Gut hormones in the control of appetite

Gut microbiota-derived short chain fatty acids act as mediators of the gut-brain axis targeting age-related neurodegenerative disorders: a narrative review

Neurodegenerative diseases associated with aging are often accompanied by cognitive decline and gut microbiota disorder. But the impact of gut microbiota on these cognitive disturbances remains incompletely understood. Short chain fatty acids (SCFAs) are major metabolites produced by gut microbiota during the digestion of dietary fiber, serving as an energy source for gut epithelial cells and/or circulating to other organs, such as the liver and brain, through the bloodstream. SCFAs have been shown to cross the blood-brain barrier and played crucial roles in brain metabolism, with potential implications in mediating Alzheimer's disease (AD) and Parkinson's disease (PD). However, the underlying mechanisms that SCFAs might influence psychological functioning, including affective and cognitive processes and their neural basis, have not been fully elucidated. Furthermore, the dietary sources which determine these SCFAs production was not thoroughly evaluated yet. This comprehensive review explores the production of SCFAs by gut microbiota, their transportation through the gut-brain axis, and the potential mechanisms by which they influence age-related neurodegenerative disorders. Also, the review discusses the importance of dietary fiber sources and the challenges associated with harnessing dietary-derived SCFAs as promoters of neurological health in elderly individuals. Overall, this study suggests that gut microbiota-derived SCFAs and/or dietary fibers hold promise as potential targets and strategies for addressing age-related neurodegenerative disorders.

Endocrine, genetic, and microbiome nexus of obesity and potential role of postbiotics: a narrative review

Obesity is a public health crisis, presenting a huge burden on health care and the economic system in both developed and developing countries. According to the WHO's latest report on obesity, 39% of adults of age 18 and above are obese, with an increase of 18% compared to the last few decades. Metabolic energy imbalance due to contemporary lifestyle, changes in gut microbiota, hormonal imbalance, inherent genetics, and epigenetics is a major contributory factor to this crisis. Multiple studies have shown that probiotics and their metabolites (postbiotics) supplementation have an effect on obesity-related effects in vitro, in vivo, and in human clinical investigations. Postbiotics such as the SCFAs suppress obesity by regulating metabolic hormones such as GLP-1, and PPY thus reducing feed intake and suppressing appetite. Furthermore, muramyl di-peptides, bacteriocins, and LPS have been tested against obesity and yielded promising results in both human and mice studies. These insights provide an overview of targetable pharmacological sites and explore new opportunities for the safer use of postbiotics against obesity in the future.

Metabolic cues impact non-oscillatory intergeniculate leaflet and ventral lateral geniculate nucleus: standard versus high-fat diet comparative study

The intergeniculate leaflet and ventral lateral geniculate nucleus (IGL/VLG) are subcortical structures involved in entrainment of the brain's circadian system to photic and non-photic (e.g. metabolic and arousal) cues. Both receive information about environmental light from photoreceptors, exhibit infra-slow oscillations (ISO) in vivo, and connect to the master circadian clock. Although current evidence demonstrates that the IGL/VLG communicate metabolic information and are crucial for entrainment of circadian rhythms to time-restricted feeding, their sensitivity to food intake-related peptides has not been investigated yet. We examined the effect of metabolically relevant peptides on the spontaneous activity of IGL/VLG neurons. Using ex vivo and in vivo electrophysiological recordings as well as in situ hybridisation, we tested potential sensitivity of the IGL/VLG to anorexigenic and orexigenic peptides, such as cholecystokinin, glucagon-like peptide 1, oxyntomodulin, peptide YY, orexin A and ghrelin. We explored neuronal responses to these drugs during day and night, and in standard vs. high-fat diet conditions. We found that IGL/VLG neurons responded to all the substances tested, except peptide YY. Moreover, more neurons responded to anorexigenic drugs at night, while a high-fat diet affected the IGL/VLG sensitivity to orexigenic peptides. Interestingly, ISO neurons responded to light and orexin A, but did not respond to the other food intake-related peptides. In contrast, non-ISO cells were activated by metabolic peptides, with only some being responsive to light. Our results show for the first time that peptides involved in the body's energy homeostasis stimulate the thalamus and suggest functional separation of the IGL/VLG cells. KEY POINTS: The intergeniculate leaflet and ventral lateral geniculate nucleus (IGL/VLG) of the rodent thalamus process various signals and participate in circadian entrainment. In both structures, cells exhibiting infra-slow oscillatory activity as well as non-rhythmically firing neurons being observed. Here, we reveal that only one of these two groups of cells responds to anorexigenic (cholecystokinin, glucagon-like peptide 1 and oxyntomodulin) and orexigenic (ghrelin and orexin A) peptides. Neuronal responses vary depending on the time of day (day vs. night) and on the diet (standard vs. high-fat diet). Additionally, we visualised receptors to the tested peptides in the IGL/VLG using in situ hybridisation. Our results suggest that two electrophysiologically different subpopulations of IGL/VLG neurons are involved in two separate functions: one related to the body's energy homeostasis and one associated with the subcortical visual system.

The Effectiveness of Nigella sativa and Ginger as Appetite Suppressants: An Experimental Study on Healthy Wistar Rats

Background

Obesity is a global pandemic that is associated with high morbidity and mortality. Natural herbs are commonly used for weight reduction and appetite suppression. Therefore, we aim to investigate the role and mechanism of Nigella sativa (NS) and ginger on weight reduction and appetite regulation.

Methods

This experimental study was performed at Imam Abdulrahman Bin Faisal University. Twenty-five female rats were distributed into 5 groups: NS (oral 1000mg/kg), Ginger (500 mg/kg), NS-ginger (both interventions), a positive control (intraperitoneal 50 μg/kg Liraglutide), and a negative control. Each intervention was given for 9 weeks. Food intake and body weight were assessed weekly. Serum lipid profile and peptides involved in appetite control (cholecystokinin (CCK), glucagon-like peptide 1(GLP-1), gastric inhibitory polypeptide (GIP), ghrelin, peptide YY, and orexin) were assayed at the end of the experiment.

Results

None of the interventions showed a statistically significant difference regarding food consumption or weight gain (p > 0.05). However, the three interventions significantly reduced total cholesterol (TC), NS and NS-ginger significantly increased HDL, NS increased ghrelin and ginger increased orexin.

Conclusion

The present dose and duration of NS, ginger, or in combination did not demonstrate a significant change in body weight or food consumption in comparison to the negative or positive controls. However, NS or ginger has improved the lipid profile by reducing TC and increasing HDL. In addition, NS or ginger can influence some of the peptides involved in appetite regulation such as the increase in ghrelin induced by NS and the reduction of orexin induced by ginger. We believe that these latter effects are novel and might indicate a promising effect of these natural products on appetite regulation.

