Ghrelin | How to Reduce Your Hunger Hormone and Prevent Weight Regain

Mar 11, 2021

Losing weight is hard but keeping it off can be even harder. I’ve heard time and time again from women who have lost the same 20 or 30 pounds multiple times in their lives. 

Why is it so hard to keep the weight off? Why on earth does it seem to take forever to lose weight, but then it can come back on so fast? There are several reasons for weight regain, and today I’m focusing on a major player...a little hormone called ghrelin. Also known as your hunger hormone. 

Have you ever lost weight and struggled with your appetite? Like you were constantly hungry, or your hunger increased after losing weight, making you feel like you’re swimming against the current to stick to your plan?

Have you ever tried intermittent fasting but felt like you had uncontrollable hunger and weren’t able to fast for as long as you would have liked? Knowing how ghrelin works, and using the 3 tips I’m going to share with you today, will help with your fasting efforts, and arm you with vital information to keep the weight off. 

Ghrelin’s primary role is to stimulate your appetite, slow your metabolism, and increase your fat storage. Not surprisingly, ghrelin levels will rise after a period of dieting, specifically with chronic calorie restriction. Said differently, your hunger hormone goes up after you lose weight to stimulate your appetite and try to make you regain your weight. It’s not fair is it?

Ghrelin is just one of the many reasons why eat less, exercise more doesn’t work for lasting weight loss. In this episode, you’ll learn three tips to lose weight in a way that helps reduce ghrelin levels so you’re less hungry, less likely to regain the weight you worked so hard to lose, and can increase your fasting window.

 

What is Ghrelin?

Ghrelin is a hormone produced in your stomach. Think of ghrelin as your appetite stimulating, weight gaining hormone. When your ghrelin levels go up, you’ll sense more hunger and want to eat more food. Plus, ghrelin slows your metabolism down and causes more of the food you eat to be stored as fat.

Ghrelin is more than just your “hunger hormone” and has effects on muscle, bone, heart and even cancer. But for the purpose of this episode, I’m just reviewing its role in weight management. 

 

What Stimulates Ghrelin?

Ghrelin is released in a pulsatile pattern, meaning that it rises and then it falls again. Some literature states that ghrelin rises before a meal and falls after you eat. However, new research is challenging that assumption and suggesting that ghrelin, like many other hormones, has its own circadian rhythm and is released before a person’s normal meal time. 

We do know that chronic calorie restriction diets and sleep deprivation also lead to more ghrelin and an increased appetite. You may think that not eating for a while - like through intermittent fasting - would stimulate your appetite as well, but research is showing otherwise. 

 

Intermittent Fasting & Ghrelin

One study measured fasting ghrelin levels in six healthy subjects every 20 minutes for 24 hours. There are a couple of important things to note here.

First, ghrelin levels are usually lowest around 9 in the morning. Recall that this is also generally the longest period of the day where you haven’t eaten. This reinforces the fact that hunger is not directly related to how long you go without food.

At 9 AM, you have not eaten for about 14 hours, yet you are the least hungry. Eating does not necessarily make you less hungry. When I'm intermittently fasting, I’ll notice very little hunger for the 16 to 18 hours of fasting, but once I start eating for the day I’m hungrier the rest of the day.

Often I’ll tell women to skip breakfast to extend their fast and they say, “Wait a minute, I thought breakfast was the most important meal of the day to boost my metabolism!?” 

I won’t get into specifics here, but I tell them that’s just good marketing by food companies. 

Very often they’re relieved and tell me they were never hungry for breakfast in the first place, but felt like they should eat it because that’s what everyone else does and that’s what other weight loss programs taught them to do. 

Now you see from the research, hunger is lowest in the morning after the initial peak before our normal breakfast time, which is possibly why breakfast is the easiest meal of the day to skip if you want to start intermittent fasting. 

If you can just ignore the hunger first thing in the morning, chances are you’ll easily make it closer to lunch before you’ll notice hunger again. 

