Mechanisms and consequences of weight gain after deep brain stimulation of the subthalamic nucleus in patients with Parkinson's disease.

Body weight gain in combination with metabolic alterations has been observed after deep brain stimulation (DBS) of subthalamic nucleus (STN) in patients with Parkinson's disease (PD), which potentially counteracts the positive effects of motor improvement. We aimed to identify stimulation-dependent effects on motor activities, body weight, body composition, energy metabolism, and metabolic blood parameters and to determine if these alterations are associated with the local impact of DBS on different STN parcellations. We assessed 14 PD patients who underwent STN DBS (PD-DBS) before as well as 6- and 12-months post-surgery. For control purposes, 18 PD patients under best medical treatment (PD-CON) and 25 healthy controls (H-CON) were also enrolled. Wrist actigraphy, body composition, hormones, and energy expenditure measurements were applied. Electrode placement in the STN was localized, and the local impact of STN DBS was estimated. We found that STN DBS improved motor function by ~ 40% (DBS ON, Med ON). Weight and fat mass increased by ~ 3 kg and ~ 3% in PD-DBS (all P ≤ 0.005). fT3 (P = 0.001) and insulin levels (P = 0.048) increased solely in PD-DBS, whereas growth hormone levels (P = 0.001), daily physical activity, and VO2 during walking were decreased in PD-DBS (all P ≤ 0.002). DBS of the limbic part of the STN was associated with changes in weight and body composition, sedentary activity, insulin levels (all P ≤ 0.040; all r ≥ 0.56), and inversely related to HOMA-IR (P = 0.033; r = - 0.62). Daily physical activity is decreased after STN DBS, which can contribute to weight gain and an unfavorable metabolic profile. We recommend actigraphy devices to provide feedback on daily activities to achieve pre-defined activity goals.

Cardiorespiratory Fitness is Associated with Glycated Hemoglobin and Triglyceride Levels in Severely Obese Men: A Retrospective Clinical Data Analysis.

BACKGROUND: Even subjects with severe obesity show a wide range of metabolic health states, with some showing marked alterations in glucose and lipid metabolism whereas others do not. In severely obese women, we could recently show that the degree of cardiorespiratory fitness is, independently of body mass and age, associated with several markers of glucose and lipid metabolism. AIMS: In our retrospective study on a clinical data set, we questioned whether such an association also exists in severely obese men. METHODS: Cardiorespiratory fitness, i. e. workload (Wpeak) and oxygen uptake (V̇O2,peak) at peak exercise, was assessed by a bicycle spiroergometry in 133 severely obese men (all BMI>35 kg m-2). The following metabolic blood markers were also measured: Fasting serum glucose, insulin, triglycerides (TG), total, low-, high-density cholesterol (Chol, LDL, HDL), uric acid, and whole blood glycated hemoglobin (HbA1c). The Chol/HDL ratio and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) were also calculated. RESULTS: Multiple stepwise linear regression models including age, body mass, and smoking status as independent variables revealed that Wpeak and V̇O2,peak, explained 4.5 to 10.7% of variance in HbA1c and TG (all beta<- 0.22; all p<0.02). Including fat free mass instead of body mass in respective models revealed that both Wpeak and V̇O2,peak were predictors of HbA1c and TG (all beta<- 0.265; all p<0.013), respectively, while Wpeak also accounted for variance in glucose and Chol (both beta<- 0.259; both p<0.023). CONCLUSIONS: Similar to previous observations in women, our data indicate that cardiorespiratory fitness assessed by bicycle ergospirometry test is associated with glucose and lipid metabolism in severely obese men. The strength of the found associations suggest a mild to moderate influence of cardiorespiratory fitness on metabolic health in severe obesity.

Sleep Loss Disrupts Morning-to-Evening Differences in Human White Adipose Tissue Transcriptome.

