Showing papers in "International Journal of Obesity in 1991"

Sex and age specific prediction formulas for estimating body composition from bioelectrical impedance: a cross-validation study.

Abstract: In 827 male and female subjects, with a large variation in body composition and an age range of 7-83 years, body composition was measured by densitometry, anthropometry and bioelectrical impedance. The relationship between densitometrically determined fat free mass (FFM) with body impedance (R), body weight (W) and body height (H) was analysed, taking age and sex into account. The intercept of the regression equation FFM = a x H2/R + b was found to be age, and (at older ages) sex dependent, increasing from age 7 to age 15, and slowly decreasing after age 16. Therefore the population was subdivided into two age categories, the one 15 years and younger, and the other 16 years and older. Each age category was randomly divided into two groups, A and B. In each age category the developed prediction formula for group A was cross-validated in group B, and vice versa. No statistically and biologically meaningful differences between predicted and measured FFM were observed in either group. Therefore the data of group A and B in each age category were combined. The best fitted prediction formula at ages less than or equal to 15 was: FFM = 0.406 x 10(4) x H2/R + 0.360 W + 5.58 H + 0.56 Sex - 6.48: n = 166, R2 = 0.97, SEE = 1.68 kg (cv% = 4.9 percent); and at ages greater than or equal to 16: FFM = 0.340 x 10(4) x H2/R + 15.34 H + 0.273 W - 0.127 age + 4.56 sex - 12.44: n = 661, R2 = 0.93, SEE = 2.63 kg (cv% = 5.0 percent).(ABSTRACT TRUNCATED AT 250 WORDS)

A meta-analysis of the factors affecting exercise-induced changes in body mass, fat mass and fat-free mass in males and females.

Abstract: A meta-analysis was performed to assess the effects of type, duration and frequency of exercise training on changes in body mass (BM), fat mass (FM), fat-free mass (FFM) and percent body fat (percent fat) both for adult males and females. Weight loss following aerobic type exercise training, though modest, was greater for males. Stepwise regression suggests that, both for males and females, energy expended during exercise and initial body fat levels (or body mass) account for most of the variance associated with changes in BM, FM and percent fat associated with aerobic-type exercise training. In females, weeks of training and duration of exercise per session were also significant predictors. These findings confirm earlier research in males concerning exercise training effects on body mass and body composition and extend them both to females and to a broader range of exercise types. Of particular interest in this regard is the finding that weight training exercise which is similar to aerobic exercise in facilitating body fat loss, can also preserve or increase fat-free mass.

Adipose tissue distribution and function.

Abstract: Adipose tissue distribution in man is dependent on genetic and environmental factors. The total and regional masses of adipose tissue are dependent on the number of adipocytes as well as their degree of filling with depot fat. Currently available evidence does not suggest a specific regional regulation of fat cell multiplication in subcutaneous depots, which instead seems to occur at a certain critical degree of filling of available adipocytes. The control of the rate of filling of adipocytes then seems to be the main factor determining the local, regional mass of adipose tissue. This in turn is regulated by the balance between the lipid accumulating and mobilization processes. The steroid hormones exert major permissive effects on these processes. It seems likely that the resulting effect of the rate of secretion of various steroid hormones, and the local density of their specific receptors, decide the regional distribution of body fat. Physiological and clinical situations with defined differences in these regulatory factors would then be expected to have characteristically different adipose tissue distribution. Sex differences include a larger subcutaneous adipose tissue in women than men, explainable at least partly by a depot in the gluteal-femoral region in women, which is essentially absent in non-obese men. Men on the other hand seem to have a larger proportion of their adipose tissue organ localized intra-abdominally. In addition, the gluteal-femoral fat cells are specifically enlarged in women, and have a higher lipoprotein lipase activity. While the larger adipose tissue in non-obese women may well be genetically linked, the specific characteristics of the gluteal-femoral adipocytes are most likely regulated by female sex steroid hormones. Another apparent sex difference is the ability of women to protect visceral depots from fat accumulation up to a certain degree of obesity, while men deposit excess fat in this region in parallel with other depots. This might, at least partly, simply be explainable by the smaller 'available space' in male than female adipose tissue. It should be emphasized that the effects of sex steroid hormones on the regulation of adipocyte metabolism occur only in concert with cortisol, which is always present. Cortisol itself expresses lipoprotein lipase activity as well as beta-adrenergic receptors (BARs), and probably has additional effects, not yet revealed. The net effect seems, however, to be lipid accumulation as seen in the apparently glucocorticoid receptor (GR) dense visceral adipose tissue in conditions of glucocorticoid excess, such as Cushing's syndrome. The effects of the sex steroid hormones should be regarded against this background.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of testosterone on abdominal adipose tissue in men.

