Body composition analysis and changes in airways function in obese adults after hypocaloric diet

STUDY OBJECTIVES: To determine the relationship between weight-loss and pulmonary function indexes, focusing on forced expiratory flows (ie, FEV(1), forced expiratory flow at 50% of vital capacity [FEF(50)], forced expiratory flow at 75% of vital capacity, and forced expiratory flow at 25 to 75% of vital capacity [FEF(25--75)]). Specifically, to determine the effect of losses in total and segmental fat mass (FM) and of modifications in lean body mass, after restricted hypocaloric diet, on pulmonary function among obese adults. DESIGN: Cross-sectional, observational. SETTINGS: Human Physiology Division, Faculty of Medicine and Surgery, "Tor Vergata" University, Rome, Italy. PATIENTS: Thirty obese adults (mean [+/- SD] baseline body mass index [BMI], 32.25 +/- 3.99 kg/m(2)), without significant obstructive airway disease, were selected from among participants in a weight-loss program. MEASUREMENTS AND RESULTS: Anthropometric, body composition (BC), and respiratory parameters of all participants were measured before and after weight loss. Total and segmental lean body and FM were obtained by dual-energy x-ray absorptiometry. Dynamic spirometric tests and maximum voluntary ventilation (MVV) were performed. The BC parameters (ie, body weight [BW], BMI, the sum skinfold thicknesses, thoracic inhalation circumference, thoracic expiration circumference, total FM, and trunk FM [FMtrunk]) were significantly decreased (p < or = .0001) after a hypocaloric diet. The mean vital capacity, FEV(1), FEF(50), FEF(25-75), expiratory reserve volume, and MVV significantly increased (p < or = 0.05) with weight loss. The correlation coefficient for Delta FEF(25--75) (r = 0.20) was numerically higher than Delta FEF(50) and Delta FEV(1) (r = 0.14 and r = 0.08, respectively) for the BW loss. Moreover, the correlation coefficient for Delta FEF(25--75) (r = 0.45) was significantly higher (p < or = 0.02) than those for Delta FEF(50) and Delta FEV(1) (r = 0.38 and r = 0.15, respectively) for FMtrunk loss. CONCLUSIONS: This study shows that a decrease in total and upper body fat obtained by restricted diet was not accompanied by a decrease in ventilatory muscle mass. FMtrunk loss was found to have improved airflow limitation, which can be correlated to peripheral airways function.     

Plasma concentrations of alpha-MSH, AgRP and leptin in lean and obese men and their relationship to differing states of energy balance perturbation

OBJECTIVE: A great deal of attention has focused on the central role of alpha melanocyte-stimulating hormone (alpha-MSH) and its antagonism at the melanocortin-4 receptor (MC4R) by agouti related protein (AgRP) in the regulation of energy balance. However, very little is known regarding the function of circulating AgRP and alpha-MSH in humans. We aimed to determine whether circulating alpha-MSH and AgRP are responsive to long-term perturbations in energy balance, in a manner consistent with their central putative functions. DESIGN AND MEASUREMENTS: Circulating alpha-MSH, AgRP and leptin were measured in both lean (n = 11) and obese (n = 18) male volunteers, some of whom (lean n = 11, obese n = 12) were then allocated one of two weight-loss dietary strategies to achieve about 5% weight loss. This was achieved by either total starvation (for 4-6 days) for rapid weight loss or a very low calorie diet (VLCD, 2.6 MJ/day) (11-12 days) for less rapid weight loss, in both the lean and obese volunteers. RESULTS: At baseline, prior to any weight loss both plasma alpha-MSH (15.8 +/- 1.2 vs. 5.8 +/- 1.0 pmol/l +/- SEM; P < 0.001) and AgRP (49.4 +/- 2.4 vs. 10.1 +/- 0.9 pg/ml +/- SEM; P < 0.001) were elevated in obese subjects compared with lean. In both cases this correlated closely with fat mass (P < 0.001), percentage body fat (P < 0.001) and leptin (P < 0.05). Plasma AgRP increased significantly during a 6-day fast in lean individuals (11.1 +/- 1.6 vs. 21.6 +/- 3.1 pg/ml +/- SEM; P < 0.05) but not in the VLCD subjects or in the obese, while alpha-MSH was not affected by any changes in energy balance in either the lean or the obese volunteers. CONCLUSION: We show a difference in alpha-MSH and AgRP in lean and obese subjects that correlates closely with body fat at baseline. We demonstrate an increase in plasma AgRP during a 6-day fast in lean individuals that is coincident with a decrease in plasma leptin. This increase in AgRP was not due to weight loss per se as there was no change in AgRP as a result of the same weight loss in the VLCD intervention in lean individuals. The source of the increase in plasma AgRP and its physiological function in the periphery remains to be elucidated but we suggest that the dynamics of the change in plasma leptin may determine the elevation in fasting plasma AgRP in lean subjects.     