CONTEXT: Chronodisruption, as caused by such conditions as perturbations of 24-hour rhythms of physiology and behavior, may promote the development of metabolic diseases. OBJECTIVE: To assess the acute effects of sleep curtailment on circadian regulation (i.e., morning-to-evening differences) of white adipose tissue (WAT) transcriptome in normal-weight men. DESIGN: Fifteen healthy men aged 18 to 30 years (mean ± SEM, 24.0 ± 0.9years) were studied. In randomized, balanced order they underwent three separate nights with regular sleep duration (8 hours of sleep between 11:00 pm and 7:00 am), sleep restriction (4 hours of sleep between 3:00 am and 7:00 am), and sleep deprivation (no sleep at all). Sleep was polysomnographically evaluated. WAT biopsy samples were taken twice at 9:00 pm and 7:00 am to assess morning-to-evening differences. WAT transcriptome profile was assessed by RNA sequencing, and expression of relevant circadian core clock genes were analyzed. Glucose homeostasis, lipid profile, and adipokines were assessed. RESULTS: Sleep restriction dramatically blunted morning-to-evening transcriptome variations with further dampening after sleep deprivation. Although most core clock genes remained stably rhythmic, morning-to-evening regulated pathways of carbohydrate and lipid metabolism were highly sensitive to sleep loss. In particular, genes associated with carbohydrate breakdown lost rhythmicity after sleep deprivation, with an overall trend toward an upregulation in the morning. In line with specific transcriptional changes in WAT, retinol-binding-protein 4 was increased and ß-cell secretory capacity was diminished. CONCLUSIONS: Acute sleep loss induces a profound restructuring of morning-to-evening WAT transcriptome with uncoupling from the local clock machinery, resulting in increased WAT carbohydrate turnover and impaired glucose homeostasis. Our data support an optimization of sleep duration and timing to prevent metabolic disorders such as obesity and type 2 diabetes.

Resting energy expenditure after Roux-en Y gastric bypass surgery.

BACKGROUND: The mechanisms by which Roux-en Y gastric bypass surgery (RYGB) provokes weight loss are incompletely understood. Enhanced energy expenditure may be one contributing mechanism. Previous results on changes in resting energy expenditure (REE) after RYGB are inconsistent. OBJECTIVES: The aim of the present study was to assess changes in REE after RYGB and whether REE predicts weight loss (percentage weight loss). SETTING: Obesity Clinic. METHODS: REE was measured by indirect calorimetry (mREE) before and 1 year after RYGB in 233 patients with severe obesity (175 women; all body mass index ≥35.0 kg·m-2) and mREE was compared with predicted REE (pREE) and expressed as percentage of pREE (%pREE). For calculation of pREE, 2 new equations were developed from an independent reference group of overweight and obese patients (852 patients; body mass index range: 27.4-73.0 kg·m-2) that were examined in exactly the same setting as the bariatric patients that were followed-up after RYGB. The new equations were based on either anthropometric (pREE-BM, %pREE-BM) or body composition (pREE-BC; %pREE-BC) parameters. RESULTS: After RYGB, absolute mREE was reduced by 20.4 ± 11.0% (-458 ± 277 kcal·d-1; P<.001). Compared with pREE-BM (post-%REE-BM) and pREE-BC (post-%REE-BC), mREE was 2.3 ± 9.4% and 1.6 ± 9.5%, respectively, higher (both P ≤ .03). Post-%pREE-BM and post- %pREE-BC after RYGB were positively correlated with percentage weight loss (r = .206 and r = .231; both P ≤ .003). CONCLUSIONS: Data indicate a slightly higher mREE than pREE after RYGB. Although the underlying mechanisms of this observation remain to be elucidated our finding may play a role for weight loss outcomes after the surgery.

Glycemic increase induced by intravenous glucose infusion fails to affect hunger, appetite, or satiety following breakfast in healthy men.

