Leptin, superoxide dismutase, and weight loss: initial leptin predicts weight loss

Objective: Our goal was to study how plasma leptin concentration, superoxide dismutase (SOD) activity, and weight loss are related in obese adults. Research Methods and Procedures: Serum leptin concentration, SOD activities, general biochemical data, and body composition measurements were obtained for 62 overweight and obese subjects before and after an 8‐week body weight reduction (BWR) regimen. The subjects were on dietary control, performed moderate aerobic and strength training exercises, and attended educational lectures. Results: The measurement results indicated that the following criteria were significantly reduced: body weight [84.4 ± 17.0 vs. 79.3 ± 16.1 (standard error) kg, p < 0.001]; BMI (31.5 ± 4.3 vs. 29.4 ± 4.2 kg/m², p < 0.001), and fat mass (33.3 ± 10.0 vs. 29.8 ± 10.4 kg, p < 0.001). Plasma leptin levels also significantly decreased from 31.5 ± 17.6 to 26.5 ± 17.2 ng/mL (p < 0.001). Additionally, SOD activity was significantly increased from 261.4 ± 66.0 to 302.7 ± 30.9 U/mL (p < 0.001). Based on linear regression analysis results, a 3.78‐ to 8.13‐kg reduction in weight can be expected after the 8‐week BWR regimen when initial leptin concentration was 5 to 30 ng/mL. Discussion: We found that an 8‐week exercise and diet program was effective in reducing weight and fat mass and, notably, had further beneficial effects on leptin resistance and SOD activity. Additionally, this study demonstrated that initial plasma leptin concentration may be used as a predictor for weight loss outcome.     

Obesity Affects Myocardial Vasoreactivity and Coronary Flow Response to Insulin

Objective: Obesity is associated with increased risk for cardiovascular diseases and peripheral endothelial dysfunction. We examined whether myocardial vasoreactivity and coronary‐flow response to insulin stimulation are altered in obesity. Research Methods and Procedures: Myocardial blood flow was quantitated in 10 obese men (body mass index, 33.6 ± 1.9 kg/m²) and 10 healthy matched non‐obese men (body mass index, 24.2 ± 1.9 kg/m²), using positron emission tomography and oxygen‐15‐labeled water. The measurements were performed basally and during adenosine infusion (140 μg/kg per minute), with or without simultaneous physiological (1 mU/kg per minute) and supraphysiological (5 mU/kg per minute) hyperinsulinemia. Results: Basal myocardial blood flow was not significantly different between obese and non‐obese subjects. Adenosine‐stimulated flow was blunted in obese (3.2 ± 0.6 mL/g per minute) when compared with non‐obese subjects (4.0 ± 1.1 mL/g per minute, p < 0.05). Simultaneous physiological hyperinsulinemia increased adenosine‐stimulated myocardial flow significantly in both groups (to 4.03 ± 1.24 and 4.85 ± 1.04 mL/g per minute in obese and non‐obese men, respectively; p < 0.05 vs. adenosine). Supraphysiological hyperinsulinemia further enhanced the adenosine‐stimulated flow in non‐obese subjects (to 5.56 ± 0.98 mL/g per minute; p < 0.05) but not in obese subjects. Discussion: Young obese, healthy men have reduced myocardial vasoreactivity, which may represent an early precursor of future coronary artery disease. Additionally, insulin‐induced enhancement of myocardial blood flow is blunted in obesity. Thus, endothelial dysfunction seems to also characterize myocardial vasculature of obese subjects.     

Effect of weight loss on free insulin-like growth factor-I in obese women with hyposomatotropism