Satiety Associated with Calorie Restriction and Time-Restricted Feeding: Peripheral Hormones

Calorie restriction (CR) is a common approach to inducing negative energy balance. Recently, time-restricted feeding (TRF), which involves consuming food within specific time windows during a 24-h day, has become popular owing to its relative ease of practice and potential to aid in achieving and maintaining a negative energy balance. TRF can be implemented intentionally with CR, or TRF might induce CR simply because of the time restriction. This review focuses on summarizing our current knowledge on how TRF and continuous CR affect gut peptides that influence satiety. Based on peer-reviewed studies, in response to CR there is an increase in the orexigenic hormone ghrelin and a reduction in fasting leptin and insulin. There is likely a reduction in glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and cholecystokinin (CCK), albeit the evidence for this is weak. After TRF, unlike CR, fasting ghrelin decreased in some TRF studies, whereas it showed no change in several others. Further, a reduction in fasting leptin, insulin, and GLP-1 has been observed. In conclusion, when other determinants of food intake are held equal, the peripheral satiety systems appear to be somewhat similarly affected by CR and TRF with regard to leptin, insulin, and GLP-1. But unlike CR, TRF did not appear to robustly increase ghrelin, suggesting different influences on appetite with a potential decrease of hunger after TRF when compared with CR. However, there are several established and novel gut peptides that have not been measured within the context of CR and TRF, and studies that have evaluated effects of TRF are often short-term, with nonuniform study designs and highly varying temporal eating patterns. More evidence and studies addressing these aspects are needed to draw definitive conclusions.

The role of cholecystokinin and peptide YY in feed intake in Atlantic halibut (Hippoglossus hippoglossus) larvae

Control of appetite and feed intake in fish larvae are still largely unexplored. Two of the key players in controlling vertebrate's feed intake are cholecystokinin (CCK) and peptide YY (PYY). Here we investigated the mRNA expression of pyy, cck and cck receptors (cckr) in the brain (head) and gut of Atlantic halibut larvae in response to three consecutive meals. We used Artemia nauplii cysts that are commonly ingested by halibut larvae when present as inert feed, and three water-soluble extracts as attractants to stimulate appetite. Cyst intake was not affected by the use of attractants and overall ingestion rate was low. Differences in mRNA expression of cck and pyy were observed between the halibut larvae that had eaten and those that had not despite readily available feed (cysts), supporting that mechanisms for control of feed intake are at least partly functional. All genes analysed were present in the brain and gut, however the different expression profiles between paralogues suggest potential divergent functions. In the gut, cck2 and pyyb mRNA expression was significantly higher in the larvae that ate cysts compared to larvae that decided to not eat, indicating that these genes play a satiety function in the halibut larvae similar to the general vertebrate scheme. However, cck2, cck2r1, and pyy mRNA expression in the brain were lower in the fed-filled larvae group compared to larvae before eating, which contrasts with the presumable anorectic function of these genes. Further research is required to fully evaluate how PYY and CCK affect the feeding biology in halibut larvae, contributing to formulate inert diets that can stimulate appetite and feed intake.

Homeostatic regulation of food intake

Food intake and energy expenditure are key regulators of body weight. To regulate food intake, the brain must integrate physiological signals and hedonic cues. The brain plays an essential role in modulating the appropriate responses to the continuous update of the body energy-status by the peripheral signals and the neuronal pathways that generate the gut-brain axis. This regulation encompasses various steps involved in food consumption, include satiation, satiety, and hunger. It is important to have a comprehensive understanding of the mechanisms that regulate food consumption as well as to standardize the vocabulary for the steps involved. This review discusses the current knowledge of the regulation and the contribution peripheral and central signals at each step of the cycle to control appetite. We also highlight how food intake has been measured. The increasingly complex understanding of regulation and action mechanisms intervening in the gut-brain axis offers ambitious targets for new strategies to control appetite.

Energy Intake of Men With Excess Weight During Normobaric Hypoxic Confinement

Due to the observations of weight loss at high altitude, normobaric hypoxia has been considered as a method of weight loss in obese individuals. With this regard, the aim of the present study was to determine the effect of hypoxia per se on metabolism in men with excess weight. Eight men living with excess weight (125.0 ± 17.7 kg; 30.5 ± 11.1 years, BMI: 37.6 ± 6.2 kg⋅m-2) participated in a randomized cross-over study comprising two 10-day confinements: normobaric (altitude of facility ≃ 940 m) normoxia (NORMOXIA; P I O2 = 133 mmHg), and normobaric hypoxia (HYPOXIA). The P I O2 in the latter was reduced from 105 (simulated altitude of 2,800 m) to 98 mmHg (simulated altitude of 3,400 m over 10 days. Before, and at the end of each confinement, participants completed a meal tolerance test (MTT). Resting energy expenditure (REE), circulating glucose, GLP-1, insulin, catecholamines, ghrelin, peptide-YY (PYY), leptin, gastro-intestinal blood flow, and appetite sensations were measured in fasted and postprandial states. Fasting REE increased after HYPOXIA (+358.0 ± 49.3 kcal⋅day-1, p = 0.03), but not after NORMOXIA (-33.1 ± 17.6 kcal⋅day-1). Postprandial REE was also significantly increased after HYPOXIA (p ≤ 0.05), as was the level of PYY. Furthermore, a tendency for decreased energy intake was concomitant with a significant body weight reduction after HYPOXIA (-0.7 ± 0.2 kg) compared to NORMOXIA (+1.0 ± 0.2 kg). The HYPOXIA trial increased the metabolic requirements, with a tendency toward decreased energy intake concomitant with increased PYY levels supporting the notion of a hypoxia-induced appetite inhibition, that could potentially lead to body weight reduction. The greater postprandial blood-glucose response following hypoxic confinement, suggests the potential development of insulin resistance.

Methodological issues in assessing change in dietary intake and appetite following gastric bypass surgery: A systematic review

Gastric bypass surgery is an effective long-term treatment for individuals with severe obesity. Changes in appetite, dietary intake, and food preferences have all been postulated to contribute to postoperative body weight regulation, however, findings are inconsistent. The aim of this systematic review was to evaluate the current literature on changes in dietary intake and appetite following gastric bypass surgery, in the context of the methodology used and the analysis, interpretation, and presentation of results. Four databases were systematically searched with terms related to "gastric bypass surgery," "appetite," and "dietary intake," and 49 papers (n = 2384 patients after gastric bypass) were eligible for inclusion. The evidence indicated that only a reduction in overall energy intake and an increase in postprandial satiety are maintained beyond 6-month post-surgery, whereas relative macronutrient intake and premeal hunger remain unchanged. However, available data were limited by inconsistencies in the methods, analysis, presentation, and interpretation of results. In particular, there was a reliance on data collected by subjective methods with minimal acknowledgment of the limitations, such as misreporting of food intake. There is a need for further work employing objective measurement of appetite and dietary intake following gastric bypass surgery to determine how these mechanisms may contribute to weight regulation in the longer term.

Visceral Obesity, Metabolic Syndrome, and Esophageal Adenocarcinoma

Esophageal adenocarcinoma (EAC) represents an exemplar of obesity-associated carcinogenesis, with a progressive increase in EAC risk with increased body mass index. In this context, there is increased focus on visceral adipose tissue and associated metabolic dysfunction, including hypertension, diabetes mellitus and hyperlipidemia, or combinations of these in the metabolic syndrome. Visceral obesity (VO) may promote EAC via both directly impacting on gastro-esophageal reflux disease and Barrett's esophagus, as well as via reflux-independent effects, involving adipokines, growth factors, insulin resistance, and the microbiome. In this review these pathways are explored, including the impact of VO on the tumor microenvironment, and on cancer outcomes. The current evidence-based literature regarding the role of dietary, lifestyle, pharmacologic and surgical interventions to modulate the risk of EAC is explored.

