{"id":721,"date":"2023-03-10T18:01:49","date_gmt":"2023-03-10T18:01:49","guid":{"rendered":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/chapter\/hunger-and-eating\/"},"modified":"2026-01-15T15:56:34","modified_gmt":"2026-01-15T15:56:34","slug":"hunger-and-eating","status":"publish","type":"chapter","link":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/chapter\/hunger-and-eating\/","title":{"raw":"Hunger and Eating: Learn It 1\u2014Metabolism","rendered":"Hunger and Eating: Learn It 1\u2014Metabolism"},"content":{"raw":"<section class=\"textbox learningGoals\">\r\n<ul>\r\n\t<li>Describe how hunger and eating are regulated<\/li>\r\n\t<li>Understand the link between metabolism, obesity, and health<\/li>\r\n\t<li>Describe anorexia and bulimia nervosa and their negative impacts<\/li>\r\n<\/ul>\r\n<\/section>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Eating is essential for survival, and it's no surprise that powerful drives exist to ensure we seek out sustenance. While this section focuses primarily on the physiological mechanisms that regulate hunger and eating, social, cultural, and economic influences also play important roles in food consumption. We'll explore how hunger is regulated, how the body manages weight, and the consequences of disordered eating.<\/p>\r\n<h2>Physiological Mechanisms<\/h2>\r\n<h3 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">Hunger Signals<\/h3>\r\n\r\n[caption id=\"attachment_6890\" align=\"alignright\" width=\"522\"]<a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03202401\/3ce5275484855e103238ba1db10bc0923a5995e5.jpeg\"><img class=\" wp-image-6890\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03202401\/3ce5275484855e103238ba1db10bc0923a5995e5.jpeg\" alt=\"An outline of the top half of a human body contains illustrations of the brain and the stomach in their relative locations. A line extends from the location of the hypothalamus in the brain illustration, out to the left, past the outline, where it meets a box labeled \u201cHunger.\u201d Down-facing arrows connect that box to a box labeled \u201cFood,\u201d and the box labeled \u201cFood\u201d to a box labeled \u201cSatiety.\u201d A line extends out to the right from the box labeled \u201cSatiety,\u201d and meets with the illustration of the stomach.\" width=\"522\" height=\"439\" \/><\/a> <strong>Figure 1<\/strong>. Hunger and eating are regulated by a complex interplay of hunger and satiety signals that are integrated in the brain.[\/caption]\r\n\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Multiple physiological mechanisms trigger hunger:<\/p>\r\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\r\n\t<li class=\"whitespace-normal break-words pl-2\"><strong>Stomach contractions<\/strong> of an empty stomach send chemical messages signaling the need to eat<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\"><strong>Glucose levels<\/strong> \u2014 When blood glucose drops, the pancreas and liver generate chemical signals that induce hunger (Konturek et al., 2003)<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\"><strong>Ghrelin<\/strong> \u2014 Often called the \"hunger hormone,\" ghrelin is released by the stomach when it's empty and stimulates appetite<\/li>\r\n<\/ul>\r\n<h3 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">Satiety Signals<\/h3>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"><strong>Satiation<\/strong>\u2014the feeling of fullness and satisfaction after eating\u2014is also regulated by physiological mechanisms:<\/p>\r\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\r\n\t<li class=\"whitespace-normal break-words pl-2\"><strong>Glucose increases<\/strong> signal the pancreas and liver to shut off hunger (Drazen &amp; Woods, 2003)<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\"><strong>Gastrointestinal signals<\/strong> \u2014 Food passing through the digestive tract provides important satiety signals to the brain (Woods, 2004)<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\"><strong>Leptin<\/strong> \u2014 This hormone, produced by adipose (fat) tissue, signals fullness to the brain. Higher fat stores lead to more leptin, which typically reduces appetite<\/li>\r\n<\/ul>\r\n<h3 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">The Brain's Role<\/h3>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">The various hunger and satiety signals are integrated in the brain, particularly in the <strong>hypothalamus<\/strong> and <strong>hindbrain<\/strong> (Ahima &amp; Antwi, 2008; Woods &amp; D'Alessio, 2008). The hypothalamus contains distinct populations of neurons:<\/p>\r\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\r\n\t<li class=\"whitespace-normal break-words pl-2\"><strong>Orexigenic neurons<\/strong> (appetite-stimulating) \u2014 including NPY and AgRP neurons<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\"><strong>Anorexigenic neurons<\/strong> (appetite-suppressing) \u2014 including POMC and CART neurons<\/li>\r\n<\/ul>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">The balance of activity between these neural populations ultimately determines whether we feel hungry or full.