Everything You Need To Know about Ghrelin and Leptin

Ghrelin and leptin are two hormones naturally found in your body. Ghrelin, the "hunger hormone," tells your brain when you are hungry. Leptin, the "fullness hormone," tells your brain when you are full. Both hormones work together to regulate appetite and weight.

However, ghrelin and leptin may not work as they should in some people. For example, people with obesity may experience leptin resistance, which is when the brain does not recognize the fullness signal from leptin.

There are currently no medications or supplements recommended to increase your levels of ghrelin or leptin for weight management. However, there may be other ways to manage both hormone levels in your body.

Function

Ghrelin and leptin are two natural hormones that affect your appetite and weight regulation.

Ghrelin, also known as the hunger hormone, was discovered by researchers in 1999. Its function is to tell your brain your stomach is empty and it is time to eat. Ghrelin also plays a small role in heart and blood vessel health, inflammation, and psychological processes like reward processing and memory. The hormone is primarily made in your stomach and travels throughout the body.

Leptin, the fullness hormone, was discovered in 1994. The main function of leptin is to tell your brain, specifically the hypothalamus, that you are full. The hypothalamus is the part of your brain that helps with many important bodily functions, including appetite, weight management, body temperature, and the sleep-wake cycle.

Leptin also helps regulate your body's metabolism, or how energy is made and used in the body. The hormone is primarily made within the body's fat (adipose) tissue. Leptin may also affect other body functions, such as the immune system and reproductive health.

Ghrelin Levels

Ghrelin levels vary throughout the day, increasing when you are fasting or when your stomach is empty. The levels then decrease after you have eaten and your stomach is full. The release of ghrelin is a natural response by your body, which protects you from starvation. Certain nutrients have varying effects on ghrelin release. For example, carbohydrates and proteins lower ghrelin release more than fats.

Levels in the blood range from 300-800 picograms per milliliter (pg/mL), based on which phase of hunger you are in. The lower your ghrelin level, the more full you feel and the less likely you are to eat. The higher your ghrelin level, the hungrier you feel, and the more likely you are to take in food or calories.

If you start a diet that limits your food intake, ghrelin levels will likely rise. The longer you diet and the more weight you lose, the higher the ghrelin level will become. With a higher ghrelin level, you will feel hungrier more often, and it may be more difficult to maintain weight loss.

Studies have found that while fasting, blood ghrelin levels are lower in people with obesity and higher in people with more muscle. Some research has also found that after eating, the decrease in ghrelin levels is lower in people with obesity than in people in the normal weight range for body mass index (BMI). Lower ghrelin levels have also been reported in people with insulin resistance and type 2 diabetes.

Ghrelin resistance is not well understood or considered as relevant as leptin resistance. Researchers believe ghrelin resistance occurs to help protect against weight gain when food is available and protect energy levels when food is not available.

Your healthcare provider will not routinely check your ghrelin levels. However, they can measure your levels by taking a blood sample. Talk with your provider to learn more about ghrelin tests.

Leptin Levels

The amount of leptin in your body is directly related to the amount of fat tissue in your body. Since people who are overweight or obese have a larger amount of fat tissue, and Ieptin is made in fat tissue, leptin levels in the body are also higher.

Normal leptin levels typically range from 3-18 nanograms per milliliter (ng/mL) and are often higher in women than men. In people with a BMI over 30 (considered obese), leptin levels can be as high as 30 ng/mL.

When you eat, body fat and leptin levels increase. Increased fat tissue in the body gives the cells more energy, increasing leptin production and levels, which usually leads to you feeling full and the body using that energy. Once leptin levels are high, the hormone tells your brain that you have had enough to eat.

When leptin levels are low, your appetite increases and your brain tells your body that you need to eat. Falling leptin levels are associated with moments of less energy in the body, such as when restricting calorie intake or exercising. The decrease in leptin levels triggers a feeling of hunger. You also burn energy, or calories, at a slower rate. When dieting, your leptin levels are usually considered low.

Your healthcare provider will not routinely check your leptin levels. However, they can measure your levels by taking a blood sample. Talk with your provider to learn more about leptin tests.

