Chronic pramlintide decreases feeding via a reduction in meal size in male rats

Amylin, a pancreatic hormone, is well-established to suppress feeding by enhancing satiation. Pramlintide, an amylin analog that is FDA-approved for the treatment of diabetes, has also been shown to produce hypophagia. However, the behavioral mechanisms underlying the ability of pramlintide to suppress feeding are unresolved. We hypothesized that systemic pramlintide administration in rats would reduce energy intake, specifically by reducing meal size. Male rats were given b.i.d. administration of intraperitoneal pramlintide or vehicle for 1 week, and chow intake, meal patterns, and body weight were monitored throughout the test period. Consistent with our hypothesis, pramlintide decreased chow intake mainly via suppression of meal size, with corresponding reductions in meal duration on several days. Fewer effects on meal number or feeding rate were detected. Pramlintide also reduced weight gain over the 1-week study. These results highlight that the behavioral mechanisms by which pramlintide produces hypophagia are similar to those driven by amylin itself, and provide important insight into the ability of this pharmacotherapy to promote negative energy balance over a period of chronic administration.

The estrogenic reduction in water intake stimulated by dehydration involves estrogen receptor alpha and a potential role for GLP-1

It is well documented that estrogens inhibit fluid intake. Most of this research, however, has focused on fluid intake in response to dipsogenic hormone and/or drug treatments in euhydrated rats. Additional research is needed to fully characterize the fluid intake effects of estradiol in response to true hypovolemia. As such, the goals of this series of experiments were to provide a detailed analysis of water intake in response to water deprivation in ovariectomized female rats treated with estradiol. In addition, these experiments also tested if activation of estrogen receptor alpha is sufficient to reduce water intake stimulated by water deprivation and tested for a role of glucagon like peptide-1 in the estrogenic control of water intake. As expected, estradiol reduced water intake in response to 24 and 48 h of water deprivation. The reduction in water intake was associated with a reduction in drinking burst number, with no change in drinking burst size. Pharmacological activation of estrogen receptor alpha reduced intake. Finally, estradiol-treatment caused a leftward shift in the behavioral dose response curve of exendin-4, the glucagon like peptide-1 agonist. While the highest dose of exendin-4 reduced 10 min intake in both oil and estradiol-treated rats, the intermediate dose only reduced intake in rats treated with estradiol. Together, this series of experiments extends previous research by providing a more thorough behavioral analysis of the anti-dipsogenic effect of estradiol in dehydrated rats, in addition to identifying the glucagon like peptide-1 system as a potential bioregulator involved in the underlying mechanisms by which estradiol reduces water intake in the female rat.

Meat- and plant-based products induced similar satiation which was not affected by multimodal augmentation

Little is known about how plant-based products influence satiation compared to corresponding meat-based products. As augmented reality (AR) intensifies sensory experiences, it was hypothesized to improve satiation. This study compared satiation between intake of meatballs and plant-based balls and plant-based balls intensified with AR for visual, olfactory, and haptic sensory properties. Intake order of the meatballs, plant-based balls, and augmented plant-based balls, eaten on separate days, was randomized. Satiation was measured from twenty-eight non-obese adults as ad libitum intake of the balls and extra snacks, and as subjective appetite sensations. Liking and wanting to eat the products were also investigated. There were no differences between the products in satiation. Before tasting the augmented plant-based balls were less liked than the meatballs (p = 0.002) or plant-based balls (p = 0.046), but after eating the first ball or eating the ad libitum number of balls the differences in liking disappeared. Wanting evaluations were similar for each product and decreased during eating (p < 0.001). A group of participants susceptible to AR was found (n = 11), described by decreased intake when augmentation was applied. Among the sub-group, wanting to eat the augmented balls was lower before tasting (p = 0.019) and after eating the first ball (p = 0.002) and appetite was less suppressed after eating the balls ad libitum (p = 0.01), when compared to non-susceptible participants. We conclude that meatballs and plant-based balls were equal in inducing satiation, and multisensory augmentation did not influence satiation. However, the augmentation decreased liking evaluations before tasting. Further studies are needed to explore differences between consumer groups in susceptibility to augmentation.

Paradoxical effects of feeding status on food consumption and learning performance in zebrafish (Danio rerio)

Associative learning is often studied using food reward as the unconditioned stimulus (US). With warm-blooded species, to get the subject more motivated the solution has been to feed less, making the subject hungrier. Here we show the opposite with zebrafish. We randomly assigned zebrafish to two groups: a once-a-day-fed and a five-times-a-day-fed group, with the same amount of food fed per occasion for fish of both groups, a feeding regimen that lasted for three months. Subsequently, we trained fish by pairing food (US) with a red cue card (the conditioned stimulus, CS), which were placed together in one arm of a plus-maze across eight training sessions. We also ran unpaired training, in which the CS and US were presented in different arms. We found the previously once-a-day-fed zebrafish to consume less food throughout habituation and training sessions compared to the previously five-times-a-day-fed ones. Furthermore, five-times-a-day-fed fish in the paired group swam significantly closer to the CS during a post-training probe trial compared to the five-times-a-day-fed unpaired fish, a paired training effect that was absent in once-a-day-fed fish. Groups did not differ in health or general activity. In sum, elevated chronic feeding improved food consumption and enhanced learning and memory performance without affecting activity levels in adult zebrafish.

Reasons for meal termination, eating frequency, and typical meal context differ between persons with and without a spinal cord injury

Overeating associated with neurogenic obesity after spinal cord injury (SCI) may be related to how persons with SCI experience satiation (processes leading to meal termination), their eating frequency, and the context in which they eat their meals. In an online, cross-sectional study, adults with (n = 688) and without (Controls; n = 420) SCI completed the Reasons Individuals Stop Eating Questionnaire-15 (RISE-Q-15), which measures individual differences in the experience of factors contributing to meal termination on five scales: Physical Satisfaction, Planned Amount, Decreased Food Appeal, Self-Consciousness, and Decreased Priority of Eating. Participants also reported weekly meal and snack frequency and who prepares, serves, and eats dinner with them at a typical dinner meal. Analysis revealed that while Physical Satisfaction, Planned Amount, and Decreased Food Appeal were reported as the most frequent drivers of meal termination in both groups, scores for the RISE-Q-15 scales differed across the groups. Compared to Controls, persons with SCI reported Physical Satisfaction and Planned Amount as drivers of meal termination less frequently, and Decreased Food Appeal and Decreased Priority of Eating more frequently (all p < 0.001). This suggests that persons with SCI rely less on physiological satiation cues for meal termination than Controls and instead rely more on hedonic cues. Compared to Controls, persons with SCI less frequently reported preparing and serving dinner meals and less frequently reported eating alone (all p < 0.001), indicating differences in meal contexts between groups. Individuals with SCI reported consuming fewer meals than Controls but reported a higher overall eating frequency due to increased snacking (p ≤ 0.015). A decrease in the experience of physical fullness, along with a dependence on a communal meal context and frequent snacking, likely contribute to overeating associated with neurogenic obesity after SCI.

A Randomized, Controlled Trial of Efficacy and Safety of Cannabidiol in Idiopathic and Diabetic Gastroparesis

BACKGROUND & AIMS

Cannabis (delta-9-tetrahydrocannabinol), a nonselective cannabinoid-receptor agonist, relieves nausea and pain. Cannabidiol (CBD), a cannabinoid receptor 2 inverse agonist with central effects, also reduces gut sensation and inflammation. We compared the effects of 4 weeks of treatment with pharmaceutical CBD vs placebo in patients with idiopathic or diabetic (diabetes mellitus) gastroparesis.

METHODS

We performed a randomized, double-blinded, placebo-controlled study of CBD twice daily (Epidiolex escalated to 20 mg/kg/d; Jazz Pharmaceuticals, Dublin, Ireland) in patients with nonsurgical gastroparesis with delayed gastric emptying of solids (GES). Symptoms were assessed by the Gastroparesis Cardinal Symptom Index Daily Diary. After 4 weeks of treatment, we measured GES, gastric volumes, and Ensure (Abbott Laboratories, Abbott Park, IL) satiation test (1 kcal/mL, 30 mL/min) to assess volume to comfortable fullness and maximum tolerance. Patients underwent specific FAAH and CNR1 genotyping. Statistical analysis compared 2 treatments using analysis of variance including baseline measurements and body mass index as covariates.

RESULTS

Among 44 patients (32 idiopathic, 6 diabetes mellitus type 1, and 6 diabetes mellitus type 2), 5 patients did not tolerate full-dose escalation; 3 withdrew before completing 4 weeks of treatment (2 placebo, 1 CBD); 95% completed 4 weeks of treatment and diaries. Compared with placebo, CBD reduced the total Gastroparesis Cardinal Symptom Index score (P = .008), inability to finish a normal-sized meal (P = .029), number of vomiting episodes/24 hours (P = .006), and overall symptom severity (P = .034). Patients treated with CBD had a higher volume to comfortable fullness and maximum tolerance and slower GES. FAAH rs34420 genotype significantly impacted nutrient drink ingestion. The most common adverse events reported were diarrhea (14 patients), fatigue (8 patients), headache (8 patients), and nausea (7 patients).