<\/p>\r\n<section class=\"textbox connectIt\" aria-label=\"Connect It\">\r\n<h3 class=\"text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold\">New Insights: GLP-1 and Appetite Regulation<\/h3>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Recent advances in obesity treatment have deepened our understanding of hunger regulation. <strong>Glucagon-like peptide-1 (GLP-1)<\/strong> is a hormone released by intestinal cells when nutrients are detected. GLP-1 plays a crucial role in signaling satiety to the brain.<\/p>\r\n<h4 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">How GLP-1 Works<\/h4>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">GLP-1 acts on receptors throughout the brain, particularly in:<\/p>\r\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\r\n\t<li class=\"whitespace-normal break-words pl-2\">The <strong>hypothalamus<\/strong>, where it activates satiety-promoting neurons and inhibits hunger-promoting neurons<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">The <strong>brainstem<\/strong> (area postrema and nucleus of the solitary tract), which lacks a blood-brain barrier and serves as a key entry point for appetite-regulating signals<\/li>\r\n<\/ul>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">GLP-1 also <strong>slows gastric emptying<\/strong>, meaning food stays in the stomach longer, prolonging feelings of fullness.<\/p>\r\n<h4 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">GLP-1 Medications<\/h4>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Medications that mimic GLP-1 (such as semaglutide, marketed as Ozempic and Wegovy) have transformed obesity treatment. These drugs bind to GLP-1 receptors in the brain, reducing hunger signals and increasing satiety. Clinical trials show average weight loss of 15-20% of body weight\u2014far exceeding previous medications.<\/p>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">The success of these medications confirms what researchers long suspected: <strong>hunger and satiety are not simply matters of willpower but are powerfully regulated by hormonal and neural systems<\/strong>. Understanding these biological mechanisms helps explain why weight loss can be so challenging and why pharmacological interventions can be effective for some individuals.<\/p>\r\n<\/section>\r\n<section data-depth=\"1\">\r\n<h2>Metabolism and Body Weight<\/h2>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Body weight is affected by multiple factors, including genetics, environment, and the balance between calories consumed and calories burned. When caloric intake exceeds use, the body stores excess energy as fat. When we consume fewer calories than we burn, stored fat is converted to energy.<\/p>\r\n<section class=\"textbox keyTakeaway\">\r\n<h3>metabolic rate<\/h3>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"><strong>Metabolic rate<\/strong> is the amount of energy expended in a given period. There is tremendous individual variability in metabolic rates\u2014people with higher rates burn calories more easily than those with lower rates. Metabolic rate is influenced by:<\/p>\r\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\r\n\t<li class=\"whitespace-normal break-words pl-2\">Body size and composition (muscle burns more calories than fat)<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Age (metabolism tends to slow with age)<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Sex (males typically have higher metabolic rates)<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Genetics<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Physical activity level<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Hormones (including thyroid hormones)<\/li>\r\n<\/ul>\r\n<\/section>\r\n<h2 class=\"text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold\">Theories of Weight Regulation<\/h2>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Most people's weight fluctuates within a relatively narrow range over time, even without conscious effort. This observation led researchers to propose theories about how body weight is regulated.<\/p>\r\n<section class=\"textbox keyTakeaway\">\r\n<h3>set point theory<\/h3>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"><strong>Set-point theory<\/strong> proposes that each person's body establishes and attempts to maintain a stable body weight that is partly genetically predetermined. According to this view, efforts to move weight significantly from the set point are resisted by compensatory changes in hunger, satiety, and energy expenditure (Speakman et al., 2011).