Appetite
Peptide YY
Ghrelin
Satiation
Hypothalamus
Leptin
Obesity
Body Weight
Appetite Stimulants
Nutrient-specific preferences by lambs conditioned with intraruminal infusions of starch, casein, and water. (1/419)
We hypothesized that lambs discriminate between postingestive effects of energy and protein and associate those effects with a food's flavor to modify food choices. Based on this hypothesis, we predicted that 1) lambs would acquire a preference for a poorly nutritious food (grape pomace) eaten during intraruminal infusions of energy (starch) or protein (casein) and that 2) shortly after an intraruminal infusion of energy or protein (preload), lambs would decrease their preferences for foods previously conditioned with starch or casein, respectively. Thirty lambs were allotted to three groups and conditioned as follows. On d 1, lambs in each group received grape pomace containing a different flavor and water was infused into their rumens as they ate the pomace. On d 2, the flavors were switched so each group received a new flavor and a suspension of starch (10% of the DE required per day) replaced the water infusion. On d 3, the flavors were switched again, and a suspension of casein (2.7 to 5.4% of the CP required per day) replaced the starch infusion. Conditioning was repeated during four consecutive trials. Lambs in Trial 1 had a basal diet of alfalfa pellets (e.g., free access from 1200 to 1700) and 400 g of rolled barley. Lambs in Trials 2, 3, and 4 received a restricted amount of alfalfa pellets (990 g/d) as their basal diet. After conditioning, all animals received an infusion of water, and, 30 min later, they were offered a choice of the three flavors previously paired with water, starch, or casein. On the ensuing days, the choice was repeated, but starch, casein, and barley replaced the water preload. The nutrient density of the infused preloads was increased during consecutive trials. Lambs preferred the flavors paired with starch > water > casein during Trial 1 (P < .05) and the flavors paired with starch > casein > water during Trials 2 (P < .05), 3 (P < .001), and 4 (P < .001). Preloads of casein decreased preferences for flavors previously paired with casein (P < .10 [Trial 2]; P < .001 [Trial 3], and increased preferences for flavors paired with starch (P < .05 [Trial 2]; P < .001 [Trial 3]). Preloads of energy (barley) had the opposite effect (P < .05 [Trial 3]). These results indicate that lambs discriminated between the postingestive effects of starch and casein and associated the effects with specific external cues (i.e., added flavors) to regulate macronutrient ingestion. (+info)The role of apolipoprotein A-IV in food intake regulation. (2/419)
Apolipoprotein (apo) A-IV is a glycoprotein synthesized by the human intestine. In rodents, both the small intestine and the liver secrete apo A-IV; the small intestine, however, is by far the major organ responsible for the circulating apo A-IV. Intestinal apo A-IV synthesis is markedly stimulated by fat absorption and appears not to be mediated by the uptake or reesterification of fatty acids to form triglycerides. Rather, it is the formation of chylomicrons that acts as a signal for the induction of intestinal apo A-IV synthesis. Intestinal apo A-IV synthesis is also enhanced by a factor from the ileum and that factor is probably peptide tyrosine-tyrosine (PYY). The inhibition of food intake by apo A-IV is probably mediated centrally. The stimulation of intestinal synthesis and secretion of apo A-IV by lipid absorption are rapid; thus, apo A-IV likely plays a role in the short-term regulation of food intake. Other evidence suggests that apo A-IV may also be involved in the long-term regulation of food intake and body weight. Chronic ingestion of a high fat diet blunts the intestinal apo A-IV response to lipid feeding and may explain why the chronic ingestion of a high fat diet predisposes both animals and humans to obesity. (+info)Geriatric cachexia: the role of cytokines. (3/419)
Weight loss in elderly patients is a common clinical problem. Wasting and cachexia are associated with severe physiologic, psychologic, and immunologic consequences, regardless of the underlying causes. Cachexia has been associated with infections, decubitus ulcers, and even death. Multivariate analyses of risk and prognostic factors in community-acquired pneumonia in the elderly have found that age by itself is not a significant factor related to prognosis. Among the significant risk factors, only nutritional status is amenable to medical intervention. Cachexia in the elderly may have profound consequences: medical, cognitive, and psychiatric disorders may diminish self-reliance in activities of daily living, thus reducing quality of life and increasing the frequency of secondary procedures, hospitalizations, and the need for skilled care. Cachexia is associated with higher-than-normal concentrations of tumor necrosis factor alpha (TNF-alpha), interleukin (IL) 1, IL-6, serotonin, and interferon gamma. The role of these proinflammatory cytokines has been established in the cachexia seen in cancer and AIDS patients. Reduction in the concentrations of these cytokines is associated with weight gain. Drugs that promote appetite stimulation and weight gain, such as progestational agents, cyproheptadines, pentoxifylline, and thalidomide may work by down-regulating these proinflammatory cytokines. An understanding of the relation between cachexia and negative regulatory cytokines may point to effective treatment of geriatric cachexia as well. (+info)p-Chloroamphetamine (PCA) suppresses ingestive behavior in male rats. (4/419)