Comparison of epicardial,abdominal and regional fat compartments in response to weight loss

Background and aimsEchocardiographic measurement of epicardial fat (EF) seems to be a reliable and diagnostic marker of visceral adipose tissue (VAT). However, the weight loss-induced changes in EF have not been compared with those in VAT or the truncal depot. In this study, we aimed to compare the weight loss-induced changes in EF, VAT and other regional fat compartments in obese men.Methods and resultsIn this study, 27 moderately obese men (age 45.8 ± 1.7 years; body mass index 30.5 ± 0.7 kg/m²) followed a daily low-calorie diet as part of a clinical 12-week weight loss interventional study. We evaluated the EF thickness by transthoracic echocardiography, assessed the abdominal fat tissues by computed tomography scans, and examined the regional and whole body fat compartments by dual X-ray absorptiometry. An average decrease of 26.8% in the initial calorie intake corresponded to post-program reductions of 17.2%, 11.0%, 16.6%, and 29.8% in EF thickness (P < 0.001), body mass, percentage fat mass, and abdominal fat compartments, respectively. The percentage change in VAT in response to weight loss was twice as high as the substantial change in EF tissue (P < 0.001).ConclusionThe results of the study suggest that a low-calorie diet-induced weight loss decreases EF thickness. Moderate diet-induced weight loss alone may represent an effective nonpharmacological strategy for reducing EF, which is a unique, pathogenic fat depot and an emerging marker of VAT.     

Knee strength maintained despite loss of lean body mass during weight loss in older obese adults with knee osteoarthritis

BACKGROUND: The effects of weight loss on muscle function in older adults have not been well studied. This study determined the effects of a 6-month weight-loss intervention on muscle strength and quality in older obese adults with knee osteoarthritis. METHODS: Participants were randomized to a weight loss (WL) (n = 44, 70 +/- 6 years) or weight stable (WS) (n = 43, 69 +/- 6 years) group. The WL intervention consisted of weekly educational meetings, a meal replacement diet, and a three-session-per-week structured exercise program to achieve 10%-12% weight loss. The WS intervention included bimonthly group meetings and newsletters. Body composition and knee extensor strength were measured at baseline and after intervention. RESULTS: The WL group decreased body weight, lean body mass, fat mass, and percent body fat (p <.001 for all). Concentric extension strength increased 25% in WL (p >.05), whereas eccentric extension decreased 6% in WS (p =.028). Concentric muscle quality (strength per kg body weight or lean body mass) increased in WL (p <.05), whereas eccentric muscle quality decreased in WS (p <.05). Changes in lean body mass and fat mass were inversely associated with changes in most muscle strength and quality measures (p <.05). Men and women did not differ in response to the intervention in knee strength outcomes. CONCLUSIONS: Hypocaloric dieting in combination with exercise training had beneficial effects on muscle strength/quality, despite loss of lean body mass in this sample of older men and women. Greater fat loss was associated with greater gains in muscle strength and quality. More studies are needed regarding the mechanisms by which loss of fat mass increases muscle strength and quality.     

Immunoreative insulin in obesity of adult women

The levels of immunoreactive insulin (IRI) in 58 obese women and 14 controls were studied. The investigation revealed: (1) higher IRI levels in obese patients compared to controls, with a tendency to normalization after weight reduction (2) a correlation between IRI values and the degree of obesity, the amount of fat and lean body mass. The closest relation was found between stimulated IRI values and the Broca index (3) the ratio glucose/insulin was lower in the obese women before and after a glucose load. After a decrease of body weight by 11 per cent this ratio did not change significantly (4) a negative correlation between the glucose/insulin ratio and body weight, overweight, body fat and lean body mass.     