CONCLUSIONS

CBD provides symptom relief in patients with gastroparesis and improves the tolerance of liquid nutrient intake, despite slowing of GES.

CLINICALTRIALS

gov NCT #03941288.

Chronic nicotine exposure influences learning and memory in the honey bee

In insects, nicotine activates nicotinic acetylcholine receptors, which are expressed throughout the central nervous system. However, little work has been done to investigate the effects of chronic nicotine treatment on learning or other behaviors in non-herbivorous insects. To examine the effects of long term nicotine consumption on learning and memory, honey bees were fed nicotine containing solutions over four days. Bees were able to detect nicotine at 0.1 mM in sucrose solutions, and in a no choice assay, bees reduced food intake when nicotine was 1 mM or higher. Treatment with a low dose of nicotine decreased the proportion of bees able to form an associative memory when bees were conditioned with either a massed or spaced appetitive olfactory training paradigm. On the other hand, higher doses of nicotine increased memory retention and the proportion of bees responding to the odor during 10 min and 24 h recall tests. The reduction in nicotine containing food consumed may also impact response levels during learning and recall tests. These data suggest that long term exposure to nicotine has complex effects on learning and memory.

Longitudinal patterns of breastfeeding and its association with adiposity and subjective indicators of satiety/appetite in the first 2 years of life

Evidence about the association between breastfeeding and its duration with growth, appetite and satiety indicators, and adiposity in low and middle-income countries facing nutritional transition is scarce. The aim of this study was to evaluate the association between longitudinal patterns of breastfeeding (exclusive [EBF] and continued [CBF]) with adiposity and growth, and the mediating role of appetite and satiety indicators in these associations in Mexican children during the first 2 years of life. Information from 378 mother-child pairs from the MAS-Lactancia birth cohort was analysed. Information was collected at birth and at months 1, 3, 6, 9, 12, 18 and 24 of life. Duration of EBF and CBF was computed. Linear mixed models were used to assess the association of EBF and CBF with growth and adiposity. Path analysis was used for mediation analysis. Compared with the reference group (EBF duration <1 month), males with >3 to ≤6 months of EBF had less abdominal circumference (β = -0.66, p = 0.05), Z-score weight-for-length (β = -0.17, p = 0.19) and length-for-age (β = -0.49, p < 0.01). Participants without CBF beyond 6 months had higher BMI Z-score (β = 0.19, p < 0.01), abdominal circumference (β = 0.62, p < 0.01) and skinfold sum (β = 0.80, p = 0.09), and o difference in length-for-age. For EBF, mediation was confirmed for satiety responsiveness on the association with BMI Z-Score, for food fussiness for the association with abdominal circumference and length-for-age Z-score, and enjoyment of food on the association with length-for-age Z-score. For CBF, mediation was confirmed for food fussiness in the association with length-for-age. This study suggests that a longer exposure to EBF and CBF is associated with lower adiposity in children under 2 years of age, and that this association could be partially mediated by appetite and satiety indicators.

A preliminary evaluation of habituation and dishabituation of operant responding in mice

Previous research has suggested that operant response decrements within experimental sessions are due in part to habituation to the repeated presentation of reinforcers. One way to assess the role of habituation in within-session response decrements is to conduct a test for dishabituation, a phenomenon in which a habituated response to a given stimulus recovers following the presentation of some strong or novel stimulus other than the habituated stimulus. Dishabituation of operant responding has been demonstrated on several occasions in the literature, but studies with non-human subjects have thus far been limited to those using rats and pigeons. Two experiments attempting to replicate these findings with mice were conducted. Two groups of mice nose-poked for a sweetened condensed milk/water reinforcer on either a fixed-ratio 4 or variable-interval 15 s schedule of reinforcement. During testing, baseline sessions were then alternated with two test conditions and a control condition. Test conditions included a 5 s auditory stimulus or flashing of the house light presented mid-session. Control conditions were identical to baseline. Dishabituation was not observed for either group in Experiment 1. In Experiment 2, dishabituation was not observed for the fixed-ratio 4 group but was observed for the variable interval 15 s group. Considerations for further study of operant dishabituation in mice are discussed.

Further evidence for sensitivity to energy density and a two-component model of meal size: Analysis of meal calorie intakes in Argentina and Malaysia

Previously, we demonstrated a non-linear association between meal caloric intake and meal energy density (ED, kcal/g) in data from a controlled trial in the US and from free-living participants in the UK [1]. In both datasets, meal caloric intake increased with ED in lower energy-dense meals (below ∼1.75 kcal/g) and decreased in higher energy-dense meals (above ∼1.75 kcal/g). In the current study, we sought to explore whether this pattern extends to data from free-living participants in Argentina (N = 2738 meals) and Malaysia (N = 4658 meals). Again, a significant breakpoint was found in both the Argentinean (2.04 kcal/g (SE = 0.06)) and Malaysian (2.17 kcal/g (SE = 0.06)) datasets with mean centered meal caloric intake increasing with ED below the breakpoint and decreasing above the breakpoint. These results lend further support for our two-component theoretical model of meal size (g) in which a volume signal is dominant in lower energy-dense meals and a calorie-content signal is dominant in higher energy-dense meals. Together, our research adds to evidence supporting human sensitivity to calories and exposes a complexity in the correspondence between meal energy content and meal size in everyday (non-manipulated) meals. Further research is needed to provide causal evidence for this sensitivity and whether individual variation impacts meal size and energy balance.

Cerebellar Prediction and Feeding Behaviour

Given the importance of the cerebellum in controlling movements, it might be expected that its main role in eating would be the control of motor elements such as chewing and swallowing. Whilst such functions are clearly important, there is more to eating than these actions, and more to the cerebellum than motor control. This review will present evidence that the cerebellum contributes to homeostatic, motor, rewarding and affective aspects of food consumption.Prediction and feedback underlie many elements of eating, as food consumption is influenced by expectation. For example, circadian clocks cause hunger in anticipation of a meal, and food consumption causes feedback signals which induce satiety. Similarly, the sight and smell of food generate an expectation of what that food will taste like, and its actual taste will generate an internal reward value which will be compared to that expectation. Cerebellar learning is widely thought to involve feed-forward predictions to compare expected outcomes to sensory feedback. We therefore propose that the overarching role of the cerebellum in eating is to respond to prediction errors arising across the homeostatic, motor, cognitive, and affective domains.

elegans

Fasting is a popular dietary strategy because it grants numerous advantages, and redox regulation is one mechanism involved. However, the precise redox changes with respect to the redox species, organelles and tissues remain unclear, which hinders the understanding of the metabolic mechanism, and exploring the precision redox map under various dietary statuses is of great significance. Twelve redox-sensitive C. elegans strains stably expressing genetically encoded redox fluorescent probes (Hyperion sensing H2O2 and Grx1-roGFP2 sensing GSH/GSSG) in three organelles (cytoplasm, mitochondria and endoplasmic reticulum (ER)) were constructed in two tissues (body wall muscle and neurons) and were confirmed to respond to redox challenge. The H2O2 and GSSG/GSH redox changes in two tissues and three organelles were obtained by confocal microscopy during fasting, refeeding, and satiation. We found that under fasting condition, H2O2 decreased in most compartments, except for an increase in mitochondria, while GSSG/GSH increased in the cytoplasm of body muscle and the ER of neurons. After refeeding, the redox changes in H2O2 and GSSG/GSH caused by fasting were reversed in most organelles of the body wall muscle and neurons. In the satiated state, H2O2 increased markedly in the cytoplasm, mitochondria and ER of muscle and the ER of neurons, while GSSG/GSH exhibited no change in most organelles of the two tissues except for an increase in the ER of muscle. Our study systematically and precisely presents the redox characteristics under different dietary states in living animals and provides a basis for further investigating the redox mechanism in metabolism and optimizing dietary guidance.

Secretin modulates appetite via brown adipose tissue-brain axis

PURPOSE

Secretin activates brown adipose tissue (BAT) and induces satiation in both mice and humans. However, the exact brain mechanism of this satiety inducing, secretin-mediated gut-BAT-brain axis is largely unknown.

METHODS AND RESULTS

In this placebo-controlled, single-blinded neuroimaging study, firstly using [18F]-fluorodeoxyglucose (FDG) PET measures (n = 15), we established that secretin modulated brain glucose consumption through the BAT-brain axis. Predominantly, we found that BAT and caudate glucose uptake levels were negatively correlated (r = -0.54, p = 0.037) during secretin but not placebo condition. Then, using functional magnetic resonance imaging (fMRI; n = 14), we found that secretin improved inhibitory control and downregulated the brain response to appetizing food images. Finally, in a PET-fMRI fusion analysis (n = 10), we disclosed the patterned correspondence between caudate glucose uptake and neuroactivity to reward and inhibition, showing that the secretin-induced neurometabolic coupling patterns promoted satiation.

