Key Moments

How Our Hormones Control Our Hunger, Eating & Satiety

Andrew HubermanAndrew Huberman
Science & Technology6 min read100 min video
Apr 19, 2021|1,394,419 views|35,260|2,126
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TL;DR

Hormones like MSH, ghrelin, and CCK regulate hunger. Sunlight, meal timing, omega-3s, and glucose control are key.

Key Insights

1

Hormones from the gut, liver, pancreas, and brain, in conjunction with the nervous system, control hunger, appetite, and satiety.

2

Melanocyte-stimulating hormone (MSH), activated by UV light to the eyes, suppresses appetite, while ghrelin stimulates it, often linked to meal timing.

3

Cholecystokinin (CCK), released by the gut, blunts appetite and is stimulated by fatty acids (like omega-3s and CLA) and amino acids (like glutamine).

4

Highly processed foods, particularly those with emulsifiers, disrupt the gut lining, hindering satiety signals and increasing cravings.

5

Managing blood glucose through meal composition, order of consumption, and exercise is crucial for metabolic health and hormonal balance.

6

Tools like proper meal timing, specific nutrient intake (e.g., omega-3s, glutamine), sunlight exposure, and mindful carbohydrate consumption can regulate appetite and satiety.

NEURAL AND HORMONAL REGULATION OF APPETITE

The intricate control of hunger, eating, and satiety involves a complex interplay between the nervous system and various hormones. Key brain areas like the hypothalamus and insular cortex play significant roles. The ventromedial hypothalamus acts as an accelerator and brake for feeding, while the insular cortex processes sensory information from the mouth, influencing enjoyment and desire to eat. Early experiments, such as parabiosis in rats, demonstrated the existence of blood-borne factors influencing appetite, highlighting the role of endocrine signals.

THE ARCATE NUCLEUS AND KEY APPETITE HORMONES

The arcuate nucleus in the brain is central to appetite regulation, housing distinct neuron populations. Proopiomelanocortin (POMC) neurons release Alpha-Melanocyte-Stimulating Hormone (MSH), which powerfully reduces appetite. Conversely, AgRP neurons stimulate eating and are activated during hunger. MSH release is uniquely stimulated by ultraviolet light exposure to the eyes, linking sunlight to appetite suppression, while AgRP neuron activity increases when starved.

GHRELIN AND THE CLOCKWORK OF HUNGER

Ghrelin, a hormone secreted from the gastrointestinal tract, is a primary driver of hunger and food anticipation. Its release is triggered by declining blood glucose levels and is influenced by the body's internal clock, leading to predictable hunger pangs at regular meal times. Regular meal timing helps synchronize ghrelin secretion, and shifting meal schedules requires gradual adaptation due to the neuroplasticity of the ghrelin system.

CHOLECYSTOKININ (CCK) AND SATIETY SIGNALS

Cholecystokinin (CCK), released from the GI tract, is a crucial hormone for promoting satiety and reducing hunger. Its release is stimulated by specific dietary components, notably omega-3 fatty acids, conjugated linoleic acid (CLA), and certain amino acids like glutamine. Ingesting these nutrients helps signal to the brain that sufficient intake has occurred, blunting appetite and preventing overeating. Adequate CCK signaling is vital for maintaining healthy appetite levels.

THE DETRIMENTAL EFFECTS OF HIGHLY PROCESSED FOODS

Highly processed foods, often containing emulsifiers, pose a significant threat to appetite regulation. Emulsifiers can strip the gut's mucosal lining, impairing the detection of nutrients and hindering the deployment of satiety signals like CCK. This damage disrupts the gut-brain axis, leading to increased cravings and overconsumption. Recent studies demonstrate that even when matched for calories and macronutrients, processed foods lead to greater food intake and weight gain due to these disruptive mechanisms.

INSULIN, GLUCOSE MANAGEMENT, AND METABOLIC HEALTH

Insulin plays a critical role in managing blood glucose levels, preventing detrimental spikes that can damage neurons. The order in which macronutrients are consumed significantly impacts glucose and insulin response; eating fibrous foods or proteins before carbohydrates can blunt glucose spikes. Exercise, particularly post-meal movement, also enhances glucose regulation by promoting its uptake into muscles. Maintaining stable blood glucose is essential for overall health, influencing everything from cognitive function to hormonal balance.

SUPPLEMENTS AND PHARMACOLOGICAL TOOLS FOR APPETITE CONTROL

Various supplements and prescription drugs can modulate appetite and metabolic factors. Metformin and Berberine, for instance, strongly reduce blood glucose by activating the AMPK pathway. Other compounds like chromium, L-carnitine, and magnesium may have modest effects on blood glucose. Ingredients like capsaicin and acidic substances such as apple cider vinegar can also influence glucose levels. Understanding the mechanisms behind these tools, like the impact of caffeine on glucose or stevia's potential benefits, allows for more informed choices.