Appetite problem in cancer patients: Pathophysiology, diagnosis, and treatment

AIM

This study aims to review the current evidence regarding appetite problem in cancer patients, mainly focusing on pathophysiology, diagnosis, and treatment.

INTRODUCTION

Anorexia is the common symptom of malnutrition in cancer patients. Recently, the understanding of the pathophysiological mechanism of the appetite problem in cancer patients has been increasing that give impact to rigorous research to find the therapies for improving appetite in cancer patients.

DISCUSSION

The development of anorexia in cancer patients is a complex process that involves many cytokines, receptors, chemical mediators/substances, hormones, and peptides. Growth and differentiation factor-15 (GDF-15) and toll-like receptor (TLR-4) have recently been found to be implicated in the pathogenesis of anorexia. To help diagnose the appetite problem in cancer patients, several questionnaires can be used, starting from well-known questionnaires such as Functional Assessment of Anorexia Cachexia Therapy (FAACT), Visual Analog Scale (VAS), European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ30). Several drugs with different mechanisms of action have been studied to help in improving appetite in cancer patients. New repurposed agents such as anamorelin, mirtazapine, thalidomide, and eicosapentaenoic acid (EPA) have shown a beneficial effect in improving appetite and quality of life in cancer patients, however more phase 3 clinical trial studies is still needed.

CONCLUSION

The pathophysiology of appetite problems in cancer patients is a complex process that involves many factors. Several drugs that target those factors have been studied, however more phase 3 clinical trial studies are needed to confirm the findings from previous studies.

Impact of Gut and Metabolic Hormones on Feeding Reward

Ingestion of food activates a cascade of endocrine responses (thereby reflecting a contemporaneous feeding status) that include the release of hormones from the gastrointestinal (GI) tract, such as cholecystokinin (CCK), glucagonlike peptide YY (PYY), peptide PP, and oleoylethanolamide, as well as suppression of ghrelin secretion. The pancreas and adipose tissue, on the other hand, release hormones that serve as a measure of the current metabolic state or the long-term energy stores, that is, insulin, leptin, and adiponectin. It is well known and intuitively understandable that these hormones target either directly (by crossing the blood-brain barrier) or indirectly (e.g., via vagal input) the "homeostatic" brainstem-hypothalamic pathways involved in the regulation of appetite. The current article focuses on yet another target of the metabolic and GI hormones that is critical in inducing changes in food intake, namely, the reward system. We discuss the physiological basis of this functional interaction, its importance in the control of appetite, and the impact that disruption of this crosstalk has on energy intake in select physiological and pathophysiological states. We conclude that metabolic and GI hormones have a capacity to strengthen or weaken a response of the reward system to a given food, and thus, they are fundamental in ensuring that feeding reward is plastic and dependent on the energy status of the organism. © 2021 American Physiological Society. Compr Physiol 11:1425-1447, 2021.

Effect of Fasting-Mimicking Diet or Continuous Energy Restriction on Weight Loss, Body Composition, and Appetite-Regulating Hormones Among Metabolically Healthy Women with Obesity: a Randomized Controlled, Parallel Trial

BACKGROUND

Fasting-mimicking diet (FMD) has been recently promoted to achieve similar metabolic changes of fasting. The purpose of our study was to compare the effect of FMD versus continuous energy restriction (CER) on anthropometric measurements, body composition, glucose metabolism, and serum levels of leptin, neuropeptide Y (NPY), and total ghrelin.

METHODS

A randomized controlled trial (RCT) was conducted on 60 women with obesity aged 18-55 years. Subjects received either a 5-day FMD (low in energy, sugars, and proteins, but high in unsaturated fats) or a CER (an average daily energy deficit of 500 kcal) for 2 months. Anthropometric and biochemical factors were measured at baseline and the end of the study. Serum levels of leptin, total ghrelin, and NPY were tested with an ELISA kit. Physical activity and dietary intakes were also recorded.

RESULTS

There was no significant difference in weight loss between the two groups: mean weight change for CER was - 2.29 (standard deviation [SD], 1.95) kg compared to - 1.13 (2.27) kg for FMD (p = 0.06). There was more reduction in the basal metabolic rate (BMR) in the CER group (p = 0.045). Favorable effects on fat mass and muscle mass were only seen in the FMD group. Although insulin resistance was reduced in the FMD group compared to the CER group, results were not significant after adjustment. After controlling for potential confounders, there was a significant increase in serum levels of total ghrelin (p = 0.048) and NPY (p = 0.041) following CER; however, results for circulating leptin were not statistically significant (p = 0.48).

CONCLUSIONS

There was no significant difference in weight loss following FMD and CER. However, FMD was more effective at reducing insulin resistance and regulating appetite-regulating hormones as well as preserving muscle mass and BMR.

TRIAL REGISTRATION

This trial was registered at the Iranian Clinical Trial Registry ( https://www.irct.ir/trial/40881 ) with the IRCT identification number IRCT20190717044244N1.

A Pilot Study of Gut-Brain Signaling After Octreotide Therapy for Unintentional Weight Loss After Esophagectomy

BACKGROUND

Recurrence-free patients after esophageal cancer surgery face long-term nutritional consequences, occurring in the context of an exaggerated postprandial gut hormone response. Acute gut hormone suppression influences brain reward signaling and eating behavior. This study aimed to suppress gut hormone secretion and characterize reward responses and eating behavior among postesophagectomy patients with unintentional weight loss.

METHODS

This pilot study prospectively studied postoperative patients with 10% or greater body weight loss (BWL) beyond 1 year who were candidates for clinical treatment with long-acting octreotide (LAR). Before and after 4 weeks of treatment, gut hormone secretion, food cue reactivity (functional magnetic resonance imaging), eating motivation (progressive ratio task), ad libitum food intake, body composition, and symptom burden were assessed.

RESULTS

Eight patients (7 male, age: mean ± SD 62.8 ± 9.4 years, postoperative BWL: 15.5 ± 5.8%) participated. Octreotide LAR did not significantly suppress total postprandial plasma glucagon-like peptide-1 response at 4 weeks (P = .08). Postprandial symptom burden improved after treatment (Sigstad score median [range]: 12 [2-28] vs 8 [3-18], P = .04) but weight remained stable (pre: 68.6 ± 12.8 kg vs post: 69.2 ± 13.4 kg, P = .13). There was no significant change in brain reward system responses, during evaluation of high-energy or low-energy food pictures, nor their appeal rating. Moreover, treatment did not alter motivation to eat (P = .41) nor ad libitum food intake(P = .46).

CONCLUSION

The protocol used made it feasible to characterize the gut-brain axis and eating behavior in this cohort. Inadequate suppression of gut hormone responses 4 weeks after octreotide LAR administration may explain the lack of gut-brain pathway alterations. A higher dose or shorter interdose interval may be required to optimize the intervention.