CONCLUSION

These findings suggest that secretin may modulate the BAT-brain metabolic crosstalk and subsequently the neurometabolic coupling to induce satiation. The study advances our understanding of the secretin signaling in motivated eating behavior and highlights the potential role of secretin in treating eating disorders and obesity.

TRIAL REGISTRATION

EudraCT no. 2016-002373-35, registered 2 June 2016; Clinical Trials no. NCT03290846, registered 25 September 2017.

Neonatal overnutrition, but not neonatal undernutrition, disrupts CCK-induced hypophagia and neuron activation of the nucleus of the solitary tract and paraventricular nucleus of hypothalamus of male Wistar rats

Metabolic programming may be induced by reduction or enhancement of litter size, which lead to neonatal over or undernutrition, respectively. Changes in neonatal nutrition can challenge some regulatory processes in adulthood, such as the hypophagic effect of cholecystokinin (CCK). In order to investigate the effects of nutritional programming on the anorexigenic function of CCK in adulthood, pups were raised in small (SL, 3 pups per dam), normal (NL, 10 pups per dam), or large litters (LL, 16 pups per dam), and on postnatal day 60, male rats were treated with vehicle or CCK (10 µg/Kg) for the evaluation of food intake and c-Fos expression in the area postrema (AP), nucleus of solitary tract (NTS), and paraventricular (PVN), arcuate (ARC), ventromedial (VMH), and dorsomedial (DMH) nuclei of the hypothalamus. Overnourished rats showed increased body weight gain that was inversely correlated with neuronal activation of PaPo, VMH, and DMH neurons, whereas undernourished rats had lower body weight gain, inversely correlated with increased neuronal activation of PaPo only. SL rats showed no anorexigenic response and lower neuron activation in the NTS and PVN induced by CCK. LL exhibited preserved hypophagia and neuron activation in the AP, NTS, and PVN in response to CCK. CCK showed no effect in c-Fos immunoreactivity in the ARC, VMH, and DMH in any litter. These results indicate that anorexigenic actions, associated with neuron activation in the NTS and PVN, induced by CCK were impaired by neonatal overnutrition. However, these responses were not disrupted by neonatal undernutrition. Thus, data suggest that an excess or poor supply of nutrients during lactation display divergent effects on programming CCK satiation signaling in male adult rats.

Food-grade titanium dioxide (E171) differentially affects satiation in mice fed a regular or a high fat diet

Food-grade titanium dioxide (E171) is a widely used food additive and the toxicity after oral consumption is still under research, although it has been already banned in some countries. The consumption of this additive occurs mainly through ultra-processed food products which also contain high amounts of fat. High fat diets (HFD) impair the physiological system controlling satiation and satiety, which are responsible for control of food intake and energy status. The impact of E171 on animal behavior has been poorly explored and here we hypothesize that E171 could worsen the effects on feeding behavior induced by HFD. Therefore, we aimed to evaluate the effects of E171 on the feeding pattern and the behavioral satiety sequence (BSS) of mice fed with a regular diet (RD) or a HFD after 1 and 16 weeks of exposure. The results showed that RD + E171 increased food intake and feeding time, but the prototypical structure of the BSS pattern (feeding→ grooming-activity → resting), was preserved. Conversely, food consumption was not altered in HFD + E171, but the BSS pattern was disrupted as the animals prolonged resting time and spent less time being active. Our findings suggest that E171 delayed the onset of satiation in mice fed with RD but induced the opposite effect in mice fed with HFD.

Association Between Food Intake and Gastrointestinal Symptoms in Patients With Obesity

BACKGROUND AND AIMS

Hunger, satiation, postprandial satiety, and hedonic eating constitute key food intake parameters. We aim to study whether these symptoms are associated with gastrointestinal symptoms (GIS) in patients with obesity.

METHODS

This is a cross-sectional study of patients with obesity. Patients completed the following validated biomarkers and questionnaires: hunger was measured via visual analog scale (100 mm) following a standard meal, satiation was measured via ad libitum meal (calories to fullness; kcal), postprandial satiety was measured via gastric emptying scintigraphy (T_1/2; mins), and hedonic eating was measured via the Hospital Anxiety and Depression Scale questionnaire. Participants completed the abridged Bowel Disease Questionnaire to evaluate their GIS. We calculated the odds ratios (ORs) adjusted for sex, weight, and age between food intake parameters <25^th or >75^th percentile observed in a prior cohort of 450 participants with obesity and GIS.

RESULTS

A total of 274 participants (41 ± 10 [SD] years, 75% females, body mass index 39 ± 8 kg/m²) were included in the analysis. Increased hunger was associated with a lower prevalence of lumpy stools (OR = 0.18, P = .02). Satiation was associated with abdominal pain/discomfort (relieved by defecation [OR = 2.4, P = .02] or associated with change in stool consistency [OR = 2.92, P < .01]), loose/watery stools (OR = 2.09, P = .02), and bloating (OR = 2.49, P < .01). Abnormal postprandial satiety was associated with bloating (OR = 2.26, P < .01) and loose/watery stools (OR = 1.84, P = .04). Hedonic eating was associated with abdominal pain/discomfort with stool frequency change (OR = 2.4, P = .02), >3 bowel movements per day (OR = 1.93, P = .048), bloating (OR = 2.49, P = .01), abdominal pain after meals >1 per month (OR = 4.24, P < .01), and nausea >1 per week (OR = 4.51, P < .01).

CONCLUSION

Alterations in hunger, satiation, postprandial satiety, and hedonic eating are associated with GIS in patients with obesity.

Postural and visual aftereffects to a slanted floor in lying and sitting positions

After lying on a slanted floor for a while with the eyes closed, we may perceive it to be less slanted than at the beginning. After viewing a slanted floor while lying on a flat base, we may perceive it to be more horizontal. We investigated these postural and visual adaptations and their interactions with participants lying and sitting on the floor. The participants were adapted to a floor that was posturally, visually, or jointly slanted, and were asked to estimate the test slants around the adapting slant. The estimates were described as a linear function of the test slant with a high goodness-of-fit over the adapting slant. This supported normalization, not satiation, view. Second, the slope of the function, i.e., sensitivity to slant, in the lying position was low in the postural and visual conditions but high in the joint condition, whereas the sensitivity in the sitting position was equally high in all conditions. This was explained by an increase in visual and non-visual cues to the gravitational vertical in the sitting position, and by an abnormal pattern of intracorporeal hydrostatic pressure in the lying position. Third, in both body positions, the angle at which the slant appeared horizontal, i.e., the subjective horizontal (SH), was larger in the postural condition than in the visual condition. Finally, when the postural and visual adaptations were joint, the SH in the lying position was somewhere between the postural- and visual-alone SHs, whereas the SH in the sitting position approximated the visual-alone SH.

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.

Construct validation of the Reasons Individuals Stop Eating Questionnaire (RISE-Q) and the development of the RISE-Q-15

Consumers vary in the explanations they give for meal termination. The Reasons Individuals Stop Eating Questionnaire (RISE-Q) was developed to measure these satiation processes. Individual differences in satiation may be associated with a general capacity to recognise and respond to contextual and interoceptive cues. The aims of the present study were to validate the factor structure of the RISE-Q and to explore its construct validity. In particular, we tested the prediction that a latent variable "Sensitivity to Internal Satiation Cues" is associated with high satiety responsiveness, high scores on the RISE-Q Physical Satisfaction (PS) and Decreased Food Appeal (DFA) scales and a healthy BMI. Participants (n = 216 adults) completed an online survey which included the RISE-Q, Mindful Eating Questionnaire, Multidimensional Assessment of Interoceptive Awareness, Adult Eating Behaviour Questionnaire (AEBQ) and self-reported height and weight. Confirmatory Factor Analysis supported the 5-factor structure of the RISE-Q, but model fit was improved by a new short form (RISE-Q-15) of the questionnaire. Construct validity replicated for most RISE-Q subscales, but not RISE-Q and BMI. Structural Equation Modelling demonstrated that Sensitivity to Internal Satiation Cues was associated with RISE-Q PS but not with the DFA, whereas AEBQ Satiety Responsiveness was associated with DFA, but not with PS. The RISE-Q-15 may be more sensitive to specific meal termination behaviours than pre-existing questionnaires, and due to its low participant burden, it provides a useful tool to explore further multiple processes of satiation in various contexts.

