Ghrelin is a hormone that is produced and released in the stomach. It is often called the “hunger hormone” because it increases appetite. It also promotes blood sugar regulation, prevents muscle breakdown and protects the heart. Here is what ghrelin is, its functions, and how a person can manage its levels in their body.
Ghrelin is a hormone produced mainly in the stomach when it is empty. It is also produced in the small intestine, the brain and the pancreas. Ghrelin travels through the blood to the brain, where it acts on the hypothalamus. The hypothalamus is a part of the brain that produces hormones that regulate hunger, mood, thirst, and many other important body functions. Ghrelin is often called the hunger hormone because its primary role is to regulate appetite. When ghrelin activates its receptor, the growth hormone secretagogue receptor, it prompts you to eat more and store extra fat.
In people who are trying to lose weight or who have recently lost weight, ghrelin levels are often higher, making it difficult to maintain weight loss. For example, a 2020 study looked at people with diabetes who participated in a two-year weight management program. Participants who initially lost weight slowly gained it back over the duration of the study. The researchers found that weight loss was associated with increased ghrelin levels and increased hunger, which might make it difficult to maintain weight.
Ghrelin can also signal the body to decrease brown fat thermogenesis. When this happens, the body burns less fat at rest. Brown fat is known for its thermogenic properties and ability to increase total calories burned. Studies show that ghrelin also affects a person’s sleep/wake cycle, taste sensation, and reward-seeking behavior. Because it plays a role in reward processing, many experts believe that high levels of ghrelin may contribute to food and alcohol abuse. Ghrelin also has many functions in the body, including improving heart health, preventing muscle wasting, and influencing bone metabolism. Finally, it can also stimulate the secretion of gastric acid and accelerate gastric emptying.
What causes ghrelin levels to rise?
Ghrelin levels fluctuate frequently throughout the day and are primarily controlled by dietary intake. Ghrelin levels generally increase when the stomach is empty and decrease following the person has eaten. Some studies show that people with obesity have higher levels of circulating ghrelin. This can lead to a permanent state of hunger and make it difficult to lose weight.
However, research remains contradictory on this point. Yet a 2015 review suggests that ghrelin levels are low in obese people and even lower in obese people who also have an eating disorder. Diet is also known to stimulate ghrelin secretion. In addition, diets can also lower leptin levels, which is known as the “satiety hormone”. Combined, these factors can make it difficult to lose weight and maintain it over the long term.
People with obesity and Prader-Willi syndrome (PWS) have very high levels of circulating ghrelin, which may play a role in their constant hunger pangs and difficulty controlling their weight. Also, people with Hashimoto’s thyroiditis, anorexia nervosa, bulimia, and cachexia due to the disease tend to have higher hunger hormone levels. Ghrelin levels can also be higher during times of stress. It is believed that a high level of ghrelin has an anxiolytic effect on the body.
How to Increase Ghrelin Levels
Although high ghrelin levels are generally viewed as unfavorable and associated with increased appetite, some people may benefit from higher ghrelin levels. For example, someone who has trouble gaining weight or suffers from wasting syndrome may benefit from the appetite-stimulating effects of ghrelin.
More recent studies suggest that administration of ghrelin may be useful in patients with cancer cachexia, as it may help reverse weight loss and protein breakdown in catabolic states. Although short-term administration of ghrelin appears to be safe and well tolerated, we need more studies on its efficacy and safety before recommending it. Animal research on how cannabis increases appetite by stimulating ghrelin production also shows promise in supporting its use in the treatment of disease-induced anorexia. Additionally, a human study in men with HIV found that tetrahydrocannabinol (THC), the psychoactive compound in cannabis, can stimulate the release of ghrelin.
How to Lower Ghrelin Levels
Ghrelin levels may increase following weight loss. Decreasing ghrelin levels in the body can help decrease a person’s appetite, prevent weight regain, or promote weight loss. However, it is important to note that other studies point out that monitoring changes in ghrelin alone is not sufficient to predict weight regain following weight loss in most people. Behavioral, physiological and environmental factors also play a role in weight regain.
Naturally lower your ghrelin levels
– Follow a healthy diet
Ghrelin levels tend to increase when you diet and don’t eat enough calories. Avoiding an empty stomach and following a nutrient-dense diet can help limit ghrelin secretion.
The main elements that make up a healthy diet are:
– vegetables of all types
– fruit, especially whole fruit
– cereals, at least half of which are whole grains
– low-fat dairy products
– lean proteins
– oils, such as olive oil and those found naturally in nuts and fatty fish.
Certain foods can also lower ghrelin levels. Foods high in fiber might lower ghrelin levels.
– Get enough sleep
Poor sleep habits are linked to increased ghrelin levels and decreased leptin levels, which leads to increased appetite and hunger. For the best sleep, aim for a minimum of 7 hours of sleep in a 24-hour period.
– Eat more protein
Consuming protein-rich meals and snacks can promote satiety and reduce ghrelin levels. In fact, many mealtime studies have shown a significant reduction in hunger and increased satiety following high-protein meals. Researchers suggest consuming between 1.2-1.6 grams of protein per kilogram of body weight per day or 25-30% of daily calories to aid in weight management and appetite suppression. Most people can follow a high-protein diet by eating chicken breast, beans, lentils, low-fat dairy products, and shellfish.
– Limit stress
Although it is almost impossible to eliminate stress completely, studies show that high levels of chronic stress can lead to high levels of ghrelin. In addition to signaling hunger, ghrelin can affect brain function. The exact mechanism is unclear and the mixed results make it difficult to draw conclusions regarding ghrelin’s role in stress. Some animal studies suggest it may reduce anxiety and have antidepressant properties, while other studies suggest it may promote these behaviors. Regular physical activity, getting enough sleep, and practicing yoga or meditation can help reduce stress.
– Physical exercise
Researchers have found that acute physical exercise suppresses ghrelin production. However, they also found that long-term exercise programs can have the opposite effect and increase ghrelin production. The exact mechanism for these effects is unclear, but researchers believe it is likely due to high redistribution of blood flow and weight loss from exercise.
Résumé
Ghrelin is known as the hunger hormone due to its key role in appetite regulation. High levels of ghrelin lead to increased appetite and food intake. However, the body needs ghrelin because it is involved in many processes. These include improving heart health, influencing bone metabolism and preventing muscle breakdown. A person who wants to lower ghrelin levels in the body naturally can consider eating a healthy, fiber-rich diet, getting enough protein, exercising, getting enough sleep, and reducing stress.