What are ghrelin and leptin?

The two digestive hormones that hold the remote control to your feelings of hunger and appetite are ghrelin and leptin. As with many hormones, these two are paired but have opposing functions. One says Go and the other says Stop. Ghrelin (your go hormone) gets secreted by the stomach when it’s empty and increases your appetite. It sends a message to your brain that you need to eat. When your stomach is full, fat cells usher out the other hormone, leptin, so your brain gets the message that you are full and need to stop eating.

From The Mind-Beauty Connection: 9 Days to Less Stress, Gorgeous Skin, and a Whole New You by Amy Wechsler.

Dr. Michael Roizen, MD
Internal Medicine

Think of any classic mano-a-mano matchup: Ali vs. Frazier. Dog vs. cat. Waiter vs. chef. In any classic battle pitting one opponent against another, there's a simple equation: One wins, one loses. That's essentially what you need to know about two hormones that are pitted against each other in the supreme battle of hunger versus satisfaction. When the level of leptin is high in your body, that's when you feel satisfied, with little desire to eat. When the level of ghrelin (think gremlin) is high, that's when your body sends emergency signals to the pantry: Hungry. Send food. Now.
You don't need to be an endocrinologist to realize that this hormonal battle largely dictates how much, how often, and how smart you eat. Of course, the trick in all this is there's no little nodule on your body that regulates these hormone levels; you have to do all the regulation internally - primarily through your food choices, by focusing on foods that make leptin level surge and ghrelin levels plummet. Ghrelin works in the short-term, shooting up when your body feels hungry and shooting down when the stomach is full or 70 calories of healthy fat (like six walnuts) hits your intestinal wall (the intestine comes right after the stomach as one goes from mouth down) or sugar hits your brain, except when your body consumes fructose (easily found in some simple sugars, especially the sweetener, high fructose corn syrup).
If you can make leptin knock ghrelin on its rear, then you're more likely to obtain your ideal body shape.

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Various physiologic feedback mechanisms involving the mouth, stomach, intestines, and brain all work together to increase or decrease your hunger. Many hormones play a role.

When your stomach is empty, the hormone ghrelin, which is produced mainly in the stomach, signals your brain that you need to take in food. Your body produces more ghrelin during fasting (such as between meals) in order to stimulate hunger, and it produces less after food is consumed.

Another hormone, leptin, which is produced in fat tissue, helps regulate your body fat by affecting hunger. As your fat stores increase, leptin signals the brain to decrease your level of hunger and food intake.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.