Health Outcomes of Gastric Bypass Patients Compared to Nonsurgical,Nonintervened Severely Obese

Favorable health outcomes at 2 years postbariatric surgery have been reported. With exception of the Swedish Obesity Subjects (SOS) study, these studies have been surgical case series, comparison of surgery types, or surgery patients compared to subjects enrolled in planned nonsurgical intervention. This study measured gastric bypass effectiveness when compared to two separate severely obese groups not participating in designed weight‐loss intervention. Three groups of severely obese subjects (N = 1,156, BMI ≥ 35 kg/m²) were studied: gastric bypass subjects (n = 420), subjects seeking gastric bypass but did not have surgery (n = 415), and population‐based subjects not seeking surgery (n = 321). Participants were studied at baseline and 2 years. Quantitative outcome measures as well as prevalence, incidence, and resolution rates of categorical health outcome variables were determined. All quantitative variables (BMI, blood pressure, lipids, diabetes‐related variables, resting metabolic rate (RMR), sleep apnea, and health‐related quality of life) improved significantly in the gastric bypass group compared with each comparative group (all P < 0.0001, except for diastolic blood pressure and the short form (SF‐36) health survey mental component score at P < 0.01). Diabetes, dyslipidemia, and hypertension resolved much more frequently in the gastric bypass group than in the comparative groups (all P < 0.001). In the surgical group, beneficial changes of almost all quantitative variables correlated significantly with the decrease in BMI. We conclude that Roux‐en‐Y gastric bypass surgery when compared to severely obese groups not enrolled in planned weight‐loss intervention was highly effective for weight loss, improved health‐related quality of life, and resolution of major obesity‐associated complications measured at 2 years.     

Peptide YY levels are elevated after gastric bypass surgery

Objective: Mechanisms that promote effective and sustained weight loss in persons who have undergone Roux‐en‐Y gastric bypass surgery are incompletely understood but may be mediated, in part, by changes in appetite. Peptide YY (PYY) is a gut‐derived hormone with anorectic properties. We sought to determine whether gastric bypass surgery alters PYY levels or response to glucose. Research Methods and Procedures: PYY and ghrelin levels after a 75‐gram oral glucose tolerance test were measured in 6 morbidly obese patients 1.5 ± 0.7 (SE) years after gastric bypass compared with 5 lean and 12 obese controls. Results: After substantial body weight loss (36.8 ± 3.6%) induced by gastric bypass, the PYY response to an oral glucose tolerance test was significantly higher than in controls (p = 0.01). PYY increased ～10‐fold after a 75‐gram glucose load to a peak of 303.0 ± 37.0 pg/mL at 30 minutes (p = 0.03) and remained significantly higher than fasting levels for all subsequent time‐points. In contrast, PYY levels in obese and lean controls increased to a peak of ～2‐fold, which was only borderline significant. Ghrelin levels decreased in a symmetric but opposite fashion to that of PYY. Discussion: Gastric bypass results in a more robust PYY response to caloric intake, which, in conjunction with decreased ghrelin levels, may contribute to the sustained efficacy of this procedure. The findings provide further evidence for a role of gut‐derived hormones in mediating appetite changes after gastric bypass and support further efforts to determine whether PYY_3–36 replacement could represent an effective therapy for obesity.     

Impact of surgically induced weight loss on cardiovascular autonomic function: one-year follow-up

Objective: To determine the impact of surgically induced weight loss on cardiovascular autonomic function in subjects with severe obesity and examine whether the effect was comparable for persons with and without diabetes. Research Methods and Procedures: Twenty‐six severely obese individuals (BMI = 48 ± 7 kg/m²) underwent bariatric surgery (laparoscopic Roux‐en‐Y gastric bypass, n = 21; laparoscopic adjustable gastric banding, n = 5). Cardiovascular autonomic function (heart rate variation during deep breathing and the Valsalva maneuver) was assessed before and 6 and 12 months after surgery. Results: Twelve months after bariatric surgery, there was a 28% decrease in BMI. There was an increase in all parasympathetic indices of autonomic function (all assessment modalities, p < 0.05) with weight loss. The amount of improvement from baseline for all measures of autonomic function did not differ for those with or without diabetes. Discussion: Surgically induced weight loss 12 months after surgery has a favorable effect on cardiovascular autonomic function in severely obese individuals with and without diabetes.     

