The Thermic Effect of Food and Obesity: A Critical Review

DE JONGE, LILIAN, GEORGE BRAY. The thermic effect of food and obesity: A critical review. This review has examined the factors that influence the thermic effect of food (TEF) by evaluating 49 studies that have compared subjects who are obese with those who are lean. Meal size, meal composition, the nature of the previous diet, insulin resistance, physical activity, and ageing influence TEF. In the studies of individuals who are obese or lean, of those who used intravenous glucose infusions, all but one found an impaired thermic response. A total of 29 out of 49 studies of individuals of normal weight or with obesity were identified where there was no difference in age between the groups, and where the subjects who were “overweight” were clearly obese. Of these 29, 22 reported a statistically significant reduction in TEF, 3 studies were not designed to look primarily at the effect of obesity on TEF, and the other 4 may not have had sufficiently palatable meals. From this review, we conclude that the reduction of TEF in obesity is related to the degree of insulin resistance, which may be influenced by a low level of sympathetic activity.     

The Crosstalk Between Brain Mediators Regulating Food Intake Behavior in Birds: A Review

International Journal of Peptide Research and Therapeutics - Appetite is controlled by a complex system of central and peripheral signals interacting to modulate the ingestion response. Several...     

Association Between Antioxidant Intake/Status and Obesity: a Systematic Review of Observational Studies

The global prevalence of obesity has doubled in recent decades. Compelling evidences indicated that obesity was associated with lower concentrations of specific antioxidants which may play a role in the development of obesity-related diseases such as cardiovascular disease. The present review aimed to synthesize the evidence from studies on the association between obesity and antioxidant micronutrients in a systematic manner. Data bases including MEDLINE, Science Direct, and Cochrane were searched from inception to October 2015. Thirty-one articles were reviewed using the MOOSE checklist. Lower concentrations of antioxidants have been reported in obese individuals among age groups worldwide. Circulatory levels of carotenoids, vitamins E and C, as well as zinc, magnesium, and selenium were inversely correlated with obesity and body fat mass. However, studies demonstrated inconsistencies in findings. Lower status of carotenoids, vitamins E and C, zinc, magnesium, and selenium appears to be associated with adiposity. Intervention studies may be needed to establish the causality of these associations.     

The Carbohydrate Sensitive Rat as a Model of Obesity

Background

Sensitivity to obesity is highly variable in humans, and rats fed a high fat diet (HFD) are used as a model of this inhomogeneity. Energy expenditure components (basal metabolism, thermic effect of feeding, activity) and variations in substrate partitioning are possible factors underlying the variability. Unfortunately, in rats as in humans, results have often been inconclusive and measurements usually made after obesity onset, obscuring if metabolism was a cause or consequence. Additionally, the role of high carbohydrate diet (HCD) has seldom been studied.

Methodology/Findings

Rats (n=24) were fed for 3 weeks on HCD and then 3 weeks on HFD. Body composition was tracked by MRI and compared to energy expenditure components measured prior to obesity. Results: 1) under HFD, as expected, by adiposity rats were variable enough to be separable into relatively fat resistant (FR) and sensitive (FS) groups, 2) under HCD, and again by adiposity, rats were also variable enough to be separable into carbohydrate resistant (CR) and sensitive (CS) groups, the normal body weight of CS rats hiding viscerally-biased fat accumulation, 3) HCD adiposity sensitivity was not related to that under HFD, and both HCD and HFD adiposity sensitivities were not related to energy expenditure components (BMR, TEF, activity cost), and 4) only carbohydrate to fat partitioning in response to an HCD test meal was related to HCD-induced adiposity.

Conclusions/Significance

The rat model of human obesity is based on substantial variance in adiposity gains under HFD (FR/FS model). Here, since we also found this phenomenon under HCD, where it was also linked to an identifiable metabolic difference, we should consider the existence of another model: the carbohydrate resistant (CR) or sensitive (CS) rat. This new model is potentially complementary to the FR/FS model due to relatively greater visceral fat accumulation on a low fat high carbohydrate diet.     