Observed behavioral indicators of child satiation at mealtime: Associations with child characteristics and parent-reported child eating behaviors

The notion of promoting parents' recognition of child satiation to reduce overfeeding and overeating in children is prevalent. To do so, it is important to identify common behaviors that may indicate satiation and can be easily recognized by parents. Relatively little work has focused on identifying behaviors that may indicate child satiation as they occur during naturalistic mealtimes, which is an important context for parents to observe their children's eating behavior. Hence, the goal of the current study is to examine whether observed behavioral indicators of child satiation at mealtimes are associated with child characteristics (i.e., sex, age, and BMIz) and parent-reported child appetitive traits. We coded observed behaviors thought to indicate satiation, specifically mealtime disengagement and mealtime negativity, in a cohort of 240 families with children between 4- and 8-years old (53% boys). First, we documented the occurrence of child disengagement and negativity during naturalistic mealtimes. Second, we found that lower child BMIz and being a boy were associated with greater mealtime disengagement, but child age was not associated with mealtime disengagement. No associations were found between child characteristics and mealtime negativity. Third, we found that mealtime disengagement and mealtime negativity were associated with mother-reported satiety responsiveness on the Child Eating Behavior Questionnaire. Taken together, our findings suggest observed mealtime disengagement and mealtime negativity behaviors could be helpful indicators of child satiation in a naturalistic mealtime context.

The effect of a brief mindfulness intervention on perception of bodily signals of satiation and hunger

An increasing number of studies investigate the effects of mindfulness on food intake and weight outcomes, while the underlying mechanisms by which mindfulness exerts its effects have received less attention. We conducted two pre-registered studies to shed light on the frequently proposed yet largely understudied hypothesis that mindfulness improves awareness of bodily signals of satiation and hunger. We assessed the ability to perceive the onset of bodily signals of satiation with the two-step water load test (Study 1) and the ability to perceive the onset of bodily signals of hunger with the preload test (Study 2). A brief mindfulness exercise (body scan) did not impact the perception of satiation but improved the ability to perceive bodily signals of hunger. After the consumption of a standardized preload, participants in the two experimental conditions felt equally satiated; nevertheless, those in the mindfulness condition perceived the onset of hunger 18min earlier than those in the control condition and this effect persisted also in the presence of control variables. These findings together suggest that even a single and short mindfulness exercise can improve perception of hunger signals substantially, while more intensive mindfulness training may be needed to impact perception of satiation signals.

The Satiation Framework: Exploring processes that contribute to satiation

Satiation has been described as a process that leads to the termination of eating and controls meal size. However, studies have shown that the termination of eating can be influenced by multiple behavioral and biological processes over the course of a meal as well as those related to the context in which the meal is consumed. To expand understanding of how individuals experience satiation during a meal, we recently developed the Reasons Individuals Stop Eating Questionnaire (RISE-Q). The development of the RISE-Q revealed five distinct factors reported to contribute to meal termination: Planned Amount, Self-Consciousness, Decreased Food Appeal, Physical Satisfaction, and Decreased Priority of Eating. Thus, we define satiation as a series of dynamic processes that emerge over the course of a meal to promote meal termination. We suggest that each of the factors identified by the RISE-Q represents a distinct process, and illustrate the contribution of each process to meal termination in the Satiation Framework. Within this framework the prominence of each process as a reason to stop eating likely depends on meal context in addition to individual variability. Therefore, we discuss contexts in which different processes may be salient as determinants of meal termination. Expanding the definition of satiation to include several dynamic processes as illustrated in the Satiation Framework will help to stimulate investigation and understanding of the complex nature of meal termination.

The messy satiation effect: Understanding how eating messily can accelerate the rate of satiation and reduce consumption

The visual presentation of food plays an important role in shaping the food choices that consumers make. In the current research, we explore the impact that one's eating manner, and by extension, how messy or neat food becomes as a result, can have on enjoyment and consumption over the course of an eating episode. In a series of five studies, we find that eating in a messy manner, which degrades the visual appeal of one's food, can accelerate the rate of satiation and decrease consumption, a phenomenon we term the messy satiation effect. This effect occurs because the disgust response induced by the visual degradation of a food's presentation decreases tastiness perceptions. Accordingly, we position the messy satiation effect as a simple intervention that can be used in some circumstances to combat overconsumption and therefore increase healthier eating patterns through reducing intake, thus providing contributions to both theory and practice.

Hindbrain orexin 1 receptors blunt intake suppression by gastrointestinal nutrients and cholecystokinin in male rats

Hypothalamic orexin neurons project to many brain areas, including hindbrain structures such as the nucleus of the solitary tract (NTS) and area postrema (AP), where orexin 1 receptors (OX1Rs) are expressed. Hindbrain administration of orexin-A increases feeding and meal size, and blockade of hindbrain OX1Rs with the selective antagonist SB334867 has the opposite effect. Here we asked whether hindbrain OX1R stimulation or blockade alter rats' sensitivity to gastrointestinal satiety signals. Rats received 4th intracerebroventricular (icv) injections of vehicle or orexin-A, at a dose with no effect on its own, prior to an intragastric (IG) infusion of saline or a satiating volume of Ensure. IG Ensure suppressed subsequent chow intake, but orexin-A pretreatment significantly attenuated this IG nutrient-induced satiety at 2 h into the dark phase. In a second experiment, rats received NTS injections of vehicle or orexin-A before intraperitoneal (IP) injection of vehicle or the satiation hormone cholecystokinin (CCK). NTS orexin-A pretreatment completely blocked the intake-suppressive effect of CCK on dark-phase chow intake. Finally, we investigated the role of endogenous hindbrain OX1R activation by pretreating rats with 4th-icv injection of vehicle or SB334867 followed by IG infusion of saline or Ensure just before a chocolate Ensure licking test session. IG nutrient infusion suppressed Ensure intake, and blockade of hindbrain OX1Rs significantly prolonged that intake-suppressive effect. We conclude that hindbrain OX1Rs are a mechanism though which hypothalamic orexin neurons can reduce animals' sensitivity to gastrointestinal nutrient load, allowing them to consume more food.

Nitric oxide and l-arginine have mixed effects on mammalian feeding in condition of a high motivation to feed

Feeding inhibition caused by satiation in rats is partially mediated by the unconventional neurotransmitter nitric oxide (NO). Thus, in satiated rats blocking NO production increases feeding, and treatment with the NO precursor l-arginine or with an NO donor reduces feeding beyond that caused by satiation. Do NO and l-arginine also inhibit feeding when feeding motivation is high? When feeding motivation in satiated animals was hedonically increased by offering a highly attractive food, blocking NO production reduced the quantity eaten, rather than increasing it, indicating that hedonic aspects of food are partially mediated by NO. Increasing NO via an NO donor or l-arginine did not further increase the quantity eaten, indicating a ceiling effect. The NO donor, but not l-arginine, also decreased some motivation-dependent parameters of feeding. When feeding motivation was increased by hunger, quantities of food eaten were unaffected by an NO donor, blocker or precursor, with only the blocker of NO production affecting feeding patterning. We also examined effects on feeding of dissolving l-arginine in drinking water over 3 weeks. Chronic l-arginine administration had different effects during the first and in subsequent weeks, increasing feeding at first, but not later. The data indicate that NO has complex, state dependent effects on both the quantity of food eaten, and on patterns of feeding, probably reflecting different sites and mechanisms of action in the nervous system.

Clinical Evidence and Mechanisms of High-Protein Diet-Induced Weight Loss

Several clinical trials have found that consuming more protein than the recommended dietary allowance not only reduces body weight (BW), but also enhances body composition by decreasing fat mass while preserving fat-free mass (FFM) in both low-calorie and standard-calorie diets. Fairly long-term clinical trials of 6-12 months reported that a high-protein diet (HPD) provides weight-loss effects and can prevent weight regain after weight loss. HPD has not been reported to have adverse effects on health in terms of bone density or renal function in healthy adults. Among gut-derived hormones, glucagon-like peptide-1, cholecystokinin, and peptide tyrosine-tyrosine reduce appetite, while ghrelin enhances appetite. HPD increases these anorexigenic hormone levels while decreasing orexigenic hormone levels, resulting in increased satiety signaling and, eventually, reduced food intake. Additionally, elevated diet-induced thermogenesis (DIT), increased blood amino acid concentration, increased hepatic gluconeogenesis, and increased ketogenesis caused by higher dietary protein contribute to increased satiety. The mechanism by which HPD increases energy expenditure involves two aspects: first, proteins have a markedly higher DIT than carbohydrates and fats. Second, protein intake prevents a decrease in FFM, which helps maintain resting energy expenditure despite weight loss. In conclusion, HPD is an effective and safe tool for weight reduction that can prevent obesity and obesity-related diseases. However, long-term clinical trials spanning more than 12 months should be conducted to further substantiate HPD effects.