Adipocyte Fatty Acid‐binding Protein as a Determinant of Insulin Sensitivity in Morbid‐obese Women

The aim of the study was to evaluate human plasma circulating levels of adipocyte fatty acid‐binding protein (A‐FABP) and its relationship with proinflammatory adipocytokines and insulin resistance in a severely obese cohort, before and 1 year after a surgical gastric bypass. Plasmatic levels of A‐FABP were measured in 77 morbid‐obese women before and 1 year after bariatric surgery. Anthropometrical parameters and body composition by bioelectrical impedance analysis were determined. Circulating levels of soluble tumor necrosis factor receptor 2 (sTNFR2), Interleukin 18 (IL‐18), adiponectin, and high‐sensitive C‐reactive protein (hsCRP) were also analyzed. Insulin resistance by homeostasis model assessment of insulin resistance (HOMA‐IR) index was calculated. After massive weight loss, A‐FABP plasmatic levels decreased significantly [7.6 (8.9) vs. 4.3 (5.1); P < 0,001] but no association with circulating adipokines or proinflammatory cytokines, both at the beginning and at the end of follow‐up, was observed. A decrease in sTNFR2, IL‐18, hsCRP, and an increase in adiponectin levels (P < 0.001 in all cases) were observed after the gastric bypass. HOMA‐IR index improved 1 year after surgery and after multiple regression analysis remained associated with A‐FABP after controlling for confounding variables (β = 0.322, P = 0.014; R² for the model 0.281). In morbid‐obese women, plasma A‐FABP concentrations were dramatically reduced after gastric bypass surgery. After weight loss this protein contributed to HOMA‐IR index independently of proinflammatory/antinflammatory cytokine profile. Further studies are warranted to elucidate the role of A‐FABP in the pathogenesis of insulin resistance in morbid obesity.     

Obesity and sexual quality of life

Objectives : Reduced sexual quality of life is a frequently reported yet rarely studied consequence of obesity. The objectives of this study were to 1) examine the prevalence of sexual quality‐of‐life difficulties in obese individuals and 2) investigate the association between sexual quality of life and BMI class, sex, and obesity treatment—seeking status. Research Methods and Procedures : Subjects consisted of 1) 500 participants in an intensive residential program for weight loss and lifestyle modification (BMI = 41.3 kg/m²), 2) 372 patients evaluated for gastric bypass surgery (BMI = 47.1 kg/m²), and 3) 286 obese control subjects not seeking weight loss treatment (BMI = 43.6 kg/m²). Participants completed the Impact of Weight on Quality of Life‐Lite, a measure of weight‐related quality of life. Responses to the four Sexual Life items (assessing enjoyment, desire, performance, and avoidance) were analyzed by BMI, sex, and group. Results : Higher BMI was associated with greater impairments in sexual quality of life. Obese women reported more impairment in sexual quality of life than obese men for three of four items. Gastric bypass surgery candidates reported more impairment in sexual quality of life than residential patients and controls for most items. In general, residential patients reported levels of impairment greater than or equal to controls. Discussion : Obesity is associated with lack of enjoyment of sexual activity, lack of sexual desire, difficulties with sexual performance, and avoidance of sexual encounters. Sexual quality of life is most impaired for women, individuals with Class III obesity, and patients seeking gastric bypass surgery.     

Blood Pressure and Pulse Pressure during Long‐Term Weight Loss in the Obese: The Swedish Obese Subjects (SOS) Intervention Study