Abstract: Recent studies in men have shown that abdominal fat increases with age and decreasing testosterone concentrations Furthermore, in cell culture, testosterone expresses an increased lipolytic potential and depresses lipoprotein lipase activity (LPL) in adipose cells These metabolic characteristics are found in abdominal adipose tissue in young men In order to see whether abdominal fat masses in moderately obese middle-aged men might be diminished by testosterone, this hormone was given either as a single injection (500 mg) or in moderate doses (40 mg X 4) for 6 weeks in an oral preparation, bypassing the liver When measured 1 week after the single dose, abdominal LPL tended to decrease After 6 weeks a dramatic decrease of abdominal LPL was found, as well as an increase in the lipolytic responsiveness to norepinephrine, both changes confined solely to the abdominal, and not femoral adipose tissue regions The waist/hip circumference decreased in 9 out of the 11 examined men No untoward effects were seen in behavioural variables, blood pressure, triglyceride or cholesterol values, and liver function tests These preliminary results suggest that administration of testosterone in moderate doses to middle-aged men lead to adaptations of the metabolism of adipose tissue expected to be followed by a diminution of this mass

Ideal body weight estimated from the body mass index with the lowest morbidity.

Abstract: The ideal body weight (kg) of each individual can be calculated by the following formula: ideal body mass index x the height (m)2, since body mass index is expressed by the body weight in kilogram divided by the height squared in meters. We investigated an ideal body mass index with respect to morbidity in 4565 Japanese men and women aged 30-59 years. Ten medical problems served as indices of morbidity: lung disease, heart disease, upper gastrointestinal disease, hypertension, renal disease, liver disease, hyperlipidemia, hyperuricemia, diabetes mellitus and anemia. The value of body mass index associated with the lowest morbidity was 22.2 kg/m2 in men and 21.9 kg/m2 in women, according to the quadratic regression curves relating body mass index to morbidity. From these findings, we propose that the ideal body weight is 22 x height (m)2. Our recommendations apply to the age group studied, namely 30-59 years.

Improvement of glucose and lipid metabolism associated with selective reduction of intra-abdominal visceral fat in premenopausal women with visceral fat obesity.

Abstract: Visceral fat obesity (VFO) with predominant intra-abdominal fat accumulation has been shown to be more often associated with metabolic disorders than subcutaneous fat obesity (SFO). In the present study, changes in fat distribution and their effects on metabolic complications were investigated in forty premenopausal female obese patients in whom substantial weight reduction was obtained by means of a low calorie diet. Analysis of fat distribution by CT scanning demonstrated that visceral fat decreased to a greater extent than abdominal subcutaneous fat, which was particularly evident in VFO patients. On the other hand, change of fat distribution was small in SFO patients. That is, visceral to subcutaneous abdominal fat ratio (V/S ratio) decreased from 0.62 +/- 0.36 to 0.46 +/- 0.33 in VFO, whereas from 0.23 +/- 0.07 to 0.20 +/- 0.09 in SFO after weight reduction. Although obese patients, especially those with VFO, were frequently associated with glucose intolerance and hyperlipidemia, marked diminution was observed in the elevated levels of plasma glucose area on 75g OGTT, serum total cholesterol and triglyceride after weight reduction. By the examination of interrelationship between the changes in body weight, BMI, total and regional fat volume and changes in glucose and lipid metabolism, we found that the decrease in the V/S ratio and visceral fat volume were more strongly correlated with the improvement in plasma glucose and lipid metabolism compared to the decrease in body weight, BMI, total fat volume and abdominal subcutaneous fat volume. Furthermore, partial correlation analyses demonstrated that the metabolic improvements were associated with changes in visceral abdominal fat after control for changes in total adipose tissue volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Patterns of change in weight/stature2 from 2 to 18 years: findings from long-term serial data for children in the Fels longitudinal growth study.