Intestinal glucagon-like peptide-1 effects on food intake: Physiological relevance and emerging mechanisms

The gut-brain hormone glucagon-like peptide-1 (GLP-1) has received immense attention over the last couple of decades for its widespread metabolic effects. Notably, intestinal GLP-1 has been recognized as an endogenous satiation signal. Yet, the underlying mechanisms and the pathophysiological relevance of intestinal GLP-1 in obesity remain unclear. This review first recapitulates early findings indicating that intestinal GLP-1 is an endogenous satiation signal, whose eating effects are primarily mediated by vagal afferents. Second, on the basis of recent findings challenging a paracrine action of intestinal GLP-1, a new model for the mediation of GLP-1 effects on eating by two discrete vagal afferent subsets will be proposed. The central mechanisms processing the vagal anorexigenic signals need however to be further delineated. Finally, the idea that intestinal GLP-1 secretion and/or effects on eating are altered in obesity and play a pathophysiological role in the development of obesity will be discussed. In summary, despite the successful therapeutic use of GLP-1 receptor agonists as anti-obesity drugs, the eating effects of intestinal GLP-1 still remain to be elucidated. Specifically, the findings presented here call for a further evaluation of the vago-central neuronal substrates activated by intestinal GLP-1 and for further investigation of its pathophysiological role in obesity.

Ghrelin and Orexin Interact to Increase Meal Size Through a Descending Hippocampus to Hindbrain Signaling Pathway

BACKGROUND

Memory and cognitive processes influence the amount of food consumed during a meal, yet the neurobiological mechanisms mediating these effects are poorly understood. The hippocampus (HPC) has recently emerged as a brain region that integrates feeding-relevant biological signals with learning and memory processes to regulate feeding. We investigated whether the gut-derived hormone ghrelin acts in the ventral HPC (vHPC) to increase meal size through interactions with gut-derived satiation signaling.

METHODS

Interactions between vHPC ghrelin signaling, gut-derived satiation signaling, feeding, and interoceptive discrimination learning were assessed via rodent behavioral neuropharmacological approaches. Downstream neural pathways were identified using transsynaptic virus-based tracing strategies.

RESULTS

vHPC ghrelin signaling counteracted the food intake-reducing effects produced by various peripheral biological satiation signals, including cholecystokinin, exendin-4 (a glucagon-like peptide-1 receptor agonist), amylin, and mechanical distension of the stomach. Furthermore, vHPC ghrelin signaling produced interoceptive cues that generalized to a perceived state of energy deficit, thereby providing a potential mechanism for the attenuation of satiation processing. Neuroanatomical tracing identified a multiorder connection from vHPC neurons to lateral hypothalamic area orexin (hypocretin)-producing neurons that project to the laterodorsal tegmental nucleus in the hindbrain. Lastly, vHPC ghrelin signaling increased spontaneous meal size via downstream orexin receptor signaling in the laterodorsal tegmental nucleus.

CONCLUSIONS

vHPC ghrelin signaling increases meal size by counteracting the efficacy of various gut-derived satiation signals. These effects occur via downstream orexin signaling to the hindbrain laterodorsal tegmental nucleus, thereby highlighting a novel hippocampus-hypothalamus-hindbrain pathway regulating meal size control.

Blunted satiety in fatty Zucker rats

Levels of weight gain have hit an epidemic level with rates of overweight and obesity diagnoses topping all-time highs. Elevated body weight has been linked to increased rates of cardiac problems, blood pressure issues, and risk of developing type 2 diabetes. Leptin, a hormone produced by the body that is involved in energy balance by inhibiting hunger has been implicated as an underlying mechanism that differentially contributes to food-seeking motivation. Using a scientifically validated animal model of obesity, the fatty Zucker rat, which has mutated leptin receptor genes, leptin's role in behavioral motivation can be assessed. Animals were on a 2 -h food access restriction with one-hour access to rewards in session and one hour of free-feeding access. Pre-session and post-session food access differences were evaluated in looking at motivation for food rewards during satiation while responding on differing levels of fixed-ratio schedules. The results showed robust differential behavior from satiation, demonstrating a basis for a biological mechanism involving leptin sensitivity that could underlie obesity. Although further experimentation is needed, understanding leptin could help bridge the gap in our understanding of satiation and non-satiation.

Comparative effectiveness trial comparing MyPlate to calorie counting for mostly low-income Latino primary care patients of a federally qualified community health center: study design, baseline characteristics

BACKGROUND

Primary care-based behavior change obesity treatment has long featured the Calorie restriction (CC), portion control approach. By contrast, the MyPlate-based obesity treatment approach encourages eating more high-satiety/high-satiation foods and requires no calorie-counting. This report describes study methods of a comparative effectiveness trial of CC versus MyPlate. It also describes baseline findings involving demographic characteristics and their associations with primary outcome measures and covariates, including satiety/satiation, dietary quality and acculturation.

METHODS

A comparative effectiveness trial was designed to compare the CC approach (n = 130) versus a MyPlate-based approach (n = 131) to treating patient overweight. Intervenors were trained community health workers. The 11 intervention sessions included two in-home health education sessions, two group education sessions, and seven telephone coaching sessions. Questionnaire and anthropometric assessments occurred at baseline, 6- and 12 months; food frequency questionnaires were administered at baseline and 12 months. Participants were overweight adult primary care patients of a federally qualified health center in Long Beach, California. Two measures of satiety/satiation and one measure of post-meal hunger comprised the primary outcome measures. Secondary outcomes included weight, waist circumference, blood pressure, dietary quality, sugary beverage intake, water intake, fruit and vegetable fiber intake, mental health and health-related quality of life. Covariates included age, gender, nativity status (U.S.-born, not U.S.-born), race/ethnicity, education, and acculturation.

ANALYSIS

Baseline characteristics were compared using chi square tests. Associations between covariates and outcome measures were evaluated using multiple regression and logistic regression.

RESULTS

Two thousand eighty-six adult patients were screened, yielding 261 enrollees who were 86% Latino, 8% African American, 4% White and 2% Other. Women predominated (95%). Mean age was 42 years. Most (82%) were foreign-born; 74% chose the Spanish language option. Mean BMI was 33.3 kg/m²; mean weight was 82 kg; mean waist circumference was 102 cm. Mean blood pressure was 122/77 mm. Study arms on key baseline measures did not differ except on dietary quality and sugary beverage intake. Nativity status was significantly associated with dietary quality.

CONCLUSIONS

The two treatment arms were well-balanced demographically at baseline. Nativity status is inversely related to dietary quality.

TRIAL REGISTRATION

NCT02514889 , posted on 8/4/2015.

Issues in Measuring and Interpreting Human Appetite (Satiety/Satiation) and Its Contribution to Obesity

PURPOSE OF REVIEW

The goals of this paper are to report current research practices in investigations of human appetite control and to assess their relationships with emerging theoretical principles. Appetite is often distinguished by the separation of homeostatic and hedonic processes.

RECENT FINDINGS

This report assesses the validity of a homeostatic toolkit to measure subjectively perceived hunger and its relationship to the developing processes of satiation (control of meal size) and satiety (control of the post-eating period). The capacity of a procedure to measure the influence of hedonic processes on food intake is also evaluated. A major issue is the relationship between the pattern of eating behaviour (influenced by the underlying drive to eat and the inhibition induced by the act of eating itself) and the parallel underlying profile of hormonal and other metabolic biomarkers. Increasing recognition is being given to individual variability in the expression of appetite, and the fact that the use of the average (mean) response conceals important information about the nature of appetite control. There is a growing interest in the identification of satiety phenotypes that operate in parallel to metabolic phenotypes. Interestingly, energy expenditure (metabolic and behavioural) contributes to an energy balance framework for understanding energy intake (appetite).

Effect of Pre-meal Water Consumption on Energy Intake and Satiety in Non-obese Young Adults

I determined whether water consumption reduces energy intake and affects satiety in non-obese young adults. The final subjects consisted of 15 individuals (8 women and 7 men) with average ages of 26.4 and 23.5 years for women and men, respectively. When subjects drank water before eating a test meal, they ate a lower amount of the test meal compared to eating test meals under waterless and postload water conditions (preload water: 123.3 g vs. waterless: 161.7 g or postload water: 163.3 g, p < 0.05). Water consumption after eating a test meal did not affect energy intake. When the subjects drank water before eating a test meal, despite consuming a lower amount, the subjects did not feel significantly less satiety than eating meals under waterless or postload water conditions. The finding that pre-meal water consumption led to a significant reduction in meal energy intake in young adults suggests that pre-meal water consumption may be an effective weight control strategy, although the mechanism of action is unknown.