Objective: Recently we reported a complete relapse in the blood pressure (BP) of obese subjects despite a maintained 16% weight loss over 8 years. This relapse is now analyzed as a function of several variables. Pulse pressure (PP) is an independent risk factor of cardiovascular mortality. We now examine the development of PP in the obese and whether it can be modified by weight‐reducing gastric surgery. Research Methods and Procedures: A total of 1157 patients treated with gastric surgery and 1031 obese controls (body mass index of 41.0 ± 4.6 kg/m² [mean ± SD], age 48 ± 6 years) were followed for 5.5 ± 2.1 (range 3 to 10) years. To separate the effect of weight change from effect of time on BP, the patients were divided in cohorts based on follow‐up time. Results: Gastric surgery resulted in a maximum weight loss after 1 year that was followed by a moderate relapse. After 5.5 years, weight loss in the intervention group was 18 ± 11% of initial body weight. Very little weight change was seen in controls. Systolic BP decreased in the intervention group during the first 6 months but had relapsed to control values at last examination. The adjusted change in PP was +4.7 mm Hg in obese controls but +2.9 mm Hg in the intervention group (p < 0.001). Final BP values were more closely related to follow‐up time and ongoing weight increase than to initial body weight or initial weight loss. Discussion: Effects of time (aging) and weight change per year on BP can be separated. An early increase in PP could be observed in the obese. This increase could be modified by weight‐reducing gastric surgery.     

Impact of bariatric surgery on type 2 diabetes

The management and prevention of diabetes through lifestyle modifications and weight loss should be the mainstay of therapy in appropriate candidates. Although the results from the Diabetes Prevention Trial and the Finnish Prevention Study support this approach, over 95% of patients not participating in a prevention research study are unable to achieve and maintain any significant weight loss over time. Bariatric surgery for weight loss is an emerging option for more sustainable weight loss in the severely obese subject, especially when obesity is complicated by diabetes or other co-morbidities. The two most common types of procedures currently used in the United States are adjustable gastric bands and Roux-en-Y gastric bypass. These procedures can be performed laparoscopically, further reducing the perioperative morbidity and mortality associated with the surgery. While the gastric bypass procedure usually results is greater sustained weight loss (40–50%) than adjustable gastric banding (20–30%), it also carries greater morbidity and nutritional/metabolic issues, such as deficiencies in iron, B12, calcium, and vitamin D. Following bariatric surgery most subjects experience improvements in diabetes control, hypertension, dyslipidemia, and other obesity-related conditions. In patients with impaired glucose tolerance most studies report 99–100% prevention of progression to diabetes, while in subjects with diabetes prior to surgery, resolution of the disease is reported in 64–93% of the cases. While improvements in insulin resistance and beta-cell function are related to surgically induced weight loss, the rapid post-operative improvement in glycemia is possibly due to a combination of decreased nutrient intake and changes in gut hormones as a result of the bypassed intestine. Post-prandial hyperinsulinemic hypoglycemia associated with nesidioblastosis has been described in a series of patients following gastric bypass surgery, and may be related to the described changes in GLP-1 and other gut hormones.     

Contribution of adipose tissue to plasma 25-hydroxyvitamin D concentrations during weight loss following gastric bypass surgery

Roux-en-y gastric bypass (RYGB) surgery is associated with dramatic improvements in obesity-related comorbidity, but also with nutritional deficiencies. Vitamin D concentrations are depressed in the severely obese, but the impact of weight loss via RYGB is unknown. We determined associations between adiposity and systemic 25-hydroxyvitamin D (25(OH)D) during weight loss and the immediate and longer-term effects of RYGB. Plasma 25(OH)D concentrations and fat mass (FAT) were determined by immunoassay and air displacement plethysmography, respectively, at 0 (before RYGB surgery), and at 1, 6, and 24 months in severely obese white and African American (AA) women (n = 20). Decreases in adiposity were observed at 1, 6, and 24 months following RYGB (P < 0.05). Plasma 25(OH)D concentrations increased at 1 month (P = 0.004); a decreasing trend occurred over the remainder months after surgery (P = 0.02). Despite temporary improvement in vitamin D status, a high prevalence of vitamin D insufficiency was observed (76, 71, 67, and 82%, at baseline, 1, 6, and 24 months, respectively), and plasma 25(OH)D concentrations were lower in AA compared to white patients (P < 0.05). Strong positive baseline and 1 month cross-sectional correlations between FAT and plasma 25(OH)D were observed, which remained after adjustment for age and race subgroup (β = 0.76 and 0.61, respectively, P = 0.02). In conclusion, 25(OH)D concentrations increased temporarily and then decreased during the 24 months following RYGB. The acute increase and the positive associations observed between adipose tissue mass and systemic 25(OH)D concentrations suggest storage in adipose tissue and release during weight loss.     

