Ghrelin and Weight Loss: The Hunger Hormone Explained

Inside us, there’s a team of hormones running the show, especially when it comes to keeping our weight in check and deciding when we feel hungry. One standout player in this lineup is ghrelin, a hormone that can play a big role in whether we pack on extra pounds or not. You’ll find all the intriguing facts about it right here.

What Is Ghrelin?

Also known as “the hunger hormone” or lenomorelin (2), Ghrelin is a hormone that aids in increasing appetite (3). In some cases, increased appetite leads to weight gain and obesity (1).

The hunger hormone is produced in the stomach and duodenum, then travels throughout your blood to specifically signal your hypothalamus that the body needs “fuel” and should conserve more energy to find food (1) (3).

It is also known that ghrelin is produced and released in small amounts by the pancreas, intestine, and brain. Apart from stimulating appetite, it also increases food intake and promotes fat storage. Also, beside travelling to the hypothalamus, an area of the brain that is important in appetite control, ghrelin is also shown to act on regions of the brain involved in reward processing, such as the amygdala (4).

Moreover, ghrelin is also said to stimulate the release of the growth hormone from the pituitary gland, which (unlike ghrelin) breaks down fat tissue and causes muscle buildup (4).

How Does Ghrelin Function?

Ghrelin makes you consume more food and take in more fat and calories (2). Concerning this, researchers found that infusing ghrelin into rodents stimulates them to feed – causing obesity in these rodents (1).

Researchers from Germany have suggested that the levels of ghrelin play a big role in determining how fast one becomes hungry after eating (5). Typically, ghrelin is only released when your stomach is empty. As a matter of fact, ghrelin levels are at its peak just before you eat, and at its lowest levels about an hour after you consumed food. The low ghrelin levels are sustained for about three hours (3).

Some researchers, however, believe that the hunger hormone is not as important in determining appetite as suggested. Rather, the role of ghrelin in regulating body weight may be a more complex process than what is thought (5). It has been found that ghrelin plays a role in what is known as meal-time hunger and the regulation of weight gain and weight loss over time (1).

A Note on Leptin, Ghrelin, and Obesity

It’s known that ghrelin and leptin work together to facilitate feeding, energy balance, and weight management (6). More specifically, ghrelin is considered as leptin’s counterpart, since leptin – which is an appetite-regulating hormone made up of fat cells that are produced by adipose tissue – suppresses appetite with increased levels (1).

Since leptin is produced by the body based on body fat percentage, weight gain translates to high levels of leptin, while weight loss results in the opposite, along with increased hunger (6).

Lower levels of the appetite-suppressant leptin occur when one is thin, while higher levels are associated when you are fat. However, an obesity expert from the University of California, San Francisco, Mary Dallman, PhD, reports that a lot of obese people possess a built up resistance to the appetite-suppressing effects of leptin (5).

On one hand, a person under-eating is said to have higher levels of ghrelin, while an overeating individual has the opposite. Surely, ghrelin levels are also known to be increased in children with anorexia nervosa (5).

How Does Ghrelin Levels Change During a Diet?

Ghrelin signals your brain to eat. When one is on a diet, the levels of hunger hormone usually increase, intensifying hunger and making it difficult to lose weight (2).

As you begin your diet, your ghrelin levels initially start to go up. This change persists over the course of weeks. A study in humans found that during a 6-month diet, ghrelin levels increased by 24 percent (2).

In another study, researchers found that during a 3-month weight loss diet study, the levels almost doubled from 770 to 1,322 pmol/liter (2).

A 6-month bodybuilding diet, which consists of severe dietary restrictions that causes an extremely low level of body fat, resulted in a 40-percent increased ghrelin levels. As a result, an individual becomes hungrier and will have more difficulty maintaining new weight (2).

Simply put, ghrelin levels significantly increase when one is on a weight loss diet. Thus, the longer the diet, the more that ghrelin levels would increase (2).

Contrary to what is expected, obesity is linked to unusually high concentrations of leptin. Some research suggests that these high concentrations of leptin make leptin receptors inactive and also impair its mechanism to eliminate excess fat. With the excess production of leptin, the body’s appetite suppression system is unable to function properly (7).

How Does Ghrelin Affect the Growth Hormone and Metabolism?

Ghrelin and other related growth hormone secretagogues increase body weight and fat mass. One way they do this is by triggering receptors in one part of the brain known as the arcuate nucleus, which is responsible for controlling leptin and insulin sensitivity (6).

At times, ghrelin can also override signals from the GI tract to your brain that tell you to stop eating, including those caused by gastric distension – or the pressure placed on the stomach while it expands. The hunger hormone is also said to be capable of contributing to cellular changes, including alterations in endothelial cells lining the blood vessels (6).