Objective: It has been hypothesized that increased free insulin‐like growth factor (IGF)‐I levels generated from an increase in IGF‐binding protein (IGFBP) protease activity could be the inhibitory mechanism for the decreased growth hormone (GH) secretion observed in obese subjects. Research Methods and Procedures: In this study, we determined basal and 24‐hour levels of free IGF‐I and ‐II, total IGF‐I and ‐II, IGFBP‐1, as well as basal IGFBP‐2, ?3, and ?4, acid‐labile subunit (ALS), IGFBP‐1, ?2, and ?3 protease activity, and 24‐hour GH release in obese women before and after a diet‐induced weight loss. Sixteen obese women (age, 29.5 ± 1.4 years) participated in a weight loss program and 16 age‐matched non‐obese women served as controls. Results: Circulating free IGF‐I and 24‐hour GH release were significantly decreased in obese women at before weight loss compared with non‐obese women (1.29 ± 0.12 vs. 0.60 ± 0.09 μg/L; p < 0.001 and 862 ± 90 vs. 404 ± 77 mU/24 hours; p < 0.001, respectively). Free IGF‐I and 24‐hour GH release were not inversely correlated to each other. IGFBP‐1 and ?2 levels were decreased, whereas ALS, IGFBP‐3 and ?4, and IGFBP‐1, ?2, and ?3 protease activity were similar in obese and non‐obese women. Eight of the 16 obese women achieved an average weight loss of 30 ± 5 kg during 26 to 60 weeks of dieting. After the considerable weight loss, significant differences in free IGF‐I, GH release, and IGFBP‐1 and ?2 levels were no longer present between previously obese and non‐obese women. Discussion: We showed that circulating free IGF‐I is markedly decreased in severely obese women and does not per se mediate the concomitant hyposomatotropism. The decreased levels of free IGF‐I seem to be transient and restored to normal levels after weight loss.     

Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese women

Objective: To examine the effects of dietary protein and obesity classification on energy‐restriction‐induced changes in weight, body composition, appetite, mood, and cardiovascular and kidney health. Research Methods and Procedures: Forty‐six women, ages 28 to 80, BMI 26 to 37 kg/m², followed a 12‐week 750‐kcal/d energy‐deficit diet containing higher protein (HP, 30% protein) or normal protein (NP, 18% protein) and were retrospectively subgrouped according to obesity classification [pre‐obese (POB), BMI = 26 to 29.9 kg/m²; obese (OB), BMI = 30 to 37 kg/m²). Results: All subjects lost weight, fat mass, and lean body mass (LBM; p < 0.001). With comparable weight loss, LBM losses were less in HP vs. NP (?1.5 ± 0.3 vs. ?2.8 ± 0.5 kg; p < 0.05) and POB vs. OB (?1.2 ± 0.3 vs. ?2.9 ± 0.4 kg; p < 0.005). The main effects of protein and obesity on LBM changes were independent and additive; POB‐HP lost less LBM vs. OB‐NP (p < 0.05). The energy‐restriction‐induced decline in satiety was less pronounced in HP vs. NP (p < 0.005). Perceived pleasure increased with HP and decreased with NP (p < 0.05). Lipid‐lipoprotein profile and blood pressure improved and kidney function minimally changed with energy restriction (p < 0.05), independently of protein intake. Discussion: Consuming a higher‐protein diet and accomplishing weight loss before becoming obese help women preserve LBM. Use of a higher‐protein diet also improves perceptions of satiety and pleasure during energy restriction.     

Modest Lifestyle Intervention and Glucose Tolerance in Obese African Americans

Objective: Previous studies have demonstrated the benefit of short‐term diets on glucose tolerance in obese individuals. The purpose of this study was to evaluate the effectiveness of modest lifestyle changes in maintaining improvements in glucose tolerance induced by short‐term energy restriction in obese African Americans with impaired glucose tolerance or type 2 diabetes mellitus. Research Methods and Procedures: An intervention group (n = 45; 47 ± 1 year [mean ± SE]), 105 ± 4 kg; body mass index: 39 ± 1 kg/m²) received an energy‐restricted diet (943 ± 26 kcal/d) for 1 week, followed by a lifestyle program of reduced dietary fat (?125 kcal/d) and increased physical activity (+125 kcal/d) for 1 year. Body weight and plasma concentrations of glucose, insulin, and C‐peptide during an oral glucose tolerance test were measured at baseline, 1‐week, and 4‐month intervals. A control group (n = 24; 48 ± 1 year; 110 ± 5 kg; body mass index: 41 ± 2 kg/m²) underwent these measurements at 4‐month intervals. Results: No changes in weight or glucose tolerance were observed in the control group. The intervention group had significant (p < 0.05) improvements in body weight and glucose tolerance in response to the 1‐week diet, which persisted for 4 months (p < 0.001 vs. control for change in weight). A total of 19 subjects (42%) continued the intervention program for 1 year, with sustained improvements (weight: ?4.6 ± 1.0 kg; p < 0.001 vs. control; oral glucose tolerance test glucose area: ?103 ± 44 mM · min; p < 0.05 vs. control). Discussion: A modest lifestyle program facilitates weight loss and enables improvements in glucose tolerance to be maintained in obese individuals with abnormal glucose tolerance. However, attrition was high, despite the mild nature of the program.     