Appetite Control across the Lifecourse: The Acute Impact of Breakfast Drink Quantity and Protein Content. The Full4Health Project

Understanding the mechanisms of hunger, satiety and how nutrients affect appetite control is important for successful weight management across the lifecourse. The primary aim of this study was to describe acute appetite control across the lifecourse, comparing age groups (children, adolescents, adults, elderly), weight categories, genders and European sites (Scotland and Greece). Participants (n = 391) consumed four test drinks, varying in composition (15% (normal protein, NP) and 30% (high protein, HP) of energy from protein) and quantity (based on 100% basal metabolic rate (BMR) and 140% BMR), on four separate days in a double-blind randomized controlled study. Ad libitum energy intake (EI), subjective appetite and biomarkers of appetite and metabolism (adults and elderly only) were measured. The adults' appetite was significantly greater than that of the elderly across all drink types (p < 0.004) and in response to drink quantities (p < 0.001). There were no significant differences in EI between age groups, weight categories, genders or sites. Concentrations of glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) were significantly greater in the elderly than the adults (p < 0.001). Ghrelin and fasting leptin concentrations differed significantly between weight categories, genders and sites (p < 0.05), while GLP-1 and PYY concentrations differed significantly between genders only (p < 0.05). Compared to NP drinks, HP drinks significantly increased postprandial GLP-1 and PYY (p < 0.001). Advanced age was concomitant with reduced appetite and elevated anorectic hormone release, which may contribute to the development of malnutrition. In addition, appetite hormone concentrations differed between weight categories, genders and geographical locations.

Regulation of melanocortin-4-receptor (MC4R) expression by SNP rs17066842 is dependent on glucose concentration

Melanocortin-4-receptor (MC4R) gene codes for a G-protein-coupled receptor that is highly expressed in the hypothalamus and involved in the regulation of appetite. Single-nucleotide polymorphisms (SNPs) in the MC4R gene region have been associated with obesity, type 2-diabetes (T2D) and with antipsychotic-induced weight gain. Of these, rs17066842 (G>A) in the MC4R promoter region is the top variant associated with obesity and diabetes. In this study, we investigated the effect of rs17066842 on MC4R expression at various glucose concentrations using reporter gene expression in the SH-SY5Y cell line and regulation of MC4R expression in human cerebral organoids. We observed that higher glucose concentrations significantly reduced MC4R mRNA expression in SH-SY5Y cells. In addition, at high glucose concentrations, the luciferase reporter plasmid containing the MC4R promoter insert with the G-allele of rs170066842 showed significantly reduced activity compared to the A-allele carrying plasmid. The immediate early gene product, early growth-response 1 (EGR-1), was identified to bind to the sequence containing the G-allele at rs17066842 but not to the A-allele-containing sequence. Interestingly, in human induced pluripotent stem cell (hiPSC)-derived cerebral organoids, we observed increased MC4R expression in response to high glucose exposure. These opposite observations might suggest that glucose regulation is complex and may be cell-specific. This study provides evidence that rs17066842 regulates MC4R gene expression through binding of EGR-1 and that this process is influenced by glucose concentration.

Effects of Age on Acute Appetite-Related Responses to Whey-Protein Drinks, Including Energy Intake, Gastric Emptying, Blood Glucose, and Plasma Gut Hormone Concentrations-A Randomized Controlled Trial

Protein-rich supplements are used commonly to increase energy intake in undernourished older people. This study aimed to establish age effects on energy intake, appetite, gastric emptying, blood glucose, and gut hormones in response to protein-rich drinks. In a randomized double-blind, order, 13 older men (age: 75 ± 2 yrs, body mass index (BMI): 26 ± 1 kg/m²) and 13 younger (23 ± 1 yrs, 24 ± 1 kg/m²) men consumed (i) a control drink (~2 kcal) or drinks (450 mL) containing protein/fat/carbohydrate: (ii) 70 g/0 g/0 g (280 kcal/'P_280'), (iii) 14 g/12.4 g/28 g (280 kcal/'M_280'), (iv) 70 g/12.4 g/28 g (504 kcal/'M_504'), on four separate days. Appetite (visual analog scales), gastric emptying (3D ultrasonography), blood glucose, plasma insulin, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1) concentrations (0-180 min), and ad-libitum energy intake (180-210 min) were determined. Older men, compared to younger men, had higher fasting glucose and CCK concentrations and lower fasting GLP-1 concentrations (all p < 0.05). Energy intake by P₂₈₀ compared to control was less suppressed in older men (increase: 49 ± 42 kcal) than it was in younger men (suppression: 100 ± 54 kcal, p = 0.038). After the caloric drinks, the suppression of hunger and the desire to eat, and the stimulation of fullness was less (p < 0.05), and the stimulation of plasma GLP-1 was higher (p < 0.05) in older men compared to younger men. Gastric emptying, glucose, insulin, ghrelin, and CCK responses were similar between age groups. In conclusion, ageing reduces the responses of caloric drinks on hunger, the desire to eat, fullness, and energy intake, and protein-rich nutrition supplements may be an effective strategy to increase energy intake in undernourished older people.

Mechanisms controlling hormone secretion in human gut and its relevance to metabolism

The homoeostatic regulation of metabolism is highly complex and involves multiple inputs from both the nervous and endocrine systems. The gut is the largest endocrine organ in our body and synthesises and secretes over 20 different hormones from enteroendocrine cells that are dispersed throughout the gut epithelium. These hormones include GLP-1, PYY, GIP, serotonin, and CCK, each of whom play pivotal roles in maintaining energy balance and glucose homeostasis. Some are now the basis of several clinically used glucose-lowering and weight loss therapies. The environment in which these enteroendocrine cells exist is also complex, as they are exposed to numerous physiological inputs including ingested nutrients, circulating factors and metabolites produced from neighbouring gut microbiome. In this review, we examine the diverse means by which gut-derived hormones carry out their metabolic functions through their interactions with different metabolically important organs including the liver, pancreas, adipose tissue and brain. Furthermore, we discuss how nutrients and microbial metabolites affect gut hormone secretion and the mechanisms underlying these interactions.

Maternal coconut oil intake on lactation programs for endocannabinoid system dysfunction in adult offspring

Maternal exposure to coconut oil metabolically programs adult offspring for overweight, hyperphagia and hyperleptinemia. We studied the neuroendocrine mechanisms by which coconut oil supplementation during breastfeeding as well as continued exposure of this oil throughout life affect the feeding behavior of the progeny. At birth, pups were divided into two groups: Soybean oil (SO) and Coconut oil (CO). Dams received these oils by gavage (0.5 g/kg body mass/day) during lactation. Half of the CO group continued to receive CO in chow throughout life (CO + C). Adult CO and CO + C groups had overweight; the CO group had hyperphagia, higher visceral adiposity, and hyperleptinemia, while the CO + C group had hypophagia only. The CO group showed higher DAGLα (endocannabinoid synthesis) but no alteration of FAAH (endocannabinoid degradation) or CB1R. Leptin signaling and GLP1R were unchanged in the CO group, which did not explain its phenotype. Hyperphagia in these animals can be due to higher DAGLα, increasing the production of 2-AG, an orexigenic mediator. The CO + C group had higher preference for fat and lower hypothalamic GLP1R content. Continuous exposure to coconut oil prevented an increase in DAGLα. The CO + C group, although hypophagic, showed greater voracity when exposed to a hyperlipidemic diet, maybe due to lower GLP1R, since GLP1 inhibits short-term food intake.