Association between insulin resistance and lean mass loss and fat mass gain in older men without diabetes mellitus

OBJECTIVES: To examine the associations between insulin resistance and changes in body composition in older men without diabetes mellitus. DESIGN: Longitudinal cohort study of older men participating in the Osteoporotic Fractures in Men (MrOS) study. SETTING: Six U.S. clinical centers. PARTICIPANTS: Three thousand one hundred thirty‐two ambulatory men aged 65 and older at baseline. MEASUREMENTS: Baseline insulin resistance was calculated for men without diabetes mellitus using the homeostasis model assessment of insulin resistance (HOMA‐IR). Total lean, appendicular lean, total fat, and truncal fat mass were measured using dual energy X‐ray absorptiometry scans at baseline and 4.6 ± 0.3 years later in 3,132 men with HOMA‐IR measurements. RESULTS: There was greater loss of weight, total lean mass, and appendicular lean mass and less gain in total fat mass and truncal fat mass with increasing quartiles of HOMA‐IR (P<.001 for trend). Insulin‐resistant men in the highest quartile had higher odds of 5% or more loss of weight (odds ratio (OR)=1.88, 95% confidence interval (CI)=1.46–2.43), total lean mass (OR=2.09, 95% CI=1.60–2.73) and appendicular lean mass (OR=1.57, 95% CI=1.27–1.95) and lower odds of 5% or more gain in total fat mass (OR=0.56, 95% CI=0.45–0.68) and truncal fat mass (OR=0.52, 95% CI=0.42–0.64) than those in the lowest quartile. These findings remained significant after accounting for age, site, baseline weight, physical activity, and change in physical activity. These associations were also independent of other metabolic syndrome features and medications. CONCLUSION: Greater lean mass loss and lower fat mass gain occurred in insulin‐resistant men without diabetes mellitus than in insulin‐sensitive men. Insulin resistance may accelerate age‐related sarcopenia.     

Body composition and energy expenditure: relationship and changes in obese subjects before and after biliopancreatic diversion

Changes in total and segmental body composition were studied in 101 obese women before and 2, 6, 12, and 24 months after biliopancreatic diversion (BPD) and data 24 months after surgery were matched to 53 control subjects. The patients were studied by anthropometry, indirect calorimetry, and double-emission x-ray absorptiometry (DXA). The combination of calorimetry and body composition analysis allowed estimation of visceral and muscle lean mass. We observed a significant (analysis of variance [ANOVA]: P <.05) progressive reduction of fat and lean body mass (LBM) following BPD, with stabilization of both parameters between 12 and 24 months at levels not different from controls. Fat loss was significant in the arms, legs, and trunk segments. After 24 months, there was no significant difference in segmental fat mass between post-BPD patients and controls. Calorimetric data seem to confirm lean body mass (LBM) reduction. Visceral lean mass (kg) was significantly reduced from 8.1 +/- 2.2 in obese subjects to 6.5 +/- 1.8 in post-BPD patients at 24 months (P <.05); the control value was 7.2 +/- 1.8. Muscular lean mass (kg) was also significantly reduced, from 50.2 +/- 5.8 to 39.8 +/- 5.7 in the same subjects (P <.05), with a control value of 42.5 +/- 5.9. The decrease in muscle and visceral LBM reached control values without significant differences. Viscera/muscle ratio in pre-BPD patients was preserved in post-BPD patients at 24 months, but it was reduced during weight loss. Body composition studies showed a logarithmic relationship between fat and lean mass and a physiological contribution of lean mass to weight loss in the BPD patients. In conclusion, weight loss after BPD was achieved with an appropriate decline of LBM and with all parameters reaching, at stable weight, values similar to weight-matched controls.     