Low Plasma Leptin Concentration and Low Rates of Fat Oxidation in Weight‐Stable Post‐Obese Subjects

Objective: A low resting metabolic rate for a given body size and composition, a low rate of fat oxidation, low levels of physical activity, and low plasma leptin concentrations are all risk factors for body weight gain. The aim of the present investigation was to compare resting metabolic rate (RMR), respiratory quotient (RQ), levels of physical activity, and plasma leptin concentrations in eight post‐obese adults (2 males and 6 females; 48.9 ± 12.2 years; body mass index [BMI]: 24.5 ± 1.0 kg/m²; body fat 33 ± 5%; mean ± SD) who lost 27.1 ± 21.3 kg (16 to 79 kg) and had maintained this weight loss for ≥2 months (2 to 9 months) to eight age‐ and BMI‐matched control never‐obese subjects (1 male and 7 females; 49.1 ± 5.2 years; BMI 24.4 ± 1.0 kg/m²; body fat 33 ± 7%). Research Methods and Procedures: Following 3 days of weight maintenance diet (50% carbohydrate and 30% fat), RMR and RQ were measured after a 10‐hour fast using indirect calorimetry and plasma leptin concentrations were measured using radioimmunoassay. Levels of physical activity were estimated using an accelerometer over a 48‐hour period in free living conditions. Results: After adjustment for fat mass and fat‐free mass, post‐obese subjects had, compared with controls, similar levels of physical activity (4185 ± 205 vs. 4295 ± 204 counts) and similar RMR (1383 ± 268 vs. 1430 ± 104 kcal/day) but higher RQ (0.86 ± 0.04 vs. 0.81 ± 0.03, p < 0.05). Leptin concentration correlated positively with percent body fat (r = 0.57, p < 0.05) and, after adjusting for fat mass and fat‐free mass, was lower in post‐obese than in control subjects (4.5 ± 2.1 vs. 11.6 ± 7.9 ng/mL, p < 0.05). Discussion: The low fat oxidation and low plasma leptin concentrations observed in post‐obese individuals may, in part, explain their propensity to relapse.     

Effects of acute and chronic protein intake on metabolism, appetite, and ghrelin during weight loss

Objective: This study evaluated the effects of acute and chronic consumption of higher dietary protein on energy expenditure, macronutrient use, appetite, and appetite‐regulating hormones during weight loss in women. Research Methods and Procedures: Thirty‐eight women chronically consuming a 750 kcal/d energy‐deficit diet with a protein content of 30% (higher protein‐chronic diet, HP‐CD, n = 21) or 18% (normal protein‐chronic diet, NP‐CD, n = 17) for 9 weeks were tested. On separate days, metabolic, appetite, and hormonal responses were measured over 4 hours when the women consumed a higher protein‐acute meal (HP‐AM) (30% of energy as protein) or a normal protein‐acute meal (NP‐AM) (18% of energy as protein). Results: With chronic diet groups combined, HP‐AM led to lower respiratory exchange ratio (0.829 ± 0.005 vs. 0.843 ± 0.008; p < 0.05), lower carbohydrate oxidation (p < 0.05), and higher fat oxidation (p < 0.05) compared with NP‐AM. HP‐AM also led to reduced self‐reported postprandial hunger (p < 0.001) and desire to eat (p < 0.001) and lower postprandial ghrelin (252 ± 16 vs. 274 ± 18 ng/mL · 240 minutes, p < 0.05) compared with NP‐AM. No differences in postprandial energy expenditure (PPEE) occurred between meals. When combining acute meals, respiratory exchange ratio was lower (p < 0.05) and protein oxidation (p < 0.001) was higher in the HP‐CD vs. NP‐CD. An acute meal‐by‐chronic diet interaction was observed with PPEE such that HP‐AM led to greater PPEE in the HP‐CD vs. NP‐CD (28.7 ± 2.7 vs. 19.9 ± 2.7 kcal/min for 195 minutes; p < 0.05). Conclusions: During weight loss, thermogenesis and protein use appear to be influenced by chronic protein intake, while appetite and ghrelin are more responsive to acute protein intake.     

