0.9 kg). However, after ST, there were significant reductions in IAAT (143.9 +/- 13.3 vs. 130.0 +/- 12.4 cm2), the IAAT-to-subcutaneous adipose tissue ratio (0.48 +/- 0.04 vs. 0.44 +/- 0.04), and midthigh subcutaneous adipose tissue (141.7 +/- 11.5 vs. 133.6 +/- 10.8 cm2) and an increase in midthigh muscle (52.9 +/- 2.6 vs. 58.0 +/- 2.0 cm2) (all P < 0.05). In conclusion, significant reductions in IAAT and an increase in strength and muscle area were observed after a strength-training program in healthy older women. These changes may be important in preventing the negative health outcomes associated with the age-related increase in intra-abdominal obesity.     

Serum leptin is increased in growth hormone-deficient adults: relationship to body composition and effects of placebo-controlled growth hormone therapy for 1 year

The gene product from the ob gene, leptin, has recently been characterized in humans. The circulating level of leptin is related to body mass index (BMI) and more closely to estimates of total body fat, whereas visceral fat has been reported to be of minor importance. However, it is unknown if leptin is directly regulated by hormones that influence substrate metabolism and body composition. We studied leptin in adult growth hormone (GH)-deficient (GHD) patients substituted with GH treatment for 12 months in a parallel double-blind, placebo-controlled study. Twenty-seven GHD adults aged 44.9 +/- 1.9 years underwent anthropometric measurements for determination of regional and total body fat (BMI, waist to hip ratio [WHR], computed tomographic [CT] scan, dual-energy x-ray absorptiometry [DEXA] scan, and bioimpedance analysis [BIA]) before and after 12 months of placebo-controlled GH substitution (2 IU/m2) in a parallel design. The same measurements were performed in 42 healthy adults aged 39.1 +/- 1.7 years. The logarithm of serum leptin levels correlated positively with abdominal subcutaneous fat and total body fat (BIA and DEXA) in untreated GHD patients and healthy subjects. Fasting insulin did not correlate with leptin levels in either of the groups. After 12 months of GH administration, the body composition of GHD patients was significantly changed with respect to a marked decrease in body fat. The relations of leptin to the estimates of body fat were maintained, and leptin was furthermore related to BMI and fasting insulin. In multiple linear regression analyses, additional estimates of visceral adiposity (intraabdominal fat and maximal anterior-posterior diameter determined by CT scan) were significant determinants of leptin in the healthy subjects. The increase in fasting insulin levels during GH substitution correlated negatively with the reduction in leptin levels (r = -.823, P = .003). At baseline, leptin levels were increased in the patients compared with controls in both sexes (women, 21.8 +/- 3.3 v 11.3 +/- 1.4 ng/mL, P = .002; men, 8.1 +/- 1.2 v 4.7 +/- 0.7 ng/mL, P = .008). Leptin levels were similar in GHD patients treated for 12 months compared with healthy controls for both women and men (women, 15.9 +/- 2.3 and 11.3 +/- 1.4 ng/mL, P = .163; men, 7.1 +/- 2.8 and 4.7 +/- 0.7 ng/mL, P = .759). In healthy adults and in GHD patients, leptin levels were significantly higher in women than in men (11.3 +/- 1.4 v 4.7 +/- 0.7 ng/mL, P < .001; 21.8 +/- 3.3 v 8.1 +/- 1.2 ng/mL, P < .001). Gender remained a significant determinant of leptin levels in several models of multiple linear regression analysis also including age, estradiol levels, insulin, and estimates of body fat. We conclude that leptin is increased but not differently regulated in GHD patients compared with normal subjects, and that leptin levels are closely related to estimates of body fat. This relationship is maintained during a decrease in body fat due to GH substitution.     

