Showing papers in "International Journal of Obesity in 1993"

Techniques for the measurement of visceral fat: a practical guide.

Abstract: The measurement of fat distribution has become an important issue in obesity research. Numerous techniques have been developed to assess visceral fat because this fat seems to be most strongly associated with metabolic disorders. This review focuses on methods for the direct and indirect assessment of visceral fat ranging from multiple-scan computerized tomography to anthropometric measurements. The principles of techniques, their accuracy and reproducibility as well as aspects of costs and safety are discussed. Comparison of the different methods shows that imaging techniques, such as computerized tomography and magnetic resonance imaging, are the optimal techniques available for accurate assessment of visceral fat. Methods other than imaging techniques have limited potential in the measurement of changes in visceral fat deposition. Anthropometric measurements can be useful to classify subjects into different types of fat distribution for diagnosis of abdominal obesity, and for general application in epidemiological studies. The choice of a particular technique should be based on a balance of practical and financial considerations and the aim of the study. Involvement of ionizing radiation exposure may be an important element in the decision-making process.

Swedish obese subjects (SoS) - an intervention study of obesity. Baseline evaluation of health and psychosocial functioning in the first 1743 subjects examined

Abstract: This part of an on-going intervention trial analyses impacts of obesity on psychosocial factors and health. The study sample comprised 800 obese men (BMI > or = 34 kg/m2) and 943 women (BMI > or = 38 kg/m2) ranging in age from 37 to 57 years. All participants completed standardized health-related quality of life measures, a validated obesity-specific eating inventory and study-specific questionnaires on current and past health status, use of medical care and medications, socioeconomic status, dietary habits, physical activity habits, weight history and familial history of obesity. Chronic patients and population samples were used as reference. The obese reported distinctly poorer current health and less positive mood states than the reference subjects, women being worse than men. Anxiety and/or depression on a level indicating psychiatric morbidity were more often seen in the obese and again women reported more affliction than men. Furthermore, the average poor mental well-being was worst than in chronically ill or injured patients, such as rheumatoid, cancer survivors and spinal cord injured persons. Predictors of perceived health and psychosocial functioning could be discerned using a comprehensive system of statistical analyses (16-28% explained variance). A background of both somatic and psychiatric morbidity was decisive for the health and psychosocial functioning in the obese; joint symptoms and angina pectoris dominated among somatic variables. Physical inactivity was the most prominent of traditional risk factors. The number of dieting attempts and body image were important weight correlates. Our results provide further evidence to the effect that severe obesity is a crippling condition.

Recreational physical activity and ten-year weight change in a US national cohort

Abstract: Clinical research has established that increases in physical activity cause weight loss among the obese, but less is known about the influence of physical activity on longer-term weight change in the general population. Data from the NHANES-I Epidemiologic Follow-up Study (1971-1975 to 1982-1984) were used to examine the relationship between self-reported recreational physical activity level (low, medium, high) and measured weight change after ten years among 3515 men and 5810 women aged 25-74 years. Cross-sectional analyses at both the baseline and follow-up surveys revealed that recreational physical activity was inversely related to body weight. Low recreational physical activity reported at the follow-up survey was strongly related to major weight gain (> 13 kg) that had occurred during the preceding ten years. The estimated relative risk of major weight gain for those in the low activity level at the follow-up survey compared to those in the high activity level was 3.1 (95% Cl = 1.6-6.0) in men and 3.8 (2.3-6.5) in women. In addition, the relative risk for persons whose activity level was low at both the baseline and follow-up surveys was 2.3 (0.9-5.8) in men and 7.1 (2.2-23.3) in women. However, no relationship was found between baseline physical activity level and subsequent weight gain among either men or women. The lack of a relationship may be due to mis-specification of physical activity because of changes in activity over time. These findings suggest that low physical activity may be both a cause and a consequence of weight gain.(ABSTRACT TRUNCATED AT 250 WORDS)

Snoring and sleep apnoea in men: association with central obesity and hypertension.

Abstract: The objective of this study was to examine the relationship between sleep apnoea, measures of obesity and blood pressure. The study was cross-sectional in design, involving 1464 consecutive men undergoing sleep studies at two non-hospital sleep laboratories. Detailed sleep studies, body mass index (BMI), neck, hip and waist circumferences and morning and evening blood pressures were measured in each patient. Twenty-eight per cent of patients were obese (BMI > 30 kg/m2) and 47% were overweight (BMI 26-30 kg/m2). Body fat distribution in these patients was typically central with a mean waist-hip ratio (WHR) for the entire group of 0.99 with over 80% of patients having a WHR more than 0.94. Increasing severity of sleep apnoea measured either by respiratory disturbance index (RDI) or minimum oxygen saturation in sleep (MOS) was associated with increasing central obesity and morning but not evening blood pressure. Normal weight patients (BMI < 25 kg/m2) with sleep apnoea were characterized by increased waist and hip circumferences and increased morning diastolic blood pressure compared to patients without sleep apnoea. The best explanatory variables for sleep apnoea were waist (r2 = 0.156, P < 0.001) and age (r2 = 0.013, P = 0.003) only. Morning but not evening blood pressure was related to sleep apnoea independently of obesity and age. We concluded that patients with sleep apnoea are centrally obese. Waist circumference is a better predictor for sleep apnoea than neck circumference or BMI suggesting that the link between obesity and sleep apnoea cannot be explained solely by neck fat deposition.(ABSTRACT TRUNCATED AT 250 WORDS)

A new index of abdominal adiposity as an indicator of risk for cardiovascular disease. A cross-population study.