Meal-dependent fluctuations of blood glucose and corresponding endocrine signals such as insulin are thought to provide important regulatory input for central nervous processing of hunger and satiety. Since food intake also triggers the release of numerous gastrointestinal signals, the specific contribution of changes in blood glucose to appetite regulation in humans has remained unclear. Here we tested the hypothesis that inducing glycemic fluctuations by intravenous glucose infusion is associated with concurrent changes in hunger, appetite, and satiety. In a single blind, counter-balanced crossover study 15 healthy young men participated in two experimental conditions on two separate days. 500 ml of a solution containing 50 g glucose or 0.9% saline, respectively, was intravenously infused over a 1-h period followed by a 1-h observation period. One hour before start of the respective infusion subjects had a light breakfast (284 kcal). Blood glucose and serum insulin concentrations as well as self-rated feelings of hunger, appetite, satiety, and fullness were assessed during the entire experiment. Glucose as compared to saline infusion markedly increased glucose and insulin concentrations (peak glucose level: 9.7 ± 0.8 vs. 5.3 ± 0.3 mmol/l; t(14) = -5.159, p < 0.001; peak insulin level: 370.4 ± 66.5 vs. 109.6 ± 21.5 pmol/l; t(14) = 4.563, p < 0.001) followed by a sharp decline in glycaemia to a nadir of 3.0 ± 0.2 mmol/l (vs. 3.9 ± 0.1 mmol/l at the corresponding time in the control condition; t(14) = -3.972, p = 0.001) after stopping the infusion. Despite this wide glycemic fluctuation in the glucose infusion condition subjective feelings of hunger, appetite satiety, and fullness did not differ from the control condition throughout the experiment. These findings clearly speak against the notion that fluctuations in glycemia and also insulinemia represent major signals in the short-term regulation of hunger and satiety.

Comprehensive assessment of physical functioning in bariatric surgery candidates compared with subjects without obesity.

BACKGROUND: Obesity appears to be associated with reduced physical performance, but comprehensive assessments of physical functioning are lacking in subjects with severe obesity, in particular in comparison with subjects without obesity. This precludes an objective assessment of the degree of impairment. OBJECTIVE: To compare motor skills and cardiopulmonary fitness between subjects with severe obesity (OB) (i.e., candidates for bariatric surgery) and control subjects without obesity (non-OB). SETTING: Cantonal Hospital, Switzerland. METHODS: Flexibility, movement speed, balance, maximal isometric strength, and cardiopulmonary fitness were tested in 45 OB (body mass index: 42.6±.9 kg/m(2); age: 35±1.7 years; 33 women) and 32 non-OB (body mass index: 23±.4 kg/m(2); age: 38.5±2.1 years; 25 women) subjects. RESULTS: In comparison with the non-OB group, the OB group showed reduced shoulder flexibility (P<.001) but comparable hamstrings flexibility (P = .3). Speed-related tasks (i.e., timed up-and-go test and timed lying-to-standing test) indicated that the OB group was slower than the non-OB group (all P<.007). Strength-related tasks indicated a greater absolute back muscle and knee-extensor strength (all P<.002) in the OB group with no difference in knee-flexor strength (both P>.8). However, when related to weight, the OB group showed reduced maximal strength (all P<.002). Bicycle spiroergometry indicated that absolute oxygen consumption at peak exercise and at the anaerobic threshold did not differ between groups (both P>.06). Related to weight, however, values were lower in the OB than in the non-OB group (both P< .001). CONCLUSION: Data indicate a differential pattern of functional impairment in bariatric surgery candidates compared with subjects without obesity. These findings might help to establish tailored intervention protocols to improve physical performance in such subjects.

Subjective and objective physical activity patterns after Roux-en Y gastric bypass surgery compared with non-operated obese and non-obese control women.

