Ghrelin and Leptin: How Hunger and Fullness Hormones Work

Ghrelin and leptin are the two main hormones behind hunger and fullness. Ghrelin, made mostly in the stomach, rises before meals and tells your brain it is time to eat; leptin, made by fat tissue, tells your brain how much energy you have stored. In one study, ghrelin nearly doubled just before each meal and fell back within an hour of eating (Cummings and colleagues, 2001). Short sleep and dieting both push the balance toward hunger: two nights of short sleep raised ghrelin by 28% and lowered leptin by 18% in healthy young men (Spiegel and colleagues, 2004). This guide covers what each hormone does, leptin resistance, why dieting makes you hungrier, how to lower ghrelin naturally, and where other fullness signals such as OEA fit.

It is educational, not medical advice.

Key Takeaways

Ghrelin is the hunger signal: it rises before meals and falls after eating (Cummings and colleagues, 2001).
Leptin is the long-term energy signal: blood levels track body fat (Considine and colleagues, 1996).
Short sleep tips the balance: more ghrelin, less leptin and more hunger after just two short nights (Spiegel and colleagues, 2004).
Protein helps: higher-protein meals increase fullness and the hormones that signal it (Leidy and colleagues, 2015).

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Diagram: Ghrelin and leptin: ghrelin is made in the stomach and rises before meals; leptin is made by fat tissue and tracks energy stores. In studies, short sleep raised ghrelin 28% and lowered leptin 18%, and diet weight loss raised ghrelin 24%.

What Is Ghrelin?

Ghrelin is often called the hunger hormone. It is produced mainly by the stomach, and in a study that took blood samples 38 times over 24 hours, ghrelin rose nearly twofold right before each meal and dropped to its lowest point within an hour after eating (Cummings and colleagues, 2001). The same study found ghrelin between meals followed a daily rhythm, rising through the day and falling overnight (Cummings and colleagues, 2001). In simple terms, ghrelin is the "time to eat" signal.

What Is Leptin?

Leptin is made by fat cells and acts as a long-term signal of how much energy your body has stored. In a study of 275 adults, blood leptin levels rose with the percentage of body fat (Considine and colleagues, 1996). Leptin is less about any one meal and more about telling your brain, over days and weeks, whether your energy reserves are full or running low.

Ghrelin vs Leptin at a Glance

	Ghrelin	Leptin
Made mainly in	The stomach	Fat tissue
Main message	Time to eat	Energy stores are full
Time scale	Rises before each meal, falls after	Changes slowly with body fat
After short sleep	Goes up	Goes down
After diet-induced weight loss	Goes up	Goes down

Sources: (Cummings and colleagues, 2001; Considine and colleagues, 1996; Spiegel and colleagues, 2004; Cummings and colleagues, 2002; Sumithran and colleagues, 2011).

What Is Leptin Resistance?

If leptin signals fullness and higher body fat means more leptin, why doesn't more leptin simply turn hunger down? In the 1996 study, people with obesity had about four times as much leptin in their blood as people of normal weight, and the researchers concluded that most were insensitive to their own leptin (Considine and colleagues, 1996). That reduced response is what people mean by leptin resistance. It is a research concept rather than something you can test for at a routine checkup.

Why Dieting Makes You Hungrier

Your body defends its energy stores. In a 6-month diet program, losing about 17% of body weight was linked with a 24% rise in 24-hour ghrelin levels (Cummings and colleagues, 2002). In another study of 50 adults on a very low calorie diet, weight loss lowered leptin, and one year later the hormones that encourage weight regain still had not returned to their starting levels (Sumithran and colleagues, 2011). This is one reason slow, steady changes you can keep up tend to work better than crash diets.

If you feel hungry most of the time, our guide to why you might always feel hungry covers the everyday causes and what helps.

Sleep, Ghrelin and Leptin

Sleep is one of the strongest everyday levers. In a crossover study, two nights of restricted sleep in healthy young men lowered leptin by 18%, raised ghrelin by 28% and increased hunger by 24%, with the biggest jump in appetite for calorie-dense, high-carbohydrate foods (Spiegel and colleagues, 2004). Our guides to how to fall asleep fast and how to stop sugar cravings build on this.

