Uploaded March 2026 | Updated September 2026, 1 week ago
Leptin and ghrelin are two hormones that exert opposing influences in the regulation of appetite and energy balance. In this video, I discuss the roles of leptin and ghrelin in appetite and their potential involvement in obesity.
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TRANSCRIPT
Leptin and ghrelin are two hormones that exert opposing influences in the regulation of appetite and energy balance. Leptin is produced mainly by fat cells, and circulating leptin levels increase as body fat increases, reflecting the amount of stored energy in the body. Leptin acts on receptors in several brain regions, most notably the hypothalamus, where it suppresses food intake by inhibiting appetite-stimulating neurons and activating neurons that reduce feeding behavior. Ghrelin is produced mainly by the stomach and is released when energy availability is low, such as during a period of fasting. Ghrelin levels typically rise before meals and fall after eating, and thus may play an important role as a short-term driver of hunger and feeding. Ghrelin also exerts many of its effects through receptors in the hypothalamus, where it activates neurons that promote feeding behavior. Ghrelin may also influence the reward system, which could increase food intake for the sake of pleasure, independent of energy availability.
In general, leptin inhibits hunger and ghrelin stimulates it, and the balance between the two forms part of a broader system that helps regulate feeding behavior and body weight. When we lose weight, for example, ghrelin levels tend to increase and leptin decreases—mechanisms that are thought to help us maintain a consistent weight over time. The role of leptin and ghrelin in obesity, however, is still unclear. Leptin levels in obesity are higher than normal, but the brain is often less responsive to leptin—a phenomenon called leptin resistance. Ghrelin levels are typically lower in people with obesity, and do not fall as significantly after a meal nor rise as much before a meal. It’s possible these more stable ghrelin levels could result in less restricted eating periods and contribute to obesity, but more research is needed to confirm this.
REFERENCES
Cui H, López M, Rahmouni K. The cellular and molecular bases of leptin and ghrelin resistance in obesity. Nat Rev Endocrinol. 2017 Jun;13(6):338-351. doi: 10.1038/nrendo.2016.222. Epub 2017 Feb 24. PMID: 28232667; PMCID: PMC8904083.
Davis J. Hunger, ghrelin and the gut. Brain Res. 2018 Aug 15;1693(Pt B):154-158. doi: 10.1016/j.brainres.2018.01.024. Epub 2018 Jan 31. PMID: 29366626.
Klok MD, Jakobsdottir S, Drent ML. The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review. Obes Rev. 2007 Jan;8(1):21-34. doi: 10.1111/j.1467-789X.2006.00270.x. PMID: 17212793.
Rosenbaum M, Leibel RL. 20 years of leptin: role of leptin in energy homeostasis in humans. J Endocrinol. 2014 Oct;223(1):T83-96. doi: 10.1530/JOE-14-0358. Epub 2014 Jul 25. PMID: 25063755; PMCID: PMC4454393.
Skoracka K, Hryhorowicz S, Schulz P, Zawada A, Ratajczak-Pawłowska AE, Rychter AM, Słomski R, Dobrowolska A, Krela-Kaźmierczak I. The role of leptin and ghrelin in the regulation of appetite in obesity. Peptides. 2025 Apr;186:171367. doi: 10.1016/j.peptides.2025.171367. Epub 2025 Feb 19. PMID: 39983918.
📝 Pass your next test with my neuroscience videos!
I’m Marc, a university professor at Penn State, and I’m here to take you on a journey into the fascinating world of the brain. I created this channel to break down complex topics into easy-to-understand snippets—perfect for both students and curious minds alike. 📚
My goal is to make learning neuroscience fun and accessible. Whether you're a student looking to supplement your studies or simply eager to understand the basics of the brain, this channel is for you.
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Leptin and ghrelin are two hormones that exert opposing influences in the regulation of appetite and energy balance. In this video, I discuss the roles of leptin and ghrelin in appetite and their potential involvement in obesity.