Ingestive behavior was activated in male rats by intraoral intake and intake from a bottle of 1-M solution of sucrose. Intraperitoneal injection of p-chloroamphetamine (PCA), releasing central 5-hydroxytryptamine (5-HT) from serotonergic nerve terminals, inhibited ingestion of the sucrose solution. Significant inhibition of sucrose intake by PCA was observed at 1.25 and 2.5 mg/kg dose in a bottle intake test, and at 5.0 mg/kg dose in an intraoral intake test. These findings suggested that 1.25 and 5.0 mg/kg of PCA suppressed appetitive ingestive behavior and consummatory ingestive behavior in male rats, respectively. (+info)Simultaneous observation of ingestive and copulatory behavior of the male rat. (5/419)
In a preliminary test male rats were allowed to ingest a 1 M solution of sucrose from a drinking spout. After daily intake of sucrose became stabilized, the males were given a sexually receptive or non-receptive female and the bottle filled with sucrose solution simultaneously. The ingestive and copulatory behavior was observed for 60 min under illumination by a red lamp. The data obtained from this study showed that the ingestive behavior of males was suppressed by the presence of sexually receptive females and, conversely, the sexual behavior of males was not affected by the presence of a bottle of sucrose. These results suggest that the presence of a sexual partner inhibits appetitive ingestive behavior, i.e., the responses used by male rats to obtain food. (+info)Origins of nutritional imbalance in cancer. (6/419)
Some parallels and differences are considered between the nutritional circumstances that favor carcinogenesis and those that favor tumor growth and host cachexia. From evidence on deletion of physiological feeding controls and changes in feeding behavior during tumor growth and from evidence on differences in sets of available feeding controls and in feeding behavior among normal individuals, it is suggested that acquisition of possibly carcinogenic dietary habits may originate, in part, from innate deficits in physiological feeding controls. (+info)Neurobiology of zinc-influenced eating behavior. (7/419)
Zinc is an essential nutrient that is required in humans and animals for many physiological functions, including immune and antioxidant function, growth and reproduction. Many aspects of zinc deficiency-induced anorexia have been well studied in experimental animals, most notably the laboratory rat. There is evidence that suggests zinc deficiency may be intimately involved with anorexia in humans: if not as an initiating cause, then as an accelerating or exacerbating factor that may deepen the pathology of the anorexia. The present review describes recent research investigating the relationship between zinc deficiency and the regulation of food intake, along with advances in the understanding of the food intake and body weight regulation systems. For more comprehensive reviews of zinc nutrition and zinc deficiency, readers are referred to the other reviews in this volume and the review text of Mills (1989). An excellent review focused solely on zinc status and food intake has been presented by O'Dell and Reeves (1989). (+info)Secretory, endocrine and autocrine/paracrine function of the adipocyte. (8/419)
Obesity is a major public health problem in Western countries, and >55% of adult Americans are overweight or obese. A major contributor to the epidemic of obesity is the current environment, which is characterized by increased availability of high energy foods and decreased physical activity. Several studies also demonstrated that genetic susceptibility contributes to obesity in some populations. Obesity research has focused primarily on the role of the hypothalamus in neuroendocrine regulation of food intake. However, a growing number of studies support a potential contribution of adipose tissue, via its newly discovered secretory function, to the pathogenesis of obesity and co-morbid conditions including cardiovascular disease, diabetes and hypertension. This paper will review the role of four factors secreted by adipose tissue (leptin, agouti, angiotensin II and prostaglandins) and their functions in the regulation of energy balance and whole-body homeostasis. Several other peptide and nonpeptide substances are secreted from adipose tissue; their function and regulation have been documented extensively. (+info)Appetite regulation refers to the physiological and psychological processes that control and influence the desire to eat food. This complex system involves a variety of hormones, neurotransmitters, and neural pathways that work together to help maintain energy balance and regulate body weight. The hypothalamus in the brain plays a key role in appetite regulation by integrating signals from the digestive system, fat cells, and other organs to adjust feelings of hunger and fullness.