Next, notice how there are three distinct peaks that correspond to our normal meal times. This indicates that there is a learned pattern to ghrelin’s release. If you’re used to eating at 8 AM, noon, and 6 PM, you’ll get hungry about those times. This can help you mentally prepare for hunger around your normal meal times when you’re fasting to mentally prepare and expect that hunger to pass relatively quickly. 

Another study showed that over 3 days of fasting, ghrelin gradually decreased. This means that patients were far less hungry despite not having eaten for the past three days. This study also showed a clear circadian rhythm to ghrelin and highlights the fact that hunger “comes in waves”

Notice in this graph, men are the white bar and women are the black bar. Research has shown that women have a higher amount of ghrelin, which may be why we tend to feel stronger food cravings compared to men...rarely do I hear my husband say, “I just need some chocolate.” Both men and women had a significant decline in ghrelin, but the women showed a greater overall decline than men after this three day fast. 

I often hear from women that they thought fasting would be so hard, but in fact it’s easier than they anticipated, especially if they follow my recommendations of priming with protein the day before a fast, staying distracted, and being well hydrated. 

I’ve been doing a 24-hour fast once a week for the last couple months and hope to make this a regular part of my lifestyle. I was most surprised that my hunger didn’t compound. I thought each hunger wave would get bigger and bigger until I couldn’t take it anymore and just succumbed to the food. These graphs reflect what I felt, and what many of my clients feel, the ghrelin and hunger level gradually decreased over the day. 

Here are a few other notes about the hormonal changes of fasting.

Notice that cortisol does go up during fasting. That’s because fasting is a hormonal stressor on your body. I never do my 24-hour fast unless I’m well rested. It’s going to be harder due to increased ghrelin and cortisol levels. If you’re not sleeping well, don’t beat yourself up if fasting seems hard for you. There are plenty of strategies to make it easier, but first and foremost focus on improving your sleep. 

Insulin also goes down, which is great because it allows your body to tap into stored energy for fuel and  helps reduce insulin resistance. One study showed that people who fast for 24 hours once a month are about half as likely to be insulin resistant and develop diabetes as those who don’t. Growth hormone goes up during fasting to help preserve your muscle when you’re fasted. 

Intermittent fasting is one of the best weight loss strategies, and when you pair it with proper nutrition, you’re well on your way to keeping the weight off. 

 

Carbohydrate, Protein, and Fat Effects on Ghrelin

Different types of macronutrients will affect ghrelin differently. This means the food you put into your mouth has a direct impact on your hunger and satiety after that meal. As a quick refresh, there are three types of macronutrients - carbohydrates made up of fibers, starches, and sugars, proteins, and fats. 

This study found glucose (a type of carbohydrate), consistently caused a decrease in ghrelin levels. Protein had no effect on ghrelin, and fat caused a significant decrease in ghrelin levels, but only in women. 

The secretion of other hormones that signal a feeling of fullness, or satiety such as cholecystokinin (CCK) and peptide YY which are involved in short‐term regulation of food intake are also impacted by the type of food you eat. 

CCK and peptide YY are triggered by protein and dietary fat, but not starches and sugars. I like to say this is why we always have room for dessert even after a huge meal - because those simple carbs don’t trigger our satiety hormones. 

To hammer this point home, it’s important to include protein and healthy fat in your meal. If you just have a meal or snack that’s primarily carbohydrates, like cereal, oatmeal, pancakes and syrup, even just fruit, you’re not going to be triggering your satiety hormones, and further, you’re going to cause a blood sugar spike, which inevitably leads to a drop, and that dip in blood sugar will make you want to eat again. 

Normally, after we eat, ghrelin levels go down, so we aren’t hungry anymore. But research has shown that in people who are obese with insulin resistance, their ghrelin doesn’t go down as much as someone with a healthy BMI and better insulin sensitivity. Certainly not all people with obesity eat an excess of food, that’s not the only cause of weight gain, but many of them do report they struggle with appetite control, and this suppressed reduction in ghrelin following a meal may be one of the reasons why. 

Interestingly, this study found that this phenomenon of a suppressed reduction in ghrelin only occurred after a glucose load. In contrast, the presence of obesity did not alter ghrelin response to the lipid or protein loads. Remember there that ghrelin (or hunger) was significantly reduced after eating fat, and was not affected after eating protein. 