Obesity is associated with decreasing levels of the circulating soluble leptin receptor in humans

OBJECTIVE: Leptin plays a major role in the regulation of body weight. It circulates in both free and bound form. One of the leptin receptor isoforms exists in a circulating soluble form that can bind leptin. In the present study, we measured the soluble leptin receptor (SLR) levels in lean and obese humans. We investigated the relationship between plasma SLR levels, plasma leptin levels and the degree of obesity. We also examined whether SLR concentrations could be modulated by fat mass loss induced by a 3 month weight-reducing diet. SUBJECTS: A total of 112 obese (age 18-50 y; body mass index (BMI) 30-44 kg/m2; 23 men and 89 women), 38 overweight (age 19-48 y; BMI 25-29 kg/m2; 10 men and 28 women) and 63 lean (age 18-50 y; BMI 17-24 kg/m2; 16 men and 47 women) humans. MEASUREMENTS: A direct double monoclonal sandwich enzyme-linked immunosorbent assay (ELISA) was used for the quantitative measurement of the soluble human leptin receptor. Leptin was measured by radioimmunoassay (RIA). Body composition was assessed by biphotonic absorptiometry DEXA (dual energy X-ray absorptiometry). RESULTS: We observed that the SLR is present in human plasma (range 10-100 ng/ml). SLR levels were lower in obese and overweight than lean subjects (28.7+/-8.8, 40.2+/-14.9, 51.2+/-12.5 ng/ml, respectively) and were inversely correlated to leptin and percentage of body fat (r=-0.74 and r=-0.76; respectively; P<0.0001). The ratio of circulating leptin to SLR was strongly related to the percentage of body fat (r=0.91; P<0.0001). Interestingly a gender difference was observed in SLR levels, which were higher in obese and overweight men than in obese and overweight women. In obese subjects after a 3 month low-calorie diet, SLR levels increased in proportion to the decrease in fat mass. In the gel filtration profile, SLR coeluted exactly with the bound leptin fractions. CONCLUSION: Obesity, in humans is associated with decreasing levels of the circulating soluble leptin receptor (SLR). The relationship of SLR with the degree of adiposity suggests that high SLR levels may enhance leptin action in lean subjects more than in obese subjects.     

Leptin plasma levels as a marker of sparing-energy mechanisms in obese women.

OBJECTIVE: To investigate possible relationships between leptin and energy expenditure (EE), both in the condition of stable body weight and during weight loss. SUBJECTS: Seventy four Caucasian, adult obese women with stable body weight (including 10 obese women studied before and during a body weight-reducing program). MEASUREMENTS: Resting EE (REE) and substrate oxidation rates by indirect calorimetry; plasma leptin concentrations by radioimmunoassay (RIA). RESULTS: In conditions of stable body weight, leptin values showed a significant, negative relationship with REE, as expressed in absolute values (P = 0.030) and as adjusted for the variation in lean body mass (LBM) (P = 0.017). This negative relationship was independent of both LBM and fat mass (FM). Linear regression analysis was used to obtain the equation linking REE and LBM; then both predicted REE and the percent deviation from predicted REE were calculated for each subject. Leptin values were negatively related (P < 0.0001) to the deviation from predicted REE. During active body weight loss, the modifications of both REE (delta REE) and lipid oxidation (delta lipid oxidation) were significantly negatively related to leptin concentrations, which were measured before the dieting period (P < 0.03 for both). CONCLUSION: In obese women, high plasma leptin concentrations are associated with a low rate of REE, when body weight is stable, and with a reduction of REE and lipid oxidation, in response to a hypocaloric diet. This suggests that, in severely obese women, leptin is a marker of sparing energy mechanisms operating in both basal and reducing weight conditions.     

Comparison of a low-fat diet to a low-carbohydrate diet on weight loss, body composition, and risk factors for diabetes and cardiovascular disease in free-living, overweight men and women