The hormones leptin and ghrelin are also important regulators of appetite. Leptin is released from fat cells and acts on the hypothalamus to suppress appetite and promote weight loss, while ghrelin is produced in the stomach and stimulates appetite and promotes weight gain. Other factors that can influence appetite regulation include stress, emotions, sleep patterns, and cultural influences.
Abnormalities in appetite regulation can contribute to the development of eating disorders such as anorexia nervosa, bulimia nervosa, and binge eating disorder, as well as obesity and other health problems. Understanding the mechanisms of appetite regulation is an important area of research for developing effective treatments for these conditions.
Appetite is the desire to eat or drink something, which is often driven by feelings of hunger or thirst. It is a complex process that involves both physiological and psychological factors. Physiologically, appetite is influenced by the body's need for energy and nutrients, as well as various hormones and neurotransmitters that regulate hunger and satiety signals in the brain. Psychologically, appetite can be affected by emotions, mood, stress levels, and social factors such as the sight or smell of food.
In medical terms, a loss of appetite is often referred to as anorexia, which can be caused by various factors such as illness, medication, infection, or psychological conditions like depression. On the other hand, an excessive or abnormal appetite is known as polyphagia and can be a symptom of certain medical conditions such as diabetes or hyperthyroidism.
It's important to note that while "anorexia" is a medical term used to describe loss of appetite, it should not be confused with the eating disorder anorexia nervosa, which is a serious mental health condition characterized by restrictive eating, distorted body image, and fear of gaining weight.
Peptide YY (PYY) is a small peptide hormone consisting of 36 amino acids, that is released by the L cells in the intestinal epithelium in response to feeding. It is a member of the neuropeptide Y (NPY) family and plays a crucial role in regulating appetite and energy balance.
After eating, PYY is released into the circulation and acts on specific receptors in the hypothalamus to inhibit food intake. This anorexigenic effect of PYY is mediated by its ability to decrease gastric emptying, reduce intestinal motility, and increase satiety.
PYY has also been shown to have effects on glucose homeostasis, insulin secretion, and inflammation, making it a potential therapeutic target for the treatment of obesity, diabetes, and other metabolic disorders.
Ghrelin is a hormone primarily produced and released by the stomach with some production in the small intestine, pancreas, and brain. It is often referred to as the "hunger hormone" because it stimulates appetite, promotes food intake, and contributes to the regulation of energy balance.
Ghrelin levels increase before meals and decrease after eating. In addition to its role in regulating appetite and meal initiation, ghrelin also has other functions, such as modulating glucose metabolism, insulin secretion, gastric motility, and cardiovascular function. Its receptor, the growth hormone secretagogue receptor (GHS-R), is found in various tissues throughout the body, indicating its wide range of physiological roles.
Satiation is a term used in the field of nutrition and physiology, which refers to the feeling of fullness or satisfaction that one experiences after eating food. It is the point at which further consumption of food no longer adds to the sensation of hunger or the desire to eat. This response is influenced by various factors such as the type and amount of food consumed, nutrient composition, energy density, individual appetite regulatory hormones, and gastric distension.
Satiation plays a crucial role in regulating food intake and maintaining energy balance. Understanding the mechanisms underlying satiation can help individuals make healthier food choices and prevent overeating, thereby reducing the risk of obesity and other related health issues.
The medical definition of "eating" refers to the process of consuming and ingesting food or nutrients into the body. This process typically involves several steps, including:
1. Food preparation: This may involve cleaning, chopping, cooking, or combining ingredients to make them ready for consumption.
2. Ingestion: The act of taking food or nutrients into the mouth and swallowing it.
3. Digestion: Once food is ingested, it travels down the esophagus and enters the stomach, where it is broken down by enzymes and acids to facilitate absorption of nutrients.
4. Absorption: Nutrients are absorbed through the walls of the small intestine and transported to cells throughout the body for use as energy or building blocks for growth and repair.