RYGB increases the satiating effect of intrajejunal lipid infusions in female rats

We used a novel rat model to investigate the physiological bases of early satiation after Roux-en-Y gastric bypass surgery (RYGB). Female rats were subjected to RYGB or sham surgery. Chronic infusion catheters were placed in the Roux limb of RYGB rats and the corresponding anatomical locus of the jejuna of sham-RYGB rats. Rats were also ovariectomized and chronically treated with either estradiol (E2; 2 μg each 4th day SC) or the oil vehicle. Testing was begun 10-12 wk after surgery. Intrajejunal lipid infusions (10 min, 4.4 mL, 8.8 kcal) were performed just before test meals of a low-energy artificially sweetened gel diet (0.1 kcal/g) that RYGB rats ingest avidly. Intrajejunal lipid infusions reduced test-meal size more in RYGB rats than sham-operated rats, indicating that, at least after prolonged adaptation to surgery, the satiating actions of lipids acting intra- or post-jejunally are increased by RYGB and that accelerated meal appearance in the intestines after RYGB is not necessary for this effect. The satiating effects of intrajejunal lipid infusions were similar in E2-and oil-treated rats, suggesting that the effect was not dependent on an activational effect of estrogens. In a second experiment, pretreatment with the cholecystokinin A-receptor antagonist devazepide reduced the satiating effect of intrajejunal lipid infusions in E2-treated RYGB rats. Although these data are preliminary due to the smaller numbers of rats than in the first experiment, they suggest that cholecystokinin-mediated jejunal satiation contributes to early satiation after RYGB in ovariectomized rats with peri-ovulatory levels of estradiol. The results of these experiments may be relevant to understanding RYGB outcome in pre- and postmenopausal women.

Satiation deficits and binge eating: Probing differences between bulimia nervosa and purging disorder using an ad lib test meal

Purging disorder (PD) has been included as a named condition within the DSM-5 category of Other Specified Feeding or Eating Disorder and differs from bulimia nervosa (BN) in the absence of binge-eating episodes. The current study evaluated satiation through behavioral and self-report measures to understand how this construct may explain distinct symptom presentations for bulimia nervosa (BN) and purging disorder (PD). Women (N = 119) were recruited from the community if they met DSM-5 criteria for BN (n = 57), PD (n = 31), or were free of eating pathology (n = 31 controls). Participants completed structured clinical interviews and questionnaires and an ad lib test meal during which they provided reports of subjective states. Significant group differences were found on self-reported symptoms, ad lib test meal intake, and subjective responses to food intake between individuals with eating disorders and controls and between BN and PD. Further, ad lib intake was associated with self-reported frequency and size of binge episodes. In a multivariable model, the amount of food consumed during binges as reported during clinical interviews predicted amount of food consumed during the ad lib test meal, controlling for other binge-related variables. Satiation deficits distinguish BN from PD and appear to be specifically linked to the size of binge episodes. Future work should expand exploration of physiological bases of these differences to contribute to novel interventions.

Body mass variability is represented by distinct functional connectivity patterns

Understanding weight-related differences in functional connectivity provides key insight into neurocognitive factors implicated in obesity. Here, we sampled three groups from human connectome project data: 1) 47 pairs of BMI-discordant twins (n = 94; average BMI-discordancy 6.7 ± 3.1 kg/m²), 2) 47 pairs of gender and BMI matched BMI-discordant, unrelated individuals, and 3) 47 pairs of BMI-similar twins, to test for body mass dependent differences in between network functional connectivity. Across BMI discordant samples, three networks appeared to be highly sensitive to weight status; specifically, a network comprised of gustatory processing regions, a visual processing network, and the default mode network (DMN). Further, in the BMI-discordant twin sample, twins with lower BMI had stronger connectivity between striatal/thalamic and prefrontal networks (pFWE = 0.04). We also observed that individuals with a higher BMI than their twin had stronger connectivity between cerebellar and insular networks (pFWE = 0.04). Connectivity patterns observed in the BMI-discordant twin sample were not seen in a BMI-similar sample, providing evidence that the results are specific to BMI discordance. Beyond the involvement of gustatory and visual networks and the DMN, little overlap in results were seen between the two BMI-discordant samples. In concordance with previous findings, we hypothesize that stronger cortical-striatal-thalamic connectivity associated with lower body mass in twins may facilitate increased regulation of hedonically motivated behaviors. In twins with higher body mass, increased cerebellar-insula connectivity may be associated with compromised satiation signaling, an interpretation dovetailing prior research. The lack of overlapping results between the two BMI discordant samples may be a function of higher study design sensitivity in the BMI-discordant twin sample, relative to the more generalizable results in the unrelated sample. These findings demonstrate that distinct connectivity patterns can represent weight variability, adding to mounting evidence that implicates atypical brain functioning with the accumulation and/or maintenance of elevated weight.

Subjective feelings of appetite of wholegrain breakfasts evaluated under controlled, laboratory and 'at home' conditions

BACKGROUND

Appetite regulating properties of foods are usually investigated under laboratory conditions, whereas in real life, foods are consumed under at home conditions. The objective of this study was to compare the acute effects of breakfasts when tested in a laboratory condition and in an at home condition. Appetite regulating properties of two bread breakfasts and two cereal breakfasts were also compared.

SUBJECTS AND METHODS

In this randomized cross-over trial balanced for laboratory and at home test conditions, thirty-two women consumed five breakfasts, i.e. two bread breakfasts, two cereal breakfasts and one fried-egg breakfast. Visual analogue scales for measuring appetite were captured via an on-line scoring system and were analyzed as incremental area under the curve, as satiation phase and as satiety phase.

RESULTS

Location effects were limited to two small effects only. An overall location effect in hunger feelings was observed (p = 0.040), which occurred specifically during the short satiation period (p = 0.0002) where hunger feelings scored higher under laboratory conditions. Similarly, a location effect was observed for desire to eat (p = 0.001); this was again higher under laboratory conditions. No other location effects were observed. Bread breakfasts did not differ in their appetite regulating properties. The Steel Cut oatmeal breakfast was reported to be more satiating (p = 0.001) as compared to the ready-to-eat cereal.

CONCLUSIONS

Whereas the five breakfasts varied somewhat in their appetite regulating properties, evaluation under laboratory conditions overall did not result in different appetite scores compared to the at home conditions. This suggests that at home testing may be a useful alternative to laboratory test conditions for nutrition research.

Macronutrient manipulations of cheese resulted in lower energy content without compromising its satiating capacity

Manipulation of food's macronutrient composition in order to reduce energy content without compromising satiating capacity may be helpful in body weight control. For cheeses, substituting fat with protein may provide such opportunity. We aimed at examining the acute effect of cheeses with different macronutrient compositions on accumulated energy intake and subjective appetite sensation. A total of thirty-nine normal-weight (average BMI 24·4 kg/m²) men and women completed the partly double-blind, randomised crossover study with high-protein/low-fat (HP/LF, 696 kJ), high-protein/high-fat (HP/HF, 976 kJ) and low-protein/high-fat (LP/HF, 771 kJ) cheeses. After overnight fasting, 80 g cheese were served with 70 g bread, 132 g juice and 125 g coffee/tea/water. Ad libitum spaghetti bolognaise was served after 3 h and energy intake assessed. Subjective appetite ratings were assessed using visual analogue scales. Composite appetite scores were calculated and evaluated relatively to energy intake. Total accumulated energy intake was 188·3 (se 97·4) kJ lower when consuming the HP/LF compared with the HP/HF (P ≤ 0·05), but, compared with the LP/HF cheese, the difference was not significant (177·0 (se 100·4) kJ lower; P = 0·08). In relation to energy intake, the composite appetite score was lower when consuming the HP/LF compared with the HP/HF (P = 0·003) and the LP/HF (P = 0·007) cheeses. Thereby, no compensatory eating following consumption of the HP/LF compared with the HP/HF cheese was found. The HP/LF cheese resulted in an increased feeling of satiety in relation to its lower energy content compared with both HP/HF and LP/HF cheeses.

Pre- and postprandial variation in implicit attention to food images reflects appetite and sensory-specific satiety

Implicit attentional processes are biased toward food-related stimuli, with the extent of that bias reflecting relative motivation to eat. These interactions have typically been investigated by comparisons between fasted and sated individuals. In this study, temporal changes in implicit attention to food were assessed in relation to natural, spontaneous changes in appetite occurring before and after an anticipated midday meal. Non-fasted adults performed an emotional blink of attention (EBA) task at intervals, before and after consuming preferred, pre-selected sandwiches to satiety. Participants were required to detect targets within a rapid visual stream, presented after task-irrelevant food (preferred or non-preferred sandwiches, or desserts) or non-food distractor images. All categories of food distractor preferentially captured attention even when appetite levels were low, but became more distracting as appetite increased preprandially, reducing task accuracy maximally as hunger peaked before lunch. Postprandially, attentional capture was markedly reduced for images of the specific sandwich type consumed and, to a lesser extent, for images of other sandwich types that had not been eaten. Attentional capture by images of desserts was unaffected by satiation. These findings support an important role of selective visual attention in the guidance of motivated behaviour. Naturalistic, meal-related changes in appetite are accompanied by changes in implicit attention to visual food stimuli that are easily detected using the EBA paradigm. Preprandial enhancement of attention capture by food cues likely reflects increases in the incentive motivational value of all food stimuli, perhaps providing an implicit index of wanting. Postprandial EBA responses confirm that satiation on a particular food results in relative inattention to that food, supporting an important attentional component in the operation of sensory-specific satiety.

