Ghrelin Hormone: Role, Testing, and Health Impact

What Is Ghrelin?

Ghrelin is a hormone made mainly in the stomach, often called the “hunger hormone.” It sends signals to the brain, especially the hypothalamus, to make you feel hungry. Ghrelin levels rise before meals and drop after eating, helping your body know when it’s time to eat.

But ghrelin doesn’t only control hunger. It also:

• Stimulates the release of growth hormone, which helps with growth and metabolism
• Regulates blood sugar and insulin levels
• Affects digestion, heart health, and energy balance
• Plays a role in stress response and emotional eating

Doctors and researchers are studying ghrelin as a biomarker for:

• Obesity and weight gain - Higher levels can make it harder to lose weight
• Stress-related conditions - Ghrelin may increase after emotional or physical stress
• Eating disorders - Imbalances in ghrelin levels are often seen in conditions like anorexia or binge eating

Understanding ghrelin levels can help doctors learn more about a person’s appetite control, stress response, and metabolic health.

When Is Ghrelin Testing Recommended?

Ghrelin testing isn’t part of routine blood tests, but doctors may recommend it in specific situations where appetite, weight, or hormone balance is affected.

You might need a ghrelin test if:

• You have unexplained weight loss or gain 
• You are being tested for an eating disorder
• You have symptoms of a growth hormone disorder
• You are part of a study or treatment for obesity or metabolic syndrome
• You show signs of stress-related eating or emotional eating

Doctors use this test to better understand the hormonal causes of appetite changes, not just the symptoms themselves.

How Is Ghrelin Testing Conducted?

Ghrelin is measured with a blood test. A healthcare provider takes a blood sample from a vein in your arm. The sample is then tested in a lab to measure the level of total or active ghrelin in your blood.

There are two main forms of ghrelin:

• Acylated (active) ghrelin - the form that stimulates hunger
• Unacylated (inactive) ghrelin - which may still play a role in metabolism

Some labs test for total ghrelin, while others focus on the active form.

Is Ghrelin Part of Standard Blood Panels?

No. Ghrelin is not included in common tests like the CBC, CMP, or thyroid panel. It is a specialized test ordered only when a doctor needs to investigate hormone or appetite-related conditions.

Test Preparation Tips

To get accurate results:

• Fasting is usually required - You may be asked not to eat or drink (except water) for 10 to 12 hours before the test.
• Avoid stress and heavy exercise before the test, as these can affect ghrelin levels.
• Always tell your doctor about any supplements or medications you are taking.

Following these instructions helps make sure your ghrelin levels reflect your true baseline.

What Are the Normal Ghrelin Levels?

Normal ghrelin levels can vary based on whether the test measures total ghrelin or active (acylated) ghrelin, and also on factors like age, weight, and time of day.

• Ghrelin typically ranges from 162 pg/mL to 860 pg/mL

Note: Units of measurement and the normal ranges can differ depending on the laboratory and the specific methods used. Always discuss your results with your healthcare provider to understand what they mean for you

What Do Abnormal Ghrelin Levels Mean?

When ghrelin levels are too high or too low, it can affect your appetite, weight, and even your mood. These changes may be linked to certain health conditions or lifestyle factors.

Ghrelin High Levels

High levels of ghrelin may lead to increased hunger and weight gain, especially if the body doesn’t respond well to the hunger signals.

Common causes include:

• Dieting or calorie restriction - The body increases ghrelin to try to restore energy balance.
• Anorexia nervosa - People with this condition often have high ghrelin levels because the body is trying to increase appetite.
• Lack of sleep - Poor sleep can raise ghrelin, making you feel hungrier the next day.
• Prader-Willi syndrome - A rare genetic disorder where ghrelin remains high and causes constant hunger.

To help manage high ghrelin levels:

• Eat regular, balanced meals - Include protein, fiber, and healthy fats to keep you full longer.
• Get enough sleep - Aim for 7-9 hours per night to help regulate hunger hormones.
• Avoid extreme calorie restriction - Very low-calorie diets can increase ghrelin and make weight loss harder.
• Stay active - Physical activity may help lower ghrelin levels over time.

Ghrelin Low Levels

Low ghrelin levels can reduce appetite and may lead to unintended weight loss or other health issues, especially when the body needs more energy but doesn’t feel hunger.

Possible causes include:

• Obesity - Ghrelin levels are often lower in people with obesity, possibly due to the body’s reduced hunger signaling.
• After bariatric surgery - Some weight-loss surgeries, like gastric bypass, lower ghrelin levels to reduce appetite.
• Chronic inflammation or illness - Some long-term illnesses can decrease ghrelin production.
• Hypothalamic disorders - Conditions that affect the brain's hunger control center may lead to low ghrelin.

To help manage low ghrelin levels:

• Eat nutrient-dense foods - Focus on small, frequent meals that are high in calories and nutrients.
• Monitor weight changes - Keep track of any unintentional weight loss and report it to your doctor.
• Talk to a specialist - If you’re not feeling hungry despite needing to eat, a healthcare provider can help explore the cause.
• Avoid skipping meals - Even if appetite is low, eating on a schedule can help support energy and overall health.

Which Specialist Should You Consult?

If your ghrelin levels are abnormal, the right specialist depends on your symptoms and underlying health concerns. Here are the most common options:

• Endocrinologist - A hormone specialist who can help with appetite, weight, and metabolism issues, including ghrelin imbalances.
• Nutritionist or Dietitian - Can support you in creating a balanced eating plan to manage hunger and maintain a healthy weight.
• Psychiatrist or Psychologist - If your ghrelin levels are linked to an eating disorder or stress-related condition, mental health support can be key.
• Gastroenterologist - If stomach-related issues are affecting hormone levels or digestion.
• Primary Care Physician - A good first step. They can review your results and refer you to a specialist if needed.