Other research suggests that obese people may have an overly active ghrelin receptor known as GHS-R, which often leads to increased calorie intake. Still, regardless of how much fat you have, ghrelin levels increase and make you feel hungry when you initiate a diet. This is a natural response by your body to keep you from starvation (2).

If you’ll embark on a diet, your appetite increases while your leptin levels go down. Your metabolic rate tends to decrease significantly, especially when you restrict calories for a long period (2).

Research published in the journal Addiction Biology mentioned that ghrelin reduces fat utilization and is a vital component of the food reward cascade controlled by the brain’s pleasure-reward system. Since ghrelin levels are negatively correlated with weight, dieting – especially a severe calorie-restrictive one – tends to increase ghrelin output (6).

Ghrelin has also been found to play a major role in inducing short-term food consumption and long-term weight gain. In addition, the hormone also has other roles, which include effecting:

• Regulation of growth hormone and insulin secretion (6)
• Metabolism of glucose and lipids (6)
• Gastrointestinal motility (6)
• Blood pressure and heart rate (6)
• Neurogenesis, or the process wherein neurons are generated from neural stem cells (6)

What Increases Ghrelin?

On average, your ghrelin levels fluctuate throughout the day – initially rising before a meal, then eventually decreasing after. This key hormone is responsible for burning fat and managing your weight (8).

Ghrelin increases your appetite, slows down your metabolism, and lessens your body’s fat-burning ability – making it essential for weight loss, as reported by the Obesity Action Coalition (8).

Are you feeling like you’re accomplishing the opposite of your weight loss goals? – Maybe it’s because of habits that are undoubtedly raising ghrelin without your knowledge. Here are some ways you may be pumping up your hunger hormone (8):

1. You lack sleep.

A full night’s sleep probably helps to make you less hungry when you wake up. During your sleep, the body reduces ghrelin (8).

A study published in the journal PLoS Medicine showed a strong correlation between short sleep duration and high levels of ghrelin and low levels of leptin (as well as obesity) (8).

Over time, getting less than the recommended seven to nine hours of good sleep regularly can lead to increased levels of ghrelin, which means increased calorie intake, larger appetite, and weight gain. This might also explain those insomnia-induced “midnight munchies (1).”

On one hand, getting enough uninterrupted sleep each night means decreased ghrelin – which translates into reduced appetite (1). So, getting into bed and having a complete good night’s sleep is essential for you to lose that belly fat (8).

2. You experience too much stress.

According to research done at the UT Southwestern Medical Center, chronic stress causes ghrelin to rise, which – on the good side – does help to diminish behaviors associated with anxiety and depression. On the negative side, however, ghrelin leads you to overeat and eventually gain weight – also known as “stress munchies. Your body’s natural defense against the significant amount of stress causes you to eat more, gain more weight, and stress more (8).”

More ghrelin is released directly in response to stressful situations, which explains why a lot of people have the tendency to wat when they are stressed. By sustaining the stress cycle, ghrelin then contributes to weight gain by maintaining an individual’s stress levels and causing strong urges to either snack or overeat (6).

3. You take in highly carbohydrates.

When it comes to diet, consuming foods with highly refined carbohydrates, especially in the absence of enough protein and fiber, triggers increased ghrelin levels. This is because the high-quality fiber and protein helps to reduce ghrelin levels to the point that the human brain receives the signal that the body has eaten enough while the body has received the signal (through a full appetite) that it is okay to stop eating (1).

This fact explains why many people find themselves eating potato chip after potato chip or a lot of highly refined bread without satisfying their appetite. These foods do not contain sufficient protein or fiber to turn off the ghrelin signals to the brain. Since the body does not receive the signal of a satisfied appetite, it allows the body to continue eating (1).

Typically, the levels of ghrelin should increase before meal time to let you know that it is time to eat, and decrease after a mealtime. However, consuming refined carbohydrates could disrupt this normal flow (1).

4. You’re consuming too much fructose.

Snack foods and sodas are never a good nutritional source, especially that they are loaded with fructose. According to research conducted by the American Society for Clinical Nutrition, fructose prevents insulin and leptin from elevating back to normal levels after eating, while also increasing ghrelin and triglycerides (8).

Initially, you’re stuffing yourself with food. In the long run, you’re faced with weight gain and insulin resistance (8).

5. You are on a low-calorie diet.

Losing weight via a calorie-restricted diet lowers your circulating leptin levels and increases ghrelin, thereby increasing your appetite. A lot of people end up gaining more weight back after halting the extremely-limiting diets; if they restricted fat in their diet, they would have lower body fat without increased ghrelin/ appetite levels, according to research from The Journal of Clinical Endocrinology and Metabolism (8).