A study protocol for a randomised crossover study evaluating the effect of diets differing in carbohydrate quality on ileal content and appetite regulation in healthy humans

Introduction: A major component of the digesta reaching the colon from the distal ileum is carbohydrate. This carbohydrate is subject to microbial fermentation and can radically change bacterial populations in the colon and the metabolites they produce, particularly short-chain fatty acids (SCFA). However, very little is currently known about the forms and levels of carbohydrate in the ileum and the composition of the ileal microbiota in humans. Most of our current understanding of carbohydrate that is not absorbed by the small intestine comes from ileostomy models, which may not reflect the physiology of an intact gastrointestinal tract. Methods: We will investigate how ileal content changes depending on diet using a randomised crossover study in healthy humans. Participants will be inpatients at the research facility for three separate 4-day visits. During each visit, participants will consume one of three diets, which differ in carbohydrate quality: 1) low-fibre refined diet; 2) high-fibre diet with intact cellular structures; 3) high-fibre diet where the cellular structures have been disrupted (e.g. milling, blending). On day 1, a nasoenteric tube will be placed into the distal ileum and its position confirmed under fluoroscopy. Ileal samples will be collected via the nasoenteric tube and metabolically profiled, which will determine the amount and type of carbohydrate present, and the composition of the ileal microbiota will be measured. Blood samples will be collected to assess circulating hormones and metabolites. Stool samples will be collected to assess faecal microbiota composition. Subjective appetite measures will be collected using visual analogue scales. Breath hydrogen will be measured in real-time as a marker of intestinal fermentation. Finally, an in vitro continuous fermentation model will be inoculated with ileal fluid in order to understand the shift in microbial composition and SCFA produced in the colon following the different diets. Registration: ISRCTN11327221.

Profiles of peptide YY and ghrelin, levels of hunger and satiety, and ad libitum intake in obese and non-obese Indonesian women

INTRODUCTION

The current study aimed to assess profiles of peptide YY and ghrelin, visual analog scales (VAS) for hunger and satiety, and ad libitum intake in obese and non-obese women.

METHODS

This open-label non-randomized interventional study involved obese (BMI ≥ 25-35 kg/m2) and non-obese (BMI 18.5-23.0 kg/m2) women subjects. Levels of peptide YY and ghrelin were determined by radioimmunoassay and enzyme-linked immunosorbent assay (ELISA), respectively, while the degrees of hunger and satiety were measured using visual analog scale (VAS) questionnaires. The results were compared in fasting condition and in 15, 60, 120, and 180 minutes after breakfast with balance composition formulation. This study also compared the ad libitum intake within 4 hours after breakfast.

RESULTS

As compared to the non-obese group, the obese group have significantly lower levels of peptide YY in fasting, and in 15, 60, 120, and 180 minutes post-prandial, and smaller AUC (Area Under the Curve) of fasting peptide YY. Furthermore, the obese group showed significantly higher ad libitum intake. The obese group also have lower levels of ghrelin and lower VAS for hunger and higher in VAS for satiety as compared to the non-obese group.

CONCLUSIONS

There were significant differences in peptide YY level, 4 hours after breakfast ad libitum intake, ghrelin level, and VAS for hunger and satiety, between obese group and non-obese one.

Central Modulation of Energy Homeostasis and Cognitive Performance After Bariatric Surgery

In moderately or morbidly obese patients, bariatric surgery has been proven to be an effective therapeutic approach to control body weight and comorbidities. Surgery-mediated modulation of brain function via modified postoperative secretion of gut peptides and vagal nerve stimulation was identified as an underlying mechanism in weight loss and improvement of weight-related diseases. Increased basal and postprandial plasma levels of gastrointestinal hormones like glucagon-like peptide 1 and peptide YY that act on specific areas of the hypothalamus to reduce food intake, either directly or mediated by the vagus nerve, are observed after surgery while suppression of meal-induced ghrelin release is increased. Hormones released from the adipose tissue like leptin and adiponectin are also affected and leptin plasma levels are reduced in treated patients. Besides homeostatic control of body weight, surgery also changes hedonistic behavior in regard to food intake and cognitive performance involving the limbic system and prefrontal areas.

Hypothalamic Integration of the Endocrine Signaling Related to Food Intake

Hypothalamic integration of gastrointestinal and adipose tissue-derived hormones serves as a key element of neuroendocrine control of food intake. Leptin, adiponectin, oleoylethanolamide, cholecystokinin, and ghrelin, to name a few, are in a constant "cross talk" with the feeding-related brain circuits that encompass hypothalamic populations synthesizing anorexigens (melanocortins, CART, oxytocin) and orexigens (Agouti-related protein, neuropeptide Y, orexins). While this integrated neuroendocrine circuit successfully ensures that enough energy is acquired, it does not seem to be equally efficient in preventing excessive energy intake, especially in the obesogenic environment in which highly caloric and palatable food is constantly available. The current review presents an overview of intricate mechanisms underlying hypothalamic integration of energy balance-related peripheral endocrine input. We discuss vulnerabilities and maladaptive neuroregulatory processes, including changes in hypothalamic neuronal plasticity that propel overeating despite negative consequences.

Effect of Age on Blood Glucose and Plasma Insulin, Glucagon, Ghrelin, CCK, GIP, and GLP-1 Responses to Whey Protein Ingestion

Protein-rich supplements are used widely to prevent and manage undernutrition in older people. We have previously shown that healthy older, compared to younger, adults have less suppression of energy intake by whey protein-although the effects of age on appetite-related gut hormones are largely unknown. The aim of this study was to determine and compare the acute effects of whey protein loads on blood glucose and plasma gut hormone concentrations in older and younger adults. Sixteen healthy older (eight men, eight women; mean ± SEM: age: 72 ± 1 years; body mass index: 25 ± 1 kg/m²) and 16 younger (eight men, eight women; 24 ± 1 years; 23 ± 0.4 kg/m²) adults were studied on three occasions in which they ingested 30 g (120 kcal) or 70 g (280 kcal) whey protein, or a flavored-water control drink (~2 kcal). At regular intervals over 180 min, blood glucose and plasma insulin, glucagon, ghrelin, cholecystokinin (CCK), gastric inhibitory peptide (GIP), and glucagon-like peptide-1 (GLP-1) concentrations were measured. Plasma ghrelin was dose-dependently suppressed and insulin, glucagon, CCK, GIP, and GLP-1 concentrations were dose-dependently increased by the whey protein ingestion, while blood glucose concentrations were comparable during all study days. The stimulation of plasma CCK and GIP concentrations was greater in older than younger adults. In conclusion, orally ingested whey protein resulted in load-dependent gut hormone responses, which were greater for plasma CCK and GIP in older compared to younger adults.

Appetite-Controlling Endocrine Systems in Teleosts

Mammalian studies have shaped our understanding of the endocrine control of appetite and body weight in vertebrates and provided the basic vertebrate model that involves central (brain) and peripheral signaling pathways as well as environmental cues. The hypothalamus has a crucial function in the control of food intake, but other parts of the brain are also involved. The description of a range of key neuropeptides and hormones as well as more details of their specific roles in appetite control continues to be in progress. Endocrine signals are based on hormones that can be divided into two groups: those that induce (orexigenic), and those that inhibit (anorexigenic) appetite and food consumption. Peripheral signals originate in the gastrointestinal tract, liver, adipose tissue, and other tissues and reach the hypothalamus through both endocrine and neuroendocrine actions. While many mammalian-like endocrine appetite-controlling networks and mechanisms have been described for some key model teleosts, mainly zebrafish and goldfish, very little knowledge exists on these systems in fishes as a group. Fishes represent over 30,000 species, and there is a large variability in their ecological niches and habitats as well as life history adaptations, transitions between life stages and feeding behaviors. In the context of food intake and appetite control, common adaptations to extended periods of starvation or periods of abundant food availability are of particular interest. This review summarizes the recent findings on endocrine appetite-controlling systems in fish, highlights their impact on growth and survival, and discusses the perspectives in this research field to shed light on the intriguing adaptations that exist in fish and their underlying mechanisms.