Resistin,Adiponectin, Ghrelin,Leptin, and Proinflammatory Cytokines: Relationships in Obesity

Objective: To evaluate interactions among leptin, adiponectin, resistin, ghrelin, and proinflammatory cytokines [tumor necrosis factor receptors (TNFRs), interleukin‐6 (IL‐6)] in nonmorbid and morbid obesity. Research Methods and Procedures: We measured these hormones by immunoenzyme or radiometric assays in 117 nonmorbid and 57 morbidly obese patients, and in a subgroup of 34 morbidly obese patients before and 6 months after gastric bypass surgery. Insulin resistance by homeostasis model assessment, lipid profile, and anthropometrical measurements were also performed in all patients. Results: Average plasma lipids in morbidly obese patients were elevated. IL‐6, leptin, adiponectin, and resistin were increased and ghrelin was decreased in morbidly obese compared with nonmorbidly obese subjects. After adjusting for age, gender, and BMI in nonmorbidly obese, adiponectin was positively associated with HDLc and gender and negatively with weight (β = ?0.38, p < 0.001). Leptin and resistin correlated positively with soluble tumor necrosis factor receptor (sTNFR) 1 (β = 0.24, p = 0.01 and β = 0.28, p = 0.007). In the morbidly obese patients, resistin and ghrelin were positively associated with sTNFR2 (β = 0.39, p = 0.008 and β = 0.39, p = 0.01). In the surgically treated morbidly obese group, body weight decreased significantly and was best predicted by resistin concentrations before surgery (β = 0.45, p = 0.024). Plasma lipids, insulin resistance, leptin, sTNFR1, and IL‐6 decreased and adiponectin and ghrelin increased significantly. Insulin resistance improved after weight loss and correlated with high adiponectin levels. Discussion: TNFα receptors were involved in the regulatory endocrine system of body adiposity independently of leptin and resistin axis in nonmorbidly obese patients. Our results suggest coordinated roles of adiponectin, resistin, and ghrelin in the modulation of the obesity proinflammatory environment and that resistin levels before surgery treatment are predictive of the extent of weight loss after bypass surgery.     

Bypassing the duodenum does not improve insulin resistance associated with diet-induced obesity in rodents

Roux-en-y gastric bypass (RYGB) surgery rapidly improves glucose tolerance and reverses insulin resistance in obese patients. It has been hypothesized that this effect is mediated by the diversion of nutrients from the proximal small intestine. We utilized duodenal-jejunal bypass (DJB) as a modification of gastric bypass to determine the effect of nutrient diversion from the foregut without gastric restriction on insulin resistance in obese rats. The effects of DJB or Sham surgery on glucose homeostasis were determined in both high-fat-fed Long-Evans and Wistar rats. Body weight and food intake were measured weekly postoperatively, and body composition was monitored before and after surgery. Glucose tolerance was tested before and as early as 1 month postoperation; additionally, in Wistar rats, insulin sensitivity was determined by a hyperinsulinemic-euglycemic clamp (HIEC). DJB did not affect body weight, body composition, glucose tolerance, or insulin concentrations over the period of the study. The average glucose infusion rate (GIR) during the HIEC was 6.2 ± 1.16 mg/kg/min for Sham rats compared to 7.2 ± 1.71 mg/kg/min for DJB rats (P = 0.62), and neither endogenous glucose production (EGP; P = 0.81) nor glucose utilization (glucose disappearance (R(d)), P = 0.59) differed between DJB and Sham rats. DJB does not affect insulin resistance induced by a high-fat diet in Long-Evans and Wistar rats. These data suggest that duodenal bypass alone is an insufficient mechanism to alter insulin sensitivity independent of weight loss in obese, nondiabetic rodents.     