6. You’re not eating frequently enough.

According to research published in The Journal of Clinical Endocrinology and Metabolism, the hunger hormone ghrelin is produced, secreted, and runs on a four-hour schedule. In order to keep its levels in check, you need to eat within these parameters (8).

Since ghrelin is increased before a meal, you’ll experience an unpleasant snowball-like situation if you don’t consume food to lower ghrelin levels. Still, eating on this type of schedule is not out of the ordinary; if you consume three meals interspersed with one or two snacks, your ghrelin levels will remain balanced (8).

7. You lack consumption of a high-protein breakfast.

Protein is known as the most satiating macronutrient. In a study published in The American Journal of Clinical Nutrition found that men who consumed a breakfast high in protein – compared to a breakfast high in carbohydrates – had experienced less ghrelin concentrations (8).

Protein increases the feelings of satiety and lessens the need to intake food further, a part of it is because they cannot be stored in the body. Our bodies metabolize them almost immediately. Unlike carbs, however, the digestion process takes longer (8).

How to Control Your Hunger Hormone?

Ghrelin is known as a cyclic hormone due to its fluctuating levels, depending whether you have an empty stomach or not. What you eat and when you eat impacts your hunger hormone ghrelin. If you are currently experiencing unsuccessful dieting, here are some important tips to help you control the hunger hormone, minimize your cravings, decrease your hunger, and make you feel more satisfied (9).

1. Get a Good Night’s Sleep

Most people require 7 to 9 hours of rest. Studies have shown that ghrelin levels were increased in those who have less than 7 hours of sleep per night. In a 2004 study, participants with a short span of sleep – specifically less than 7.7 hours – had reduced leptin and elevated ghrelin (10).

The differences between these two were known to increase appetite, which could explain the increased body mass index (BMI) observed with short sleep duration (10).

In general, getting a good amount of sleep leads to improved levels of ghrelin, reduced hunger, and decreased body weight. On one hand, getting less than 7 hours of sleep causes ghrelin levels and cravings for carbohydrates, sweets, and processed foods to increase (9).

To help you improve your sleep, follow these sleep hygiene tips (9):

• Consistency is key. Go to bed each night at the same time and wake up each morning at the same time. This includes weekends (9).
• Make a conducive bedroom space. Your bedroom should be a relaxing place that is quiet, comfortable, dark, and of a comfortable temperature (9).
• Steer clear of blue lights. When going to bed, be sure to keep blue light-emitting devices like smartphones, tablets, computers, and televisions from interfering with the body’s ability to produce melatonin (9).
• Avoid alcohol, caffeine, and large meals in the late evening. Eating too late, drinking alcohol or caffeinated beverages interferes with a healthy night’s sleep (9).
• Exercise. Physical activity during the day helps you get a good night’s sleep. Try to exercise early in the day to avoid interfering with your sleep schedule (9).

2. Eat a Healthy Balanced Diet

Here are some things to keep in mind when it comes to controlling your ghrelin levels with a proper diet:

• Eat on a schedule: Having a schedule for meal intake is necessary to prevent significant increases to your diet, which often leads to extreme hunger and overeating (11).
• Consume plenty of protein and fiber: A protein-packed breakfast may help suppress the naturally higher ghrelin levels that your body experiences after fasting overnight. More so, a high-fiber diet is best for weight management as well as for gut health (11).
• Consume more probiotic and prebiotic foods: Prebiotics feed healthy gut bacteria, while probiotics – which are sources of good bacteria – are naturally found in fermented foods, yogurt, and kefir (11).
• Avoid processed foods: Doing so will help you avoid taking in additives and preservatives that lessens the diversity of the microbiome and promotes inflammation, which negatively impacts hunger and overall health (11).
• Consume foods that turns of your hunger switch: These types of foods include:
  • Eggs (12)
  • Jerusalem artichokes (12)
  • Oats (12)
  • Boiled potatoes (12)
  • Halibut (12)
  • Oysters (12)
  • Red apples (12)
  • Apple cider vinegar (12)
  • Nuts (12)

Points to Ponder

As the hunger hormone, ghrelin is necessary for the body to signal the mind that it once again needs nourishment from foods. Given its major role in hunger, appetite, and food intake, it does cause big effects on weight loss and weight maintenance (2).

With a sustainable and enjoyable diet plan, along with proper sleep and de-stressing exercises, you can have a normal appetite and a healthy body that does not keep itself up at night for a midnight munchie.

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