Relation of Food Intake Behaviors and Obesity Development in Young Common Marmoset Monkeys

Objective : Increasing prevalence of childhood obesity and associated risks of adult type disease have led to worldwide concern. It remains unclear how genetic predisposition, environmental exposure to obesogenic food, and developmental programming interact to lead to overweight and obese children. The development of a nonhuman primate model of obesity, and particularly juvenile obesity, is an important step to elucidating the factors associated with obesity and evaluating intervention strategies. Design and Methods : Infant marmosets were followed from birth to 12 months of age. Feeding phenotypes were determined through the use of behavioral observation, solid food intake trials, and liquid feeding trials monitored via lickometer. Results : Marmosets found to be obese at 12 months of age (more than 14%body fat) start consuming solid food sooner and initiate more time off of care givers. These individuals developed stable feeding phenotypes that included being more efficient consumers during liquid intake trials, drinking more grams of diet per contact with the licksit. Conclusions : The weaning process appears to be particularly important in the development of feeding phenotypes and the development of juvenile obesity for the marmosets, and thus this is the time that should be focused upon for intervention testing in both nonhuman primates and children.     

Food Intake in Prader-Willi Syndrome and Controls with Obesity After Administration of a Benzodiazepine Receptor Agonist

Benzodiazepine receptor (BZR) agonists, used extensively for their anxiolytic effects, have been shown to increase food intake in many mammalian species. Little information, however, is available on the effects of BZR agonists on feeding behaviors of humans. Food intake was evaluated in a 60-minute free-feeding standardized test after the acute administration of the BZR agonist chlordiazepoxide (CDP, Librium; 5 mg or 20 mg) or placebo. Subjects were 12 individuals with the Prader Willi syndrome (PWS), a disorder characterized by extreme hyperphagia and morbid obesity, and 11 controls with obesity. PWS subjects showed the characteristic hyperphagia associated with the appetite disorder, consuming more than six times as many sandwiches as controls with obesity. Results revealed no significant effect of either dose of CDP on the food intake of either group. Serum assays revealed that dose-dependent, clinically effective levels of CDP and active metabolites were achieved. These results suggest that acute administration of the BZR agonist CDP, at the therapeutic levels used, may not increase food intake in populations with obesity. However, the chronic effects of CDP on appetite in human populations still need to be explored.     

Isolated Lung Perfusion as an Adjuvant Treatment of Colorectal Cancer Lung Metastases: A Preclinical Study in a Pig Model

Background

The lung is a frequent site of colorectal cancer (CRC) metastases. After surgical resection, lung metastases recurrences have been related to the presence of micrometastases, potentially accessible to a high dose chemotherapy administered via adjuvant isolated lung perfusion (ILP). We sought to determine in vitro the most efficient drug when administered to CRC cell lines during a short exposure and in vivo its immediate and delayed tolerance when administered via ILP.

Methods

First, efficacy of various cytotoxic molecules against a panel of human CRC cell lines was tested in vitro using cytotoxic assay after a 30-minute exposure. Then, early (operative) and delayed (1 month) tolerance of two concentrations of the molecule administered via ILP was tested on 19 adult pigs using hemodynamic, biological and histological criteria.

Results

In vitro, gemcitabine (GEM) was the most efficient drug against selected CRC cell lines. In vivo, GEM was administered via ILP at regular (20 µg/ml) or high (100 µg/ml) concentrations. GEM administration was associated with transient and dose-dependant pulmonary vasoconstriction, leading to a voluntary decrease in pump inflow in order to maintain a stable pulmonary artery pressure. After this modulation, ILP using GEM was not associated with any systemic leak, systemic damage, and acute or delayed histological pulmonary toxicity. Pharmacokinetics studies revealed dose-dependant uptake associated with heterogenous distribution of the molecule into the lung parenchyma, and persistent cytotoxicity of venous effluent.

Conclusions

GEM is effective against CRC cells even after a short exposure. ILP with GEM is a safe and reproducible technique.     