Sustained Weight Loss in Obese Subjects Has Benefits That Are Independent of Attained Weight

Objective: To explore the hypothesis that sustained weight loss in severely obese patients may have benefits that are independent of their attained BMI. Research Methods and Procedures: We conducted a comparison of two weight‐stable groups with BMI in the 30 to 35 kg/m² range. Subjects (n = 79) were selected obese patients 3 years after laparoscopic adjustable gastric band surgery, and controls (n = 79) were obese patients seeking weight loss therapy. Subjects were selected in a de‐identified manner from our database to best match the control group. A range of clinical, biochemical, and questionnaire measures were obtained to assess obesity‐related health status Results: Subjects maintained a mean weight loss of 32.8 ± 18 kg after surgery. The weight loss subjects had significantly lower fasting plasma glucose, insulin, and triglyceride concentrations, along with higher high‐density lipoprotein‐cholesterol levels and better indirect measures of insulin sensitivity when compared with controls (p < 0.05 for all). In addition, aminotransferase levels, neutrophil counts, and globulin levels were also significantly lower in weight loss subjects. All differences in laboratory variables remained significant after controlling for BMI. The subjects also reported better health‐related quality of life, fewer symptoms of depression, and greater satisfaction with their appearance than controls. Discussion: These findings suggest that the post‐weight loss state conveys benefits that are greater than predicted by the attained BMI. These findings may have important implications regarding the expectations of weight loss therapy, and mechanisms for this effect should be carefully sought.     

Gastric bypass reduces fat intake and preference

Roux-en-Y gastric bypass is the most effective therapy for morbid obesity. This study investigated how gastric bypass affects intake of and preference for high-fat food in an experimental (rat) study and within a trial setting (human). Proportion of dietary fat in gastric bypass patients was significantly lower 6 yr after surgery compared with patients after vertical-banded gastroplasty (P = 0.046). Gastric bypass reduced total fat and caloric intake (P < 0.001) and increased standard low-fat chow consumption compared with sham controls (P < 0.001) in rats. Compared with sham-operated rats, gastric bypass rats displayed much lower preferences for Intralipid concentrations > 0.5% in an ascending concentration series (0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 5%) of two-bottle preference tests (P = 0.005). This effect was demonstrated 10 and 200 days after surgery. However, there was no difference in appetitive or consummatory behavior in the brief access test between the two groups (P = 0.71) using similar Intralipid concentrations (0.005% through 5%). Levels of glucagon-like peptide-1 (GLP-1) were increased after gastric bypass as expected. An oral gavage of 1 ml corn oil after saccharin ingestion in gastric bypass rats induced a conditioned taste aversion. These findings suggest that changes in fat preference may contribute to long-term maintained weight loss after gastric bypass. Postingestive effects of high-fat nutrients resulting in conditioned taste aversion may partially explain this observation; the role of GLP-1 in mediating postprandial responses after gastric bypass requires further investigation.     

Muscle fiber type is associated with obesity and weight loss

The purpose of this study was to test the hypothesis that muscle fiber type is related to obesity. Fiber type was compared 1) in lean and obese women, 2) in Caucasian (C) and African-American (AA) women, and 3) in obese individuals who lost weight after gastric bypass surgery. When lean (body mass index 24.0 +/- 0.9 kg/m(2), n = 28) and obese (34.8 +/- 0.9 kg/m(2), n = 25) women were compared, there were significant (P < 0.05) differences in muscle fiber type. The obese women possessed fewer type I (41.5 +/- 1.8 vs. 54.6 +/- 1.8%) and more type IIb (25.1 +/- 1.5 vs. 14.4 +/- 1.5%) fibers than the lean women. When ethnicity was accounted for, the percentage of type IIb fibers in obese AA was significantly higher than in obese C (31.0 +/- 2.4% vs. 19.2 +/- 1.9%); fewer type I fibers were also found in obese AA (34.5 +/- 2.8% vs. 48.6 +/- 2.2%). These data are consistent with the higher incidence of obesity and greater weight gain reported in AA women. With weight loss intervention, there was a positive relationship (r = 0.72, P < 0.005) between the percentage of excess weight loss and the percentage of type I fibers in morbidly obese patients. These findings indicate that there is a relationship between muscle fiber type and obesity.     

Sympathetic support of energy expenditure and sympathetic nervous system activity after gastric bypass surgery

Objective:

This study was designed to determine how gastric bypass affects the sympathetically‐mediated component of resting energy expenditure (REE) and muscle sympathetic nerve activity (MSNA).

Design and Methods:

We measured REE before and after beta‐blockade in seventeen female subjects approximately three years post‐gastric bypass surgery and in nineteen female obese individuals for comparison. We also measured MSNA in a subset of these subjects.