Abstract: Serial weight/stature2 (W/S2) data recorded semi-annually from 2 to 18 years in the Fels longitudinal study were analyzed to establish an approach for the investigation of long-term serial changes in body fatness during childhood and adolescence in individuals. To describe patterns of change in body fatness during childhood and adolescence, a family of mathematical models was fitted to individual serial W/S2 data recorded from 250 boys and 246 girls. The selected models fitted the W/S2 data well as judged by the root mean square errors. Based on the fitted models, variables representing patterns of change in an individual were derived. These included estimated value of W/S2 at 2 years of age (W/S(2)2yr), minimum value of W/S2 (W/S2min), age at minimum value of W/S2 (Amin), maximum velocity of W/S (Vmax), age at maximum velocity of W/S2 (AVmax), maximum value of W/S2 (W/S2max), and age at maximum value of W/S2 (Amax). There were highly significant correlations between observed W/S2 at 18 years and all the derived variables except AVmax indicating, for example, that in both sexes about 25 percent of the variation in W/S2 at 18 years could be explained by when Amin occurs or by the value of W/S2min. The negative correlations (r = -0.5) between Amin and W/S2 at 18 years suggested that the earlier children reach their nadir in W/S2, the earlier they began to increase in adiposity and the fatter they were at 18 years. Likewise, the positive correlations (r approximately 0.3 and 0.5, respectively) between the W/S(2)2yr or W/S2min and W/S2 at 18 years indicated that increased childhood adiposity may lead to increased adult adiposity.

Socioeconomic status differences in health behaviors related to obesity: the Healthy Worker Project.

Abstract: Obesity and health behaviors that influence energy balance (diet, exercise, and dieting to lose weight) were examined in a population of 2108 and 2539 working men and women in relation to socioeconomic status (SES). The hypothesis investigated was that the inverse relationship between SES and obesity observed in a number of studies is due to the fact that the distribution of obesity relevant health behaviors differs by social class. Body mass index (BMI), as expected, was found to be inversely related to SES. Higher SES was also associated with several behaviors that contribute importantly to energy balance. High SES respondents reported a lower fat diet, more exercise, and a higher prevalence of dieting to control weight. However, lower smoking rates were observed in upper SES men and women and higher alcohol consumption was reported in upper SES women. Both of these associations appear to be inconsistent with the hypothesis that the inverse association between SES and obesity is caused by differences in health behaviors. In multiple regression analyses, SES remained a significant predictor of BMI after controlling for all measured health behaviors. Weaknesses in the methodologies for measuring health behaviors and possible effects of obesity itself on social mobility are suggested as possible explanations for the residual association between obesity and SES.

Multivitamin prophylaxis in prevention of post-gastric bypass vitamin and mineral deficiencies.

Abstract: One hundred forty patients were followed for a mean 24.2 months after gastric bypass. Postop multivitamin (MV) prophylaxis was recommended for all patients and 90 of 140 patients (64 percent) were regularly compliant. Deficiencies in iron, vitamin B-12 or folate were recognized in 88 of 140 patients (63 percent). Thirty of 45 patients (67 percent) with iron deficiency developed anemia. Forty-three of the 52 patients who did not have deficiencies were regularly taking MV vs 47 of 88 patients who developed deficiencies (P less than 0.001). MV prophylaxis was successful in preventing folate (P less than or equal to 0.05) and vitamin B-12 deficiencies (P less than or equal to 0.02) but did not prevent development of iron deficiency or subsequent anemia. There was no correlation between taking prescribed supplements and resolution of either iron deficiency of anemia. B-12 and folate supplements corrected deficiencies in 73 percent of cases. We conclude that oral MV prophylaxis is useful in preventing folate and B-12 deficiency after gastric bypass. Additional prophylactic iron supplements should be provided for women to prevent iron deficiency and associated anemia.

Body mass index and patterns of mortality among Seventh-day Adventist men.