Plasma Levels of Adiponectin,a Novel Adipocyte‐Derived Hormone,in Sleep Apnea**

Objective: Obstructive sleep apnea (OSA) is associated with obesity, sympathetic activation, systemic inflammation, and cardiovascular morbidity. Obesity, β‐adrenergic agonists, and inflammation are linked to decreased expression and/or secretion of an adipose tissue‐derived antiatherogenic hormone, adiponectin. The purpose of the study was to investigate whether OSA affected plasma levels of adiponectin, which might help explain OSA‐associated cardiovascular morbidity. Research Methods and Procedures: We randomly selected 68 otherwise healthy male subjects, either with moderate/severe OSA [apnea‐hypopnea index (AHI) ≥ 20; n = 35] or without OSA (AHI ≤ 5; n = 33). The diagnosis of OSA was made based on prospective full polysomnography. Adiponectin was measured before polysomnography between 8 and 10 PM . Results: AHI was higher in the OSA group (49.5 ± 4.4 vs. 2.9 ± 0.4 events/h; p < 0.001). OSA subjects were also more obese, with greater BMI (33 ± 1 vs. 30 ± 1; p = 0.016) and percentage body fat (29 ± 1% vs. 26 ± 1%; p = 0.030). Adiponectin levels were 7.67 ± 0.73 and 6.33 ± 0.51 μg/mL in the OSA and non‐OSA groups, respectively, and this difference was significant in covariate analysis (taking into account age, hemodynamic characteristics, measures of body fat, and OSA severity) (p = 0.009). After excluding from both groups the subjects with extreme BMI, such that the OSA and non‐OSA study cohorts had similar BMI and percentage body fat, subjects with OSA had significantly higher plasma adiponectin (8.49 ± 0.92 vs. 6.32 ± 0.55 μg/mL; p = 0.042), differences also evident in covariate analysis (p = 0.017). Discussion: Plasma adiponectin levels are elevated in otherwise healthy subjects with OSA. Therefore, low adiponectin is unlikely to explain the association between OSA and cardiovascular disease.     

Baroreflex sensitivity in obesity: relationship with cardiac autonomic nervous system activity

Objective: The aim of this study was to test the hypothesis that baroreflex sensitivity (BRS), assessed by indirect measurement of aortic pressure, is blunted in obesity. Additionally, the potential effect of cardiac autonomic nervous system (ANS) activity, aortic compliance, and metabolic parameters on BRS of obese subjects was investigated. Research Methods and Procedures: A group of 30 women with BMI >30 kg/m² and a group of 30 controls with BMI <25 kg/m² were examined. BRS was estimated by the sequence technique, cardiac ANS activity by short‐term spectral analysis of heart rate variability (HRV), and aortic compliance by the method of applanation tonometry. Results: BRS was lower in obese women (9.18 ± 3.77 vs. 19.63 ± 9.16 ms/mm Hg, p < 0.001). The median values (interquartile range) of the power of both the high‐frequency and low‐frequency components of the HRV were higher in the lean than in the obese participants [1079.2 (202.7 to 1716.9) vs. 224.1 (72.7 to 539.6) msec², p = 0.001 and 411.8 (199.3 to 798.0) vs. 235.8 (99.4 to 424.5) msec², p = 0.01 respectively]. Low‐to‐high‐frequency ratio values were higher in the obese subjects [0.82 (0.47 to 2.1) vs. 0.57 (0.28 to 0.89), p = 0.02]. Aortic augmentation values were not significantly different between lean and obese subjects. Multivariate analysis demonstrated a significant and independent association between BRS and age (p = 0.003), BMI (p < 0.001), and high‐frequency power of HRV (p < 0.001). These variables explained 72% of the variation of BRS values. Discussion: BRS is severely reduced in obese subjects. BMI, age, and the parasympathetic nervous system activity are the main determinants of BRS. Baroreflex behavior is of clinical relevance because an attenuated BRS represents a negative prognostic factor in cardiovascular diseases, which are common in obesity.     