For what sleep studies found about appetite and weight, see does lack of sleep cause weight gain?

How to Reduce Ghrelin and Support Leptin Naturally

Eat protein at every meal: higher-protein meals increase fullness and the gut hormones that signal it (Leidy and colleagues, 2015).
Sleep 7 or more hours: short sleep raises ghrelin and lowers leptin (Spiegel and colleagues, 2004).
Avoid crash diets: rapid weight loss is followed by hormone changes that push hunger up (Cummings and colleagues, 2002; Sumithran and colleagues, 2011).
Eat on a regular schedule: ghrelin rises before your usual mealtimes (Cummings and colleagues, 2001), so steady meal times make hunger more predictable.
Add fiber and whole foods: vegetables, beans and whole grains make meals more filling.

There is no over-the-counter ghrelin blocker. The habits above are the best-supported ways to keep hunger signals in balance; our guide to natural appetite suppressants covers foods and supplements studied for appetite.

Other Fullness Signals: Where OEA Fits

Ghrelin and leptin are not the only signals. Your gut also makes OEA (oleoylethanolamide), a fat-derived compound produced in the small intestine after you eat. In rats, fasting lowered OEA production in the gut and giving OEA reduced food intake through nerves that carry fullness signals to the brain (Rodríguez de Fonseca and colleagues, 2001). In a 60-day placebo-controlled trial in 60 adults with obesity, 250 mg of OEA a day reduced hunger, the desire to eat and cravings for sweet foods, and increased fullness, compared with placebo (Laleh and colleagues, 2018). A 2025 review of 13 randomized trials found that OEA supplements lowered fasting blood sugar, insulin and waist circumference on average (Eslahi and colleagues, 2025).

Our OEA Supplement provides 200 mg of OEA per two-capsule serving with PEA, L-theanine, acetyl-L-carnitine and green tea extract, for satiety support. The Metabolic Stack combines it with our Berberine Blend and Enhanced NMN. Learn more on our OEA ingredient page, in our OEA benefits and dosage guide and on our metabolic health and energy balance hub. Talk to your doctor before starting any supplement if you are pregnant, breastfeeding or take medication.

When to See a Doctor

See a doctor if you are hungry all the time even after full meals, if hunger comes with unusual thirst, passing urine more often, weight change you cannot explain or constant tiredness, or if appetite changes start after a new medicine. A doctor can check for causes that need treatment.

Frequently Asked Questions

What is the difference between ghrelin and leptin?

Ghrelin, made mostly in the stomach, rises before meals and signals hunger (Cummings and colleagues, 2001). Leptin, made by fat tissue, reflects your energy stores (Considine and colleagues, 1996).

Which hormone makes you hungry?

Ghrelin. It nearly doubled right before meals in one study (Cummings and colleagues, 2001).

Which hormone makes you feel full?

Leptin is the long-term fullness and energy signal; gut signals such as OEA work around meals (Considine and colleagues, 1996; Rodríguez de Fonseca and colleagues, 2001).

How can I lower ghrelin naturally?

Eat protein at each meal, sleep 7 or more hours and avoid crash diets (Leidy and colleagues, 2015; Spiegel and colleagues, 2004; Cummings and colleagues, 2002).

Is there a ghrelin blocker supplement?

There is no over-the-counter ghrelin blocker. Protein, sleep and steady eating habits are the best-supported ways to manage hunger signals.

What is leptin resistance?

A reduced response to your own leptin. Researchers proposed it after finding much higher leptin levels in people with obesity (Considine and colleagues, 1996).

Does lack of sleep affect hunger hormones?

Yes. Two short nights raised ghrelin by 28% and lowered leptin by 18% in one study (Spiegel and colleagues, 2004).

Why am I hungrier after losing weight?

Ghrelin rose 24% after diet-induced weight loss in one study, and appetite hormones stayed changed a year later in another (Cummings and colleagues, 2002; Sumithran and colleagues, 2011).