Body weight loss, effective satiation and absence of homeostatic neuropeptide compensation in male Sprague Dawley rats schedule fed a protein crosslinked diet

Food structure contributes to the induction of satiation and the maintenance of satiety following intake of a meal. There is evidence from human studies that protein-crosslinking of a milk-protein based meal may enhance satiety, but the mechanism underpinning this effect is unknown. We investigated whether a rat model would respond in a similar manner and might provide mechanistic insight into enhanced satiety by structural modification of a food source. Rats were schedule fed a modified AIN-93M based diet in a liquid form or protein-crosslinked to produce a soft-solid form. This was compared to a modified AIN-93M solid diet. Average daily caloric intake was in the order solid > liquid > crosslinked. Body composition was unaltered in the solid group, but there was a loss of fat in the liquid group and a loss of lean and fat tissue in the crosslinked group. Compared to rats fed a solid diet, acute responses in circulating GLP-1, leptin and insulin were eliminated or attenuated in rats fed a liquid or crosslinked diet. Quantification of homeostatic neuropeptide expression in the hypothalamus showed elevated levels of Npy and Agrp in rats fed the liquid diet. Measurement of food intake after a scheduled meal indicated that reduced energy intake of liquid and crosslinked diets is not due to enhancement of satiety. When continuously available ad-libitum, rats fed a liquid diet showed reduced weight gain despite greater 24 h caloric intake. During the dark phase, caloric intake was reduced, but compensated for during the light phase. We conclude that structural modification from a liquid to a solidified state is beneficial for satiation, with less of a detrimental effect on metabolic parameters and homeostatic neuropeptides.

Disruption of re-intake after partial withdrawal of gastric food contents in rats lesioned in the gelatinous part of the nucleus of the solitary tract

Sensory information from the upper gastrointestinal tract is critical in food intake regulation. Signals from different levels of the digestive system are processed to the brain, among other systems, via the vagus nerve, which mainly projects towards the nucleus of the solitary tract (NST). The objective of this study was to analyze the participation of the gelatinous part (SolG) of the NST in short-term food intake. One-third of the stomach food content was withdrawn at 5 min after the end of a meal, and food was then available ad libitum for different time periods. SolG-lesioned and control animals ingested a similar amount of the initial liquid meal, but the former consumed significantly smaller amounts and failed to compensate for the food deficit, whereas the controls re-ingested virtually the same amount as extracted. These data suggest that the SolG, as in the case of related anatomical structures such as the vagus nerve or external lateral parabrachial subnucleus, may be relevant in particular circumstances that require the rapid processing of vagal-related food intake adjustment associated to the upper gastrointestinal tract.

No impact of repeated extinction exposures on operant responding maintained by different reinforcer rates

Greater rates of intermittent reinforcement in the presence of discriminative stimuli generally produce greater resistance to extinction, consistent with predictions of behavioral momentum theory. Other studies reveal more rapid extinction with higher rates of reinforcers - the partial reinforcement extinction effect. Further, repeated extinction often produces more rapid decreases in operant responding due to learning a discrimination between training and extinction contingencies. The present study examined extinction repeatedly with training with different rates of intermittent reinforcement in a multiple schedule. We assessed whether repeated extinction would reverse the pattern of greater resistance to extinction with greater reinforcer rates. Counter to this prediction, resistance to extinction was consistently greater across twelve assessments of training followed by six successive sessions of extinction. Moreover, patterns of responding during extinction resembled those observed during satiation tests, which should not alter discrimination processes with repeated testing. These findings join others suggesting operant responding in extinction can be durable across repeated tests.

Comparison of oro-sensory exposure duration and intensity manipulations on satiation

Oro-sensory exposure (OSE) is an important factor in the regulation of food intake with increasing OSE leading to lower food intake. Oral processing time and taste intensity both play an important role in OSE but their individual contribution to satiation is unknown. We aimed to determine the independent and combined effects of oral processing time and taste intensity on satiation. Fifty eight participants (23±9y, BMI 22±2kg/m²) participated in a 2×2 factorial randomized crossover study in which they consumed one of four gel-based model foods until satiation during four sessions. Model foods were offered ad libitum and differed in texture (soft or hard texture, yielding shorter and longer oral processing time) and sweetness (low or high intensity). Model foods were isocaloric and were matched for flavor and palatability. Outcome measures were intake of the model food and the microstructure of eating behavior, such as number of chews and eating rate. There was an overall significant effect of texture (p<0.001) but not sweetness (p=0.33) on intake with a 29.2% higher intake of the soft model foods compared to the hard model foods. After correction for palatability the difference in intake between the soft and hard model foods was 21.5% (p<0.001). The number of chews was significantly lower for the soft (10.1±6.2) than for the hard (26.9±6.2) model foods (p<0.001), which resulted in a significantly lower eating rate (soft, 26.3±10.2 and hard, 15.3±7.1g/min, p<0.001). These results show that increasing texture hardness of gel model foods decreases food intake independent of sweet taste intensity. The higher number of chews and faster eating rate may cause this effect. In conclusion, oro-sensory exposure duration rather than taste intensity appears to be the main determinant of food intake.

Effects of polydextrose with breakfast or with a midmorning preload on food intake and other appetite-related parameters in healthy normal-weight and overweight females: An acute, randomized, double-blind, placebo-controlled, and crossover study

Polydextrose (PDX) reduces subsequent energy intake (EI) when administered at midmorning in single-blind trials of primarily normal-weight men. However, it is unclear if this effect also occurs when PDX is given at breakfast time. Furthermore, for ecological validity, it is desirable to study a female population, including those at risk for obesity. We studied the effects of PDX, served as part of a breakfast or midmorning preload, on subsequent EI and other appetite-related parameters in healthy normal-weight and overweight females. Per earlier studies, the primary outcome was defined as the difference in subsequent EI when PDX was consumed at midmorning versus placebo. Thirty-two volunteers were enrolled in this acute, double-blind, placebo-controlled, randomized, and crossover trial to examine the effects of 12.5 g of PDX, administered as part of a breakfast or midmorning preload, on subsequent EI, subjective feelings of appetite, well-being, and mood. Gastric emptying rates and the blood concentrations of glucose, insulin, cholecystokinin, ghrelin, glucagon-like peptide 1 (GLP-1), and peptide tyrosine-tyrosine were measured in the group that received PDX as part of their breakfast. There were no differences in EI between volunteers who were fed PDX and placebo. PDX intake with breakfast tended to elevate blood glucose (P = 0.06) during the postabsorptive phase, significantly lowered insulin by 15.7% (P = 0.04), and increased GLP-1 by 39.9% (P = 0.02); no other effects on blood parameters or gastric emptying rates were observed. PDX intake at midmorning reduced hunger by 31.4% during the satiation period (P = 0.02); all other subjective feelings of appetite were unaffected. Volunteers had a uniform mood profile during the study. PDX was well tolerated, causing one mild adverse event throughout the trial.

Modulation of sweet preference by the actual and anticipated consequences of eating

Previous research has shown that non-human animals exhibit an inverted-U pattern of sweet preference, with consumption increasing across moderate levels of sweetness and then declining for high levels of sweetness. In rodents, this pattern reflects an avoidance of the postingestive effects of consuming energy-dense sugar solutions (conditioned satiation). Here, we examined whether humans also adjust their preferences to compensate for the anticipated energy content/satiating outcomes of consuming sweetened foods. In two experiments (each N = 40), participants were asked to taste and imagine eating small (15 g) and large (250 g) portions of five novel desserts that varied in sweetness. Participants evaluated the desserts' expected satiety, expected satiation, and expected sickliness. A measure of estimated energy content was also derived using a computerized energy compensation test. This procedure was completed before and after consuming a standard lunch. Across both experiments, results confirmed that participants preferred a less sweet dessert when asked to imagine eating a large versus a small portion, and when rating the dessert in a fed versus fasted state. We also obtained evidence that participants anticipated more energy from the sweeter desserts (even in Experiment 2 when half of the participants were informed that the desserts were equated for energy content). However we found only partial evidence for anticipated satiation-expected sickliness was related systematically to increases in sweetness, but expected satiation and expected satiety were only weakly influenced. These findings raise questions about the role of sweetness in the control of food intake (in humans) and the degree to which 'sweet-calorie learning' occurs in complex dietary environments where sweetness may actually be a poor predictor of the energy content of foods.