Effect of Lifestyle Modification on Adipokine Levels in Obese Subjects with Insulin Resistance

Objective: To study the effect of weight loss in response to a lifestyle modification program on the circulating levels of adipose tissue derived cytokines (adipokines) in obese individuals with insulin resistance. Research Methods and Procedures: Twenty‐four insulin‐resistant obese subjects with varying degrees of glucose tolerance completed a 6‐month program consisting of combined hypocaloric diet and moderate physical activity. Adipokines [leptin, adiponectin, resistin, tumor necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6)] and highly sensitive C‐reactive protein were measured before and after the intervention. Insulin sensitivity index was evaluated by the frequently sampled intravenous glucose tolerance test. Results: Participants had a 6.9 ± 0.1 kg average weight loss, with a significant improvement in sensitivity index and reduction in plasma leptin (27.8 ± 3 vs. 23.6 ± 3 ng/mL, p = 0.01) and IL‐6 (2.75 ± 1.51 vs. 2.3 ± 0.91 pg/mL, p = 0.012). TNF‐α levels tended to decrease (2.3 ± 0.2 vs. 1.9 ± 0.1 pg/mL, p = 0.059). Adiponectin increased significantly only among diabetic subjects. The reductions in leptin were correlated with the decreases in BMI (r = 0.464, p < 0.05) and with changes in highly sensitive C‐reactive protein (r = 0.466, p < 0.05). Discussion: Weight reduction in obese individuals with insulin resistance was associated with a significant decrease in leptin and IL‐6 and a tendency toward a decrease in circulating TNF‐α, whereas adiponectin was increased only in diabetic subjects. Further studies are needed to elucidate the relationship between changes of adipokines and the health benefits of weight loss.     

Body Weight Modulates Cholesterol Metabolism in Non‐Insulin Dependent Type 2 Diabetics

Objective: Cholesterol metabolism was studied in 64 subjects with type 2 diabetes who had body weight ranging from normal to obese, to find out whether weight interferes with cholesterol metabolism in diabetes. Research Methods and Procedures: Cholesterol absorption was measured with peroral isotopes and by assaying serum plant sterol and cholestanol to cholesterol ratios, cholesterol synthesis with sterol balance, and measuring serum cholesterol precursor ratios. Results: The study population was divided into normal‐weight (body mass index, 24.1 ± 0.4 kg/m²; mean ± SEM; n = 20) and obese (31.0 ± 0.5 kg/m²; n = 44) groups. Despite similar serum cholesterol and blood glucose values, fecal neutral sterol excretion, cholesterol and bile acid synthesis, cholesterol turnover (1649 ± 78 vs. 1077 ± 52 mg/d; p < 0.001), and serum cholesterol precursors were higher, and cholesterol absorption % (32 ± 1 vs. 40 ± 2%; p < 0.05), serum cholestanol, and plant sterols were lower in the obese vs. the non‐obese groups. Serum sex hormone‐binding globulin was positively associated with variables of cholesterol absorption, whereas blood glucose, serum insulin, and body mass index were associated with variables of cholesterol synthesis. In multiple stepwise regression analysis, cholesterol absorption percentage (R² = 24%) and body mass index (R² = 15%) were the only variables explaining the variability of cholesterol synthesis. Discussion: Body weight, through its entire range, regulates cholesterol metabolism in type 2 diabetes such that with increasing insulin resistance, cholesterol absorption is lowered and cholesterol synthesis increased.     

Ghrelin Does Not Influence Gastric Emptying in Obese Subjects

Objective: To evaluate the relationship between fasting plasma concentrations of ghrelin and gastric emptying in obese individuals compared with lean subjects. Research Methods and Procedures: We included 20 obese patients (9 men and 11 women, BMI > 30 kg/m²) and 16 nonobese control subjects (7 men and 9 women, BMI ≤ 25 kg/m²). Gastric emptying of solids (egg sandwich labeled with radionuclide) was measured at 120 minutes with (99m)Tc‐single photon emission computed tomography imaging. Ghrelin and leptin were analyzed by radioimmunoassay and ELISA methods, respectively. Results: The gastric half‐emptying time was similar in obese men and women (67.8 ± 14.79 vs. 66.6 ± 13.56 minutes) but significantly shorter (p < 0.001) than in the control population (men: 88.09 ± 11.72 minutes; women: 97.25 ± 10.31 minutes). Ghrelin levels were significantly lower in obese subjects (131.37 ± 47.67 vs. 306.3 ± 45.52 pg/mL; p < 0.0001 in men and 162.13 ± 32.95 vs. 272.8 ± 47.77 pg/mL; p < 0.0001 in women). A negative correlation between gastric emptying and fasting ghrelin levels was observed only in lean subjects (y = ?0.2391x + 157.9; R² = 0.95). Also, in the lean group, ghrelin was the only significant independent determinant of gastric emptying, explaining 98% of the variance (adjusted R²) in a multiple regression analysis. Discussion: This report shows that, in humans, gastric emptying is faster in obese subjects than in lean controls and that, whereas ghrelin is the best determinant of gastric kinetics in healthy controls, this action is lost in obesity.     