INTRODUCTION: Previous studies on physical activity after bariatric surgery provided inconsistent results. The aim of our study was to comprehensively assess physical activity by subjective (questionnaires) and objective (accelerometry) measures in women who had undergone Roux-en Y gastric bypass (RYGB) surgery and to compare results with those of women displaying grade II or higher obesity and of non-obese control women. METHODS: Our cross-sectional case-control study included 12 women in each group (RYGB, obese, non-obese). Wrist accelerometry was performed over 5 days. Two questionnaires were used to assess women's self-reported leisure- and work-time and sport-related physical activity. RESULTS: Accelerometry indicated a lower physical activity in RYGB women than in non-obese women in particular during the weekend (p=0.010), while there was no difference between RYGB and obese women (p=0.57). Questionnaires revealed that RYGB women self-report a greater leisure- and work-time physical activity than obese women and also greater work-related physical activity than non-obese women (all p≤0.032). In contrast, sport-related activities were reduced in RYGB as compared with non-obese women (p=0.011), while there was no difference between RYGB and obese women (p=0.51). Comparison of the obese and non-obese group revealed less leisure-time and sport-related activities in the obese women (both p≤0.002). DISCUSSION: Despite the preliminary character of our rather small study, data suggest a differential physical activity pattern in women who have previously undergone RYGB surgery that is characterized by rare sport activities, an increased subjective work-related physical activity and objectively reduced physical activity during the weekend as compared with non-obese control women.

Waist circumference and related anthropometric indices are associated with metabolic traits in severely obese subjects.

Increased waist circumference (WC) and related anthropometric indices have been shown to be, independently of body weight and body mass index (BMI), associated with adverse metabolic traits in many populations. It is unknown, however, whether WC also predicts adverse metabolic traits in severely obese subjects displaying a BMI greater than 35 kg/m2. To address this question, we analyzed a dataset including 838 severely obese patients (597 women, BMI 44.6 ± 6.2 kg/m2; 241 men, BMI 44.3 ± 5.7 kg/m2). Body weight, height, WC, hip circumference, and blood pressure were measured in all subjects along with the following metabolic blood markers: fasting glucose, insulin, glycolized hemoglobin levels, triglycerides, total cholesterol, low- and high-density cholesterol, and uric acid. Multivariate regression analyses indicated that WC as well as related anthropometric indices, in particular those accounting for subjects' height, were associated with many metabolic variables independently of body weight and BMI. In general, height-adjusted WC indices were more closely associated with metabolic traits in women than in men. Collectively, our findings suggest that body fat distribution also plays an important role in determining metabolic traits in severely obese subjects and that WC represents a valuable marker of abdominal/visceral obesity in this population.

Enhanced thermic effect of food after Roux-en-Y gastric bypass surgery.

CONTEXT: The mechanisms of weight loss after Roux-en-Y gastric bypass (RYGB) surgery are incompletely understood. OBJECTIVE: Our objective was to investigate changes in metabolic processing of ingested food that may contribute to the weight-reducing effect of RYGB surgery. DESIGN AND SETTING: This was a cross-sectional case-control study at the Interdisciplinary Obesity Center, Cantonal Hospital St. Gallen, St. Gallen, Switzerland. PATIENTS: Ten formerly obese women (mean ± SEM body mass index [BMI] = 26.6 ± 0.9 kg/m(2)) who had undergone RYGB surgery 41.9 ± 9.7 months before, 8 severely obese women (BMI = 40.8 ± 2.0 kg/m(2)), and 10 lean women (BMI = 20.9 ± 0.6 kg/m(2)). INTERVENTION: Intervention was a standardized liquid meal test. MAIN OUTCOME: The thermic effect of food (TEF), respiratory quotient, and circulating levels of glucose, insulin, and C-peptide were assessed before and repeatedly during the first 90 minutes after the ingestion of a standardized liquid mixed meal containing 39.2 g carbohydrates, 15.4 g protein, and 2.8 g fat. RESULTS: TEF area under curve (0-90 minutes) was significantly greater in RYGB patients than in severely obese and lean women (both P < .01). After ingestion of the mixed meal, the respiratory quotient increased to significantly greater values in the RYGB patients than in the severely obese and lean group (P < .001 for ANOVA time × group interaction). Also, the postprandial rise in circulating glucose, insulin, and C-peptide levels was remarkably higher in the RYGB patients than in the other 2 groups (all P < .001 for ANOVA time × group interaction). CONCLUSION: Data demonstrate an enhanced TEF after RYGB surgery. Although this observation likely contributes to the weight-reducing effects of the surgery, data also point to an altered metabolic processing of food in RYGB patients characterized by an enhanced glucose absorption and postprandial carbohydrate oxidation.