THE ROLE OF EXERCISE AND DIETARY STRATEGIES

Exercise, particularly Zone 2 cardio and high-intensity interval training (HIIT), significantly impacts blood sugar regulation and metabolic rate. Zone 2 cardio improves insulin sensitivity and blood sugar stability, while HIIT is effective at depleting glycogen stores and increasing basal metabolic rate. Dietary approaches like the ketogenic diet, by minimizing carbohydrate intake, inherently lead to lower blood glucose levels. These strategies, alongside mindful meal timing and nutrient intake, offer powerful, actionable tools for managing hunger and satiety.

MACRONUTRIENT ORDER AND MOVEMENT FOR BLOOD GLUCOSE CONTROL

The sequence in which foods are eaten can profoundly affect post-meal blood glucose levels. Consuming fibrous components of a meal first, followed by proteins and then carbohydrates, leads to a more gradual and modest rise in blood glucose and promotes earlier satiety. Similarly, engaging in physical activity, whether before or after a meal, helps buffer blood glucose spikes by increasing glucose uptake into muscles. These behavioral adjustments offer practical ways to manage metabolic responses directly linked to appetite signals.

SPECIFIC NUTRIENTS FOR APPETITE REGULATION

Beyond macronutrient balance, specific micronutrients and fatty acids play vital roles in appetite control. Omega-3 fatty acids, conjugated linoleic acid (CLA), and the amino acid glutamine are potent stimulators of CCK release, a hormone that signals satiety. Glutamine, in particular, has also been shown to reduce sugar cravings. Ensuring adequate intake of these components from whole foods or supplements can help regulate appetite and improve metabolic signaling, contributing to healthier eating patterns.

THE IMPACT OF CAFFEINE, VITAMINS, AND ACIDIC SUBSTANCES

Various commonly consumed substances have notable effects on blood glucose and appetite. Caffeine, contrary to some assumptions, can slightly increase blood glucose. Certain B vitamins, like B3, can stimulate appetite. Conversely, minerals like zinc and acidic substances such as apple cider vinegar or lemon juice can help lower blood glucose levels. These diverse effects highlight the complexity of dietary influences on metabolic regulation and hormonal signaling.

YERBA MATE AND GLUCAGON-LIKE PEPTIDE-1 (GLP-1)

Yerba Mate, a caffeinated tea, offers unique benefits beyond simple stimulation. It has been shown to increase levels of Glucagon-Like Peptide-1 (GLP-1), which acts as an appetite suppressant and helps regulate blood sugar levels, keeping them in a healthy euglycemic range. Additionally, Yerba Mate contains electrolytes crucial for nervous system function, making it a potentially beneficial beverage for managing energy levels and appetite, particularly during fasting periods.

HISTORICAL PERSPECTIVE AND MODERN ADVANCES

Understanding appetite and metabolic health has evolved significantly over millennia. Ancient physicians recognized high blood glucose through urine sweetness, a practice replaced by sophisticated blood analysis. Modern science has identified numerous hormones and neural pathways governing hunger and satiety, providing a mechanistic basis for dietary and lifestyle interventions. This progress underscores the importance of informed choices grounded in scientific understanding for optimizing health and well-being.

Hormonal Hunger Regulation: Do's & Don'ts

Practical takeaways from this episode

Do This

Get ample UV light (ideally sunlight) to your eyes consistently throughout the day to stimulate MSH and keep appetite in check.
Shift meal times gradually by about 45 minutes per day to retrain ghrelin secretion and gain flexibility over eating schedules.
Ensure sufficient intake of healthy fats (Omega-3s, CLAs) and essential amino acids (especially glutamine) to trigger CCK release and suppress appetite.
Eat fibrous vegetables before proteins and carbohydrates to blunt blood glucose spikes and promote earlier satiety.
Incorporate movement (even a 30-minute walk) after meals to improve blood glucose regulation.
Engage in Zone 2 cardio (30-60 minutes, 3-4 times/week) for stable blood sugar and high insulin sensitivity.
Include high-intensity interval training or resistance training to increase basal metabolic rate and encourage glucose storage in muscles rather than fat.
Consider Yerba Mate consumption to increase GLP1 and leptin, which can suppress appetite and help regulate blood sugar.
Ingest acidic foods or drinks like lemon/lime juice or apple cider vinegar to slightly lower blood glucose.