Antifungal Dosing in Obesity: A Review of the Literature

Obesity is becoming a global pandemic that is projected to increase significantly over the next few decades. Unfortunately, studies of drug dosing and pharmacokinetics have largely excluded obese patients. Currently, literature inadequately characterizes drug disposition in these patients. Only a limited selection of literature addresses antibacterial dosing in obesity, and virtually none characterizes antifungal dosing in obesity. This review discusses the changes in pharmacokinetics that occur in obesity and the available in vitro and in vivo data describing the disposition of antifungal agents in obese animals and patients.     

Hypothalamic-Specific Manipulation of Fto,the Ortholog of the Human Obesity Gene FTO,Affects Food Intake in Rats

Sequence variants in the first intron of FTO are strongly associated with human obesity and human carriers of the risk alleles show evidence for increased appetite and food intake. Mice globally lacking Fto display a complex phenotype characterised by both increased energy expenditure and increased food intake. The site of action of FTO on energy balance is unclear. Fasting reduces levels of Fto mRNA in the arcuate nucleus (ARC) of the hypothalamus, a site where Fto expression is particularly high. In this study, we have extended this nutritional link by demonstrating that consumption of a high fat diet (45%) results in a 2.5 fold increase in Arc Fto expression. We have further explored the role of hypothalamic Fto in the control of food intake by using stereotactic injections coupled with AAV technology to bi-directionally modulate Fto expression. An over expression of Fto protein by 2.5-fold in the ARC results in a 14% decrease in average daily food intake in the first week. In contrast, knocking down Arc Fto expression by 40% increases food intake by 16%. mRNA levels of Agrp, Pomc and Npy, ARC-expressed genes classically associated with the control of food intake, were not affected by the manipulation of Fto expression. However, over expression of Fto resulted in a 4-fold increase in the mRNA levels of Stat3, a signalling molecule critical for leptin receptor signalling, suggesting a possible candidate for the mediation of Fto''s actions. These data provide further support for the notion that FTO itself can influence key components of energy balance, and is therefore a strong candidate for the mediation of the robust association between FTO intronic variants and adiposity. Importantly, this provide the first indication that selective alteration of FTO levels in the hypothalamus can influence food intake, a finding consistent with the reported effects of FTO alleles on appetite and food intake in man.     

猪心脏移植中供体急性脑死亡模型的初步研究

目的建立猪心脏移植供体的急性脑死亡模型,观察急性脑死亡前及后1、5、10 min时的血流动力学和血浆中儿茶酚胺释放的变化并进行初步探讨。方法采用30~40 kg的猪8只,急性脑死亡前为对照组,急性脑死亡后为实验组。测定脑死亡前基础水平及脑死亡后1、5、10 min时血流动力学改变和血浆中儿茶酚胺释放的变化,并对二者的变化进行初步探讨。结果急性脑死亡后1 min时血流动力学及儿茶酚胺水平改变最明显,心率增加了88%,收缩压升高了132%,心排量增加了80%,肾上腺素(E)和去甲肾上腺素(NE)分别升高240%和241%,多巴胺(DA)没有明显增加。随后二者均持续下降,至10 min时已降至基础水平以下。血流动力学改变的程度及时间分布与儿茶酚胺中的肾上腺素和去甲肾上腺素一致。结论急性脑死亡可造成机体血流动力学及血浆儿茶酚胺水平的剧烈改变,血中儿茶酚胺含量升高是造成急性脑死亡后血流动力学改变的原因,其中E和NE与血流动力学改变直接相关。     

Insects as Food: A Case Study from the Northwest Amazon

In this article I examine the use of insects as food by Tukanoan Indians in the Northwest Amazon and discuss both the characteristics of the species exploited and their significance in the diet. Data on insect collection were obtained from harvest records and participant-observation. Dietary intake was determined from weighed food intake records. The insects collected belonged to over 20 species. The most important in the diet were those which formed large, highly predictable aggregations: beetle larvae (genus Rhynchophorus), ants (genus Atta), termites (genus Syntermes), and caterpillars (families Noctuidae and Saturniidae). The composition of insects is similar to that of other animal foods. Their inclusion in the diet was frequent and inversely related to the consumption of fish and game. They provided up to 12% of the crude protein derived from animal foods in men's diets and 26% in women's diets during one season of the year.     