Abstract: This study examines the relationship between body mass index (BMI) and 26-year mortality among 8828 nonsmoking, nondrinking Seventh-day Adventist men, including 439 who were very lean (BMI less than 20 kg/m2). The adjusted relative risk comparing the lowest BMI quintile (less than 22.3) to the highest (greater than 27.5 kg/m2) was 0.70 (95 percent CI 0.63-0.78) for all cause mortality, 0.60 (95 percent CI 0.43-0.85) for cerebrovascular mortality, and 0.80 (95 percent CI 0.61-1.04) for cancer mortality. Very lean men did not show increased mortality. To assess whether the protective effect associated with low BMI is modified by increasing age, the product term between BMI and attained age (age at the end of follow-up or at death) was included as a time-dependent covariate. For ischemic heart disease mortality, age-specific estimates of the relative risk for the lowest quintile relative to the highest ranged from 0.32 (95 percent CI, 0.19-0.52) at age 50 to 0.71 (95 percent CI, 0.56-0.89) at age 90. Interaction was also seen for the next lowest quintile (22.4-24.2). There was a significant trend of increasing mortality with increasing BMI for all endpoints studied. For cancer and cerebrovascular mortality the P-values for trend were 0.0001 and 0.001 respectively. For the other endpoints the P-values were less than 0.0001. Thus, there was no evidence for a J-shaped relationship between BMI and mortality in males. While the protective effect associated with the lowest BMI quintile decreased with increasing age for ischemic heart disease mortality, it remained greater than one at all ages. The relatively large number of subjects who were lean by choice, rather than as a result of preclinical disease or smoking, may explain these findings.

Successful weight loss following obesity surgery and the perceived liability of morbid obesity.

Abstract: Patients (n = 47) who lost 45 kg (100 lb) or more and who successfully maintained weight loss for at least three years following gastric restrictive surgery for morbid obesity viewed their previous morbidly obese state as having been extremely distressful. In spite of the strong proclivity for people to evaluate their own worst handicap as less disabling than other handicaps, patients said they would prefer to be normal weight with a major handicap (deaf, dyslexic, diabetic, legally blind, very bad acne, heart disease, one leg amputated) than to be morbidly obese. All patients said they would rather be normal weight than a morbidly obese multi-millionaire.

Increased upper body and overall adiposity is associated with decreased sex hormone binding globulin in postmenopausal women.

Abstract: An unfavorable body fat distribution is associated with many metabolic abnormalities including a high prevalence and incidence of noninsulin dependent diabetes mellitus and decreased high density lipoprotein cholesterol and increased triglyceride levels. One mechanism for the effect of body fat distribution on metabolic variables may be through sex hormones. We examined the relationship of body mass index (BMI), ratio of subscapular-to-triceps skinfold ratio (centrality index) and ratio of waist-to-hip ratio (WHR) to sex hormone binding globulin (SHBG) (an in vivo measure of androgenicity) in 101 postmenopausal Mexican-American and non-Hispanic white women from the San Antonio Heart Study, a population based study of diabetes and cardiovascular disease. SHBG was significantly correlated with BMI (r = -0.440, P less than 0.001), WHR (r = -0.255, P less than 0.01) and centrality index (r = -0.210, P less than 0.05). In a multiple linear regression analysis, SHBG remained significantly associated with BMI (P less than 0.001) and WHR (P less than 0.05) but not with age, ethnicity or centrality index. This work suggests that in postmenopausal women overall adiposity and an unfavorable body fat distribution are associated with increased androgenicity as measured by a lower SHBG concentration. Our finding may help to explain the association of body fat distribution with diabetes and cardiovascular risk factors in older women.

Effects of gender and age on the heritability of body mass index.

Abstract: We estimated genetic and environmental components of variance of body mass index (BMI) among 7245 same-sexed Finnish MZ and DZ twin pairs aged 18-54 years from the nationwide Finnish Twin Cohort Age accounted for 20 per cent of variance among men and 26 per cent in women The contributions of additive genetic effects, shared and non-shared environmental effects on BMI-variance were estimated by LISREL structural equation models Genetic effects accounted for 72 per cent and 68 per cent of total variance in men and non-pregnant women respectively, while 28 per cent of variance among men and 32 per cent among women was due to non-shared environmental effects This gender difference was statistically significant Models including shared environmental effects did not improve model fits The magnitude of the genetic component of BMI was also analysed separately for each 10-year age group Models with age-specific parameters for genetic and environmental effects fitted significantly better than models with effects constrained to be equal over age Our results indicate a substantial genetic component in BMI However, the magnitude of additive genetic effects decreases with age in both genders

Thyrotropin releasing hormone (TRH) immunoreactivity and thyroid function in obesity.