Avoid This

Avoid highly processed foods, which contain emulsifiers that damage the gut lining and disrupt satiety signals (CCK), leading to overeating.
Do not rely on sugar-laden foods to alleviate hunger, as they create a positive feedback loop leading to more cravings and disrupted glucose levels.
Do not take Metformin or Berberine without consulting a physician, especially if you have hypoglycemia or other health conditions, due to potential powerful side effects and interaction with existing conditions.
Do not eat carbohydrates and/or fats first in a meal if you want to avoid steep blood glucose spikes.
Do not use blue blockers during the daytime as they block beneficial UV light that stimulates MSH.

Common Questions

The hypothalamus, particularly the ventromedial hypothalamus, acts as both an accelerator and a brake on feeding behavior. The insular cortex processes tactile sensations from the mouth during eating, influencing enjoyment, avoidance, and satiety. These areas work together with hormonal signals to regulate appetite.

Topics

Mentioned in this video

Supplements
L-Carnitine

A supplement previously discussed on the podcast for its role in power output, ATP production, and sperm/egg quality.

Conjugated Linoleic Acid

A fatty acid that, along with omega-3s, stimulates the release of CCK, helping to blunt appetite and regulate consumption to healthy levels.

Chromium

A supplement shown in 29 studies to have a minor effect on reducing blood glucose.

Panax ginseng

A supplement that can have slight effects in reducing blood glucose levels.

Apple Cider Vinegar

An acidic substance that, along with lemon or lime juice, can slightly lower blood glucose by altering food absorption in the gut.

Vitamin D3K2

Mentioned as a year's supply offered by Athletic Greens, highlighting Vitamin D3's involvement in metabolic and hormonal processes crucial for health.

Yerba mate

A caffeinated tea that increases glucagon-like peptide 1 (GLP1) and leptin levels, acting as an appetite suppressant and providing alertness and electrolytes. It helps extend fasting windows.

Caffeine

A stimulant that reliably increases blood glucose levels slightly. Also acts as a diuretic, potentially affecting electrolyte balance.

Stevia

An artificial sweetener that appears to slightly lower blood glucose. While its impact on the gut microbiome is still unclear, it's considered an attractive alternative if using artificial sweeteners.

Omega-3 fatty acids

Fatty acids from sources like algae, krill, or fish oil that stimulate CCK release, reducing appetite and supporting a healthy omega-3 to omega-6 ratio, which is also antidepressant and good for gut microbiome.

Vitamin B3

A B vitamin that stimulates appetite by triggering increases in blood glucose.

Glutamine

An essential amino acid that potently triggers CCK release and can reduce sugar cravings. It can also slightly increase blood sugar levels, which diabetics should note.

Berberine

A non-prescription compound derived from plants and tree bark, often compared to Metformin due to its strong effects in lowering blood glucose and cholesterol, activating the AMPK pathway. Andrew Huberman experienced headaches and severe hypoglycemia from it.

Zinc

A mineral that appears to lower blood glucose.

Magnesium

Discussed as a tool for enhancing sleep, especially threonate and bisglycinate forms. Can also modestly reduce blood glucose.

Concepts
ventromedial hypothalamus

A specific area of the hypothalamus involved in hunger, feeding, and satiety, with paradoxical effects due to different neuron populations either promoting or inhibiting feeding.

GLUT4

Molecules involved in shuttling glucose to muscle and glycogen stores and away from body fat stores, stimulated by movement and intense exercise.

AMPK pathway

Stands for Adenosine Monophosphate-activated protein kinase pathway, which is activated by Metformin and Berberine, and is associated with fasting and low blood glucose states.

Vagus Nerve

A nerve that carries subconscious signals from sugar-sensing neurons in the gut to the brain, triggering dopamine release and promoting cravings for more sugar.

HbA1c

A measure obtainable from a blood test that provides an average readout of blood sugar levels over the previous two to three months.

Hypothalamus

An area in the forebrain containing neurons that control sexual behavior, body temperature, circadian rhythms, and feeding.

insular cortex

A brain area that processes interoception and receives input from mouth touch receptors, powerfully controlling the enjoyment, avoidance, and satiety related to eating.

Ketogenic Diet

A diet that emphasizes very low carbohydrate intake, shown in 22 studies to significantly decrease blood glucose due to the absence of foods that cause insulin and glucose spikes.

AGRP neurons

Neurons in the arcuate nucleus that stimulate eating, with activity increasing significantly when animals or people haven't eaten for a while.

Low-density lipoprotein

A type of lipoprotein that transports fats in the bloodstream; high levels are generally considered unhealthy and can be negatively impacted by elevated glucose.

High-density lipoprotein

A type of lipoprotein considered 'healthy' because it delivers fats and cholesterol to tissues that manufacture hormones like testosterone and estrogen, as well as supporting adrenal and liver function.

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