Effect of Energy‐Reduced Diets High in Dairy Products and Fiber on Weight Loss in Obese Adults

Objective: Studies suggest that high‐dairy and high‐fiber/low‐glycemic index diets may facilitate weight loss, but data are conflicting. The effects on weight loss and body fat of a high‐dairy diet and a diet high in dairy and fiber and low in glycemic index were compared with a standard diet. Research Methods and Procedures: Ninety obese subjects were recruited into a randomized trial of three diets designed to provide a calorie deficit of 500 calories/d over a 48‐week period. The study compared a moderate (not low)‐calcium diet with a high‐calcium diet. Results: Seventy‐two subjects completed the study. Significant weight and fat loss occurred with all three diets. A diet with 1400 mg of calcium did not result in greater weight (11.8 ± 6.1 kg) or fat (9.0 ± 6.0 kg) loss than a diet with 800 mg of calcium (10.0 ± 6.8 and 7.5 ± 6.6 kg, respectively). A diet with 1400 mg of calcium, increased fiber content, and fewer high‐glycemic index foods did not result in greater weight (10.6 ± 6.8 kg) or fat (8.5 ± 7.8 kg) loss than the standard diet with 800 mg of calcium. Lipid profile, high‐sensitivity C‐reactive protein, leptin, fasting glucose, and insulin improved significantly, but there were no significant differences between the experimental diets and the control diet. Discussion: We found no evidence that diets higher than 800 mg of calcium in dairy products or higher in fiber and lower in glycemic index enhance weight reduction beyond what is seen with calorie restriction alone.     

Influence of knee osteoarthritis on exercise capacity and quality of life in obese adults

Objective: The objective was to determine whether knee osteoarthritis (OA) reduces exercise ambulatory capacity and impairs quality of life (QOL) in obese individuals. Research Methods and Procedures: There were 56 subjects, with and without knee OA, who were obese. The subjects were evaluated with anthropometric measurements, a body composition assessment, maximal cardiopulmonary exercise test, 6‐minute walk test (6‐MWT), perceived exertion (RPE), self‐reported disability [Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)], and the Medical Outcomes Study Short Form 36 (SF‐36). Results: VO_2peak was significantly higher in the controls when compared with the patients (mean ± standard deviation, 1.584 ± 0.23 L/kg per min vs. 0.986 ± 0.20 L/kg per min; p < 0.001). Obese subjects without knee OA walked a significantly longer distance in the 6‐MWT than obese patients with knee OA (p < 0.001). We also observed significant negative correlation between Vo ₂max and RPE, WOMAC pain and physical limitation, and bodily pain and general health domains of short‐form 36. Discussion: Knee OA reduces exercise and ambulatory capacity and impairs QOL in obese individuals. RPE, WOMAC pain, and SF‐36 items might provide information about exercise capacity in the obese subjects with knee OA. Our study confirms that exercise capacity and QOL might be improved by energetic and intensive treatment of pain resulting from knee OA.     

Does a High‐protein Diet Improve Weight Loss in Overweight and Obese Children?

Objective: To evaluate the effect of a high‐protein diet on anthropometry, body composition, subjective appetite, and mood sensations in overweight and obese children attending a residential weight‐loss camp. Research Methods and Procedures: Children (120; BMI, 33.1 ± 5.5 kg/m²; age, 14.2 ± 1.9 years) were randomly assigned to either a standard or high‐protein diet group (15% vs. 22.5% protein, respectively). All children were assessed at baseline and at the end of the camp for anthropometry, body composition, blood pressure, biochemical variables (n = 27), and subjective appetite and mood sensations (n = 50). Results: Attendance at the weight‐loss camp resulted in significant improvements in most measures. Campers lost 5.5 ± 2.9 kg in body weight (p < 0.001) and 3.8 ± 5.4 kg in fat mass (p < 0.001) and reduced their BMI standard deviation score by 0.27 ± 0.1 (p < 0.001) and their waist circumference by 6.6 ± 2.8 cm (p < 0.001). Subjective sensations of hunger increased significantly over the camp duration, but no other changes in appetite or mood were observed. There were no significant differences between the two diets on any physical or subjective measures. Discussion: Weight‐loss camps are effective in assisting children to lose weight and improve on a range of health outcomes, independently of the protein content of the diet. The implications of an increase in hunger associated with weight loss needs to be considered. Further work is warranted to investigate whether higher levels of dietary protein are feasible or effective in longer‐term weight‐loss interventions of this type.     