Abstract: A new index of abdominal adiposity, the conicity index, and the waist-to-hip ratio (WHR) were compared as health indicators in seven European populations and two USA populations. The total sample included 1280 men and 960 women. Abdominal adiposity as detected by these indices is significantly associated with more cardiovascular risk indicators among women than it is among men. Both indices are equivalent as health indicators. However, the conicity index has several advantages over the WHR: (i) it has a theoretical (expected) range; (ii) it includes a built-in adjustment of waist circumference for height and weight, allowing direct comparisons of abdominal adiposity between individuals or even between populations; and (iii) it does not require the hip circumference to assess fat distribution.

Obesity, body fat distribution and sex hormones in men

Abstract: An unfavourable body fat distribution may cause metabolic abnormalities including diabetes and dyslipidemia. These effects may be mediated by alterations in sex hormones. In women the available data suggest that upper body adiposity is related to increased androgenicity (especially as indicated by low concentrations of sex hormone binding globulin). Few data, however, are available on these relationships in men. We therefore examined the association of total testosterone, free testosterone, oestradiol, dehydroepiandrosterone sulphate (DHEA-SO4) and sex hormone binding globulin (SHBG) to waist-to-hip ratio (WHR) and conicity index in 178 men from the San Antonio Heart Study, a population-based study of diabetes and cardiovascular disease. The conicity index is equal to the abdominal circumference divided by 0.109 x the square root of (weight/height). The conicity index and WHR were significantly inversely related to DHEA-SO4 and free testosterone. SHBG was only weakly associated with body mass index (r = -0.18, P < 0.05). After adjustment for age and body mass index, DHEA-SO4 remained inversely correlated with WHR (r = -0.22, P < 0.01) and conicity index (r = -0.31, P < 0.001) and free testosterone remained inversely associated with conicity index (r = -0.21, P < 0.01). Thus, in men, the association between unfavourable body fat distribution and increased androgenicity is inverse in contrast to the situation in women.

Dietary fat and appetite control in obese subjects: weak effects on satiation and satiety.

Abstract: The present study assessed the capacity of both high fat and high carbohydrate (CHO) foods to lead to overconsumption in 12 obese women (mean BMI = 42 kg/m2). Subjects were provided with either a low (527 kcal) or high (985 kcal) energy meal at midday. Energy intake was then measured in a later ad libitum dinner meal in which subjects ate from a range of either high fat or high CHO foods. Energy intake following exposure to these meals was then assessed using food intake diary records which were kept for the rest of the day and for the following 24 h. The energy manipulations at lunch gave rise to different levels in the rated intensity of hunger. At the dinner meal subjects consumed an average of 937 kcal following the high energy lunch and 1026 kcal following the low energy lunch (an increase of 10%). However, average intake from the high CHO dinner meal was only 677 kcal compared to 1336 kcal from the high fat dinner meal (an increase of 97%). Consequently the most important variable influencing dinner meal size was not level of hunger but the nutrient content of the range of foods consumed. Analysis of dinner meal intake revealed a significant interaction between lunch meal size and dinner meal type. This means that when hunger level was high subjects over-ate on the high fat but not the high CHO foods. Average post-dinner intakes following the high fat and high CHO meals did not differ significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid accumulation and body fat distribution is influenced by type of dietary fat fed to rats.

Abstract: The amount of fat in the diet is known to influence body weight and body composition, but it is not clear whether dietary fat composition can affect body composition independently. We studied the effects of six months of feeding diets containing lard (L), corn oil (CO), fish oil (FO) or medium chain triglycerides (MCT) on body weight and body composition in adult male Wistar rats. Although FO fats ate slightly less total energy than the other groups, there were no differences among groups in body weight at any time during the study. However, body composition, the composition of depot triglyceride, body fat distribution and insulin resistance were all influenced by the type of fat in the diet. FO rats had less total body fat, less intra-abdominal fat, and less insulin resistance than all other groups. Although some of these metabolic effects may have been secondary to a slightly lower energy intake, we believe these data demonstrate the potential impact which dietary fat composition can have on metabolism and body weight regulation.

Impaired immunity in obesity: suppressed but reversible lymphocyte responsiveness.