The asylum, the workhouse, and the voice of the insane poor in 19th-century England

OBJECTIVE: The biological role of the adrenal sex steroid precursors--DHEA and DHEA sulphate (DS) and their decline with ageing remains undefined. We observed previously that administration of a 50 daily dose of DHEA for 3 months to age-advanced men and women resulted in an elevation (10%) of serum levels of insulin-like growth factor-I (IGF-I) accompanied by improvement of self-reported physical and psychological well-being. These findings led us to assess the effect of a larger dose (100 mg) of DHEA for a longer duration (6 months) on circulating sex steroids, body composition (DEXA) and muscle strength (MedX). SUBJECTS AND DESIGN: Healthy non-obese age-advanced (50-65 yrs of age) men (n = 9) and women (n = 10) were randomized into a double-blind placebo-controlled cross-over trial. Sixteen subjects completed the one-year study of six months of placebo and six months of 100 mg oral DHEA daily. MEASUREMENTS: Fasting early morning blood samples were obtained. Serum DHEA, DS, sex steroids, IGF-I, IGFBP-1, IGFBP-3, growth hormone binding protein (GHBP) levels and lipid profiles as well as body composition (by DEXA) and muscle strength (by MedX testing) were measured at baseline and after each treatment. RESULTS: Basal serum levels of DHEA, DS, androsternedione (A), testosterone (T) and dihydrotestosterone (DHT) were at or below the lower range of young adult levels. In both sexes, a 100 mg daily dose of DHEA restored serum DHEA levels to those of young adults and serum DS to levels at or slightly above the young adult range. Serum cortisol levels were unaltered, consequently the DS/cortisol ratio was increased to pubertal (10:1) levels. In women, but not in men, serum A, T and DHT were increased to levels above gender-specific young adult ranges. Basal SHBG levels were in the normal range for men and elevated in women, of whom 7 of 8 were on oestrogen replacement therapy. While on DHEA, serum SHBG levels declined with a greater (P < 0.02) response in women (-40 +/- 8%; P = 0.002) than in men (-5 +/- 4%; P = 0.02). Relative to baseline, DHEA administration resulted in an elevation of serum IGF-I levels in men (16 +/- 6%, P = 0.04) and in women (31 +/- 12%, P = 0.02). Serum levels of IGFBP-1 and IGFBP-3 were unaltered but GHBP levels declined in women (28 +/- 6%; P = 0.02) not in men. In men, but not in women, fat body mass decreased 1.0 +/- 0.4 kg (6.1 +/- 2.6%, P = 0.02) and knee muscle strength 15.0 +/- 3.3% (P = 0.02) as well as lumbar back strength 13.9 +/- 5.4% (P = 0.01) increased. In women, but not in men, an increase in total body mass of 1.4 +/- 0.4 kg (2.1 +/- 0.7%; P = 0.02) was noted. Neither gender had changes in basal metabolic rate, bone mineral density, urinary pyridinoline cross-links, fasting insulin, glucose, cortisol levels or lipid profiles. No significant adverse effects were observed. CONCLUSIONS: A daily oral 100 mg dose of DHEA for 6 months resulted in elevation of circulating DHEA and DS concentrations and the DS/cortisol ratio. Biotransformation to potent androgens near and slightly above the range of their younger counterparts occurred in women with no detectable change in men. Given this hormonal milieu, an increase in serum IGF-I levels was observed in both genders but dimorphic responses were evident in fat body mass and muscle strength in favour of men. These differences in response to DHEA administration may reflect a gender specific response to DHEA and/or the presence of confounding factor(s) in women such as oestrogen replacement therapy.     

Urinary bombesin-like peptide levels in infants and children with bronchopulmonary dysplasia and cystic fibrosis

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 multidisciplinary 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.     

Leptin concentration in women is influenced by regional distribution of adipose tissue

Leptin concentrations in humans are increased with obesity, and women have higher leptin concentrations than men. This sex difference reflects the greater fat mass of women. However, there is evidence that factors other than the size of the adipose tissue mass contribute to serum leptin concentrations. This study was undertaken to determine whether anthropometric factors influenced leptin concentrations in our population. Leptin concentrations were measured in 375 persons from a population study of hypertension and diabetes for whom body-composition data (bio-electrical impedance analysis and anthropometry) were available. Serum leptin concentrations were more than four times higher in women than in men (18.5 +/- 13.9 compared with 3.8 +/- 3.6 ng/L, P < 0.0001). In individuals with comparable body mass indexes, these differences persisted after adjustment for either percentage fat (P < 0.05) or fat mass (P < 0.0001) by multivariate-regression analysis. After fat mass was adjusted for, the serum leptin concentration in both men and women was independent of waist circumference but in women was associated with hip circumference. Hip circumference is a proxy measure of peripheral fat and these results suggest that the larger hips of women may contribute to the sex difference in serum leptin concentration.     