5. Elimination: Undigested food and waste products are eliminated from the body through the large intestine (colon) and rectum.
Eating is an essential function that provides the body with the nutrients it needs to maintain health, grow, and repair itself. Disorders of eating, such as anorexia nervosa or bulimia nervosa, can have serious consequences for physical and mental health.
The hypothalamus is a small, vital region of the brain that lies just below the thalamus and forms part of the limbic system. It plays a crucial role in many important functions including:
1. Regulation of body temperature, hunger, thirst, fatigue, sleep, and circadian rhythms.
2. Production and regulation of hormones through its connection with the pituitary gland (the hypophysis). It controls the release of various hormones by producing releasing and inhibiting factors that regulate the anterior pituitary's function.
3. Emotional responses, behavior, and memory formation through its connections with the limbic system structures like the amygdala and hippocampus.
4. Autonomic nervous system regulation, which controls involuntary physiological functions such as heart rate, blood pressure, and digestion.
5. Regulation of the immune system by interacting with the autonomic nervous system.
Damage to the hypothalamus can lead to various disorders like diabetes insipidus, growth hormone deficiency, altered temperature regulation, sleep disturbances, and emotional or behavioral changes.
Leptin is a hormone primarily produced and released by adipocytes, which are the fat cells in our body. It plays a crucial role in regulating energy balance and appetite by sending signals to the brain when the body has had enough food. This helps control body weight by suppressing hunger and increasing energy expenditure. Leptin also influences various metabolic processes, including glucose homeostasis, neuroendocrine function, and immune response. Defects in leptin signaling can lead to obesity and other metabolic disorders.
Obesity is a complex disease characterized by an excess accumulation of body fat to the extent that it negatively impacts health. It's typically defined using Body Mass Index (BMI), a measure calculated from a person's weight and height. A BMI of 30 or higher is indicative of obesity. However, it's important to note that while BMI can be a useful tool for identifying obesity in populations, it does not directly measure body fat and may not accurately reflect health status in individuals. Other factors such as waist circumference, blood pressure, cholesterol levels, and blood sugar levels should also be considered when assessing health risks associated with weight.
Body weight is the measure of the force exerted on a scale or balance by an object's mass, most commonly expressed in units such as pounds (lb) or kilograms (kg). In the context of medical definitions, body weight typically refers to an individual's total weight, which includes their skeletal muscle, fat, organs, and bodily fluids.
Healthcare professionals often use body weight as a basic indicator of overall health status, as it can provide insights into various aspects of a person's health, such as nutritional status, metabolic function, and risk factors for certain diseases. For example, being significantly underweight or overweight can increase the risk of developing conditions like malnutrition, diabetes, heart disease, and certain types of cancer.
It is important to note that body weight alone may not provide a complete picture of an individual's health, as it does not account for factors such as muscle mass, bone density, or body composition. Therefore, healthcare professionals often use additional measures, such as body mass index (BMI), waist circumference, and blood tests, to assess overall health status more comprehensively.
Appetite depressants are medications or substances that reduce or suppress feelings of hunger and appetite. They can be prescribed to treat various medical conditions, such as obesity or binge eating disorder, where weight loss is a recommended treatment goal. Some common appetite depressants include:
1. Phentermine: This medication works by stimulating the release of certain neurotransmitters in the brain that help suppress appetite and increase metabolism. It is often prescribed for short-term use (up to 12 weeks) as part of a comprehensive weight loss plan.
2. Diethylpropion: Similar to phentermine, diethylpropion stimulates the release of neurotransmitters that suppress appetite and increase metabolism. It is also prescribed for short-term use in treating obesity.
3. Naltrexone-bupropion (Contrave): This combination medication helps manage weight by reducing appetite and increasing feelings of fullness. Naltrexone is an opioid antagonist that blocks the rewarding effects of food, while bupropion is an antidepressant that can help reduce cravings for high-calorie foods.
4. Lorcaserin (Belviq): This medication works by selectively activating serotonin receptors in the brain, which helps promote satiety and reduce appetite. It was withdrawn from the US market in 2020 due to concerns about its potential link to an increased risk of cancer.
5. Topiramate (Topamax): Although primarily used as an anticonvulsant, topiramate has also been found to have appetite-suppressing effects. It is often combined with phentermine in a single formulation (Qsymia) for the treatment of obesity.