Abstract: Although obese people have been reported to have a higher incidence of infections and some types of cancer, the immunocompetence of obese subjects remains poorly understood. To investigate whether obesity affects immunity, we studied obese subjects (BMI > 30 kg/m2) whose health was uncomplicated by any other disorder, including hyperglycemia. We compared mitogen-induced blastogenic response of peripheral blood lymphocytes in 34 obese subjects (mean +/- s.e. BMI: 38.4 +/- 2.0 kg/m2) and 35 non-obese controls (BMI: 21.3 +/- 0.4 kg/m2) who were matched for age and sex. The effects of weight reduction were also evaluated in 19 obese persons (BMI: 36.4 +/- 1.8 kg/m2) on a very low calorie diet. Mean (+/- s.e.) intracellular incorporation of [3H]-thymidine, on stimulation of T lymphocytes with either phytohaemagglutinin (PHA) or concanavalin A (Con A), and B lymphocytes with pokeweed mitogen, was significantly diminished in obese subjects compared to non-obese controls (47552 +/- 6917 vs. 83720 +/- 6252 cpm, P < 0.001; 30301 +/- 6018 vs. 45942 +/- 3723 cpm, P < 0.05; 13669 +/- 2971 vs. 23735 +/- 2048 cpm, P < 0.01, respectively). After weight reduction (BMI: 27.8 +/- 1.2 kg/m2), the mean T lymphocyte responses to PHA and Con A were increased significantly vs. baseline (98404 +/- 2444 vs. 50337 +/- 9516 cpm, P < 0.05 and 69523 +/- 15480 vs. 36695 +/- 8006 cpm, P < 0.05, respectively). Depressed blastogenesis of B lymphocytes was also augmented but was not statistically significant. The results suggest that obese subjects have underlying immune impairment in responsiveness of lymphocytes and that these impairments are reversible with adequate weight reduction.

Measurement of abdominal and intra-abdominal fat in postmenopausal women by dual energy X-ray absorptiometry and anthropometry: comparison with computerized tomography.

Abstract: The aim was to develop a model for prediction of intraabdominal adipose tissue (AT) with combined dual energy X-ray absorptiometry (DXA) and anthropometry in postmenopausal women. Intra-abdominal and subcutaneous AT from the 1st to the 4th lumbar intervertebral disk was measured by computerized tomography (CT) (as a reference method) in 25 postmenopausal women (BMI 19.9-35.1 kg/m2). Fat was measured in the corresponding region by DXA. Abdominal sagittal diameters, skinfold thicknesses, and circumferences were also measured. Measurements of abdominal fat by CT and DXA were valid (r = 0.9, s.e.e.%: 7%). Measurement of abdominal fat by DXA explained about 80% of the variation in the intra-abdominal AT (by CT), whereas the waist to hip ratio was the only variable that correlated significantly with the intra-abdominal to subcutaneous AT ratio. Abdominal fat measured by DXA, the waist to hip ratio, and the sum of trunk skinfold thicknesses could in combination accurately predict the intra-abdominal AT measured by CT (r2 = 0.91, s.e.e.% = 15%). The sagittal diameter, measured either anthropometrically or by CT, was not a superior predictor of the intra-abdominal AT. We conclude that the intra-abdominal AT can be predicted in postmenopausal women by DXA combined with anthropometry.

Techniques for the measurement of body composition : a practical guide

Abstract: This paper discusses some of the practical aspects of both reference body composition methods (densitometry, isotope dilution methods, in vivo neutron activation analysis, dual energy X-ray absorptiometry, computerized tomographic scanning and magnetic resonance imaging) and bedsides or field techniques (weight and height indices, skinfold thicknesses impedance/resistance, near infra-red interactance and 24 hour creatinine excretion) Some techniques measure gross composition, in terms of fat and fat-free mass, or the components of fat-free tissue, such as water, mineral and protein, while other methods measure the mass of individual tissues, organs or body segments The choice of a specific method for a particular study depends on various considerations including accuracy, precision, subject acceptability, convenience, cost, radiation exposure, and the need for observer training The relative advantages and disadvantages of each method are discussed with these considerations in mind

Total and intra-abdominal fat measurements by ultrasound and computerized tomography.

Abstract: Computerized tomography, a method of proven reliability for direct measurement of both total and visceral body fat, is not widely usable and alternative means of assessing body fat are required. Several anthropometric parameters, including ultrasound measurements of intra-abdominal and subcutaneous fat, were considered in 119 females (age 15-72 years, body mass index 24-51 kg/m2). Computerized tomography was also performed for total and visceral fat areas at the L4-L5 level. Reliability of each of these measurements in predicting total fat was assessed. Tertiles for visceral fat area were calculated ( 170 cm2). Only ultrasound intra-abdominal fat measurements were able to distinguish between all three VAT groups (16 +/- 10, 32 +/- 13, 50 +/- 22 mm); neither sagittal diameter nor waist/hip girth ratio were able to distinguish between the two > 114 cm2 groups. Predictive equations for total adipose tissue area confirmed weight/height ratio as the best predictor of total fat. Ultrasound intra-abdominal thickness was the 1 degree variable to enter the stepwise regression in predictive equations for visceral adipose tissue area. The 2 degrees was age, the 3 degrees sagittal diameter, the 4 degrees waist/hip girth ratio and the 5 degrees ultrasound subcutaneous abdominal thickness (adjusted r2 = 0.784; P < 0.001).