Improved Psychological Well-Being,Quality of Life,and Health Practices in Moderately Overweight Women Participating in a 12-Week Structured Weight Loss Program

Objective : To study the effects of a 12-week weight loss strategy involving increased physical activity, self-selected hypocaloric diet, and group support on psychological well-being, quality of life, and health practices in moderately obese women. Methods; Eighty women aged 20–49 years weighing between 20–50% above 1983 Metropolitan Life Insurance Tables were randomly assigned to a weight loss intervention (6279 kJ/week of physical activity, 33,258-41,462 kJ/week diet and weekly meetings) or served as controls. Subjects were tested pre and post 12-weeks. Results : The intervention group lost significant (p<0.001) body weight (kg) and body fat (%) compared to controls (-6.07 ± 4.01 kg vs. 1.31 ± 1.28 kg; 36.8%-32.5% vs. 36.2%-36.0%). Intervention subjects vs. controls achieved significant improvements (p<0.001) in body cathexis (X Change 18.6 ± 16.7 vs. 0.7 ± 8.6) and estimation of ability to achieve physical fitness (X Change 8.1 ± 7.1 vs. 0.9 ± 5.9). Various quality of life indices also improved (p<0.01) in the intervention group compared to controls (physical function: X Change 13.5.2 ± 16.7 vs. 1.4 ± 9.5; vitality: X change 21.7 ± 17.9 vs. 2.9 20.8; mental health: X change 10.4 ± 16.0 vs. 2.3 ± 10.1). Similarly, physical activity levels also improved significantly (p<0.0001) in the intervention group (4.4 ± 2.3 vs. 0.6 ± 1.3; on NASA 0–7 scale). Conclusions : Practical weight loss practices such as increased activity, self-selected hypocaloric diet, and group support are effective for weight loss and yield significant health and psychological benefits in moderately obese females.     

Post‐Exercise Substrate Utilization after a High Glucose vs. High Fructose Meal During Negative Energy Balance in the Obese

Objective: To assess the effects of negative energy balance on the metabolic response of a meal containing either glucose or fructose as the primary source of carbohydrate after exercise in obese individuals in energy balance, or negative energy balance. Research Methods and Procedures: Fourteen adults with mean body mass index (BMI) 30.3 ± 1 kg/m², age 26 ± 2 years, and weight 93.5 ± 5.4 kg, adhered to an energy‐balanced (EB) or a negative energy‐balanced (NEB) diet for 6 days. On Day 7, subjects exercised at 70% VO_2peak for 40 minutes then consumed either high glucose (50 g of glucose, HG) or high fructose (50 g of fructose, HF) liquid meal. Substrate utilization was measured by indirect calorimetry for 3 hours. Blood samples were collected before exercise and 0, 30, 60, 120, and 180 minutes after consuming the meal. Results: The HG produced 15.9% greater glycemic (p < 0.05) and 30.9% larger insulinemic (p < 0.05) responses than the HF under both EB and NEB conditions. After the NEB diet, carbohydrate and fat oxidation did not differ for HG and HF. In contrast, carbohydrate oxidation increased 31%, and fat oxidation decreased 39% with HF compared with HG after the EB diet. Thus, HF and HG consumed after exercise produced marked differences in macronutrient oxidation when obese subjects followed an EB diet, but no difference when adhering to a NEB diet. Discussion: The data suggest that the use of fructose in supplements/meals may provide no additional benefit in terms of substrate utilization during a weight loss program involving diet and exercise.     