Age-related patterns in body composition for men aged 20-79 yr

Fat-free body mass has been reported to decline by 30% between the ages of 30 and 70 yr, whereas body weight increases until age 50 yr. This study examined the age-related patterns in body composition, specifically its two components, fat-free body mass and fat mass, in 157 men aged 20-79 yr. Total body composition was assessed by hydrodensitometry and subcutaneous fat was measured with skinfolds. Approximately 15 men were tested in each of the 12 5-yr age groups (20-24, 25-29, 30-34, ... 75-79 yr). Body density, as determined by underwater weighing, was lower successively from the youngest to oldest age groups; men below age 40 yr had significantly higher (P < 0.01) body densities than the older men. Although there was a gradual decline in fat-free body mass with increasing age, there was not a significant age group effect until age 70 yr. Fat mass gradually increased with increasing age; men above age 40 yr had significantly higher (P < 0.01) total body fat when compared to the younger men. Subcutaneous body fat was similar at the distal limb locations for each age group; however, the proximal trunk locations, especially the abdomen, demonstrated significantly (P < 0.01) higher skinfold thicknesses with increasing age. In conclusion, fat-free body mass was maintained to a later age than previously reported; thus, the age-related decline in body density could be attributed to an age-related increase in body fat.     

Outcome from treatment for spinal arteriovenous malformation

BACKGROUND: prospective studies have demonstrated that a predominance of small, dense LDL particles (pattern B) precedes the clinical onset of coronary heart disease. Prevalence and characteristics of subjects with this LDL size abnormality were studied in young, nonobese, Japanese normolipidemic men. METHODS AND RESULTS: LDL peak particle diameter (PPD) was measured by continuous disc polyacrylamide gel electrophoresis in 223 nonobese normolipidemic men aged 18-20 years (mean+/-S.D. body mass index: 21.9+/-3.7 kg/m2, total cholesterol: 180+/-29 mg/dl, triglyceride: 62+/-34 mg/dl, HDL cholesterol: 58+/-12 mg/dl). Men with small LDL (PPD < 25.8 nm) were found in only 5.4% (n=12) whereas 197 men (88.3%) had a preponderance of large LDL (PPD 26.3 nm). As compared with men in a top tertile (PPD 27.5 nm) those in a low tertile (PPD < 26.9 nm) had higher serum levels of LDL cholesterol (120+/-31 vs 104+/-24 mg/dl), triglyceride (72+/-39 vs 49+/-16 mg/dl) and apolipoprotein (apo) B (84+/-21 vs 68+/-14 mg/dl), and lower HDL cholesterol (54+/-10 vs 60+/-12 mg/dl). They also had greater body mass index (23.2+/-4.6 vs 20.9+/-3.1 kg/m2) and percent body fat (21.5+/-7.7 vs 17.5+/-4.9%). LDL-PPD was positively correlated with HDL cholesterol (R=0.20, P=0.002) and was negatively correlated with apoB (R=0.34, P < 0.001), triglyceride (R=0.32, P < 0.001). percent body fat (R=0.26, P < 0.001), body mass index (R=0.24, P < 0.001), fat mass (R=0.23, P=0.001), total cholesterol (R=0.20, P=0.002). In multiple regression analysis, apoB, triglyceride, HDL cholesterol, apoAI and percent body fat explained 18% of LDLPPD variability. CONCLUSION: even in young, nonobese, normolipidemic men, LDL size appears to be associated with triglyceride-rich lipoprotein metabolism and body fat.     