Lipase inhibition: a novel concept in the treatment of obesity

Abstract: Orlistat (Ro 18-0647) is an inhibitor of gastric, carboxylester and pancreatic lipase and specifically reduces the absorption of dietary fat due to the inhibition of triglyceride hydrolysis. Orlistat can be used for the treatment of obesity. Of 52 healthy obese patients entering a four-week single-blind run-in period with diet (500 kcal-reduced, containing 30% of calories in the form of fat) and placebo three times a day, 44 patients showed compliance to the diet by reducing their body weight by 0.5-4 kg from screening. These patients were randomized for a 12-week double-blind, parallel group, placebo-controlled treatment period with diet and 50 mg Orlistat or placebo three times a day. Complete data were available for 39 patients, 20 on Orlistat (3 men, 17 women; mean weight 85.5 +/- 12.1 kg; mean body mass index 30.6 +/- 3.7 kg/m2) and 19 on placebo (3 men, 16 women; mean weight 81.9 +/- 7.9 kg; mean body mass index 30.0 +/- 2.6 kg/m2. Total weight loss after randomization was 4.3 +/- 3.4 kg in the Orlistat group and 2.1 +/- 2.8 kg in the placebo group (P = 0.025, analysis of variance with repeated measurements; 95% confidence interval for the weight loss difference 0.2-4.2 kg). Gastrointestinal side effects were seen in the Orlistat group, but in most patients the symptoms were mild or transient. One patient dropped out because of faecal incontinence. No effect was seen on vitamin A levels, but vitamin E levels became lower in the Orlistat group (P < 0.05, paired t test).(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal fat deposition in 11-year-old children

Abstract: Although the metabolic complications accompanying visceral deposition of fat are well-established, the onset and extent of such fat patterning in children has not been fully documented. This has been due to the problem of computerized tomography exposing children to a prohibitive radiation risk. Nuclear magnetic resonance imaging (MRI) has provided a feasible alternative. Specifically, the purposes of this study were to use MRI (i) to assess the extent of intra-abdominal (IA) and subcutaneous abdominal (SA) fat deposition in 11-year-old boys and girls, and (ii) to identify the most useful anthropometric indicators of IA adiposity in children. Twenty-five boys and 25 girls were selected to represent, by quintiles, the body mass index range for their age. IA fat, SA fat, and total cross-sectional areas were measured from an MRI scan at the umbilicus. Body density was assessed by hydrostatic weighing, and skinfold thicknesses, circumferences and related ratios, and stage of sexual maturity were measured. Results showed that a wide variation in IA fat deposition was present with amounts ranging from 6 to 58 cm2 (mean = 17.8 +/- 10.0) for boys and 15 to 50 cm2 (mean = 24.8 +/- 8.8) for girls. Percentage of cross-sectional area taken up by visceral fat appears to be less than in normal weight adults. Fourteen children had intra-abdominal/subcutaneous abdominal fat ratios that have been associated with higher health risk in obese adults. Waist-hip circumference ratio (WHR), which is widely used as an indicator of IA deposition in adults, was not a useful predictor in these children.(ABSTRACT TRUNCATED AT 250 WORDS)

Techniques for the measurement of human energy expenditure: a practical guide.

Abstract: We have tried to provide a brief guide to the range of techniques available for assessing energy expenditure in a variety of different settings. It is hoped that this will enable potential users to select an appropriate method for the problem in hand and to be able to trace more detailed reference material, advice or collaboration. The Appendix provides a selection of equipment suppliers known to us. It is not an exhaustive list. Many laboratories which possess some of the more elite techniques are prepared to participate in collaborative studies if approached with a sufficiently novel hypothesis or clinical problem. Since many biological questions will only be solved by harnessing the combined power of several techniques (e.g. whole-body calorimetry and DLW), such collaborative studies are often beneficial.

Effects of exercise and stress on body fat distribution in male cynomolgus monkeys.

Abstract: The effects of exercise and stress on regional and whole body adiposity were examined in an established animal model of diet-induced coronary artery atherosclerosis, the cynomolgus monkey (Macaca fascicularis) A total of 79 adult male monkeys were assigned to four experimental groups after baseline stabilization and training: (i) exercise, stress, (n = 20); (ii) exercise, no stress (n = 20); (iii) sedentary, stress (n = 20); and (iv) sedentary, no stress (n = 19) The monkeys consumed an ad libitum diet containing 188 mg cholesterol per day with 43% of calories as saturated fat Anthropometric measurements of regional and whole body adiposity were collected throughout the study A subset (n = 40) of animals representing all four groups underwent computerized tomography (CT) scans at the end of the study to determine amounts of total abdominal, intra-abdominal and subcutaneous abdominal adipose tissue Results indicate that, in general, stress interacted with exercise to affect anthropometric measurements of regional adiposity In contrast, stress had independent and significant effects on the amount and distribution of abdominal fat as measured using CT Stressed monkeys in both the exercise and sedentary groups had more intra-abdominal fat (and thus greater intra-abdominal-:subcutaneous abdominal fat ratios) than their nonstressed counterparts There were no significant interactions between exercise and stress or exercise effects on abdominal fat distribution as measured by CT These results support the belief that an arousal syndrome caused by chronic stress, and resulting in increased activity along the hypothalamo-adrenal axis, may play a role in the preferential deposition of fat in the abdomen(ABSTRACT TRUNCATED AT 250 WORDS)