🧠 Take your learning further with my free, self-paced Introduction to Neuroscience course featuring my videos, articles, and hundreds of quiz questions: neuroscientificallychallenged.com/course
If you're looking for accessible and entertaining ways to learn more about the brain, check out my books:
📚Your Brain, Explained: What Neuroscience Reveals About Your Brain and its Quirks: amazon.com/Your-Brain-Explained-Neuroscience-Reveals/dp/1473696569
📚Bizarre: The Most Peculiar Cases of Human Behavior and What They Tell Us About How the Brain Works: amazon.com/Bizarre-Peculiar-Cases-Human-Behavior/dp/139980121X
TRANSCRIPT
Leptin and ghrelin are two hormones that exert opposing influences in the regulation of appetite and energy balance. Leptin is produced mainly by fat cells, and circulating leptin levels increase as body fat increases, reflecting the amount of stored energy in the body. Leptin acts on receptors in several brain regions, most notably the hypothalamus, where it suppresses food intake by inhibiting appetite-stimulating neurons and activating neurons that reduce feeding behavior. Ghrelin is produced mainly by the stomach and is released when energy availability is low, such as during a period of fasting. Ghrelin levels typically rise before meals and fall after eating, and thus may play an important role as a short-term driver of hunger and feeding. Ghrelin also exerts many of its effects through receptors in the hypothalamus, where it activates neurons that promote feeding behavior. Ghrelin may also influence the reward system, which could increase food intake for the sake of pleasure, independent of energy availability.
In general, leptin inhibits hunger and ghrelin stimulates it, and the balance between the two forms part of a broader system that helps regulate feeding behavior and body weight. When we lose weight, for example, ghrelin levels tend to increase and leptin decreases—mechanisms that are thought to help us maintain a consistent weight over time. The role of leptin and ghrelin in obesity, however, is still unclear. Leptin levels in obesity are higher than normal, but the brain is often less responsive to leptin—a phenomenon called leptin resistance. Ghrelin levels are typically lower in people with obesity, and do not fall as significantly after a meal nor rise as much before a meal. It’s possible these more stable ghrelin levels could result in less restricted eating periods and contribute to obesity, but more research is needed to confirm this.
REFERENCES
Cui H, López M, Rahmouni K. The cellular and molecular bases of leptin and ghrelin resistance in obesity. Nat Rev Endocrinol. 2017 Jun;13(6):338-351. doi: 10.1038/nrendo.2016.222. Epub 2017 Feb 24. PMID: 28232667; PMCID: PMC8904083.
Davis J. Hunger, ghrelin and the gut. Brain Res. 2018 Aug 15;1693(Pt B):154-158. doi: 10.1016/j.brainres.2018.01.024. Epub 2018 Jan 31. PMID: 29366626.
Klok MD, Jakobsdottir S, Drent ML. The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review. Obes Rev. 2007 Jan;8(1):21-34. doi: 10.1111/j.1467-789X.2006.00270.x. PMID: 17212793.
Rosenbaum M, Leibel RL. 20 years of leptin: role of leptin in energy homeostasis in humans. J Endocrinol. 2014 Oct;223(1):T83-96. doi: 10.1530/JOE-14-0358. Epub 2014 Jul 25. PMID: 25063755; PMCID: PMC4454393.
Skoracka K, Hryhorowicz S, Schulz P, Zawada A, Ratajczak-Pawłowska AE, Rychter AM, Słomski R, Dobrowolska A, Krela-Kaźmierczak I. The role of leptin and ghrelin in the regulation of appetite in obesity. Peptides. 2025 Apr;186:171367. doi: 10.1016/j.peptides.2025.171367. Epub 2025 Feb 19. PMID: 39983918.
📝 Pass your next test with my neuroscience videos!
I’m Marc, a university professor at Penn State, and I’m here to take you on a journey into the fascinating world of the brain. I created this channel to break down complex topics into easy-to-understand snippets—perfect for both students and curious minds alike. 📚
My goal is to make learning neuroscience fun and accessible. Whether you're a student looking to supplement your studies or simply eager to understand the basics of the brain, this channel is for you.
Hit subscribe and get to know your brain, one video at a time! 🧠