Decreased leptin levels in normal weight women with hypothalamic amenorrhea: the effects of body composition and nutritional intake

Leptin is a protein encoded by the ob gene and expressed in adipocytes. A sensitive marker of nutritional status, leptin is known to correlate with fat mass and to respond to changes in caloric intake. Leptin may also be an important mediator of reproductive function, as suggested by the effects of leptin infusions to restore ovulatory function in an animal model of starvation. We hypothesized that leptin levels are decreased in women with hypothalamic amenorrhea and that leptin may be a sensitive marker of overall nutritional status in this population. We, therefore, measured leptin levels and caloric intake in 21 women with hypothalamic amenorrhea (HA) and 30 age-, weight-, and body fat-matched eumenorrheic controls. Age (24 +/- 5 vs. 24 +/- 3 yr), body mass index (20.6 +/- 1.3 vs. 21.1 +/- 1.5 kg/m2), percent ideal body weight (94.9 +/- 5% vs. 96.3 +/- 6.3%), and fat mass (14.2 +/- 3.6 vs. 15.5 +/- 2.9 kg, determined by dual energy x-ray absortiometry) did not differ between the groups. Leptin levels were significantly lower in the HA subjects compared with those in the controls (7.1 +/- 3.0 vs. 10.6 +/- 4.9 micrograms/L; P = 0.005). Total caloric intake (1768 +/- 335 vs. 2215 +/- 571 cal/day; P = 0.003), fat intake (333 +/- 144 vs. 639 +/- 261 cal/day; P < 0.0001), and insulin levels (5.6 +/- 1.2 vs. 7.4 +/- 3.2 microU/mL; P = 0.015) were lower in the women with HA than in the eumenorrheic controls. The difference in leptin levels remained significant after controlling for insulin (P = 0.023). These data are the first to demonstrate hypoleptinemia, independent of fat mass, in women with HA. The hypoleptinemia may reflect inadequate calorie intake, fat intake, and/or other subclinical nutritional disturbances in women with HA. The mechanism and reproductive consequences of low leptin in this large population of women remain unknown.     

Effects of type IV phosphodiesterase inhibition on cardiac function in the presence and absence of catecholamines

Variations in the density of the fat-free mass (DFFM) across ethnic groups is a critical factor that invalidates the use of body fat equations. It has also been suggested that resistance trained athletes may have higher body densities (BDs) than untrained subjects. Thus, the validity of using anthropometric (ANT) equations, which have mainly been derived on white nonathletic groups, has been questioned for athletic white and black men. This study compared BD and percent body fat (%BF) between 34 white (20 +/- 1 yr, 184 +/- 11 cm, 84 +/- 12 kg, 25 +/- 3 BMI) and 30 black (20 +/- 1 yr, 182 +/- 9 cm, 84 +/- 12 kg, 25 +/- 2 BMI) male collegiate athletes and determined the accuracy of 5 ANT equations in estimating %BF. Subjects were underwater weighed (UWW), and skinfold measurements were obtained from the chest, mid-axillary, abdomen, suprailiac, subscapula, triceps, and thigh. BD was obtained from UWW and estimated from the five skinfold equations. From UWW, significant (P < or = 0.05) differences were found for BD (1.075 +/- 0.007 vs 1.0817 +/- 0.009), but not for %BF (10.49 +/- 2.8 vs 11.59 +/- 3.4) for white and black subjects, respectively. Differences were noted for subcutaneous skinfold sites (abdominal (vertical), suprailiac, and thigh), sum of three and seven skinfolds, and proportion of subscapular subcutaneous fat. One out of five and five out of five ANT equations (Siri conversions) yielded significantly lower estimates compared with UWW %BF for the white and black athletes, respectively. Use of the Schutte equation for the black athletes resulted in overpredictions of %BF for five out of five equations. In addition, the Schutte equation offered slightly greater accuracy than did the Siri equation for estimating %BF in black athletes. These data confirm earlier concerns that ANT equations derived on general populations may not be as accurate for athletic populations and also suggest that correction equations are necessary for converting BD into %BF for populations differing with respect to race or training status.