Abstract: Circulating TRH-immunoreactive levels, the thyrotropin response to a TRH intravenous stimulation (200 micrograms) and thyroid hormone concentrations have been determined in 43 overweight subjects (body mass index 45 +/- 12 kg/m2, mean +/- s.d.) and 46 (body mass index 22 +/- 2 kg/m2) normal weight controls. The TRH levels measured by a recently developed, highly specific radioimmunoassay were similar among both groups (44 +/- 16 vs 40 +/- 12 fmol/ml, n.s.). The pattern of response of TSH to TRH was normal in the obese and no significant difference was observed between the peak TSH values of the obese and the normal group (8.3 +/- 2.8 vs 8.7 +/- 2.2 microU/ml, n.s.). No correlations were found between the degree of obesity and the concentrations of TRH, TSH and peripheral thyroid hormone levels. Three obese patients showed a delta-TSH of 18, 19 and 21 microU/ml at normal thyroid hormone concentrations as sign of latent hypothyroidism. These data indicate that in obesity: (a) the TSH response to i.v. TRH is not impaired, (b) circulating TRH-IR levels are not significantly changed and (c) the incidence of overt hypothyroidism is not increased.

Secular trend in body mass index in the adult population of three communities from the upper mid-western part of the USA: the Minnesota Heart Health Program

Abstract: Secular trend in body mass index (BMI) over 7 years (1980-1987) was examined in the upper mid-western part of the USA using annual cross-sectional data collected by the Minnesota Heart Health Program. Significant secular increase in BMI adjusted for age and education was found in both men (0.08 kg/m2/year, P less than 0.02) and women (0.19 kg/m2/year, P less than 0.0001). In women, the secular increase occurred throughout the distribution of body weights but the change in the upper end was two to three times greater than that in the other parts of the distribution. In men, most of the increase in BMI occurred in the upper end of the distribution. Prevalence of obesity (defined as BMI greater than or equal to 85th percentile at year 1: men, 30.16 kg/m2; women, 29.94 kg/m2) increased by 0.6 percent/year (P = 0.1) in men and by 1.0 percent/year (P = 0.002) in women. The results indicate that body weight is increasing in upper mid-western adults, probably largely as a result of already overweight individuals becoming more obese. The secular increase in BMI was not accompanied by systemic change in reported food intake and exercise, and could not be explained by decreased prevalence of smoking. Large increases in body weight, especially among those who are already overweight, may have a significant public health impact.

Regional variation of adipose differentiation in cultured stromal-vascular cells from the abdominal and femoral adipose tissue of obese women.

Abstract: The capacities of the adipocyte precursor pools to form new fat cells were compared in the abdominal and femoral adipose tissue regions of obese women. Adipose tissue samples were obtained from 24 females by needle biopsy. The stromal-vascular cells isolated by collagenase digestion were cultured in a chemically defined medium supplemented with 0.5 mumol/l insulin and 0.1 mumol/l cortisol. The extent of adipose differentiation was assessed by determination of glycerol-3-phosphate dehydrogenase (GPDH) activity after 18 days in culture. No significant differences were found between the two depots with regard to mean fat cell diameter and the number of stromal-vascular cells (abdominal vs femoral site: 134,800 +/- 7900 vs 138,800 +/- 6700 cells/g wet adipose tissue, n.s.). However, GPDH activities were significantly higher in cultured cells from the abdominal region as compared to those from the femoral depot (253.1 +/- 40.9 vs 155.8 +/- 21.4 mU/mg protein, P less than 0.01). These results suggest that regional differences exist in the capacity of adipose tissue depots to form new fat cells. This finding may help to understand changes in adipose tissue distribution during adult life.

Sonography detection of small intra-abdominal fat variations.