Overweight and obese men and women (24-61 yr of age) were recruited into a randomized trial to compare the effects of a low-fat (LF) vs. a low-carbohydrate (LC) diet on weight loss. Thirty-one subjects completed all 10 wk of the diet intervention (retention, 78%). Subjects on the LF diet consumed an average of 17.8% of energy from fat, compared with their habitual intake of 36.4%, and had a resulting energy restriction of 2540 kJ/d. Subjects on the LC diet consumed an average of 15.4% carbohydrate, compared with habitual intakes of about 50% carbohydrate, and had a resulting energy restriction of 3195 kJ/d. Both groups of subjects had significant weight loss over the 10 wk of diet intervention and nearly identical improvements in body weight and fat mass. LF subjects lost an average of 6.8 kg and had a decrease in body mass index of 2.2 kg/m2, compared with a loss of 7.0 kg and decrease in body mass index of 2.1 kg/m2 in the LC subjects. The LF group better preserved lean body mass when compared with the LC group; however, only the LC group had a significant decrease in circulating insulin concentrations. Group results indicated that the diets were equally effective in reducing systolic blood pressure by about 10 mm Hg and diastolic pressure by 5 mm Hg and decreasing plasminogen activator inhibitor-1 bioactivity. Blood beta-hydroxybutyrate concentrations were increased in the LC only, at the 2- and 4-wk time points. These data suggest that energy restriction achieved by a very LC diet is equally effective as a LF diet strategy for weight loss and decreasing body fat in overweight and obese adults.     

Body composition and hormonal responses to a carbohydrate-restricted diet

The few studies that have examined body composition after a carbohydrate-restricted diet have reported enhanced fat loss and preservation of lean body mass in obese individuals. The role of hormones in mediating this response is unclear. We examined the effects of a 6-week carbohydrate-restricted diet on total and regional body composition and the relationships with fasting hormone concentrations. Twelve healthy normal-weight men switched from their habitual diet (48% carbohydrate) to a carbohydrate-restricted diet (8% carbohydrate) for 6 weeks and 8 men served as controls, consuming their normal diet. Subjects were encouraged to consume adequate dietary energy to maintain body mass during the intervention. Total and regional body composition and fasting blood samples were assessed at weeks 0, 3, and 6 of the experimental period. Fat mass was significantly (P 相似文献   

Possible role of adiponectin and insulin sensitivity in mediating the favorable effects of lower body fat mass on blood lipids

AIMS: The objective of this study was to investigate the role of insulin sensitivity and serum adiponectin concentration as determinants, in middle-aged men, of the relationship between lower body fat and blood lipids after truncal fat has been accounted for. METHODS: Men (443) aged 39-65 yr, body mass index 18-43 kg/m(2), participated in the study. The following variables were measured: regional body fat distribution as assessed by dual-energy x-ray absorptiometry, maximal oxygen uptake, physical activity, fasting levels of serum adiponectin, triglycerides, and high-density lipoprotein- and total cholesterol. Plasma glucose and serum insulin were measured in the fasting state and after an oral glucose load. RESULTS: Lower body fat mass was inversely associated with serum triglycerides and total cholesterol and positively with serum high-density lipoprotein-cholesterol after adjustment for age, lean tissue mass, truncal fat mass, weight history, maximal oxygen uptake, and the level of physical activity (P < 0.0005). Serum adiponectin level and Matsudas insulin sensitivity index were positively intercorrelated, and both were positively correlated to lower body fat mass. When including adiponectin and insulin sensitivity in the analyses, the relationships between lower body fat mass and serum lipids were partly explained. CONCLUSION: For a given level of truncal fat mass, a large lower body fat mass is associated with an advantageous blood lipid profile, which may be partially mediated by the relationships to both insulin sensitivity and serum adiponectin level.     

Similar weight loss with low-energy food combining or balanced diets

OBJECTIVE: The goal of this study was to evaluate the effect of two diets ('food combining' or dissociated vs balanced) on body weight and metabolic parameters during a 6-week period in an in-hospital setting. SUBJECTS AND DESIGN: 54 obese patients were randomly assigned to receive diets containing 4.5 MJ/day (1100 kcal/day) composed of either 25% protein, 47% carbohydrates and 25% lipids (dissociated diet) or 25% protein, 42% carbohydrates and 31% lipids (balanced diet). Consequently, the two diets were equally low in energy and substrate content (protein, fat and carbohydrate) but widely differed in substrate distribution throughout the day. RESULTS: There was no significant difference in the amount of weight loss in response to dissociated (6.2 +/- 0.6 kg) or balanced (7.5 +/- 0.4 kg) diets. Furthermore, significant decreases in total body fat and waist-to-hip circumference ratio were seen in both groups, and the magnitude of the changes did not vary as a function of the diet composition. Fasting plasma glucose, insulin, total cholesterol and triacylglycerol concentrations decreased significantly and similarly in patients receiving both diets. Both systolic and diastolic blood pressure values decreased significantly in patients eating balanced diets. The results of this study show that both diets achieved similar weight loss. Total fat weight loss was higher in balanced diets, although differences did not reach statistical significance. Total lean body mass was identically spared in both groups. CONCLUSION: In summary at identical energy intake and similar substrate composition, the dissociated (or 'food combining') diet did not bring any additional loss in weight and body fat.     