<\/p>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">However, set-point theory has limitations:<\/p>\r\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\r\n\t<li class=\"whitespace-normal break-words pl-2\">It struggles to explain why obesity rates have risen dramatically in recent decades if we all have fixed set points<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Some predictions of the theory haven't been supported\u2014for example, studies found no lasting changes in metabolic rate between people who had lost significant weight and control groups (Weinsier et al., 2000)<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">The theory underemphasizes social and environmental factors in weight regulation<\/li>\r\n<\/ul>\r\n<\/section>\r\n<h3 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">Settling-Point Theory<\/h3>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Contemporary researchers increasingly favor <strong>settling-point theory<\/strong>, which proposes that rather than defending a single fixed weight, the body can stabilize at different \"settling points\" depending on the interaction between biology and environment.<\/p>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">In this model, body weight settles at a point where energy intake and expenditure reach equilibrium\u2014but that equilibrium point can shift based on:<\/p>\r\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\r\n\t<li class=\"whitespace-normal break-words pl-2\">Food environment (availability of high-calorie foods)<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Physical activity patterns<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Stress and sleep<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Social and economic factors<\/li>\r\n<\/ul>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">This helps explain why the same person might maintain a stable weight of 150 pounds in one environment but settle at 180 pounds in an environment with abundant high-calorie food and limited physical activity.<\/p>\r\n<h3 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">The Dual Intervention Point Model<\/h3>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">A more recent model proposes that rather than a single set point, there may be <strong>upper and lower intervention points<\/strong>\u2014boundaries beyond which the body actively defends against further weight change. Within this range, weight may drift based on environmental factors, but pushing beyond these boundaries triggers stronger physiological resistance.<\/p>\r\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">This model helps explain why:<\/p>\r\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\r\n\t<li class=\"whitespace-normal break-words pl-2\">The body strongly resists weight loss below a certain point (defending against starvation)<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Some individuals can gain significant weight before physiological \"brakes\" engage<\/li>\r\n\t<li class=\"whitespace-normal break-words pl-2\">Weight regain after dieting is so common<\/li>\r\n<\/ul>\r\n<\/section>\r\n<section data-depth=\"1\">\r\n<section class=\"textbox tryIt\">[ohm2_question height=\"200\"]4407[\/ohm2_question]<\/section>\r\n<section>\r\n<section class=\"textbox tryIt\" aria-label=\"Try It\">\r\n<p>Review the information presented above in the following exercise:<br \/>\r\n<iframe src=\"https:\/\/lumenlearning.h5p.com\/content\/1291068332047968138\/embed\" width=\"1088\" height=\"637\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\r\n<\/section>\r\n<\/section>\r\n<\/section>","rendered":"<section class=\"textbox learningGoals\">\n<ul>\n<li>Describe how hunger and eating are regulated<\/li>\n<li>Understand the link between metabolism, obesity, and health<\/li>\n<li>Describe anorexia and bulimia nervosa and their negative impacts<\/li>\n<\/ul>\n<\/section>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Eating is essential for survival, and it&#8217;s no surprise that powerful drives exist to ensure we seek out sustenance. While this section focuses primarily on the physiological mechanisms that regulate hunger and eating, social, cultural, and economic influences also play important roles in food consumption. We&#8217;ll explore how hunger is regulated, how the body manages weight, and the consequences of disordered eating.