Results:

The gastric bypass subjects had no change in REE after systemic beta‐blockade, reflecting a lack of sympathetic support of REE, in contrast to obese subjects where REE was reduced by beta‐blockade by approximately 5% (P < 0.05). The gastric bypass subjects, while still overweight (BMI = 29.3 vs 38.0 kg·m^?2 for obese subjects, P < 0.05), also had significantly lower MSNA compared to obese subjects (10.9 ± 2.3 vs. 21.9 ± 4.1 bursts·min^?1, P < 0.05). The reasons for low MSNA and a lack of sympathetically mediated support of REE after gastric bypass are likely multifactorial and may be related to changes in insulin sensitivity, body composition, and leptin, among other factors.

Conclusions:

These findings may have important consequences for the maintenance of weight loss after gastric bypass. Longitudinal studies are needed to further explore the changes in sympathetic support of REE and if changes in MSNA or tissue responsiveness are related to the sympathetic support of REE.

     

Behavioral and Psychological Factors in the Assessment and Treatment of Obesity Surgery Patients

Objective: To provide evidence‐based guidelines on the psychological and behavioral screening of weight loss surgery (WLS) candidates and the impact of psychosocial factors on behavior change after gastric bypass surgery. Research Methods and Procedures: The members of the Behavioral and Psychological subgroup of the Multidisciplinary Care Task Group conducted searches of MEDLINE and PubMed for articles related to WLS, behavior changes, and mental health, including quality of life (QOL) and behavior modification. Pertinent abstracts and literature were reviewed for references. A total of 198 abstracts were identified; 17 papers were reviewed in detail. Search periods were from 1980 to 2004. Results: We found a high incidence of depression, negative body image, eating disorders, and low QOL in severely obese patients. Our task subgroup recommended that all WLS candidates be evaluated by a licensed mental health care provider (i.e., psychiatrist, psychologist, or social worker), experienced in the treatment of severely obese patients and working within the context of a multidisciplinary care team. We also recommended development of pre‐ and postsurgical treatment plans that address psychosocial contraindications for WLS and potential barriers to postoperative success. Discussion: The psychological consequences of obesity can range from lowered self‐esteem to clinical depression. Rates of anxiety and depression are three to four times higher among obese individuals than among their leaner peers. A comprehensive multidisciplinary program that incorporates psychological and behavior change services can be of critical benefit in enhancing compliance, outcome, and QOL in WLS patients.     

Superior Appetite Hormone Profile After Equivalent Weight Loss by Gastric Bypass Compared to Gastric Banding

The goal of this study was to understand the mechanisms of greater weight loss by gastric bypass (GBP) compared to gastric banding (GB) surgery. Obese weight‐ and age‐matched subjects were studied before (T0), after a 12 kg weight loss (T1) by GBP (n = 11) or GB (n = 9), and at 1 year after surgery (T2). peptide YY_3–36 (PYY_3–36), ghrelin, glucagon‐like peptide‐1 (GLP‐1), leptin, and amylin were measured after an oral glucose challenge. At T1, glucose‐stimulated GLP‐1 and PYY levels increased significantly after GBP but not GB. Ghrelin levels did not change significantly after either surgery. In spite of equivalent weight loss, leptin and amylin decreased after GBP, but not after GB. At T2, weight loss was greater after GBP than GB (P = 0.003). GLP‐1, PYY, and amylin levels did not significantly change from T1 to T2; leptin levels continued to decrease after GBP, but not after GB at T2. Surprisingly, ghrelin area under the curve (AUC) increased 1 year after GBP (P = 0.03). These data show that, at equivalent weight loss, favorable GLP‐1 and PYY changes occur after GBP, but not GB, and could explain the difference in weight loss at 1 year. Mechanisms other than weight loss may explain changes of leptin and amylin after GBP.     

