Britta Wilms

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.

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.

Plasma omentin-1 levels are related to exercise performance in obese women and increase upon aerobic endurance training.

INTRODUCTION Omentin-1 is an adipokine that is primarily released from visceral adipose tissue stromal cells. The effects of exercise on omentin-1 regulation are not clear so far. Therefore, the effect of endurance training on circulating omentin-1 levels and its relation to exercise performance was assessed in obese women. METHODS 13 obese women (age: 44.8±3.3 years; BMI: 37.8±1.3 kg·m(-2)) participated in a 6-week endurance training program. Omentin-1, metabolic traits (glucose, insulin, HOMA-IR, lipids profile), and exercise performance (cardiopulmonary exercise test (V̇O2,peak, Wpeak), 6 min walking test, 6MWT) were assessed before and after the training. RESULTS After the training program circulating omentin-1 were 10.4% higher than before the program (690±50 ng·ml(-1) vs. 618±42; p=0.04), while body weight remained unchanged (p=0.9). Before training, omentin-1 levels were significantly correlated with Wpeak (given in absolute and relative values) as well as with 6MWT (all r≥0.603; all p≤0.029) and the correlations with absolute as well as relativeV̇O2,peak approached significance (both r≥0.534; both p≤0.060). After training, respective correlations were generally weaker and did not reach significance any longer (all r≤0.465; all p≥0.109). Neither before nor after the training program were significant correlations found between omentin-1 levels and the other measured metabolic blood markers (all p≥0.157). DISCUSSION Data show a rather strong relationship between exercise performance and circulating omentin-1 levels as well as an increase of the adipokine in response to 6-week of endurance training in obese women. Our findings may hint to a skeletal muscle-adipose tissue crosstalk in regard of omentin-1 regulation.

Cardio-respiratory fitness is independently associated with cardio-metabolic risk markers in severely obese women.

INTRODUCTION Many studies have shown an inverse relationship between cardio-respiratory fitness and cardio-metabolic risk markers in normal-weight to moderately obese subjects. However, whether such a relationship exists in severely obese subjects is not known. MATERIALS AND METHODS Cardio-respiratory fitness was measured by bicycle spiroergometry in 308 severely obese women (all BMI>35 kg/m(2)). The following cardio-metabolic risk markers were assessed: Glycolized hemoglobin levels (HbA1c), fasting glucose, insulin, calculated HOMA index, triglycerides (TG), total, low-, high-density cholesterol (Chol, LDL; HDL), Chol/HDL-Ratio, and uric acid. Computed multiple stepwise linear regression models generally included age, weight and height as independent variables. RESULTS Multiple stepwise linear regression models indicated that peak but not aerobic threshold related cardio-respiratory fitness indices were independently of age, weight and height associated with several cardio-metabolic risk markers. Specifically, maximally achieved load (Watt-peak) explained 1.4% of the variance in glucose levels (beta= -0.13; p=0.04) and 2.8% of the variance in HbA1c levels (beta= -0.18; p=0.01), while maximally achieved O2-uptake explained 3.9% of the variance in TG levels (beta= -0.20, p=0.001). CONCLUSION Our data for the first time indicate that cardio-respiratory fitness is independently associated with cardio-metabolic risk markers in severely obese women.

Eating behaviour in treatment-seeking obese subjects – Influence of sex and BMI classes

Obese subjects frequently show an adversely altered eating behaviour. However, little is known on differences in eating behaviour across different degree of obesity. We analysed data on the three factor eating questionnaire assessing cognitive restraint, disinhibition, and hunger that were filled in by 664 obese patients (469 women) who seeked treatment in our Interdisciplinary Obesity Center. Patients were divided in five BMI classes (30 - <35 kg/m(2), 35 - <40 kg/m(2), 40 - <50 kg/m(2), and >50 kg/m(2)). Multivariate regression analyses revealed that sex was significantly related to all three eating behaviour traits (all P < 0.042) but no significant relation to BMI (as a continuous variable) was observed. Women in comparison to men showed significantly higher cognitive restraint (9.7 ± 4.3 vs. 7.7 ± 4.4; P < 0.001) and disinhibition (9.0 ± 3.5 vs. 7.7 ± 3.5; P < 0.001) scores and also showed higher hunger scores (6.9 ± 3.7 vs. 6.3 ± 3.5; P = 0.042). Analyses on different BMI classes revealed that cognitive restraint decreased (P = 0.016) while disinhibition (P = 0.010) and hunger (P = 0.044) increased independently of sex with increasing BMI classes. However, above the obesity grade I class (i.e. BMI 30 - < 35 kg/m(2)) there were no differences in eating behaviour variables between the remaining BMI classes. Data indicate profound differences in eating behaviour between women and men that persist across a wide range of obesity. Furthermore, data suggest that while grade I obese patients show higher cognitive restraint and less disinhibition and hunger scores than more severe obese patients these dimensions of eating behaviour do not systematically vary across higher BMI classes.

Lactate infusion during euglycemia but not hypoglycemia reduces subsequent food intake in healthy men.