Benefits of sustained moderate weight loss in obesity

Over the last few years, weight loss has been recognised as a key factor in the control and prevention of coronary heart disease, hypertension, type 2 diabetes, hyperlipidaemia, cardiorespiratory failure and other chronic degenerative diseases. It has been shown that even a modest loss of 5% of initial body weight can reduce, eliminate or prevent these disorders in a large proportion of overweight patients. The early benefits of weight loss can be explained by the direct effects of a low calorie diet, but the long-term effects can only partially be attributed to diet, physical exercise or behavioural modifications. Long-term studies have shown that a sustained moderate weight loss of 10% improves glycemic control as a result of reduced insulin resistance, the better control or prevention of hypertension, increased HDL-and decreased LDL-cholesterol and VLDL triglycerides, improved diastolic function and the propagation of a cardiac stimulus that reduces the risk of ventricular arrhythmias. The health benefits of modest weight loss are particularly evident and useful when excess body fat is a major health hazard, as in the case of class III obesity (BMI > 40 kg/m2), which is often characterised by prevalent visceral fat accumulation. Baseline serum glucose, cholesterol, triglyceride, uric acid and blood pressure levels are usually higher in the upper body than is the case in peripheral obesity, and tend to decrease more in response to moderate weight loss. A therapeutic programme aimed at obtaining a gradual and moderate weight loss avoids the complications due to the rapid weight loss associated with inappropriate, unbalanced diets or even more harmful treatments. These complications include cholelithiasis and the subsequent risk of cholecystitis, lean body mass loss and a stable decrease in energy expenditure with a high probability of regaining weight (weight cycling syndrome). In conclusion, a large number of obese patients may be sensitive to a modest weight loss even without the achievement of ideal body weight. Sustained moderate weight loss by itself is definitely beneficial in obesity (especially "malignant" and "morbid" obesity), but also in diabetes, hypertension, hyperlipidaemia, cardiorespiratory diseases and other chronic degenerative diseases associated with any degree of excess body fat.     

Influence of clenbuterol on energy balance, thermogenesis and body composition in lean and genetically obese Zucker rats

Daily injection of lean Zucker rats with a beta 2-adrenergic agonist (clenbuterol, 1 mg/kg) for 22 day increased weight gained by 38 per cent; there were significant increases in carcass protein and water, but fat content was unaltered. Clenbuterol did not affect energy intake or expenditure, the acute thermogenic response to food, or brown adipose tissue (BAT) activity (assessed from mitochondrial purine nucleotide (GDP) binding). In obese Zucker rats, clenbuterol significantly depressed energetic efficiency and increased the thermogenic response to food and BAT activity in these mutants. Body weight gain was not significantly affected by clenbuterol in obese Zucker rats but this was because of a 19 per cent reduction in fat content accompanied by a simultaneous 13 per cent increase in protein content. The ratio of protein/fat gained during the study was increased by 50 and 173 per cent by clenbuterol in lean and obese rats, respectively. Thus, clenbuterol exhibits potent anabolic effects on lean body mass in genetically obese as well as lean rats, but also increases thermogenesis and reduces body fat content in the obese mutants.     