Abstract: The aim of this study was to check the reliability of sonography in measuring small variations in quantities of subcutaneous and intra-abdominal fat. Twenty-six obese women (BMI 39 +/- 6) underwent a 15 day very low calorie diet. The study included, both before and after very low calorie diet, computed tomography measurements of total (AT), visceral (VAT) and subcutaneous (SAT) adipose tissue areas, visceral/subcutaneous area ratio (V/S), waist/hip circumference ratio measurements (W/H), and ultrasound measurements of abdominal subcutaneous skin-muscle thickness, intra-abdominal muscle-aorta thickness and intra-abdominal/subcutaneous thickness ratio. Weight reduction was from 101 +/- 17 to 95 +/- 16 kg (P less than 0.001). W/H dropped from 0.83 +/- 0.06 to 0.82 +/- 0.07 (n.s.). VAT dropped from 158 +/- 72 to 134 +/- 61 cm2 (P less than 0.005), SAT from 572 +/- 151 to 566 +/- 164 cm2 (n.s.) and V/S from 0.29 +/- 0.15 to 0.25 +/- 0.11 (P less than 0.01). Abdominal subcutaneous fat thickness decreased from 36 +/- 8 to 35 +/- 10 mm (n.s.), intra-abdominal thickness from 39 +/- 25 to 20 +/- 20 mm (P less than 0.001) and intra-abdominal/subcutaneous from 1.1 +/- 0.7 to 0.8 +/- 0.6 (P less than 0.005). VAT measurement accurately identified small intra-abdominal fat variations. W/H could not evaluate visceral fat loss, because of simultaneous decreases in waist and hip circumferences. Ultrasound was able to measure small reductions in intra-abdominal fat.

Quality of life after gastric bypass for morbid obesity.

Abstract: One year after gastric restriction surgery, 70 per cent of 118 women completed a questionnaire about lifestyle and eating behaviour changes. Mean weight loss was 35.4 kg. Patients reported a moderate reduction in appetite, and most avoided specific foods which they previously enjoyed, usually because of epigastric discomfort and/or nausea and vomiting. Patients had initiated or resumed a mean of 1.8 activities, most of which involved physical exercise. Sexual interest, enjoyment and frequency were all increased. Raised sexual satisfaction correlated strongly with overall outcome satisfaction. Seventy-two per cent of respondents rated themselves as very pleased, and 18 per cent as fairly pleased, with the overall results of the operation, and responses to the open-ended questions were often strikingly enthusiastic. However, most patients emphasized the difficulty of adjusting to radically new eating habits in the first 2-3 months after surgery, during which they experienced their greatest need for social support and encouragement.

Body fat in the adult Danish population aged 35-65 years: an epidemiological study

Abstract: The purpose of the study was: (1) to estimate body fat and body fat distribution in the general population of Danes aged 35-65 years and thus provide tables of normal values for adult Danes in these age groups; and (2) to assess the effects of age and gender on relations between measures of obesity and of fat distribution. Hitherto, the only available results from the Danish population have been on BMI. Of the 3608 invited subjects 2987 (83 per cent) attended the examination. Body fat and fat distribution were estimated from measurements of electrical impedance and from circumference measurements. The study showed large differences in body fat and fat distribution between men and women. There was a difference in total body fat of 4.5 and 6.9 kg in men and women respectively between the groups aged 35 and 65 years. Fat percentage increased 36 per cent in women and 30 per cent in men between the groups aged 35 and 65 years. There was a difference in waist/hip ratio (WH ratio) between men and women at all age groups. Of the women 46 per cent had WH ratios above 0.8 and 14 per cent of the men had WH ratios above 1.0, suggesting that cut-off points for WH ratio as an indicator of cardiovascular risk are population specific. This may be caused by a different distribution of other cardiovascular risk factors in the Danish population than in other populations. Men had larger WH ratios per body fat mass with age, whereas in women there was no effect of age on this relation. Furthermore the WH ratio increments in this population took place before the age of 55 years in men, but after 55 years in women. The results may contribute to explain gender differences in morbidity and mortality with increasing age.

Ventilatory response of moderately obese women to submaximal exercise.