Physiology, pathophysiology and therapeutic implications of enteroendocrine control of food intake

With the increasing prevalence of obesity and its associated comorbidities, strides to improve treatment strategies have enhanced our understanding of the function of the gut in the regulation of food intake. The most successful intervention for obesity to date, bariatric surgery effectively manipulates enteroendocrine physiology to enhance satiety and reduce hunger. Areas covered: In the present article, we provide a detailed overview of the physiology of enteroendocrine control of food intake, and discuss its pathophysiologic correlates and therapeutic implications in both obesity and gastrointestinal disease. Expert commentary: Ongoing research in the field of nutrient sensing by L-cells, as well as understanding the role of the microbiome and bile acid signaling may facilitate the development of novel strategies to combat the rising population health threat associated with obesity. Further refinement of post-prandial satiety gut hormone based therapies, including the development of chimeric peptides exploiting the pleiotropic nature of the gut hormone response, and identification of novel methods of delivery may hold the key to optimization of therapeutic modulation of gut hormone physiology in obesity.

Practical combination therapy based on pathophysiology of type 2 diabetes

Type 2 diabetes is a complex, chronic, and progressive condition that often necessitates the use of multiple medications to achieve glycemic goals. Clinical guidelines generally recommend intensifying pharmacotherapy if glycemic goals are not achieved after 3 months of treatment. However, for many patients with type 2 diabetes, treatment intensification is delayed or does not occur. Initiating combination therapy early in the disease course has the potential to delay disease progression and improve patient outcomes. Guidelines generally provide a list of agents that may be used in combination regimens and emphasize individualization of treatment. The purpose of this review is to discuss the rationale for combination therapy, considering treatment effects on pathophysiologic aspects of type 2 diabetes and individual drug profiles. The combination of newer antidiabetes therapies with complementary mechanisms of action provides the opportunity to target multiple sites of tissue, organ, and cellular dysfunction.

Effect of heat exposure and exercise on food intake regulation: A randomized crossover study in young healthy men

OBJECTIVE

The effect of physical activity on food intake regulation may be moderated by environmental temperature. The aim of the study was to determine the single and combined effects of metabolic activity and temperature on energy intake and its hormonal regulation.

METHODS

A randomized crossover study was conducted in the laboratory. Ten healthy and physically active young Afro-Caribbean men participated in four experimental sessions (rest at 22°C and 31°C and cycling at 60% of their maximal oxygen uptake at 22°C and 31°C, all for 40 min). Each test period was followed by a 30-min recovery period and then an ad libitum meal. The main outcome measures were energy balance, subjective appetite, and plasma pancreatic polypeptide (PP), cholecystokinin (CCK) and ghrelin concentrations.

RESULTS

Relative energy intake was significantly decreased whereas plasma PP was increased in the exercise conditions (p=0.004 and p=0.002, respectively). Postprandial levels of CCK were elevated only in the rest conditions. Exposure to heat induced a decrease in plasma ghrelin (p=0.031).

CONCLUSIONS

Exercise induced a short-term energy deficit. However, modifications in the hormonal regulation of food intake in response to short-term heat or heat and exercise exposure seem to be minor and did not induce changes in energy intake. This trial was registered at clinicaltrials.gov as NCT02157233.

Bariatric Left Gastric Artery Embolization for the Treatment of Obesity: A Review of Gut Hormone Involvement in Energy Homeostasis

OBJECTIVE

The global population is becoming more overweight and obese, leading to increases in associated morbidity and mortality rates. Advances in catheter-directed embolotherapy offer the potential for the interventional radiologist to make a contribution to weight loss. Left gastric artery embolization reduces the supply of blood to the gastric fundus and decreases serum levels of ghrelin. Early evidence suggests that this alteration in gut hormone balance leads to changes in energy homeostasis and weight reduction. The pathophysiologic findings and current evidence associated with the use of left gastric artery embolization are reviewed.

CONCLUSION

The prevalence of obesity continues to increase at an alarming rate, and, thus far, advances in medical management have been relatively ineffective in slowing this trend. Lifestyle modifications such as diet and exercise are effective initially, but most patients regain the weight in the long term. Bariatric surgery is the most effective strategy for achieving long-term weight loss; however, as with all surgical procedures, it has potential complications.

Relationships Between Fasting Serum Amylase and Ghrelin or Peptide YY3-36 Levels in Healthy Men

OBJECTIVES

Appetite and carbohydrate metabolism are important contributors to the development of obesity. Recently, low serum amylase was shown to be associated with obesity and metabolic disorder. We investigated the relationship between amylase and ghrelin or peptide YY (PYY) levels in healthy men.

METHODS

Twenty-one men were enrolled in this cross-sectional study; all subjects were asymptomatic with no medical history. Fasting serum amylase, ghrelin, PYY3-36, anthropometry, and nutritional intake were measured. Linear regression analyses were performed to examine associations between amylase and ghrelin or PYY3-36.

RESULTS

The mean (SD) age and waist circumference of the subjects were 51.5 (10.9) years and 87.0 (4.4) cm, respectively. Amylase was found to be correlated with waist circumference (r = -0.438, P = 0.054), ghrelin (r = 0.533, P = 0.015), and PYY3-36 (r = -0.511, P = 0.021). Multivariate linear regression analysis revealed a negative association between amylase and PYY3-36 (β = -0.428, P = 0.045) but a nonsignificantly positive association between amylase and ghrelin (β = 0.260, P = 0.146).

CONCLUSIONS

Amylase levels were found to be associated with ghrelin and PYY3-36 in healthy men. Amylase, ghrelin, and PYY3-36 may play a role in obesity; further research is required to identify the underlying mechanism.

Obesity and increased risk of esophageal adenocarcinoma

There has been a substantial increase in the incidence of esophageal adenocarcinoma over the past 40 years. Meta-analyses of large prospective cohorts and population-based case-control studies demonstrate consistent associations between obesity and the development of adenocarcinoma of the esophagus and esophago-gastric junction, with an approximate doubling of risk of esophageal adenocarcinoma among patients who are obese, and an almost five-fold increased risk among those with BMI >40 kg/m². The pathologic precursor, specialized intestinal metaplasia in Barrett's esophagus, is also associated with increased adiposity. Epidemiologic evidence suggests that this cancer risk is not solely due to increased gastro-esophageal reflux, and that adipose tissue itself, in particular visceral adipose, may fuel carcinogenesis through the production of adipokines, cytokines, growth factors, and increased inflammation. The robust epidemiologic evidence linking obesity with esophageal adenocarcinoma makes it an exemplar model for investigating the molecular mechanisms underpinning obesity-associated malignant progression, which are discussed in this review.