<\/p>\n<h2>Physiological Mechanisms<\/h2>\n<h3 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">Hunger Signals<\/h3>\n<figure id=\"attachment_6890\" aria-describedby=\"caption-attachment-6890\" style=\"width: 522px\" class=\"wp-caption alignright\"><a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03202401\/3ce5275484855e103238ba1db10bc0923a5995e5.jpeg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-6890\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/855\/2015\/02\/03202401\/3ce5275484855e103238ba1db10bc0923a5995e5.jpeg\" alt=\"An outline of the top half of a human body contains illustrations of the brain and the stomach in their relative locations. A line extends from the location of the hypothalamus in the brain illustration, out to the left, past the outline, where it meets a box labeled \u201cHunger.\u201d Down-facing arrows connect that box to a box labeled \u201cFood,\u201d and the box labeled \u201cFood\u201d to a box labeled \u201cSatiety.\u201d A line extends out to the right from the box labeled \u201cSatiety,\u201d and meets with the illustration of the stomach.\" width=\"522\" height=\"439\" \/><\/a><figcaption id=\"caption-attachment-6890\" class=\"wp-caption-text\"><strong>Figure 1<\/strong>. Hunger and eating are regulated by a complex interplay of hunger and satiety signals that are integrated in the brain.<\/figcaption><\/figure>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Multiple physiological mechanisms trigger hunger:<\/p>\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\n<li class=\"whitespace-normal break-words pl-2\"><strong>Stomach contractions<\/strong> of an empty stomach send chemical messages signaling the need to eat<\/li>\n<li class=\"whitespace-normal break-words pl-2\"><strong>Glucose levels<\/strong> \u2014 When blood glucose drops, the pancreas and liver generate chemical signals that induce hunger (Konturek et al., 2003)<\/li>\n<li class=\"whitespace-normal break-words pl-2\"><strong>Ghrelin<\/strong> \u2014 Often called the &#8220;hunger hormone,&#8221; ghrelin is released by the stomach when it&#8217;s empty and stimulates appetite<\/li>\n<\/ul>\n<h3 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">Satiety Signals<\/h3>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"><strong>Satiation<\/strong>\u2014the feeling of fullness and satisfaction after eating\u2014is also regulated by physiological mechanisms:<\/p>\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\n<li class=\"whitespace-normal break-words pl-2\"><strong>Glucose increases<\/strong> signal the pancreas and liver to shut off hunger (Drazen &amp; Woods, 2003)<\/li>\n<li class=\"whitespace-normal break-words pl-2\"><strong>Gastrointestinal signals<\/strong> \u2014 Food passing through the digestive tract provides important satiety signals to the brain (Woods, 2004)<\/li>\n<li class=\"whitespace-normal break-words pl-2\"><strong>Leptin<\/strong> \u2014 This hormone, produced by adipose (fat) tissue, signals fullness to the brain. Higher fat stores lead to more leptin, which typically reduces appetite<\/li>\n<\/ul>\n<h3 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">The Brain&#8217;s Role<\/h3>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">The various hunger and satiety signals are integrated in the brain, particularly in the <strong>hypothalamus<\/strong> and <strong>hindbrain<\/strong> (Ahima &amp; Antwi, 2008; Woods &amp; D&#8217;Alessio, 2008). The hypothalamus contains distinct populations of neurons:<\/p>\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\n<li class=\"whitespace-normal break-words pl-2\"><strong>Orexigenic neurons<\/strong> (appetite-stimulating) \u2014 including NPY and AgRP neurons<\/li>\n<li class=\"whitespace-normal break-words pl-2\"><strong>Anorexigenic neurons<\/strong> (appetite-suppressing) \u2014 including POMC and CART neurons<\/li>\n<\/ul>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">The balance of activity between these neural populations ultimately determines whether we feel hungry or full.<\/p>\n<section class=\"textbox connectIt\" aria-label=\"Connect It\">\n<h3 class=\"text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold\">New Insights: GLP-1 and Appetite Regulation<\/h3>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Recent advances in obesity treatment have deepened our understanding of hunger regulation. <strong>Glucagon-like peptide-1 (GLP-1)<\/strong> is a hormone released by intestinal cells when nutrients are detected. GLP-1 plays a crucial role in signaling satiety to the brain.<\/p>\n<h4 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">How GLP-1 Works<\/h4>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">GLP-1 acts on receptors throughout the brain, particularly in:<\/p>\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\n<li class=\"whitespace-normal break-words pl-2\">The <strong>hypothalamus<\/strong>, where it activates satiety-promoting neurons and inhibits hunger-promoting neurons<\/li>\n<li class=\"whitespace-normal break-words pl-2\">The <strong>brainstem<\/strong> (area postrema and nucleus of the solitary tract), which lacks a blood-brain barrier and serves as a key entry point for appetite-regulating signals<\/li>\n<\/ul>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">GLP-1 also <strong>slows gastric emptying<\/strong>, meaning food stays in the stomach longer, prolonging feelings of fullness.