Gastric Helicobacter pylori infection is associated with adverse metabolic traits in severely obese subjects.

OBJECTIVE: Asian studies have reported on an association of Helicobacter pylori (Hp) infection with insulin resistance (IR) in normal-weight subjects. Whether such an association likewise exists in European subjects with severe obesity was questioned. DESIGN AND METHODS: To address this question, 370 severely obese patients from our database were identified, who had undergone a gastroscopy with a histological examination of gastric mucosal biopsies and a concurrent assessment metabolic blood parameters as a standard examination before bariatric surgery. RESULTS: Seventy-five (20.3%) of the subjects displayed a histologically proven Hp infection (Hp+). Sex distribution, age, and body mass index of Hp+ subjects did not differ from that of the subjects with no Hp infection (Hp-; all P > 0.293), but Hp+ subjects were significantly smaller (P = 0.006). Fasting glucose, insulin, high-sensitive C reactive protein, and alanine aminotransferase levels as well as calculated indices of IR (i.e., HOMA-IR, QUICKI) did not differ between Hp+ and Hp- subjects (all P > 0.42). However, Hp+ subjects showed significantly higher triglyceride levels and a higher total chloesterol-to-HDL ratio but lower sex-hormone binding globulin (SHGB) levels than Hp- subjects (all P ≤ 0.05). CONCLUSION: While our results obtained in European severely obese patients do not provide evidence for an enhanced IR state associated with gastric Hp infection, they suggest that the presence of the bacterium in gastric biopsies is associated with an adverse lipid profile and reduced SHGB levels.

Preoperative nutritional deficiencies in severely obese bariatric candidates are not linked to gastric Helicobacter pylori infection.

Severely obese subjects have been found to show a high prevalence of distinct nutritional deficiencies even without any bariatric intervention but the underlying reasons remain obscure. We tested the hypothesis that gastric Helicobacter pylori infection is associated with increased nutritional deficiency rates. Taking advantage of our large database, we identified 404 patients who had undergone a gastroscopy--as a standard diagnostic assessment before bariatric surgery--along with a histological examination of gastric mucosal biopsies with concurrent nutritional blood measurements. Eighty-five (21 %) of the obese patients included in the study displayed a gastric H. pylori infection. Sex distribution, age and body mass index did not differ between H. pylori+ and H. pylori- patients (P > 0.29). Referring to nutritional markers, neither serum levels of total protein, albumin, calcium, phosphate, magnesium, ferritin, zinc, copper, vitamin B12, folate and 25-OH vitamin D3 nor respective deficiency rates differed between the H. pylori+ and H. pylori- patients group (all P > 0.13). Overall, 49.5 % of the bariatric candidates displayed at least one nutritional deficiency. Our data confirm previous reports on high prevalences of nutritional deficiencies in severely obese subjects. However, they do not provide evidence for a contributing role of gastric H. pylori infection to these nutritional alterations.

Reduced circulating androgen levels after gastric bypass surgery in severely obese women.

BACKGROUND: Previous studies have shown a reduction of elevated androgen levels in premenopausal women after marked weight loss induced by bariatric surgery. In this study, we aimed to assess whether circulating androgen levels also decline after bariatric surgery in women displaying normal values preoperatively as well as in postmenopausal women. METHODS: In 36 severely obese women (six postmenopausal), levels of total testosterone, dehydroepiandresterone sulfate (DHEA-S), and sex hormone-binding globulin (SHBG) were assessed before and at ~1 year after gastric bypass. Free and bioavailable testosterone levels as well as the free androgen index were calculated by established formulas. RESULTS: After the surgery, women had lost on average 43.1 ± 1.8 kg. Independently of the pre/postmenopausal state, women showed a marked reduction in all testosterone-related androgen markers and DHEA-S levels, while SHBG levels markedly increased (all P < 0.001). Respective changes were found in both women with and without preoperatively elevated levels. Changes after the surgery in testosterone-related markers as well as in SHBG levels but not in DHEA-S levels were correlated with changes in insulin levels independently of body weight changes. CONCLUSIONS: Data show a marked reduction of androgen levels in severely obese women after a surgically induced weight loss, which is independent from the menopausal state and preoperative levels. The mechanisms and consequences of these hormonal changes induced by bariatric surgery should be addressed in further studies.