Anti-obesogenic effects of calcium prevent changes in the GLP-1 profile in adult rats primed by early weaning

SCOPE

Gut peptides regulate appetite and adipogenesis. Early weaning (EW) leads to later development of obesity that can be prevented by calcium supplementation. We evaluated gut peptides that may have a role in the establishment of this dysfunction.

METHODS AND RESULTS

At birth, lactating Wistar rats were separated in: EW, lactating rats involved with a bandage interrupting the lactation during the last 4 days of standard lactation, and C (control) dams whose pups had free access to milk during throughout lactation. At 120 days old, half of EW group received calcium supplementation (EWCa); EW and C received standard diet. At 21 days old, EW presented higher glucagon-like peptide 1 (GLP-1) in plasma and glucagon-like peptide 1 receptor (GLP1-R) in adipose tissue and hypothalamus, but lower GLP-1 and GLP1-R in the gut. At 180 days old, GLP-1 response to food intake was blunted in EW and restored by calcium. GLP-1 in the gut was lower in EW and its receptor was lower in adipose tissue, and GLP1-R was higher in the gut of calcium EW group.

CONCLUSION

Thus, EW had short- and long-term effects upon GLP-1 profile, which may have contributed to obesity development, hyperphagia, and insulin resistance due to its adipogenic and appetite control roles. Calcium supplementation was able to prevent most of the changes in GLP-1 caused by EW.

Role of corticosterone in the murine enteric nervous system during fasting

Food intake depends on a tightly controlled interplay of appetite hormones and the enteric (ENS) and central nervous system. Corticosterone (CORT) levels, which are mainly studied with regard to stress, are also increased during fasting. However, the role of CORT in the ENS remains elusive. Therefore, we investigated whether CORT modulates activity of enteric neurons and whether its intracellular regulator, 11β-hydroxysteroid dehydrogenase (HSD) type 1, is present in the myenteric plexus, using immunohistochemistry and RT-qPCR. Effects of CORT on neuronal activity and expression of neuronal markers in the myenteric plexus were assessed via Ca(2+) imaging and RT-qPCR, respectively, whereas modulations in mixing behavior were measured by video imaging. 11β-HSD-1 was present in enteric neurons along the gastrointestinal tract, and its expression increased after fasting (control: 0.58 ± 0.09 vs. fasted: 1.5 ± 0.23; P < 0.05). CORT incubation significantly reduced neuronal Ca(2+) transients in tissues stimulated by electrical pulses (control: 1.31 ± 0.01 vs. CORT: 1.27 ± 0.01, P < 0.01) and in cultured neurons (control: 1.85 ± 0.03 vs. CORT: 1.76 ± 0.03, P < 0.05). CORT decreased small intestinal mixing (P < 0.05). Incubation of muscle myenteric plexus preparations with CORT induced an increase in cannabinoid receptor 1 (CB1, P < 0.05) and synaptobrevin (P < 0.05) but not in 11β-HSD-1 mRNA expression. In addition, fasting induced significant elevations in synaptobrevin (P < 0.05) and CB1 (P < 0.01) mRNA expression. In conclusion, we suggest CORT to be a downstream factor in a feeding state-related pathway that modulates important proteins in the fine tuning of enteric neurotransmission and gastrointestinal motility.

Surgical weight loss: impact on energy expenditure

Diet-induced weight loss is often limited in its magnitude and often of short duration, followed by weight regain. On the contrary, bariatric surgery now commonly used in the treatment of severe obesity favors large and sustained weight loss, with resolution or improvement of most obesity-associated comorbidities. The mechanisms of sustained weight loss are not well understood. Whether changes in the various components of energy expenditure favor weight maintenance after bariatric surgery is unclear. While the impact of diet-induced weight loss on energy expenditure has been widely studied and reviewed, the impact of bariatric surgery on total energy expenditure, resting energy expenditure, and diet-induced thermogenesis remains unclear. Here, we review data on energy expenditure after bariatric surgery from animal and human studies. Bariatric surgery results in decreased total energy expenditure, mainly due to reduced resting energy expenditure and explained by a decreased in both fat-free mass and fat mass. Limited data suggest increased diet-induced thermogenesis after gastric bypass, a surgery that results in gut anatomical changes and modified the digestion processes. Physical activity and sustained intakes of dietary protein may be the best strategies available to increase non-resting and then total energy expenditure, as well as to prevent the decline in lean mass and resting energy expenditure.

Food restriction and refeeding induces changes in lipid pathways and fat deposition in the adipose and hepatic tissues in rats with diet-induced obesity

The aim of this study was to determine the effects of successive cycles of a moderately restrictive diet and refeeding with a high-fat diet on the metabolism of the adipose and hepatic tissues of obese rats. Rats were assigned to the following groups: a chow diet; a high-fat diet; a moderate caloric restriction; or a moderate caloric restriction plus refeeding. Some animals in each group were given [1-(14)C]triolein intragastrically, while others received an intraperitoneal injection of 3 mCi (3)H(2)O. All animals were killed by decapitation. The retroperitoneal, visceral epididymal and omental white adipose tissues, brown adipose tissue, liver and blood were immediately removed. The lipid uptake from the diet, in vivo rate of lipogenesis, percentage of fat, lipid profile and leptin concentration were analysed. The high-fat diet promoted an increase in fatty liver (P ≤ 0.05), adiposity mass (P ≤ 0.05) and the plasma concentration of leptin (P ≤ 0.05) and a decreased lipid uptake in white adipose tissue depots (P ≤ 0.05) in relation to the chow diet. The moderate caloric restriction did not reverse the changes promoted by the high-fat diet but induced a small decrease in adiposity, which was reversed after refeeding, and the animals maintained a dyslipidaemic profile and high fat deposition in the liver. We can conclude that the high-fat diet and subsequent moderate caloric restriction plus refeeding increased the risks of developing visceral obesity, dyslipidaemia and non-alcoholic fatty liver disease, which suggests that this type of experimental protocol can be used to study mechanisms related to the metabolic syndrome.

Appetite regulation and weight control: the role of gut hormones

The overwhelming increase in the prevalence of overweight and obesity in recent years represents one of the greatest threats to the health of the developed world. Among current treatments, however, gastrointestinal (GI) surgery remains the only approach capable of achieving significant weight loss results with long-term sustainability. As the obesity prevalence approaches epidemic proportions, the necessity to unravel the mechanisms regulating appetite control has garnered significant attention. It is well known that physical activity and food intake regulation are the two most important factors involved in body weight control. To regulate food intake, the brain must alter appetite. With this realization has come increased efforts to understand the intricate interplay between gut hormones and the central nervous system, and the role of these peptides in food intake regulation through appetite modulation. This review discusses the central mechanisms involved in body weight regulation and explores a suite of well characterized and intensely investigated anorexigenic and orexigenic gut hormones. Their appetite-regulating capabilities, post-GI surgery physiology and emerging potential as anti-obesity therapeutics are then reviewed.