Abstract: To investigate the effect of moderate obesity on ventilatory responses to graded exercise, we compared the ventilatory responses of ten moderately obese (35 +/- 5 percent body fat) and nine leaner women (22 +/- 2 percent body fat) during walking on a treadmill with incremental increases in percent grade. Speed remained constant at 3.0 mph. In the obese women, VO2 in l/min and ml/FFW/min, fb (b/min), VE (l/min), and HR were significantly greater (P less than 0.05) at all four absolute workloads. At 10.0 and 12.5 percent grade, VO2 (ml/kg/min) was smaller and VE/VO2 was greater in the obese women. The difference in VE/VO2 suggests a lower ventilatory threshold for the obese women. Percent VO2 max and R (VCO2/VO2) were significantly different at 12.5 percent grade only. When VO2 was divided by HR (oxygen pulse), the two groups were not significantly different at any of the four workloads tested. The groups were compared further at workloads representing approximately 55, 65, 75, and 85 percent of VO2 max. HR was not significantly different at any of the four relative exercise intensities. VE was significantly greater in the obese at 85 percent of maximum only (P less than 0.05) and fb was significantly greater at 55, 75, and 85 percent of maximum. Whereas cardiorespiratory responses of moderately obese women are increased at absolute workloads when compared to that of leaner women, HR is similar at comparable intensities of exercise. VE is also similar at comparable intensities of exercise below ventilatory threshold but fb is greater. The effect of the higher fb on exercise tolerance is unknown.(ABSTRACT TRUNCATED AT 250 WORDS)

Sex hormone metabolism in upper and lower body obesity.

Abstract: Morbid obesity has been previously shown to be associated with excessive production and metabolism of a variety of androgens and estrogens. Further, SHBG is lowered, resulting in high levels of 'free' testosterone. We have re-examined these parameters in morbidly obese women with upper vs lower body adipose distribution. Upper body obesity was associated with greater increases in production and clearance of testosterone and dihydrotestosterone compared to lower body obesity. Further, SHBG levels were lower resulting in high serum levels of free T and free E2 in this obesity phenotype. By contrast, lower body obesity was associated with increased peripheral aromatization of androstenedione resulting in higher urinary E1 production rates. The biologic significance of these hormonal differences in obesity phenotypes as well as the potential role of the androgen-estrogen environment in determining body fat distribution is considered.

Effects of weight cycling caused by intermittent dieting on metabolic rate and body composition in obese women.

Abstract: The effects of repeated periods of weight loss and regain on metabolic rate and body composition were investigated in 11 obese women (mean weight 81.98 kg, height 1.61 m, body mass index 31.44 kg/m2) studied for 18 weeks through three consecutive cycles of 2 weeks dieting followed by 4 weeks ad libitum eating. Weight loss was achieved by a very low energy diet (1861 kJ/day). Basal metabolic rate (BMR) was measured by whole-body indirect calorimetry and body composition by a variety of standard in vivo methods. During the three diet periods mean weight losses were 4.44, 3.29 and 2.98 kg although the mean overall weight loss from week 0 to 18 was only 5.93 kg. The proportion of weight lost as fat was estimated as between 67 and 105 per cent of the weight lost depending on the body composition methodology employed. Absolute BMR decreased in response to dieting by 545, 285 and 286 kJ/day. When corrected for body weight and FFM only the decreases in the first diet period were significant (P less than 0.05 and P less than 0.001 respectively). BMR had returned to normal following each 4-week ad libitum period and by the end of the study absolute BMR and BMR/kg FFM had not changed significantly, despite a significant loss of weight. Consequently BMR/kg was increased (P less than 0.01), indicative of the loss of adipose tissue. We have found no evidence in this group of obese women that weight cycling leads to a progressive decrease in BMR or increase in the proportion of body fat.

Italian Consensus Conference--overweight, obesity and health.

Abstract: On 5 and 6 April 1991, at the National Research Council (CNR) in Rome, a Consensus Conference on the relationship between overweight, obesity and health was held The conference was sponsored by FATMA (Applied Project on Disease Factors of the CNR) and UICO (Italian Society for the Study of Obesity) with the purpose of establishing guidelines for health employees The development of the conference followed the methodology set down by OMAR to obtain a rational and significant consensus on the answers to six basic questions prepared by the planning committee The questions were the pivotal point of the conference and were brought to the attention of all the attendees and widely diffused among the medical community; they were proposed with the aim of giving an exhaustive definition of obesity, to investigate its relationship with mortality and morbidity, to highlight its social characterization, to indicate methods of evaluation and recommendations for weight loss, to select groups at risk, and to focus general guidelines for research After the presentation of the state of the art on 18 topics by experts in the field, the 22 members of the consensus panel, impartial experts from a vast area of the scientific community, discussed a draft document representing the answers to the questions, which was subsequently submitted to the 307 attendees, discussed and then approved This paper is the definitive document of the Consensus Conference The introduction explains the reasons which led to the decision to promote the conference six years after the one held in the United States The methodology is then set out The questions are answered in the form of recommendations and backed up by data and scientific evidence from the literature