Differential changes in exercise performance after massive weight loss induced by bariatric surgery.

BACKGROUND: Exercise performance and pulmonary function are often impaired in severely obese subjects. Bariatric surgery represents the most effective therapy for severe obesity, but data on changes in exercise performance after massive weight loss induced by bariatric surgery have rarely been assessed so far. METHODS: Exercise performance was obtained by bicycle spiroergometry in 18 severely obese patients before and at least 1 year after bariatric surgery. Additionally, pulmonary function was assessed by spirometry. RESULTS: BMI was reduced from 46.3 ± 1.6 to 33.5 ± 1.4 kg/m(2) after surgery. Pulmonary function (forced expiratory volume within 1 s; inspiratory vital capacity) improved after weight loss (both p ≤ 0.01). At peak exercise, heart rate (HR) peak, absolute oxygen uptake (VO(2)) peak, and load peak did not differ between both assessments (all p > 0.25). However, relative (related to actual body weight) VO(2) peak and workload peak were higher after than before surgery (both p ≤ 0.005), while gross efficiency peak and ventilatory equivalent peak remained unchanged (both p > 0.30). At anaerobic threshold (AT), patients showed lower HR AT and absolute VO(2) AT after than before surgery (both p < 0.05), while absolute workload AT did not differ (p = 0.58). In turn, relative VO(2) AT did not change (p = 0.30), whereas relative workload AT was higher after surgery (p = 0.04). Also, ventilatory efficiency AT and gross efficiency AT tended to be improved (both p = 0.08). Before surgery, the patients performed 27.0 % of VO(2) peak above their AT, while this fraction increased to 35.3 % (p = 0.006). CONCLUSIONS: Results indicated differential changes in exercise performance, with the relative but not the absolute peak performance being improved after massive weight loss. Interestingly, anaerobic exercise tolerance was markedly improved after surgery.

Roux-en Y gastric bypass surgery reduces hedonic hunger and improves dietary habits in severely obese subjects.

BACKGROUND: Many obese subjects suffer from an increased hedonic drive to consume palatable foods, i.e., hedonic hunger, and often show unfavorable dietary habits. Here, we investigated changes in the hedonic hunger and dietary habits after Roux-en-Y gastric bypass (RYGB) surgery. METHODS: Forty-four severely obese patients were examined before and on average 15.9 ± 0.9 months after RYGB surgery with the Power of Food Scale (PFS), a questionnaire that reliably measures an individual's motivation to consume highly palatable foods but not actual consumptive behavior. Dietary habits were assessed by a food frequency questionnaire. RESULTS: After the RYGB procedure, patients showed markedly lower aggregated PFS scores and sub-domain scores related to generally available, physically present, as well as tasted foods than before the surgery (all P < 0.001). Changes in dietary habits after the surgery were characterized by a more frequent consumption of poultry, fish, eggs, and cooked vegetables (P < 0.008) and a less frequent consumption of chocolate (P < 0.048), cakes/biscuits/cookies (P = 0.09), and fruit juice/soft drinks (P = 0.08). CONCLUSIONS: Data show a marked reduction of the hedonic drive to consume palatable food and beneficial changes in dietary habits characterized by an increased intake of protein-rich foods and vegetables and a reduced consumption of sugar-containing snacks and beverages after RYGB surgery. Based on these findings, it can be speculated that the reduction of the hedonic drive to consume palatable foods induced by RYGB surgery helps severely obese patients to establish healthier dietary habits.

Disturbed glucoregulatory response to food intake after moderate sleep restriction.