In vivo assessment of the mitochondrial response to caloric restriction in obese women by the 2-keto[1-C]isocaproate breath test

The 2-keto[1-(13)C]isocaproate breath test has been proposed as a tool to detect mitochondrial dysfunction in alcoholic liver disease. The aim of this study was to evaluate if the 2-keto[1-(13)C]isocaproate breath test could detect in vivo dynamic changes on mitochondrial activity due to caloric restriction in obese women. Fifteen obese women (body mass index [BMI] > 30 kg/m(2)) participated in the study at baseline. Ten of these women agreed to participate on a diet program to induce body weight loss. Fifteen lean women (BMI < 25 kg/m(2)) were included as a control group. The breath test was performed by the oral administration of the tracer measuring (13)CO(2) enrichment in breath before and after ingestion using isotope ratio mass spectrometry. Body composition, resting energy expenditure, and plasma levels of insulin and leptin were measured. There were no relationships observed between the 2-keto[1-(13)C]isocaproate breath test and the plasma insulin (before diet: P =.863; after diet: P =.879), or leptin (before diet: P =.500; after diet: P =.637). In obese women before treatment, kilograms of fat free mass (P =.108), resting energy expenditure adjusted for body composition (P =.312), and the 2-keto[1-(13)C]isocaproate breath test (P =.205) were similar in comparison to lean women. However, 2-keto[1-(13)C]isocaproate oxidation tended to increase after dieting and was significantly higher than in controls (P =.015). These data suggest that the 2-keto[1-(13)C]isocaproate breath test reflected the adaptive modifications in mitochondrial oxidation in response to caloric restriction in obese women.     

Association between measures of insulin sensitivity and circulating levels of interleukin-8, interleukin-6 and tumor necrosis factor-alpha. Effect of weight loss in obese men

OBJECTIVE: To study the association between anthropometric and metabolic parameters as well as the effect of weight loss on plasma levels of the adipose tissue-derived cytokines interleukin-8 (IL-8), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) in abdominal obese men. SUBJECTS: Nineteen obese (mean body mass index (BMI): 38.6+/-0.6 kg/m(2)) and ten lean men (mean BMI: 23.4+/-0.4 kg/m(2)) were included in the study. The obese subjects received a 4.2 MJ/day diet for 8 weeks, followed by 8 weeks on energy restriction (6.2 MJ/day) and 8 weeks on a weight-maintenance diet. MEASUREMENTS: A dual energy X-ray absorptiometry (DEXA)-scan was performed to estimate body composition. Plasma levels of IL-8, IL-6 and TNF-alpha were measured by a specific ELISA method. Insulin sensitivity was assessed by the homeostasis model assessment method (HOMA). RESULTS: Plasma levels of IL-8 and IL-6 were 30-40% higher in obese as compared with lean subjects (P<0.05), whereas no group difference in TNF-alpha was observed. During the intervention, obese subjects obtained a 30% reduction in fat mass (P<0.001), fasting insulin (P<0.05) and HOMA (P<0.05). Plasma levels of TNF-alpha and IL-6 were decreased by 25-30% (P<0.001) but IL-8 was increased by 30% (P<0.001) after weight loss. IL-8 and IL-6 were correlated with measures of insulin resistance, and changes in IL-6 but not IL-8 were correlated with the improvement in insulin sensitivity after weight loss. CONCLUSION: Plasma levels of IL-8 and IL-6 were found to be increased and were correlated with measures of insulin resistance in abdominal obese male subjects. Weight loss was associated with changes in the circulating levels of IL-8, IL-6 and TNF-alpha indicating that these cytokines are influenced by weight loss.     

Low-fat, high-carbohydrate (low-glycaemic index) diet induces weight loss and preserves lean body mass in obese healthy subjects: results of a 24-week study

BACKGROUND: The traditional treatment for obesity which is based on a reduced caloric diet has only been partially successful. Contributing factors are not only a poor long-term dietary adherence but also a significant loss of lean body mass and subsequent reduction in energy expenditure. Both low-fat, high-carbohydrate diets and diets using low-glycaemic index (GI) foods are capable of inducing modest weight loss without specific caloric restriction. The purpose of this study was to investigate the feasibility and medium-term effect of a low-fat diet with high (low GI) carbohydrates on weight loss, body composition changes and dietary compliance. METHODS: Obese patients were recruited from two obesity outpatient clinics. Subjects were given advise by a dietician, then they attended biweekly for 1-hour group meetings. Bodyweight and body composition were measured at baseline and after 24 weeks. RESULTS: One hundred and nine (91%) patients completed the study; after 24 weeks the average weight loss was 8.9 kg (98.6 vs. 89.7 kg; p < or = 0.0001). There was a significant 15% decrease in fat mass (42.5 vs. 36.4 kg; p < or = 0.0001) and a decrease in lean body mass of 5% (56.1 vs. 53.3 kg; p < or = 0.0001). DISCUSSION: In this 6-month study, a low-fat, low-GI diet led to a significant reduction of fat mass; adherence to the diet was very good. Our results suggest that such a diet is feasible and should be evaluated in randomized controlled trials.     