Serum Leptin Concentrations and Weight Gain in Postobese,Postmenopausal Women

Objective : This study was designed to determine if serum leptin concentrations (adjusted for fat mass) after weight loss on a low-calorie diet predict subsequent weight gain. Research Methods and Procedures : Body composition and serum leptin concentrations were determined on 14 moderately obese, postmenopausal, nondiabetic women with a familial predisposition to obesity. Assessments were obtained under tightly controlled metabolic ward conditions of macronutrient intake and weight maintenance both before (obese state) and after a mean weight loss of 12.0 kg to normal body weight (postobese state). Four years later, without intervention, body weight and body composition were reassessed. Results : Weight loss resulted in significant decreases in fat mass (29.7 ± 5.4 vs. 20.3 ± 4.7; kg), body mass index (27.7 ± 1.6 vs. 23.0 ± 1.5; kg/m2), percent body fat (40.7 ± 4.3 vs. 33.1 ± 5.0), and serum leptin concentrations (31.8 ± 16.0 vs. 11.5 ± 5.4; ng/mL). Serum leptin concentrations were positively correlated (p<<0.05) with fat mass in both the obese and postobese states (r = 0.67 and r = 0.56, respectively). However, residual serum leptin concentrations (adjusted for fat mass) in the obese and postobese states were not related to changes in body weight (p<= 0.61 and 0.52), fat mass (p = 0.72 and 0.42), body mass index (p = 0.59 and 0.33), or percent body fat (p = 0.84 and 0.46) over the follow-up period. Discussion : These finding do not support the hypothesis that relatively low concentrations of leptin predict weight regain after weight loss. However, because the number of subjects in this study was limited, further studies are warranted.     

Race,Menopause, Health-Related Quality of Life,and Psychological Well-Being in Obese Women

Objective: To investigate the health-related quality of life (HR-QOL) in African-American (AA) and white (W) obese women. Research Methods and Procedures: Participants were 145 obese women (80 AA and 65 W; 87 premenopausal and 58 postmenopausal) who completed the Medical Outcomes Study short form, the Brief Symptom Inventory, the Life Distress Inventory, the Satisfaction With Life Scale, and the Rosenberg Self-Esteem Scale before entering a weight-loss study. The mean age of the subjects was 46.3 ± 11.1 years and the mean body mass index was 35.2 ± 4.2 kg/m². Results: Although AA women were slightly heavier (95.3 ± 10.3 kg vs. 91.5 ± 11.6 kg, p < 0.05) and less educated (14.2 ± 3.7 years vs. 15.7 ± 3.7 years, p < 0.05) than the W women in the sample, there was no difference between the two ethnic groups in any of the reported HR-QOL variables. Menopausal status had a significant effect on HR-QOL, with premenopausal women being more distressed (p = 0.002), having more limitations in social activity (p = 0.007), and having less vitality (p < 0.001) than the postmenopausal women. This was especially true in the AA women. Discussion: These data show no difference in HR-QOL between AA and W obese women and suggest that menopausal status may have an impact on HR-QOL, especially in AA women.     

Insulin Resistance in Nondiabetic Morbidly Obese Patients: Effect of Bariatric Surgery

Objective: To evaluate insulin action on substrate use and insulinemia in nondiabetic class III obese patients before and after weight loss induced by bariatric surgery. Research Methods and Procedures: Thirteen obese patients (four men/nine women; BMI = 56.3 ± 2.7 kg/m²) and 13 lean subjects (five men/eight women; BMI = 22.4 ± 0.5 kg/m²) underwent euglycemic clamp, oral glucose tolerance test, and indirect calorimetry. The study was carried out before (Study I) and after (～40% relative to initial body weight; Study II) weight loss induced by Roux‐en‐Y Gastric bypass with silastic ring surgery. Results: The obese patients were insulin resistant (whole‐body glucose use = 19.7 ± 1.5 vs. 51.5 ± 2.4 μmol/min per kilogram fat‐free mass, p < 0.0001) and hyperinsulinemic in the fasting state (332 ± 86 vs. 85 ± 5 pM, p < 0.0001) and during the oral glucose tolerance test compared with the lean subjects. Fasting plasma insulin normalized after weight loss, whereas whole‐body glucose use increased (35.5 ± 3.7 μmol/min per kilogram fat‐free mass, p < 0.05 vs. Study I). The higher insulin clearance of obese did not change during the follow‐up period. Insulin‐induced glucose oxidation and nonoxidative glucose disposal were lower in the obese compared with the lean group (all p < 0.05). In Study II, the former increased slightly, whereas nonoxidative glucose disposal reached values similar to those of the control group. Fasting lipid oxidation was higher in the obese than in the control group and did not change significantly in Study II. The insulin effect on lipid oxidation was slightly improved (p = 0.01 vs. Study I). Discussion: The rapid weight loss after surgery in obese class III patients normalized insulinemia and improved insulin sensitivity almost entirely due to glucose storage, whereas fasting lipid oxidation remained high.