CCK increases the transport of insulin into the brain

Food intake occurs in bouts or meals, and numerous meal-generated signals have been identified that act to limit the size of ongoing meals. Hormones such as cholecystokinin (CCK) are secreted from the intestine as ingested food is being processed, and in addition to aiding the digestive process, they provide a signal to the brain that contributes to satiation, limiting the size of the meal. The potency of CCK to elicit satiation is enhanced by elevated levels of adiposity signals such as insulin. In the present experiments we asked whether CCK and insulin interact at the level of the blood-brain barrier (BBB). We first isolated rat brain capillary endothelial cells that comprise the BBB and found that they express the mRNA for both the CCK1R and the insulin receptor, providing a basis for a possible interaction. We then administered insulin intraperitoneally to another group of rats and 15min later administered CCK-8 intraperitoneally to half of those rats. After another 15min, CSF and blood samples were obtained and assayed for immunoreactive insulin. Plasma insulin was comparably elevated above baseline in both the CCK-8 and control groups, indicating that the CCK had no effect on circulating insulin levels given these parameters. In contrast, rats administered CCK had CSF-insulin levels that were more than twice as high as those of control rats. We conclude that circulating CCK greatly facilitates the transport of insulin into the brain, likely by acting directly at the BBB. These findings imply that in circumstances in which the plasma levels of both CCK and insulin are elevated, such as during and soon after meals, satiation is likely to be due, in part, to this newly-discovered synergy between CCK and insulin.

The evolution of consumption and its welfare effects

In this paper the evolution of consumption is explained on the basis of a theory that connects preferences over actions to the motivational forces driving actions. More specifically, the hypotheses about what motivates consumption activities draw on insights from biology, behavioral science, and psychology. With secularly rising income, the growing consumption opportunities and the expanding consumption alter the underlying motivational forces and induce a change of preferences. As a consequence, the structure of consumption expenditures is systematically transformed. In the light of this explanation, the paper analyzes the effects of the growth and transformation of consumption on individual welfare. As turns out, the motivations driving the growth of consumption do not necessarily imply that this growth indeed results in welfare increases, particularly when the ability to spend on consumption is already high. Moreover, when preferences change, the measurement of the welfare effects of the growth and transformation of consumption depends on the arbitrary choice of a reference point. This implies an ambiguity that raises further queries about the normative foundations of the ubiquitous calls for continued consumption growth.

Thirst responses following high intensity intermittent exercise when access to ad libitum water intake was permitted, not permitted or delayed

An increase in subjective feelings of thirst and ad libitum drinking caused by an increase in serum osmolality have been observed following high intensity intermittent exercise (HIIE) compared to continuous exercise. The increase in serum osmolality is closely linked to the rise in blood lactate and serum sodium concentrations. However, during an ensuing recovery period after HIIE when serum osmolality will decrease, the resultant effect on sensations of thirst and subsequent water intake is unclear. Therefore the aim of the study was to assess the sensations of thirst and subsequent effect on ad libitum water consumption when water intake was immediately allowed, delayed or prevented following a period of HIIE.

METHODS

Twelve males (26±4 years, 80.1±9.3 kg, 1.81±0.05 m, V̇O2peak 60.1±8.9 ml·kg(-1)·min(-1)) participated in three randomised trials undertaken 7-14 days apart. Participants rested for 30 min then completed a 60 min HIIE exercise period (20×1 min at 100% V̇O2peak with 2 min rest) followed by 60 min of recovery, during which ad libitum water intake was provided immediately (W), delayed until the final 30 min (W30) or not permitted (NW). Body mass was measured at the start and end of the trial. Blood lactate and serum sodium concentrations serum osmolality and sensation of thirst were measured at baseline, immediately post-exercise and during the recovery.

RESULTS

Body mass loss was different between all trials (W: 0.25±0.45, W30: 0.49±0.37, NW: 1.29±0.37%; p<0.05). Sensations of thirst peaked post-exercise and decreased in W and W30 following water ingestion (p<0.05). Total voluntary water intake was greater in W trial (0.846±0.417 vs. 0.630±0.277l; p<0.05) but was similar during the first 30 min period of allowed drinking (0.618±0.297 vs. 0.630±0.277l; p>0.05). Serum osmolality (299±6 vs. 298±5 vs. 298±3 mOsmol·kg(-1)), blood lactate (7.1±1.1 vs. 7.2±1.1 vs. 7.1±1.2 mmol·l(-1)) and serum sodium concentrations (142±2 vs. 145±2 vs. 145±2 mmol·l(-1)) peaked post-exercise (W vs. W30 vs. NW; p<0.05) but were not different between trials (p>0.05).

CONCLUSIONS

Sensations of thirst were increased following HIIE and remained until satiated by water intake. This was despite the likely primary stimulus, serum osmolality, decreasing during the recovery period following a post-exercise peak. A combined effect of reduction in blood lactate and serum sodium concentrations, restoration of plasma volume and water intake contributed to the similar decrease in serum osmolality observed throughout the trials.

Hunger and Satiety Mechanisms and Their Potential Exploitation in the Regulation of Food Intake

Effective strategies to combat recent rises in obesity levels are limited. The accumulation of excess body fat results when energy intake exceeds that expended. Energy balance is controlled by hypothalamic responses, but these can be overridden by hedonic/reward brain systems. This override, combined with unprecedented availability of cheap, energy-dense, palatable foods, may partly explain the increase in overweight and obesity. The complexity of the processes that regulate feeding behaviour has driven the need for further fundamental research. Full4Health is an EU-funded project conceived to advance our understanding of hunger and satiety mechanisms. Food intake has an impact on and is also affected by the gut-brain signalling which controls hunger and appetite. This review describes selected recent research from Full4Health and how new mechanistic findings could be exploited to adapt and control our physiological responses to food, potentially providing an alternative solution to addressing the global problems related to positive energy balance.

Postprandial profiles of CCK after high fat and high carbohydrate meals and the relationship to satiety in humans

CONTEXT

CCK is understood to play a major role in appetite regulation. Difficulties in measuring CCK have limited the potential to assess its profile in relation to food-induced satiety. Improvements in methodology and progress in theoretical understanding of satiety/satiation make it timely for this to be revisited.

OBJECTIVE

First, examine how physiologically relevant postprandial CCK8/33(s) profiles are influenced by fat (HF) or carbohydrate (HCHO) meals. Second, to examine relationships between postprandial CCK and profiles of satiety (hunger/fullness) and satiation (meal size).

PARTICIPANTS AND DESIGN

Sixteen overweight/obese adults (11 females/5 males) participated in a randomised-crossover study (46 years, 29.8 kg/m(2)) in a university research centre. Plasma was collected preprandially and for 180 min postprandially. Simultaneously, ratings of hunger/fullness were tracked for 180 min before an ad libitum lunch was provided.

RESULTS

CCK8/33(s) levels increased more rapidly and reached a higher peak following HF compared to HCHO breakfast (F(1,15)=14.737, p<0.01). Profiles of hunger/fullness did not differ between conditions (F(1,15)=0.505, p=0.488; F(1,15)=2.277, p=0.152). There was no difference in energy intake from the ad libitum meal (HF-3958 versus HCHO-3925 kJ; t(14)=0.201, p=0.844). CCK8/33(s) profiles were not associated with subjective appetite during early and late phases of satiety; nor was there an association between CCK8/33(s) and meal size.

CONCLUSIONS

These results demonstrate CCK levels were higher after HF meal compared to HCHO isocaloric meal. There was no association between CCK levels and intensity of satiety, or with meal size. Under these circumstances, CCK does not appear to play a unique independent role in satiety/satiation. CCK probably acts in conjunction with other peptides and the action of the stomach.

Satiety Innovations: Food Products to Assist Consumers with Weight Loss, Evidence on the Role of Satiety in Healthy Eating: Overview and In Vitro Approximation

The prevalence of overweight and obesity is increasing globally, driven by the availability of energy-dense palatable foods. Most dietary strategies fail because of hunger generated by calorie restriction, and interventions that specifically control hunger and/or promote fullness may aid success. Current consumers have a limited choice of satiety-enhancing products with proven health benefits, and innovative ways to produce new foods (as structural modification) to enhance satiety/satiation may provide new opportunities. However, this potential is hindered by the cost of product testing. Within the SATIN-SATiety INnovation project-an in vitro platform has been developed to offer a cost-effective means of assessing the potential satiation/satiety effect of novel foods. This combines in vitro technologies to assess changes in colonic bacteria metabolism, appetite hormone release and the stability and bioavailability of active compounds in the new products/ingredients. This article provides a brief review of nutrients for which an impact on short-term appetite regulation has been demonstrated, and a summary of the changes to food structure which can be used to produce a change in appetite expression. Furthermore, the SATIN in vitro platform is discussed as a means of assessing the impact of nutritional and structural manipulations on appetite.