Heart rate variability in obesity.

Abstract: Analyses of beat-to-beat interval variations on a continuous electrocardiogram and cardiovascular reaction during deep breathing and handgrip exercise were used as a test for autonomic nervous function in 35 obese and 18 control women. Reduced heart rate variability (HRV) in obesity indicates depression in parasympathetic activity. Indices of HRV were smaller at 17:00 h than at 08:00 h. The more significant increase of blood pressure during handgrip in obese women might suggest over-reactivity of the sympathetic nervous system. Circulatory responses to parasympathetic activation during deep breathing and sympathetic activation during handgrip were less marked after slimming treatment than before.

Gallstones in patients with morbid obesity. Relationship to body weight, weight loss and gallbladder bile cholesterol solubility.

Abstract: Gallstones are common in obesity, and in individuals undergoing weight reduction. However, the relationships between body weight, weight reduction, gallbladder bile composition and gallstone formation are not well understood. The present studies were conducted on a cohort of 230 morbidly obese individuals presenting for bariatric surgery. Mean body weight ranged from 90-235.4 kg (mean: 136.2 kg). Body mass index (BMI) ranged from 35.4-94.7 kg/m2. Thirty-two patients (14%) had undergone prior cholecystectomy and 48 (21%) were found to have gallstones by intraoperative ultrasonography. No significant relationship was observed between gallstone prevalence and body weight. Following bariatric surgery weight loss averaged 1.57 kg/week over six months. Absolute weight loss ranged from 13.6-81.3 kg. Symptomatic gallstones requiring cholecystectomy developed in 15/150 patients (10%) over two years of follow-up. In contrast, ultrasonography detected asymptomatic gallstones in 34/92 patients (37%) six months following bariatric surgery. No relationship existed between the amount of weight lost and gallstone formation. Gallbladder bile cholesterol solubility remained constant throughout the entire weight range present in this population. No significant difference in cholesterol solubility was present between persons presenting for bariatric surgery and patients who developed symptomatic gallstones and underwent cholecystectomy following weight reduction. We conclude that gallstones are common in patients with severe obesity both before and following bariatric surgery. However, weight loss per se does not appear to be the major determinant of gallstone formation in persons who weigh in excess of 100 kg.

Low concentrations of insulin-like growth factor-I in abdominal obesity.

Abstract: Growth hormone secretion is blunted in obesity. Recent studies have shown that the sub-group of obesity with preponderance of accumulation of fat in visceral depots is associated with endocrine abnormalities. We therefore measured IGF-I concentrations in serum in 27 men who also underwent computerized tomography measurements of regional and total body fat mass. Furthermore, euglycemic-hyperinsulinemic glucose clamps were used to determine insulin resistance, and established 'risk factors' for cardiovascular disease and non-insulin dependent diabetes mellitus were measured, i.e. blood pressure, plasma lipids, and blood glucose, as well as sex steroid hormones. Visceral fat mass systolic blood pressure and triglycerides were higher (P < 0.05) in the group with low (87 +/- 4 micrograms/l) IGF-I values, compared to those with high (126 +/- 6 micrograms/l) IGF-I values, divided after the median value. IGF-I was negatively correlated with visceral fat mass (r = 0.40), independently of subcutaneous and total fat mass. As described before visceral fat mass was directly associated to a majority of the measured 'risk factors', as well as indirectly to testosterone and sex hormone binding globulin (SHBG) concentrations. The latter were also strongly related statistically to the 'risk factors'. IGF-I concentrations showed, however, weaker correlations with the metabolic factors, blood pressure or sex steroid hormones. Multivariate analyses revealed that the correlations of visceral fat with the risk factors were not influenced by IGF-I, while testosterone or SHBG totally abolished these associations. The results indicate that low serum IGF-I concentrations, suggesting deficient growth hormone secretion, are associated with visceral but not with subcutaneous or total fat masses.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of excessive appetite and metabolic changes in Prader-Willi syndrome.