<\/p>\n<h4 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">GLP-1 Medications<\/h4>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Medications that mimic GLP-1 (such as semaglutide, marketed as Ozempic and Wegovy) have transformed obesity treatment. These drugs bind to GLP-1 receptors in the brain, reducing hunger signals and increasing satiety. Clinical trials show average weight loss of 15-20% of body weight\u2014far exceeding previous medications.<\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">The success of these medications confirms what researchers long suspected: <strong>hunger and satiety are not simply matters of willpower but are powerfully regulated by hormonal and neural systems<\/strong>. Understanding these biological mechanisms helps explain why weight loss can be so challenging and why pharmacological interventions can be effective for some individuals.<\/p>\n<\/section>\n<section data-depth=\"1\">\n<h2>Metabolism and Body Weight<\/h2>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Body weight is affected by multiple factors, including genetics, environment, and the balance between calories consumed and calories burned. When caloric intake exceeds use, the body stores excess energy as fat. When we consume fewer calories than we burn, stored fat is converted to energy.<\/p>\n<section class=\"textbox keyTakeaway\">\n<h3>metabolic rate<\/h3>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"><strong>Metabolic rate<\/strong> is the amount of energy expended in a given period. There is tremendous individual variability in metabolic rates\u2014people with higher rates burn calories more easily than those with lower rates. Metabolic rate is influenced by:<\/p>\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\n<li class=\"whitespace-normal break-words pl-2\">Body size and composition (muscle burns more calories than fat)<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Age (metabolism tends to slow with age)<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Sex (males typically have higher metabolic rates)<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Genetics<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Physical activity level<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Hormones (including thyroid hormones)<\/li>\n<\/ul>\n<\/section>\n<h2 class=\"text-text-100 mt-3 -mb-1 text-[1.125rem] font-bold\">Theories of Weight Regulation<\/h2>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Most people&#8217;s weight fluctuates within a relatively narrow range over time, even without conscious effort. This observation led researchers to propose theories about how body weight is regulated.<\/p>\n<section class=\"textbox keyTakeaway\">\n<h3>set point theory<\/h3>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"><strong>Set-point theory<\/strong> proposes that each person&#8217;s body establishes and attempts to maintain a stable body weight that is partly genetically predetermined. According to this view, efforts to move weight significantly from the set point are resisted by compensatory changes in hunger, satiety, and energy expenditure (Speakman et al., 2011).<\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">However, set-point theory has limitations:<\/p>\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\n<li class=\"whitespace-normal break-words pl-2\">It struggles to explain why obesity rates have risen dramatically in recent decades if we all have fixed set points<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Some predictions of the theory haven&#8217;t been supported\u2014for example, studies found no lasting changes in metabolic rate between people who had lost significant weight and control groups (Weinsier et al., 2000)<\/li>\n<li class=\"whitespace-normal break-words pl-2\">The theory underemphasizes social and environmental factors in weight regulation<\/li>\n<\/ul>\n<\/section>\n<h3 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">Settling-Point Theory<\/h3>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">Contemporary researchers increasingly favor <strong>settling-point theory<\/strong>, which proposes that rather than defending a single fixed weight, the body can stabilize at different &#8220;settling points&#8221; depending on the interaction between biology and environment.