Decrease in visceral fat following diet-induced weight loss in upper body compared to lower body obese premenopausal women

BACKGROUND: Obesity is associated with numerous metabolic disturbances, such as insulin resistance, diabetes mellitus type 2, dyslipidemia, and hypertension. An excess of fat within the abdomen, so-called visceral adiposity, confers a greater and independent health risk of metabolic and cardiovascular complications than does adipose tissue accumulation elsewhere. The present study aimed to investigate a possible differential effect of diet-induced weight loss in visceral fat mass and metabolic parameters in obese individuals with the upper body (UBO) and lower body (LBO) obese phenotype. METHODS: The obese subjects were prescribed a liquid, very-low calorie diet to reduce 50% of their overweight (15% body weight loss). Specific body fat measurements (MRI, BIA), anthropometrics, and fasting metabolic parameters were obtained in control subjects and two groups of obese subjects (UBO and LBO) before and after weight loss. RESULTS: Weight loss was accompanied by significant decreases in total, subcutaneous, and visceral fat in both UBO and LBO women. The largest reduction in visceral fat mass was found in the UBO women (absolute decrease 223+/-32 cm(2) vs 122+/-91 cm(2) in LBO women; P=0.01), while the amount of visceral fat was reduced to normal levels in LBO women (155+/-25 cm(2) after weight loss vs 143+/-17 cm(2) in controls; P=NS). Furthermore, weight loss significantly lowered fasting glucose, total cholesterol, and LDL cholesterol concentrations in UBO women. CONCLUSION: The obese phenotype is preserved after body weight loss. UBO women have to lose a larger amount of overweight in order to bring the amount of fat in the visceral depot down to normal levels and to obtain normalization of their cardiovascular risk profile.     

Ghrelin treatment reverses the reduction in weight gain and body fat in gastrectomised mice

BACKGROUND AND AIMS: The gastric hormone ghrelin has been reported to stimulate food intake, increase weight gain, and cause obesity but its precise physiological role remains unclear. We investigated the long term effects of gastrectomy evoked ghrelin deficiency and of daily ghrelin injections on daily food intake, body weight, fat mass, lean body mass, and bone mass in mice. METHODS: Ghrelin was given by subcutaneous injections (12 nmol/mouse once daily) for eight weeks to young female mice subjected to gastrectomy or sham operation one week previously. RESULTS: Gastrectomy reduced plasma concentrations of total ghrelin (octanoylated and des-octanoylated) and active (octanoylated) ghrelin by approximately 80%. Immediately after injection of ghrelin, the plasma concentration was supraphysiological and was still elevated 16 hours later. Daily food intake was not affected by either gastrectomy or ghrelin treatment. The effect of ghrelin on meal initiation was not studied. At the end point of the study, mean body weight was 15% lower in gastrectomised mice than in sham operated mice (p<0.001); daily ghrelin injections for eight weeks partially prevented this weight loss. In sham operated mice, ghrelin had no effect on body weight. The weight of fat was reduced in gastrectomised mice (-30%; p<0.01). This effect was reversed by ghrelin, enhancing the weight of fat in sham operated mice also (+20%; p<0.05). Gastrectomy reduced lean body mass (-10%; p<0.01) and bone mass (-20%; p<0.001) compared with sham operated mice. Ghrelin replacement prevented the gastrectomy induced decrease in lean body mass but did not affect bone. In sham operated mice, ghrelin affected neither of these two parameters. CONCLUSIONS: Ghrelin replacement partially reversed the gastrectomy induced reduction in body weight, lean body mass, and body fat but not in bone mass. In sham operated mice, ghrelin only increased fat mass. Our results suggest that ghrelin is mainly concerned with the control of fat metabolism and that ghrelin replacement therapy may alleviate the weight loss associated with gastrectomy.