Leptin Resistance

Leptin resistance is commonly found in people with obesity. With leptin resistance, the fullness message that leptin sends does not reach the brain, so you do not recognize that you are full. Your body thinks you are starving, and you continue to eat. This means that you continue to produce leptin, and levels in your body remain high.

Leptin resistance makes it more difficult to lose weight because you eat more, and your body burns fewer calories to avoid starvation.

The actual mechanism of what causes leptin resistance is not yet understood. Possible mechanisms for leptin resistance include:

• Blood-brain barrier: The blood-brain barrier is a layer of cells that help keep certain things in or out of your brain. One study found that the movement of leptin from the blood to the brain is lowered by as much as 80% in people with obesity and leptin resistance. This then leads to more leptin circulating through your body.
• Inflammation: Cell inflammation may affect leptin signaling to the brain. High-fat foods are known to cause inflammation in the body, and inflammation affects people with obesity in numerous ways.
• Genetic mutations: Mutations in leptin and other genes related to the leptin signaling process may disrupt their functions.
  

Taking Ghrelin and Leptin

Neither ghrelin nor leptin supplements are currently approved by the U.S. Food and Drug Administration (FDA) or available for purchase to help with weight management.

Studies have been conducted on animals and humans where ghrelin was given intravenously (into the vein). Many of these studies found that the amount of food a person desired to eat increased with the injection. When administered, ghrelin has been shown to increase food consumption by 30% in humans.

Leptin replacement therapy has been used in many animal studies. These replacement therapies are often injected in animals to help to lower their appetite and maintain weight gain.

For certain rare conditions, leptin replacement therapy may be prescribed to increase leptin levels. This includes congenital leptin deficiency, a condition that causes mutations in the leptin gene. People with these conditions have undetectable or very low levels of leptin and require hormone injections to function normally. Despite this, no effective leptin injection has been found to manage leptin levels and weight gain in humans.

Based on how leptin works in the body, it is unlikely that taking a leptin supplement would be beneficial. Higher leptin levels do not change how the hormone is used. The brain must be able to detect the signal it receives from Ieptin for the hormone to serve its purpose. Therefore, a leptin supplement to increase levels is unlikely to help with weight loss.

While some supplements advertise ghrelin or leptin for weight loss, the hormones are not actually present in these products. Instead, other ingredients, like caffeine or stimulants, may be included.

Other Ways To Maintain Ghrelin and Leptin Levels

At this time, there are no diets, medicines, or supplements that can directly affect ghrelin and leptin levels. However, there are multiple ways you can maintain the hormone levels naturally.

Manage Your Weight

Ghrelin and leptin levels change based on what and how often you eat. Since leptin is made in fat tissues, lowering the amount of fat tissue in your body may also decrease the amount of circulating leptin. Research has also shown following an imbalanced diet and having overweight affects how well ghrelin and leptin work in the body.

Healthy weight strategies include the following:

• Exercise regularly: Regular exercise can decrease leptin levels, regardless of age or sex. Lowering the amount of fat tissue in the body through exercise also helps decrease leptin levels. Increasing muscle mass is also useful in weight management.
• Focus on a nutritious diet: Maintaining a diet low in fat, sugar, and carbohydrates yet high in protein is associated with weight loss and healthy weight management. Protein also reduces your hunger by helping you stay fuller longer.
• Follow a regular eating schedule: Inconsistent diet schedules, including starvation or overeating in one setting, affect ghrelin and leptin levels. By following a regular meal schedule with normal portions, you can help maintain normal functioning of all body processes related to weight management.

Prioritizing Sleep

Poor sleeping habits and sleep deprivation can significantly affect your health in many ways. Sleep deprivation has been linked to an increased risk of having overweight or obesity. Researchers believe that sleep deprivation increases the amount of ghrelin sent to your brain while lowering the amount of leptin. This, in turn, leads to increased hunger and weight gain.

A Quick Review

Ghrelin and leptin are hormones naturally found in your body. Ghrelin, the hunger hormone, signals to your brain when you are hungry. Leptin, the fullness hormone, signals when you are full. Both hormones work together to regulate appetite and weight.

Currently, no medications or supplements are recommended to increase ghrelin or leptin levels for weight management. However, maintaining a healthy weight and prioritizing sleep may help manage these hormones. Talk with your healthcare provider to learn more about ghrelin or leptin for weight management.