Abstract: The behavioural, cognitive and metabolic response to food intake was studied in 13 adults with the Prader-Willi syndrome (PWS) and compared to ten age-matched controls. Rates of eating were observed during one hour's access to food and feelings of hunger were assessed using a visual analogue scale. Blood was taken for estimation of glucose, insulin, cholecystokinin (CCK), prolactin, growth hormone (GH) and cortisol every 20 min for a total period of 100 min. Ten (76%) of the subjects with PWS ate steadily for the whole hour that food was available and on average consumed three times more calories than the control group. The median ratings for feelings of hunger in the PWS group changed in the expected direction but these changes were delayed compared to the control group and only reached the same level as the controls after the PWS subjects had eaten a significantly greater amount of food. In the PWS group, in contrast to the control group, feelings of hunger started to re-emerge shortly after food was removed. There were marked differences between individuals with PWS in the extent of the changes in serum prolactin levels. Increases in plasma glucose levels were inversely correlated with changes in hunger ratings in the PWS group, but not the control group. There was a significantly greater increase in serum CCK levels during the meal in the PWS group than in the control group indicating that in PWS failure of peripheral release of CCK in response to food intake was not the explanation for the impaired satiety response.

Metabolic predictors of obesity: cross-sectional versus longitudinal data.

Abstract: In prospective studies in Pima Indians, four metabolic parameters, which are known to have a familial component, have been found to predict weight gain. These are: (i) low relative resting metabolic rate (RMR, relative to the average predicted rate for body size), (ii) low level of spontaneous physical activity (SPA), (iii) high 24 h respiratory quotient (RQ) and (iv) high insulin sensitivity (IS). Cross-sectional studies show that all four parameters correlate with body size: RMR vs. fat-free mass (FFM), r = 0.87, P < 0.0001; energy cost of SPA vs. weight, r = 0.69, P < 0.001; RQ vs. body fat, r = -0.23, P < 0.05; IS vs. weight, r = -0.38, P < 0.001. When these parameters are adjusted for differences in body size, then the initial value predicts the rate of change in body weight over the subsequent years: RMR (adjusted for FFM, fat mass, age and sex), r = -0.39, P < 0.001; SPA, r = -0.35, P < 0.005 (males); RQ (adjusted for fat mass), r = 0.24, P < 0.01; IS (adjusted for weight), r = 0.34, P < 0.0001. After gaining weight, the original deviation from the value predicted on the basis of the population (e.g. low relative RMR, high RQ and high IS) tends to diminish, suggesting a progressively decreasing physiological drive for further body weight gain. Thus, the high RMR, high energy cost of SPA, low RQ and low IS seen in obesity may act to limit additional weight gain.

The influence of fatness, weight change, slimming history and other lifestyle variables on diet reporting in Danish men and women aged 35-65 years.

Abstract: The association between obesity and diet is somewhat conflicting. A population study was undertaken to examine factors influencing diet reporting and the possible differences in diet reporting in relation to such factors. Data on diet, fatness, fat distribution, physical activity, smoking, subjective weight problems, slimming history, social class, education and five year weight change were collected from an age and gender stratified sub-group of Danish men (n = 199) and women (n = 201). Diet reporting was estimated as the difference between protein intake calculated from the diet (dietary interview) and from the analysis of 24 h urine nitrogen excretion. Fatness was estimated from impedance measurements, and fat distribution from body circumference measurements. All other variables were assessed by questionnaire. The study showed that diet reporting was dependent on fatness but independent of gender and age. The fattest tertile under-reported their intake by between 20-25%. The dieters, those with subjective weight problems and those who had not been weight stable since the age of 25, under-reported their intake more than others, independent of age and gender. Men gaining or losing more than 3 kg in five years were furthermore found to under-report their intake independent of age, gender and obesity. No effects of smoking, fat distribution, physical activity, social class or education were found. The results of the present study may influence the interpretation of dietary data from other studies.

Randomized evaluation of a low fat ad libitum carbohydrate diet for weight reduction.

Abstract: Restricting dietary fat intake while consuming carbohydrates ad libitum has recently been promoted as a weight loss regimen. Sixty subjects (52 females and eight males) were randomized to low fat ad libitum carbohydrate (low-fat) or low fat with caloric restriction (low-calorie) behaviour modification treatments. Forty-nine subjects completed the 16-20 week programme. Subjects in both groups reported averaging over five exercise sessions per week during treatment. The low-calorie group lost significantly more weight (males 11.8 kg, s.d. 6.4; females 8.2 kg, s.d. 4.2) than the low-fat group (males 8.0 kg, s.d. 1.3; females 3.9 kg, s.d. 3.7). Both groups of subjects lost similar amounts of lean body mass. There was significantly greater loss of body fat in the low-calorie group. A slight reduction in RMR, adjusted for changes in lean body mass, was observed in both groups. Fat intake was reduced from 90 to 30 g per day. Subjects in both groups reduced their total energy intake with the low-calorie group consuming fewer calories per day than the low-fat group. Both groups showed significant and equivalent improvements in eating habits based on microanalysis of eating diaries. Eating in social situations and emotional eating, however, continued to cause adherence problems during treatment for both groups. Follow-up data collected 9-12 months after completion of treatment on 65% of the subjects completing the study showed no significant difference between the two groups in weight losses from baseline (low-fat group 2.6 kg; low-calorie group 5.5 kg).