STUDY OBJECTIVES: Epidemiological studies point to a strong association between short sleep duration and the development of diabetes. We examined the hypothesis that short-term sleep loss decreases glucose tolerance and insulin sensitivity and, if so, how these changes relate to hypothalamic-pituitary-adrenal (HPA) secretory activity and markers of subclinical inflammation. DESIGN: In a balanced, within-subject design, circulating glucose, insulin, C-peptide, glucagon, ACTH, cortisol, and IL-6 levels were closely monitored during a 15-h daytime period following 2 nights of restricted sleep (02:45-07:00) and 2 nights of regular sleep (bedtime 22:45-07:00), respectively. SETTING: Time-deprivation suite within a university medical center sleep laboratory. PARTICIPANTS: 15 healthy, unmedicated normal-weight men. INTERVENTION: Sleep restriction. MEASUREMENTS AND RESULTS: Pre-breakfast concentrations of blood parameters were unchanged following sleep manipulation (P > 0.30). However, insulin and glucose peak responses to breakfast intake at 08:00 were distinctly increased by sleep restriction in comparison to regular sleep (398.5 ± 57.4 vs. 284.3 ± 51.5 pmol/L and 6.8 ± 0.3 vs. 6.1 ± 0.3 mmol/L, respectively; all P < 0.02), while glucagon responses were blunted by sleep loss (P = 0.03). There were no differences in circulating ACTH, cortisol, and IL-6 concentrations between the 2 conditions (all P > 0.25). CONCLUSIONS: Data indicate an impairment of glucose tolerance after 2 days of sleep restriction to ~4 h that appears to be primarily caused by a reduction in insulin sensitivity. Unchanged HPA secretory activity and IL-6 concentrations argue against a mediation of these effects by stress-related or inflammatory mechanisms.

Hedonic hunger is increased in severely obese patients and is reduced after gastric bypass surgery.

BACKGROUND: Overeating as a pathogenetic hallmark of obesity may be promoted by an increase in hedonic hunger, ie, the drive to eat palatable foods in the absence of energy need. Gastric bypass surgery, which effectively reduces severe obesity, might also affect hedonic hunger. OBJECTIVE: The objective was to assess hedonic hunger in severely obese patients with and without a history of gastric bypass surgery. DESIGN: Severely obese patients who had not undergone gastric bypass surgery (n = 123), gastric bypass patients (n = 136), and nonobese control subjects (n = 110) were examined with the Power of Food Scale (PFS)--a questionnaire that reliably measures an individual's motivation to consume highly palatable foods. RESULTS: Compared with nonobese control subjects, severely obese patients achieved markedly higher aggregated PFS scores and subdomain scores related to generally available as well as physically present foods (all P < 0.001). On the aggregated score as well in those 2 subdomains, gastric bypass patients scored significantly lower than did non-gastric bypass obese patients (all P < 0.001) and did not differ significantly from the nonobese control group (P > 0.2). In contrast, in the PFS domain concerning food tasted, gastric bypass patients had significantly lower scores than did the nonobese control subjects (P = 0.04) and the severely obese patients (P = 0.008), both of whom did not differ significantly in this measure (P = 0.90). CONCLUSION: In comparison with nonobese control subjects, severely obese patients display a marked increase in hedonic hunger that is not observed in patients who have undergone gastric bypass surgery, suggesting that the operation normalizes excessive appetite for palatable foods, which may be an important pathophysiologic feature of severe obesity.

Short-term sleep loss decreases physical activity under free-living conditions but does not increase food intake under time-deprived laboratory conditions in healthy men.