6. Cannabis: Some studies suggest that cannabinoids, the active compounds in marijuana, may help reduce hunger and promote weight loss by interacting with the endocannabinoid system in the body. However, more research is needed to fully understand its potential as an appetite depressant.
It's important to note that appetite suppressants should only be used under the guidance of a healthcare professional and as part of a comprehensive weight management plan. These medications can have side effects and potential risks, so it's crucial to discuss their use with your doctor before starting any new treatment regimen.
Appetite stimulants are medications or substances that increase the desire to eat or improve appetite. They work by affecting brain chemicals, hormones, or other systems involved in regulating hunger and fullness. Some commonly used appetite stimulants include:
1. Megestrol acetate: a synthetic progestin hormone that is often prescribed for cancer-related weight loss and anorexia. It works by stimulating appetite and promoting weight gain.
2. Dronabinol: a synthetic form of THC, the active ingredient in marijuana. It is approved for treating AIDS-related anorexia and chemotherapy-induced nausea and vomiting. Dronabinol can increase appetite and promote weight gain.
3. Corticosteroids: medications that mimic the effects of hormones produced by the adrenal gland. They can help improve appetite, but their long-term use is associated with significant side effects.
4. Cyproheptadine: an antihistamine medication that can also stimulate appetite. It is sometimes used off-label to treat appetite loss in various conditions, such as cancer or HIV/AIDS.
5. Ghrelin agonists: these are medications that mimic the effects of ghrelin, a hormone produced by the stomach that increases hunger and appetite. Currently, there are no FDA-approved ghrelin agonists for appetite stimulation, but research is ongoing.
It's important to note that while appetite stimulants can help improve food intake in some individuals, they may not be effective for everyone, and their use should be carefully monitored due to potential side effects and interactions with other medications. Always consult a healthcare professional before starting any new medication or supplement.
In medical terms, "hunger" is not specifically defined as a clinical condition. However, it generally refers to the physiological need or desire for food and calories, driven by mechanisms in the brain and body that regulate energy balance. This sensation often arises when the body's energy stores are depleted, or when there has been a prolonged period without food intake.
Hunger is primarily mediated by hormones such as ghrelin, which stimulates appetite, and leptin, which signals satiety. The hypothalamus in the brain plays a crucial role in integrating these hormonal signals to regulate hunger and energy balance. Additionally, other factors like sleep deprivation, stress, and certain medical conditions can also influence feelings of hunger.
Satiety response is a term used in the field of nutrition and physiology to describe the feeling of fullness or satisfaction that follows food consumption. It is a complex process regulated by several factors, including the mechanical and chemical signals generated during digestion, hormonal responses, and psychological factors. The satiety response helps control food intake and energy balance by inhibiting further eating until the body has had enough time to metabolize and absorb the nutrients from the meal.
The satiety response can be influenced by various factors such as the type, volume, and texture of food consumed, as well as individual differences in appetite regulation and metabolism. Understanding the mechanisms underlying the satiety response is important for developing strategies to promote healthy eating behaviors and prevent overeating, which can contribute to obesity and other health problems.
Anorexia is a medical condition defined as a loss of appetite or aversion to food, leading to significant weight loss. It can be a symptom of various underlying causes, such as mental health disorders (most commonly an eating disorder called anorexia nervosa), gastrointestinal issues, cancer, infections, or side effects of medication. In this definition, we are primarily referring to anorexia as a symptom rather than the specific eating disorder anorexia nervosa.
Anorexia nervosa is a psychological eating disorder characterized by:
1. Restriction of energy intake leading to significantly low body weight (in context of age, sex, developmental trajectory, and physical health)
2. Intense fear of gaining weight or becoming fat, or persistent behavior that interferes with weight gain
3. Disturbed body image, such as overvaluation of self-worth regarding shape or weight, or denial of the seriousness of low body weight
Anorexia nervosa has two subtypes: restricting type and binge eating/purging type. The restricting type involves limiting food intake without engaging in binge eating or purging behaviors (such as self-induced vomiting or misuse of laxatives, diuretics, or enemas). In contrast, the binge eating/purging type includes recurrent episodes of binge eating and compensatory behaviors to prevent weight gain.
It is essential to differentiate between anorexia as a symptom and anorexia nervosa as a distinct psychological disorder when discussing medical definitions.