Preliminary studies on the gastrointestinal responses to fatty meals in obese people.

Abstract: Studies were carried out on eight obese (BMI 30-34.6 kg/m2) and seven age and sex-matched normal weight volunteers (BMI 20-25 kg/m2) to investigate the gastric emptying, mouth to caecum transit time (MCTT), plasma cholecystokinin (CCK) and sensory responses to high (30 g margarine; 1327 kJ (317 kcal)) and low (301 kJ (72 kcal)) fat soups. Gastric emptying was measured by gamma scintigraphy, MCTT was measured by the breath hydrogen technique, plasma CCK was measured using a bioassay technique and subjective sensations were recorded on visual analogue scales. The high fat meal emptied more slowly than the low fat meal in both the normal subjects (t1/2 = 86.3 +/- 9.2 vs. 36.7 +/- 2.8 min) but there were no differences in the emptying of either meal between the two groups of subjects. Increasing the fat content of the meal did not affect the mouth to caecum transit time (MCTT) in either group, nor were there differences between the groups in MCTT (180 +/- 23 vs. 188 +/- 35 min, normal vs. obese MCTT after low fat soup; 228 +/- 17 vs. 227 +/- 29 min, normal vs. obese MCTT after high fat soup). Despite similar rates of gastric emptying, the obese group showed a higher CCK production following the high fat meal than the normal weight group (540.4 +/- 65.9 vs. 336.9 +/- 51.4 pmol.min, 2 h integrated CCK production, obese vs. normal; P < 0.05). The obese group also reported feeling less hungry throughout the study than the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Ephedrine, xanthines and prostaglandin-inhibitors: actions and interactions in the stimulation of thermogenesis.

Abstract: The pivotal role of the sympathoadrenal system in the defense of le milieu interieur has, in the last 15 years, been extended to include the fat stores-a notion that forms the basis of current strategies for thermogenic stimulation in obesity therapy. The search for effective and safe sympathetic stimulants has been directed at two main levels: (i) the development of novel beta-agonists selective for thermogenesis, and (ii) the evaluation of drugs already in clinical use for other purposes (e.g. ephedrine) which could conceivably increase the release of catecholamines to levels that enhance thermogenesis without significant cardiovascular effects. A re-direction of these strategies seem inevitable because at therapeutic doses, the thermogenic effects of these sympathomimetics seem to be considerably dampened by negative feedback mechanisms that operate both extracellularly (e.g. via adenosine & prostaglandins) as well as inside the cells (via cAMP phosphodiesterases). Such a contention is supported by studies both in man and in animals showing that methylxanthines and aspirin, drugs known to be capable of interfering with these modulators, potentiate the thermogenic effects of ephedrine. Future research aimed at clarifying the types and subtypes of these negative modulators of sympathomimetic-induced thermogenesis and their targeting by more selective antagonists would no doubt be pivotal in providing the safe drug combination with the necessary thermogenic properties to assist the management of obesity.

Ephedrine, caffeine and aspirin: safety and efficacy for treatment of human obesity.

Abstract: The safety and efficacy of a mixture of ephedrine (75-150mg), caffeine (150mg) and aspirin (330mg), in divided premeal doses, were investigated in 24 obese humans (mean BMI 37.0) in a randomized double blind placebo-controlled trial. Energy intake was not restricted. Overall weight loss over 8 weeks was 2.2kg for ECA vs. 0.7 kg for placebo (p < 0.05). 8 of 13 placebo subjects returned 5 months later and received ECA in an unblinded crossover. After 8 weeks, mean weight loss with ECA was 3.2 kg vs 1.3 kg for placebo (p = 0.036). 6 subjects continued on ECA for 7 to 26 months. After 5 months on ECA, average weight loss in 5 of these was 5.2 kg compared to 0.03 kg gained during 5 months between studies with no intervention (p = 0.03). The sixth subject lost 66 kg over 13 months by self-imposed caloric restriction. In all studies, no significant changes in heart rate, blood pressure, blood glucose, insulin, and cholesterol levels, and no differences in the frequency of side effects were found. ECA in these doses is thus well tolerated in otherwise healthy obese subjects, and supports modest, sustained weight loss even without prescribed caloric restriction, and may be more effective in conjunction with restriction of energy intake.

The descriptive epidemiology of selected physical activities and body weight among adults trying to lose weight: the Behavioral Risk Factor Surveillance System survey, 1989.