I cannot emphasize enough the fact that all calories aren’t created equally. In previous episodes I’ve talked about how different types of calories affect insulin differently, and this episode proves that they also affect your satiety differently. 

And it’s common sense really. Think about how full and satiated you feel after eating 500 calories of chicken versus 500 calories of cake. It’s so important to eat real, whole foods and reduce your consumption of processed sugars and starches to reduce your insulin resistance. 

 

Sleep Deprivation and Ghrelin

Sleep deprivation will result in higher levels of ghrelin. As you can see from this study, short sleep duration not only led to increased ghrelin, or hunger hormone, but also contributed to reduce leptin, or satiety hormone.

When it comes to weight gain, sleep deprivation is at least a triple whammy because sleep recharges your willpower battery. So not only will you have higher levels of ghrelin making you more hungry, reduced levels of leptin making you feel less full, you’ll also have reduced self-control and willpower, making it more likely you’ll overeat. 

 

Ghrelin’s Effect on Adipose Tissue

If you know me, you know I’m always asking the questions “why?” and “how?” I like to know the physiology behind what I teach so I want to briefly explain how ghrelin causes a rise in blood sugar and fat storage, ultimately contributing to insulin resistance. 

There are three types of adipose, or fat, tissue: white, beige, and brown. 

Brown adipose tissue is brown because it has more mitochondria in the cells. Mitochondria are the energy producing parts of the cell. Brown adipose tissue actually burns energy. Compared to adults, babies have a higher amount of brown adipose tissue...one of the reasons my little Leah whose 9 months old is always so snuggly and warm.

White adipose tissue is the storage type of fat. Beige fat falls in the middle and acts more like brown fat to burn energy. 

Ghrelin will reduce the metabolic activity of brown fat, essentially slowing your metabolism. Ghrelin has a two-pronged effect on white fat. Ghrelin will cause your body to make more white fat, a process known as adipogenesis, and reduce it’s breakdown, or lipolysis. More fat than your body needs leads to inflammation and insulin resistance .

 

Ghrelin’s Effect on the Pancreas

Ghrelin’s effect on the pancreas serves to raise blood sugars. It reduces insulin secretion. I know this sounds counterproductive because increased insulin leads to weight gain, but remember this is the short-term effect of raising blood sugars. 

Insulin’s job is to allow blood glucose to move from the bloodstream into the cell, but ghrelin wants to increase blood sugars, at least in the short term, so it inhibits insulin.

At the same time, ghrelin will cause an increase in glucagon from the pancreas. Glucagon is the opposite of insulin. While insulin wants to lower blood glucose, glucagon wants to raise it. Glucagon signals the liver to create more glucose. What happens is that your blood sugars go up, and then your insulin will be released to bring them back down.

 

Key Takeaways

1. Ghrelin is also known as your hunger hormone. It increases after a typical chronic calorie restricted diet and makes you want to regain the weight. 

2. Ghrelin is pulsatile in nature and seems to be released in conjunction with your normal meal times.

3. Intermittent fasting helps lower ghrelin levels. Knowing that your hunger will increase around normal meal times, you can be proactive and ensure that you’re properly hydrated and distracted around those times to ride the hunger wave until it passes. Remember that intermittent fasting isn’t about eating less, it’s about eating less often. Food absolutely still matters.

4. Eating a diet high in healthy fat significantly helps lower ghrelin. Including plenty of protein in your diet will also help stipulate other satiety hormones including CCK and peptide YY. 

5. For obese individuals with insulin resistance, your ghrelin suppression is going be blunted after eating refined starches and sugars, meaning you can anticipate hunger again quickly after eating those kinds of foods. Set yourself up for success by avoiding or reducing these processed carbs.  

6. Sleep is crucial for weight loss and maintenance success. Getting enough sleep can help reduce your ghrelin levels and make intermittent fasting a lot easier. You can’t out diet and exercise the negative hormonal effects of chronic stress or sleep deprivation. 

 

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