BACKGROUND: Short sleep duration is correlated with an increased risk of developing obesity and cardiovascular disease, but the mechanisms behind this relation are largely unknown. OBJECTIVE: We aimed to test the hypothesis that acute sleep loss decreases physical activity while increasing food intake, thereby shifting 2 crucial behavioral components of energy homeostasis toward weight gain. DESIGN: In 15 healthy, normal-weight men, spontaneous physical activity was registered by accelerometry during the entire experiment, and food intake as well as relevant hormones were assessed during a 15-h daytime period after 2 nights of regular sleep (bed time: 2245-0700) and after 2 nights of restricted sleep (bed time: 0245-0700). Experiments were performed in a crossover design. RESULTS: Sleep restriction significantly decreased physical activity during the daytime spent under free-living conditions after the first night of sleep manipulation (P = 0.008). Also, intensities of physical activity were shifted toward lower levels, with less time spent with intense activities (P = 0.046). Total energy intake, feelings of hunger, and appetite as well as ghrelin and leptin concentrations during day 2 remained unaffected by acute sleep restriction. CONCLUSIONS: In contrast to our expectation, short-term sleep loss neither increased food intake nor affected concentrations of the hunger-regulating hormones leptin and ghrelin. However, the observed decrease in daytime physical activity may point to another potentially important behavioral mechanism for the health-impairing influence of sleep loss.

Seasonal variation in the deficiency of 25-hydroxyvitamin D(3) in mildly to extremely obese subjects.

BACKGROUND: Vitamin D deficiency is a common finding in obese subjects even before any bariatric operation. However, most previous studies reporting on high rates of vitamin D deficiency in obese subjects have not systematically controlled for seasonal variations. Furthermore, the existence of seasonal variation in serum 25-hydroxyvitamin D(3) levels has not been well documented in obese subjects so far. METHODS: Serum 25-hydroxyvitamin D(3) levels were measured in 248 obese subjects (body mass index: range, 30.1-68.9 kg/m(2)). Fat mass was determined using standard bioelectrical impedance analysis. RESULTS: Serum 25-hydroxyvitamin D(3) levels decreased with the increasing body mass index and fat mass (both P < 0.001) and showed a marked variation across the seasons of the year (P < 0.001), which was not affected by the degree of obesity. According to the variation in absolute levels, the prevalence of vitamin D deficiency (<50 nmol/l) was 3.8-fold higher during winter than during summer (91.2% vs. 24.3%; P < 0.001). CONCLUSION: Data show a marked seasonal variation in absolute serum 25-hydroxyvitamin D(3) concentrations and prevalence of vitamin D deficiency in subjects with mild to extreme obesity. Considering the increasing number of studies reporting on vitamin D deficiency in obesity, the present finding points to season as a crucial factor that should not be neglected when assessing serum levels of this vitamin in obese subjects.

Differential changes in dietary habits after gastric bypass versus gastric banding operations.

BACKGROUND: Reduction of food intake is an important mechanism by which bariatric procedures reduce body weight. However, only few studies have systematically assessed what patients actually eat after different types of bariatric operations. METHODS: Dietary habits were assessed by a food frequency questionnaire in 121 bariatric patients (48 gastric bypass patients, 73 gastric banding patients) during follow-up visits in our interdisciplinary obesity center as well as in 45 severely obese (body mass index (BMI)>35 kg/m2) and 45 nonobese (BMI<27 kg/m2) control subjects. RESULTS: As compared with nonobese control subjects, obese control subjects consumed more meat, white bread, and diet soft drinks. Gastric bypass patients showed an enhanced consumption of foods rich in protein such as poultry, fish, and eggs as well as of cooked vegetables, while the consumption of fatty sweets like chocolate, cake, biscuits, and cookies was found to be distinctly reduced in this patient group. In contrast, gastric banding patients reported on a reduced intake of pasta, white bread, and fresh fruits and, just like gastric bypass patients, also on an enhanced intake of poultry and fish. Direct comparison of dietary habits between the two bariatric patient groups revealed that gastric bypass patients consumed more frequently fresh fruits, eggs, and diet soft drinks but strikingly less chocolate than gastric banding patients. CONCLUSION: Collectively, data clearly point to distinct changes in dietary habits after bariatric operations which markedly differ between gastric bypass and gastric banding patients. Overall, it is tempting to conclude that gastric bypass operations lead to a healthier and a more balanced diet than gastric band implantations.