Weight loss and body fat distribution: a feasibility study using computed tomography.

Abstract: Computerized tomography (CT) was used to assess the effect of a loss of body weight (18.8 kg) on the size of five fat depots in 11 obese postmenopausal women: the abdominal subcutaneous and visceral depots, the pelvic subcutaneous and intrapelvic depots, and the thigh subcutaneous depot. The mean decrease in total body fat was 34 percent, with comparable decreases in total abdominal fat (33 percent) and total pelvic fat (32 percent). In the abdomen, visceral fat was reduced by 35 percent and subcutaneous fat by 33 percent. In the pelvic region, intrapelvic fat decreased by 51 percent and subcutaneous fat by 25 percent. The decrease in the size of the abdominal visceral fat depot was highly correlated with fat loss during treatment (r = 0.68). By contrast, the decrease in the size of the subcutaneous abdominal fat depot correlated less highly with fat loss. These preliminary findings suggest that obese postmenopausal women with large visceral fat depots will decrease the size of their visceral fat depots by weight reduction. This is good news since the adverse health effects of obesity are believed to be associated with visceral fat.

Evaluation of a new magnetic resonance imaging method for quantitating adipose tissue areas.

Abstract: We have developed a new magnetic resonance imaging (MRI) protocol to quantitate intraabdominal and subcutaneous fat and have validated it by comparing measurements of fat areas by MRI with those obtained by computed tomography (CT) in 11 asymptomatic volunteers who all had a single CT and MRI image taken at the level of the umbilicus. The new MRI protocol was based on a water-fat separation method by which the slice selection routines excite water and fat protons in different positions along the slice select direction. This method performed more reliably than earlier methods based on phase differences between water and fat signals. Fat areas measured by MRI exceeded those measured by CT by 8-22 percent, and fat areas and ratios obtained by MRI correlated well with CT (r = 0.98 for areas and, for ratios, r = 0.81). The ratio of intraabdominal/subcutaneous fat measured by MRI in seven males was significantly greater than that in four females. We also compared the new method with a previously published inversion recovery (IR) method in seven additional volunteers. Agreement between the two methods was excellent, and the major differences were technical: the IR protocol produced images that may require custom image processing programs when obtained on some scanners. Comparability of the two methods provides further reassurance of the validity of both. MRI presents an attractive opportunity for directly measuring intraabdominal fat in order to correlate this with metabolic parameters and to visualize changes during weight loss.

Lipoprotein metabolism in visceral obesity.

Abstract: The effect of obesity on peroxisomal beta oxidation has been studied previously only in the liver of genetically obese animals. We measured activity of peroxisomal acyl CoA oxidase (ACO) in livers, hearts and rectus femoris muscles of gold-thioglucose treated obese mice (n = 17) and control mice (n = 8). Since production of H2O2 by ACO could contribute to oxidative stress, activities of H2O2-metabolizing enzymes, catalase and glutathione peroxidase, were also measured. ACO activity was assayed using dichlorofluorescein and peroxidase as detectors of H2O2. ACO activity was higher in the obese liver and skeletal muscles than in their respective controls, while the heart ACO activity was unaltered. The activities of H2O2-metabolizing enzymes were unchanged or tended to be decreased in the obese tissues. There was a close correlation between the body weight and ACO activity in both liver and rectus femoris muscles. The ACO activity in the liver also correlated with the liver triacylglycerol content. These results suggest that the activation of peroxisomal beta oxidation occurring in both hepatic and extrahepatic obese tissues is closely linked to weight gain (i.e. non-genetic in nature), but that this does not enhance oxidative stress detected as reactive change of the defense system against H2O2.