Accuracy of self-reported weight among bariatric surgery candidates: the influence of race and weight cycling

Objective: Research on the accuracy of self‐reported weight has indicated that the degree of misreporting (underestimating) weight is associated with increasing weight but is variable across patient groups. We examined the degree of discrepancy between actual and self‐reported BMI in severely obese bariatric surgery candidates, and whether the degree of accuracy varied by race and by eating‐related and psychological factors. Research Methods and Procedures: Participants were 179 obese female gastric bypass surgery candidates (31 black, 22 Hispanic, 126 white) who were asked to self‐report height and weight as part of a larger assessment battery. Actual height and weight were then measured and a discrepancy score was generated (actual BMI ? reported BMI). Results: In this group of severely obese patients, degree of misreporting was unrelated to BMI. The race groups did not differ in actual or self‐reported BMI but differed significantly in the degree of misestimation between self‐reported and actual BMI. Post hoc tests indicated that black women underestimated their BMI significantly more than white women; Hispanic women did not differ from the other race groups. No eating‐related or psychological variables assessed predicted percentage discrepancy; however, the accuracy in self‐reported weight was related to history of weight cycling. Discussion: Overall, obese bariatric surgery candidates were accurate in self‐report of weight, although the degree of accuracy differed by race and weight cycling history.     

The Insulin Tolerance Test in Morbidly Obese Patients Undergoing Bariatric Surgery

Objective: To assess the effect of massive weight loss in relation to insulin resistance and its correlation to changes in glycemic homeostasis and lipid profile in severely obese patients. Research Methods and Procedures: A prospective clinical intervention study was carried out with 31 morbidly obese women (body mass index: 54.2 ± 8.8 kg/m²) divided into three groups according to their glucose tolerance test: 14 normal, 8 impaired glucose tolerance, and 9 type 2 diabetes. All subjects underwent an insulin tolerance test with intravenous bolus of 0.1 U insulin/kg body weight before silastic ring vertical gastroplasty Roux‐en‐Y gastric bypass surgery, and again at 2, 4, 6, and 12 months postoperatively. Fasting plasma glucose, hemoglobin A1c, and lipid profile were also evaluated. Results: A reduction of 68 ± 15% in initial excess body weight was evident within 1 year. Along with weight loss, the following statistically significant changes were found: an increase in the insulin‐sensitivity index (Kitt) and a decrease in fasting plasma glucose and hemoglobin A1c, most notably in the type 2 diabetes group. An overall improvement in lipid profile was observed in all three groups. Discussion: Bariatric surgery was an effective therapeutic approach for these obese patients because it reduced both weight and insulin resistance, along with improving metabolic parameters. Significant correlations were found between insulin resistance and metabolic improvements. Weight loss after bariatric surgery induced an improvement in metabolic fitness, related to the reduction in insulin resistance over a range of glucose tolerance statuses from normal to diabetic.     

Differential effects of gastric bypass and banding on circulating gut hormone and leptin levels

Objective: To quantify plasma concentrations of hormones that regulate energy homeostasis in order to establish possible mechanisms for greater weight loss after Roux‐en‐Y gastric bypass (RYGBP) compared with gastric banding (BND). Research Methods and Procedures: Four groups of women were studied: lean (n = 8; mean BMI, 21.6 kg/m²); BND (n = 9; BMI, 35.8; 25% weight loss), RYGBP (n = 9; BMI, 34.2; 36% weight loss), and controls matched for BMI to the surgical groups (n = 11; BMI, 34.4). Results: Fasting total peptide YY (PYY) and PYY_(3–36) immunoreactivity were similar among all groups, but the postprandial response in the RYGBP group was exaggerated, such that 30 minutes after the meal, total and PYY_(3–36) levels were 2‐ to 4‐fold greater compared with all other groups. Maximal postprandial suppression of total ghrelin was blunted in the BND group (13%) compared with RYGBP (27%). Postprandial suppression of octanoylated ghrelin was also less in BND (29%) compared with RYGBP (56%). Fasting insulin was lower in RYGBP (6.6 μU/mL) compared with BND (10.0 μU/mL). Compared with lean controls, leptin concentrations were significantly higher in BND but not in RYGBP. There was a greater increase in post‐meal satiety in the RYGBP group compared with BND and overweight controls. Discussion: The differences between RYGBP and BND subjects in postprandial concentrations of PYY and ghrelin would be expected to promote increased satiety and earlier meal termination in RYGBP and may aid in greater weight loss. The differences in insulin and leptin concentrations associated with these procedures may also reflect differences in insulin sensitivity and energy partitioning.