<\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">In this model, body weight settles at a point where energy intake and expenditure reach equilibrium\u2014but that equilibrium point can shift based on:<\/p>\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\n<li class=\"whitespace-normal break-words pl-2\">Food environment (availability of high-calorie foods)<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Physical activity patterns<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Stress and sleep<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Social and economic factors<\/li>\n<\/ul>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">This helps explain why the same person might maintain a stable weight of 150 pounds in one environment but settle at 180 pounds in an environment with abundant high-calorie food and limited physical activity.<\/p>\n<h3 class=\"text-text-100 mt-2 -mb-1 text-base font-bold\">The Dual Intervention Point Model<\/h3>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">A more recent model proposes that rather than a single set point, there may be <strong>upper and lower intervention points<\/strong>\u2014boundaries beyond which the body actively defends against further weight change. Within this range, weight may drift based on environmental factors, but pushing beyond these boundaries triggers stronger physiological resistance.<\/p>\n<p class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\">This model helps explain why:<\/p>\n<ul class=\"[li_&amp;]:mb-0 [li_&amp;]:mt-1 [li_&amp;]:gap-1 [&amp;:not(:last-child)_ul]:pb-1 [&amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\">\n<li class=\"whitespace-normal break-words pl-2\">The body strongly resists weight loss below a certain point (defending against starvation)<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Some individuals can gain significant weight before physiological &#8220;brakes&#8221; engage<\/li>\n<li class=\"whitespace-normal break-words pl-2\">Weight regain after dieting is so common<\/li>\n<\/ul>\n<\/section>\n<section data-depth=\"1\">\n<section class=\"textbox tryIt\"><iframe loading=\"lazy\" id=\"ohm4407\" class=\"resizable\" src=\"https:\/\/ohm.one.lumenlearning.com\/multiembedq.php?id=4407&theme=lumen&iframe_resize_id=ohm4407&source=tnh&show_question_numbers\" width=\"100%\" height=\"200\"><\/iframe><\/section>\n<section>\n<section class=\"textbox tryIt\" aria-label=\"Try It\">\n<p>Review the information presented above in the following exercise:<br \/>\n<iframe loading=\"lazy\" src=\"https:\/\/lumenlearning.h5p.com\/content\/1291068332047968138\/embed\" width=\"1088\" height=\"637\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<\/section>\n<\/section>\n<\/section>\n","protected":false},"author":20,"menu_order":14,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Hunger and Eating\",\"author\":\"OpenStax College\",\"organization\":\"\",\"url\":\"https:\/\/openstax.org\/books\/psychology-2e\/pages\/10-2-hunger-and-eating\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Download for free at https:\/\/openstax.org\/books\/psychology-2e\/pages\/1-introduction\"},{\"type\":\"original\",\"description\":\"Modification and adaptation, addition of link to learning\",\"author\":\"\",\"organization\":\"Lumen Learning\",\"url\":\"\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"\"}]","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"part":711,"module-header":"learn_it","content_attributions":[{"type":"cc","description":"Hunger and Eating","author":"OpenStax College","organization":"","url":"https:\/\/openstax.org\/books\/psychology-2e\/pages\/10-2-hunger-and-eating","project":"","license":"cc-by","license_terms":"Download for free at https:\/\/openstax.org\/books\/psychology-2e\/pages\/1-introduction"},{"type":"original","description":"Modification and adaptation, addition of link to learning","author":"","organization":"Lumen Learning","url":"","project":"","license":"cc-by","license_terms":""}],"internal_book_links":[],"video_content":null,"cc_video_embed_content":{"cc_scripts":"","media_targets":[]},"try_it_collection":null,"_links":{"self":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapters\/721"}],"collection":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/wp\/v2\/users\/20"}],"version-history":[{"count":21,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapters\/721\/revisions"}],"predecessor-version":[{"id":7492,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapters\/721\/revisions\/7492"}],"part":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/parts\/711"}],"metadata":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapters\/721\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/wp\/v2\/media?parent=721"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapter-type?post=721"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/wp\/v2\/contributor?post=721"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/wp\/v2\/license?post=721"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}