Considering that lactate is known to interact with central glucose-sensing networks, we tested whether hyperlactatemia affects food intake in humans. According to a balanced within-subject 2×2 design, 12 healthy, fasted men (age: 20-40 years; BMI: 20-26 kg/m(2)) were intravenously infused lactate and saline, respectively, for 105 min during concomitant euglycemic and hypoglycemic, respectively, insulin infusion of 75 min. Ten minutes after the simultaneous end of infusions, free-choice food intake was assessed at 10:25 h. Lactate decreased food intake following euglycemia as compared to the other three conditions in which food intake did not differ. Results point to an anorexigenic effect of lactate under euglycemic conditions.

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.

Type 2 Diabetes is Associated with Lower Cardiorespiratory Fitness Independent of Pulmonary Function in Severe Obesity

Both severe obesity and type 2 diabetes (T2DM) are associated with reduced pulmonary function and reduced cardiorespiratory fitness. We investigated whether T2DM further aggravates the impaired pulmonary function and cardiorespiratory fitness in subjects with severe obesity. In this cross-sectional study pulmonary function (forced expiratory volume within 1 s, FEV1; vital capacity, VC) was assessed in 65 severely obese subjects with T2DM (T2DM group) and 65 severely obese subjects without T2DM (non-T2DM group), pairwise matched for sex, age, weight, and height. In 30 of the matched pairs, cardiorespiratory fitness was assessed by an incremental bicycle test (peak workload, Wpeak, oxygen uptake, V̇O2,peak). FEV1 and VC did not differ between the T2DM and non-T2DM group (all p≥0.110), whereas Wpeak and V̇O2,peak - absolute values as well as relative to body mass - were significantly lower in subjects with T2DM compared to those without T2DM (all p≤0.030). Objective markers of maximal exertion, i. e., maximal heart rate and respiratory exchange ratio, did not differ between the 2 groups (both p≥0.245). The presence of T2DM in subjects with severe obesity is associated with lower cardiorespiratory fitness but with no further reduction in pulmonary function compared to subjects with severe obesity but without T2DM. While the cause-effect relationship of this association is not yet clear, these findings highlight the interplay between cardiorespiratory fitness and metabolic health, even in subjects with severe obesity.

Estimation of energy expenditure in wheelchair-bound spinal cord injured individuals using inertial measurement units

A healthy lifestyle reduces the risk of cardio-vascular disease. As wheelchair-bound individuals with spinal cord injury (SCI) are challenged in their activities, promoting and coaching an active lifestyle is especially relevant. Although there are many commercial activity trackers available for the able-bodied population, including those providing feedback about energy expenditure (EE), activity trackers for the SCI population are largely lacking, or are limited to a small set of activities performed in controlled settings. The aims of the present study were to develop and validate an algorithm based on inertial measurement unit (IMU) data to continuously monitor EE in wheelchair-bound individuals with a SCI, and to establish reference activity values for a healthy lifestyle in this population. For this purpose, EE was measured in 30 subjects each wearing four IMUs during 12 different physical activities, randomly selected from a list of 24 activities of daily living. The proposed algorithm consists of three parts: resting EE estimation based on multi-linear regression, an activity classification using a k-nearest-neighbors algorithm, and EE estimation based on artificial neural networks (ANNs). The mean absolute estimation error for the ANN-based algorithm was 14.4% compared to indirect calorimeter measurements. Based on reference values from the literature and the data collected within this study, we recommend wheeling 3 km per day for a healthy lifestyle in wheelchair-bound SCI individuals. Combining the proposed algorithm with a recommendation for physical activity provides a powerful tool for the promotion of an active lifestyle in the SCI population, thereby reducing the risk for secondary diseases.

Sagittal Abdominal Diameter does not Predict Metabolic Traits Better than Waist Circumference-Related Measures of Abdominal Obesity in Obese Subjects

BACKGROUND Recently, we showed that in subjects with a body mass index (BMI) >35 kg/m2 waist circumference (WC) is associated with metabolic traits but associations were weaker in men than in women. AIMS To confirm our previous observation that anthropometric measures of abdominal obesity are closer linked to metabolic traits in obese women than obese men. To test whether sagittal abdominal diameter (SAD) provides a better prediction of metabolic traits in obese subjects than WC related measures. METHODS SAD and WC along with metabolic traits were assessed in 204 women and 69 men (BMI 30.1-64.0 kg/m2). RESULTS In women, abdominal obesity measures were associated with glycated hemoglobin levels (HbA1c), fasting serum glucose, insulin, triglycerides (TG), total cholesterol (Chol), high-density lipoprotein (HDL), and uric acid levels as well as Chol/HDL ratio and homeostatic model assessment of insulin resistance (HOMA-IR) independently of age and BMI. SAD predicted serum insulin and Chol better than WC, whereas WC was superior to SAD in predicting HbA1c, glucose, HOMA-IR, TG, HDL, Chol/HDL, and uric acid. Of note, the combination of SAD and WC provided a better prediction of insulin, HOMA-IR, TG, and uric acid than each of these anthropometric alone. In men, only fasting glucose, Chol, and uric acid levels were associated with abdominal obesity markers. CONCLUSION Data show various associations between anthropometric measures of abdominal obesity and metabolic traits in obese women but overall much less in obese men. Most metabolic traits are better predicted by WC than by SAD.