How Our Hormones Control Our Hunger, Eating & Satiety

This video explores the complex interplay between the brain and hormones that dictate when we feel hungry and when we feel full. Dr. Huberman explains how factors like sunlight, meal timing, and specific nutrients—such as Omega-3s and amino acids—trigger chemical signals that can either accelerate or brake our appetite. He also provides actionable tools, ranging from behavioral adjustments like the "45-minute rule" for shifting meal times to supplements like berberine for managing blood glucose.

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1. The Neural Control Centers of Hunger

Hunger isn't just a feeling in your stomach; it's a sophisticated dialogue between your body and your brain, specifically the hypothalamus. Located at the base of the forebrain, the hypothalamus acts as a master control station. Within it, the ventromedial hypothalamus (VMH) serves as both an accelerator and a brake for eating. Research on "parabiosed" rats—animals physically linked to share a blood supply—proved that signals in the blood (hormones) communicate with these brain regions to regulate body weight.

Beyond the hypothalamus, the insular cortex processes the "interoception" or internal sensations of eating. This area cares deeply about the tactile nature of food—the crunch of a carrot or the consistency of urchin. For many, the mere act of chewing is pleasurable and can satisfy the nervous system without necessarily requiring calories.

"The insular cortex has neurons that get input from your mouth, from the touch receptors in your mouth... it cares about chewing and the consistency of foods."

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2. Sunlight and the "Brake" on Appetite: Alpha-MSH

One of the most fascinating "brakes" on hunger is Alpha-MSH (Melanocyte-Stimulating Hormone). Released by POMC neurons in the arcuate nucleus, this hormone reduces appetite. Interestingly, Alpha-MSH is activated by ultraviolet (UV) light hitting the eyes. This explains why many people feel less hungry during the bright summer months and more ravenous during the dark winter.

To leverage this, Huberman suggests getting ample sunlight (without sunglasses, if safe) throughout the day. This keeps Alpha-MSH levels healthy, helping to naturally keep appetite in check. While some underground subcultures inject synthetic MSH for tanning and weight loss, Huberman warns against this due to extreme side effects like priapism (prolonged erections) and hyper-pigmentation.

"Getting ample light, ideally sunlight... stimulates MSH... and keeps the desire to eat or appetite in check, in healthy ranges." ☀️

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3. Ghrelin: The Hormonal Clock of Hunger

If MSH is the brake, Ghrelin is the accelerator. Secreted by the GI tract when blood glucose is low, Ghrelin stimulates AgRP neurons to make you crave food. Ghrelin acts like a "hormonal clock"; it doesn't just react to hunger, it predicts it based on your habitual eating schedule. If you eat lunch every day at noon, Ghrelin will spike at 11:45 AM, making your stomach growl.

You can "train" your Ghrelin levels using the 45-minute rule. If you want to shift your eating window (for example, to start intermittent fasting), move your mealtime by only 45 minutes each day. This allows your neural circuits to adapt via neuroplasticity without the "excruciating" hunger pangs of a sudden change.

"Ghrelin is sort of like a clock, a hormonal clock that makes you want to eat at particular times." ⏰

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4. Satiety Signals: CCK and Amino Acid Foraging

Cholecystokinin (CCK) is a hormone released by the gut that tells the brain "No mas!" (no more). It is specifically triggered by:

• Fatty Acids: Specifically Omega-3s and Conjugated Linoleic Acid (CLA).
• Amino Acids: Especially L-Glutamine.
• Sugar: (Though sugar triggers other "craving" loops that often override CCK).

We are essentially "foraging" for these nutrients. If a meal is low in essential amino acids or healthy fats, the body may keep the hunger signal "on" until those requirements are met. L-Glutamine is particularly noted for its ability to reduce sugar cravings when taken as a supplement or found in foods like cottage cheese.

"We are basically always eating until we reach a threshold level of fatty acids and amino acids in our gut."

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5. The Danger of Processed Foods and Emulsifiers

A "calorie is NOT a calorie" when it comes to highly processed foods. These products often contain emulsifiers (like soy lecithin) designed to extend shelf life. These chemicals can strip away the mucosal lining of the gut, causing the neurons that sense nutrients to retract. This "blunts" the satiety signal, meaning you can consume thousands of calories without the brain ever receiving the message to stop.

Furthermore, hidden sugars in processed foods create a positive feedback loop: they trigger dopamine in the brain, making you want more, while the emulsifiers prevent you from feeling full.

"Emulsifiers strip away the mucosal lining of the gut... and as a consequence, the signals like CCK never get deployed." 🚫🍔

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6. Managing Blood Glucose and Insulin

Insulin manages glucose (blood sugar) to prevent it from damaging neurons. High blood sugar (hyperglycemia) can lead to neuropathies and blindness. To maintain stable "euglycemic" levels, Huberman suggests several strategies:

1. Food Order Matters: Eating fibrous vegetables first, followed by protein, and then carbohydrates can blunt the glucose spike.
2. Movement: Engaging in Zone 2 cardio (30–60 minutes) or high-intensity resistance training increases GLUT-4 activity, which shuttles glucose into muscles rather than fat stores.
3. The Post-Meal Walk: A simple 10–30 minute walk after eating can significantly stabilize blood sugar.

"The order that you consume each macro-nutrient has a pretty profound influence on the rate of insulin and glucose secretion into the blood."

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7. Supplements and Compounds: Berberine and Yerba Mate

For those looking for extra help in managing blood glucose, Huberman discusses Berberine, a plant-based compound that mimics the prescription drug Metformin. Both activate the AMPK pathway to lower blood sugar and increase insulin sensitivity. However, Berberine is potent and can cause headaches or extreme hypoglycemia if not used carefully.

Finally, Huberman highlights Yerba Mate as a powerful tool. Unlike coffee, Mate increases GLP-1 (Glucagon-like peptide 1), which suppresses appetite and helps regulate blood sugar. It also provides essential electrolytes (sodium, potassium, magnesium) that keep neurons firing correctly during a fast.

"Yerba Mate... has been shown to increase something called glucagon-like peptide GLP-1... and it acts as a pretty nice appetite suppressant." 🧉

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Conclusion

Understanding the hormonal landscape of hunger empowers us to move beyond "willpower" and instead work with our biology. By leveraging sunlight for Alpha-MSH, managing meal timing to control Ghrelin, ensuring adequate intake of Omega-3s and Glutamine for CCK, and avoiding the gut-disrupting emulsifiers in processed foods, we can achieve a healthy, stable relationship with eating. Whether through simple post-meal walks or strategic supplementation with Yerba Mate, these science-based tools provide a roadmap for better metabolic health and longevity.