Abstract: Few population-based studies have described the physical activity patterns of individuals trying to lose weight. We analysed cross-sectional, self-reported data from 6125 men and 12,557 women (> or = 18 years of age) from 40 states who reported in the 1989 Behavioral Risk Factor Surveillance System (BRFSS) survey that they were trying to lose weight. The BRFSS is a state-based telephone survey of non-institutionalized US adults, which utilizes a multi-stage cluster design based on the Waksberg method of random digit dialing. Walking was the most prevalent physical activity (48%), followed by aerobics (8%), gardening (5%), cycling (5%), and running (4%); however, activity choices varied by socio-demographic characteristics. Among both sexes, the prevalence of overweight (BMI > or = 30 kg/m2) decreased significantly with increasing level of activity (P < or = 0.001). Regression results showed that among both sexes and in most age groups, those who ran or jogged, performed aerobics, or cycled weighed less (P < or = 0.001) than those who reported no activity--independent of height, race, education, smoking, and caloric restriction. Walking was also associated with lower weight (P < or = 0.001) among persons aged 40 or older. Because walking is highly prevalent among persons in most socio-demographic strata and is accessible and low risk, its relative merits should be stressed in developing interventions for weight loss and maintenance.

Decreased physical activity in Pima Indian compared with Caucasian children.

Abstract: Since reduced physical activity might be a risk factor for body weight gain, we studied the relationship between physical activity and body composition in 43 Pima Indian children (22 male/21 female, mean +/- s.d.: 9.9 +/- 1.1 years) and 42 Caucasian children (21 male/21 female, 9.7 +/- 1.2 years). A list of usual sport leisure activities was established (e.g. bicycling, swimming, basketball) and the subjects were asked how much time they had devoted to each activity over the past week and the last year. Data on time spent playing outside (excluding sport leisure activities for the estimation of physical activity) and watching television/videos were also collected. Pima Indians were taller (143 +/- 9 vs. 137 +/- 8 cm, P < 0.001), heavier (48.6 +/- 15.8 vs. 32.9 +/- 7.8 kg, P < 0.0001) and fatter (39 +/- 16 vs. 24 +/- 7% fat, P < 0.001) than Caucasians. Pima Indian girls showed significantly lower past year and past week sport leisure activity than Caucasian girls (P < 0.01) and spent significantly more time watching television/videos (P < 0.05). Pima boys also showed significantly lower past week sport leisure activity than Caucasian boys (P < 0.05). In Pima Indian boys, past year sport leisure activity correlated negatively (P < 0.05) with body mass index (r = -0.49) and percentage body fat (r = -0.56). However, such correlations were not found in Pima Indian girls, possibly due their very low levels of activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Central obesity in rhesus monkeys: association with hyperinsulinemia, insulin resistance and hypertriglyceridemia?

Abstract: Total body fat and anthropometric assessments of fat distribution were examined in 23 lean and obese rhesus monkeys (Macaca mulatta). In addition, the relationships of central obesity to hyperinsulinemia, insulin resistance, glucose intolerance and hyperlipidemia were studied. Total body fat (as determined by the tritiated water dilution method), plasma glucose, insulin, lipoproteins (triglyceride, cholesterol and HDL- and LDL-cholesterol) and free fatty acids (FFA), and glucose disappearance rate (KG) and peripheral insulin-stimulated glucose uptake (M) were obtained. Results showed that abdominal circumference was the best predictor of body fat (r = 0.90; P < 0.001). There were strong linear relationships between abdominal circumference and plasma insulin (r = 0.66), glucose tolerance (r = -0.53), and M rate (r = -0.59) (all P < 0.05) but not to plasma glucose, lipoprotein fractions, or free fatty acids. When the subjects were grouped according to degree of obesity and insulin resistance (lean normals, obese insulin sensitive, and obese insulin resistant), the obese resistant monkeys had significantly higher plasma insulin levels, lower glucose tolerance, and significantly higher plasma triglyceride levels. We conclude that the spontaneously obese rhesus monkey is an excellent model of central obesity. Furthermore, in this model upper body obesity appears to be facilitative in the development of hyperinsulinemia, glucose intolerance and hypertriglyceridemia but does not appear to be causally related. In the rhesus monkey and in humans as well, we propose that the link between central obesity and these metabolic abnormalities may be peripheral insulin resistance.

Abdominal body mass distribution and elevated blood pressure are associated with increased risk of death from cardiovascular diseases and cancer in middle-aged men. The results of a 15- to 20-year follow-up in the Paris prospective study I.

Abstract: The associations of blood pressure (BP), body mass index (BMI) and iliac-to-thigh circumference index (CI) with total, cardiovascular and cancer mortality were investigated in 7312 middle-aged men, initially free of coronary heart disease, known cancer and not treated for hypertension, who have been followed for 15 to 20 years in the Paris prospective study I. Using Cox survival regression analysis, total mortality (1208 deaths) was found to be highest in relatively lean men (BMI or = 96 mmHg) and central pattern of body mass distribution (CI > 1.82). Cancer causes accounted for a large proportion of the increased mortality risk. In parallel, mortality from cardiovascular diseases increased independently with blood pressure and iliac-to-thigh circumference index, but increased with body mass index only in men with low blood pressure (mean BP < 96 mmHg). Taking into account serum cholesterol and cigarette smoking levels as covariates and excluding deaths occurring 5 to 10 years after the examination only slightly attenuated the intensity of this pattern of association.