Pregnancy as a Risk Factor for Obesity: Lessons from the Stockholm Pregnancy and Weight Development Study

Pregnancy and maternal body weight development are intertwined in complicated patterns. In most studies, an increase in maternal body weight with age and parity has been reported. For women who develop obesity, pregnancies can, in retrospect, be identified as important triggering life events. In a retrospective analysis of 128 women at our Obesity Unit, 73% of these severely obese patients had retained more than 10 kg in connection with a pregnancy. For the general population, the effect of a pregnancy on future weight development is surprisingly difficult to predict. In The Stockholm Pregnancy and Weight Development Study, the effects of pregnancy on weight retention one year after delivery were studied in 1423 women. Data were collected retrospectively from routine pregnancy records and then extended prospectively 6 and 12 months after delivery. The mean weight retention associated with a pregnancy one year after delivery was estimated to about 0.5 kg, with a range of-12 to 26 kg. Fourteen percent of the women gained more than 5 kg. Weight increase during pregnancy was the strongest predict or for sustained weight retention 1 year later. Pre-pregnancy weight did not predict the weight development outcome. The lactation pattern had only a minor influence on weight development Smoking cessation was an important predictor for sustained weight increase. More weight retention was observed in those women who reported a change in lifestyle as regarded eating habits, meal patterns, and physical activity, suggesting that eventual body weight after pregnancy is more determined by the changes in association with that particular pregnancy than with the lifestyle before.     

Social Models Provide a Norm of Appropriate Food Intake for Young Women

It is often assumed that social models influence people’s eating behavior by providing a norm of appropriate food intake, but this hypothesis has not been directly tested. In three experiments, female participants were exposed to a low-intake model, a high-intake model, or no model (control condition). Experiments 1 and 2 used a remote-confederate manipulation and were conducted in the context of a cookie taste test. Experiment 3 used a live confederate and was conducted in the context of a task during which participants were given incidental access to food. Participants also rated the extent to which their food intake was influenced by a variety of factors (e.g., hunger, taste, how much others ate). In all three experiments, participants in the low-intake conditions ate less than did participants in the high-intake conditions, and also reported a lower perceived norm of appropriate intake. Furthermore, perceived norms of appropriate intake mediated the effects of the social model on participants’ food intake. Despite the observed effects of the social models, participants were much more likely to indicate that their food intake was influenced by taste and hunger than by the behavior of the social models. Thus, social models appear to influence food intake by providing a norm of appropriate eating behavior, but people may be unaware of the influence of a social model on their behavior.     

Self-Esteem and Obesity in Children and Adolescents: A Literature Review

The relationship between self-esteem and obesity has not received a great deal of empirical evaluation using strong research methodologies. Thus, it is not clear whether self-esteem is consistently related to obesity, whether the relationship is global or specific to physical appearance, whether the relationship differs by demographic variables such as age, gender or race/ethnicity, or whether self-esteem moderates weight changes during weight loss treatment programs. This review examines these questions using empirical evidence from 35 studies on the relationship between self-esteem and obesity in children and adolescents. Thirteen of 25 cross sectional studies clearly showed lower self-esteem in obese adolescents and children. Five of the six cross-sectional studies that included a measure of body esteem found lower body esteem in obese compared to normal weight children and adolescents. Results from two prospective studies examining initial self-esteem and later obesity were inconsistent. Results from six of eight treatment studies showed that weight loss treatment programs appear to improve self-esteem. However, it is unclear whether increases in self-esteem are related to enhanced weight loss. Many studies were methodologically weak primarily due to small and select samples and lack of appropriate comparison groups. Implications for prevention and treatment of childhood obesity are discussed.