Energy intake and appetite-related hormones following acute aerobic and resistance exercise

Previous research has shown that resistance and aerobic exercise have differing effects on perceived hunger and circulating levels of appetite-related hormones. However, the effect of resistance and aerobic exercise on actual energy intake has never been compared. This study investigated the effect of an acute bout of resistance exercise, compared with aerobic exercise, on subsequent energy intake and appetite-regulating hormones. Ten active men completed 3 trials in a counterbalanced design: 45 min of resistance exercise (RES; free and machine weights), aerobic exercise (AER; running), or a resting control trial (CON). Following exercise or CON, participants had access to a buffet-style array of breakfast foods and drinks to consume ad libitum. Plasma concentrations of a range of appetite-regulating hormones were measured throughout each trial. Despite significantly higher energy expenditure with AER compared with RES (p < 0.05), there was no difference in total energy intake from the postexercise meal between trials (p = 0.779). Pancreatic polypeptide was significantly higher prior to the meal after both RES and AER compared with CON. In contrast, active ghrelin was lower following RES compared with both CON and AER (p ≤ 0.05), while insulin was higher following RES compared with CON (p = 0.013). In summary, the differential response of appetite-regulating hormones to AER and RES does not appear to influence energy intake in the postexercise meal. However, given the greater energy expenditure associated with AER compared with RES, AER modes of exercise may be preferable for achieving short-term negative energy balance.

Appetite-related hormone levels in obese women with and without binge eating behavior

OBJECTIVE: The aim of this study was to evaluate serum levels of appetite-related hormones (peptide YY3-36, total ghrelin, leptin and insulin) before and after consumption of a meal in obese women with and without binge eating episodes and normal weight women. METHODS: Twenty-five women aged 32-50 years were invited to participate in this study, including 9 normal weight women without binge eating episodes (20-25kg/m², group 1), 9 obese women with binge eating episodes (³30kg/m², group 2), and 7 obese women without binge eating episodes (group 3). Four blood samples were collected from each participant, one being 60 minutes before and three being 15, 45 and 90 minutes after a meal. The composition of the meal was 55% carbohydrates, 15% protein and 30% lipids. RESULTS: Group 3 presented increased HOMA-IR (M=2.5, SD=1.04) when compared with group 1 (M=1.5, SD=0.53) and group 2 (M=1.8, SD=0.58), p=0.04. Body mass index (p<0.0001), leptin (p<0.0001) and insulin (p=0.01) were higher in group 3 than in the other groups before and after the meal. Additionally, total ghrelin (p=0.003) and PYY3-36 (p=0.02) levels were lower in group 2 than in the other groups before and after the meal. After adjustment for body mass index, only the lower PYY3-36 level of group 2 remained statistically different from the other groups (p=0.01). CONCLUSION: Our study suggests that lower levels of PYY 3-36 are associated with binge eating in obese women.

Ghrelin and PYY levels in adolescents with severe obesity: effects of weight loss induced by long-term exercise training and modified food habits

This study investigated (a) changes in ghrelin and peptide YY (PYY) concentrations during a weight reduction programme and (b) baseline ghrelin and PYY levels as predictors of weight loss in 32 severely obese adolescents (BMI z score = 4.1). Subjects spent an academic year in an institution for childhood obesity. Fasting ghrelin and PYY, leptin, insulin levels and insulin resistance were measured at baseline (month 0) and during the programme (months 3, 6, 9). In addition, 15 normal-weight teenagers served as reference for the baseline assessments. At baseline, obese teenagers had lower ghrelin and PYY concentrations than normal-weight adolescents (P < 0.05). Moreover, they showed significantly higher leptin, insulin levels and homeostasis model assessment (HOMA) (P < 0.0001). During the lifestyle modification, there was a significant decrease in body weight among obese teenagers, associated with an increase in ghrelin (apparent from month 6; P < 0.05), a decrease in leptin (from month 3; P < 0.05) and a decrease in insulin and HOMA (from month 3; P < 0.0001), without any significant change in PYY. Anthropometrical changes were correlated neither with baseline ghrelin levels nor with changes in ghrelin and PYY after the lifestyle modification. However, higher baseline PYY tended to correlate with greater anthropometrical changes (P < 0.1). In adolescents with severe obesity, a long-term combination of supervised aerobic exercises and a balanced diet led to weight reduction and increased ghrelin concentrations, without any change in PYY concentrations. Moreover, baseline PYY concentrations might be considered as predictors of weight loss.

Characterization of the diurnal rhythm of peptide YY and its association with energy balance parameters in normal-weight premenopausal women

PYY may play a role in modulating satiety and energy expenditure; increasing PYY postprandially has been studied largely in single-meal responses. The diurnal rhythm of PYY and its role in energy balance have not been fully characterized. The purpose of our study was to characterize features of the diurnal rhythm of PYY and determine its role in regulating energy balance. This study was a cross-sectional analysis of 11 subjects in whom 24-h repeated blood sampling was conducted at baseline of a larger prospective study. Breakfast (B), lunch (L), dinner (D), and a snack (S) occurred between 0900 and 1900. Total PYY was assayed every hour from 0800 to 1000, every 20 min from 1000 to 2000, and every hour from 2000 to 0800. PYY variables included total AUC, postprandial peaks, and 24-h mean. Energy balance variables included energy intake, RMR, RQ, and NEAT. PYY postprandial peaks were significantly higher than fasting (P < 0.05). Twenty-four-hour peak PYY occurred after L and was significantly higher than all other peaks (P < 0.05). A cubic curve function accounted for most of the variance in PYY (r(2) = 69.9%, P < 0.01). Fasting PYY (0800) correlated with postprandial peaks at B (r = 0.77, P = 0.01), L (r = 0.71, P = 0.01), and D (r = 0.65, P = 0.03). The only significant association between PYY and energy expenditure was that RMR (kcal/24 h) correlated with 24-h mean PYY (r = 0.71, P = 0.013) and total AUC (r = 0.69, P = 0.019). We conclude that PYY displays a meal-driven diurnal rhythm and is correlated to RMR, a major contributor to energy expenditure. Thus, PYY varies in accordance with energy content and RMR, supporting a role for PYY in energy balance modulation.

Postexercise water immersion increases short-term food intake in trained men

PURPOSE

The performance of exercise while immersed in cold water has been shown to influence energy intake in the subsequent meal. In addition, cold water immersion (CWI) itself has been shown to reduce the concentration of the hormone leptin, high concentrations of which signal satiety. Taken together, these findings raise the question of whether the common practice of postexercise CWI by athletes acutely affects energy intake. Hence, this study investigated the acute effect of CWI after exercise on subsequent energy intake and macronutrient preferences as well as the circulating levels of a range of appetite-related hormones.

METHODS

Ten physically active men participated in three randomized, counterbalanced trials consisting of 40 min of treadmill running (70% VO(2peak)), followed by 20 min of CWI (15°C), neutral water immersion (NWI; 33°C), or a resting control with no immersion (CON). Participants were then given a 30-min access to a buffet-type breakfast of precisely known quantity and nutrient composition from which they could consume ad libitum.

RESULTS

Participants consumed significantly more energy after both CWI (mean ± SD = 4893 ± 1554 kJ, P = 0.006) and NWI (5167 ± 1975 kJ, P = 0.010) compared with CON (4089 ± 1585 kJ). However, there was no significant difference in total energy intake between the CWI and the NWI trials (P = 0.595). These changes were associated with a significant interaction effect of time and trial on both leptin (P = 0.045) and active ghrelin (P = 0.046).

CONCLUSION

Postexercise water immersion is associated with higher energy intake in the subsequent meal compared with CON. This is an important consideration for trained men using water immersion as a method of recovery from exercise.