The Hunger Hormones

Understand how the different hormones work and what you can do to optimise your hormones to achieve an ideal weight.

The are several hormones that play a vital role in satiety.  In this post, I want to delve into the effects of diet and lifestyle on the hormones that plays a vital role in controlling hunger, which then has an impact on weight and other health issues. 

Hormones are chemical messengers in our bodies.  When they are released into the body, they give instructions for things to happen.  It can happen that these hormones are not working like they are supposed to, and these hormonal imbalances can lead to feelings of being hungry even though you have just eaten.  When we understand how they work together, we can influence how well or poorly these hormones function.  We can improve our health and weight by making changes to help the hormones be balanced.

First, there are a set of hormones that tell your body that you are full or satiated.  Then there are a set of hormones that tell your body you are hungry.  Let’s have a look at them.

Hormones that tell your body you’re satiated:

  1. Leptin
  2. CCK (cholecystokinin)
  3. OXM (Oxyntomodulin)
  4. PPY (Peptide YY)
  5. GLP-1 (Glucagon-Like Peptide-1)
  6. Adiponectin

Hormones that tell your body you’re hungry:

  1. Ghrelin
  2. Insulin
  3. Cortisol
  4. Glucagon
  5. Neuropeptide Y (NPY)

Hormones that tell your body that you are full / satiated:


1. Leptin

Leptin is often referred to as the “fullness hormone”, and it plays a key role in energy intake and energy expenditure. It signals to the brain that the body is fed and that there is sufficient energy storage.

Leptin is primarily produced by the fat cells (adipocytes) and by the cells that line the stomach. The fat cells use leptin to inform the brain how much body fat they are carrying. High levels of fat tell your brain that you have plenty of fat stored and to stop eating, while low levels tell your brain that the fat stores are low and you need to eat.

As leptin is linked to the fat mass, the more fat you have on your body, the more leptin you produce. So, while it seems logical that if you have more body fat that you should be eating less because of the higher levels of leptin, this is often not the case. Researchers at Thomas Jefferson University did a study on the efficacy of leptin in obese and lean people. The research suggested that although the leptin levels were higher in obese individuals, the leptin was not available for the brain to receive the fullness signals.

This is called leptin resistance – when your body is producing leptin, but the brain is not seeing it. This resistance to leptin results in the brain thinking that the body needs energy, even though the body has more than enough stored energy. So, the brain then sends hormones to signal to eat more, and to reduce your metabolism to conserve energy and burn fewer calories. Not ideal if you are overweight and you want to lose weight!

And to make matters worse, leptin continues to rise as people gain weight. It’s like your brain is starving and your body is obese! And despite that you have just eaten a meal, the brain is not reading the leptin, and so you continue to feel hungry.

2. Cholecystokinin (CCK)


This is a gut hormone that is released after a meal by the cells that line the duodenum (the first part of your small intestine), specifically when the cells detect the presence of fat. 

This hormone plays a role in a few things:

  • It instructs the pancreas to release digestive enzymes from the pancreas, and bile from the gallbladder and liver.
  • It signals to the stomach to slow down the speed of digestion so that the small intestine can effectively digest the fats.
  • It also seems to be involved in the short-term to increase the sensation of fullness, and that is the reason why many believe you should eat a healthy fat with every meal.

3.  Oxyntomodulin (OXM)


Oxyntomodulin is a peptide hormone that is released from the gut when you eat, and it signals a change in energy status to the brain, specifically to decrease food intake.

4. Peptide YY (PYY)


Another hormone that is released by the gut is Peptide YY when you eat, and it is especially sensitive to protein.  PYY signals to the gallbladder and pancreas to stop producing digestive enzymes.  It also helps to slow down the digestion process, which helps nutrient absorption. 


5. Glucagon-Like Peptide-1 (GLP-1)


GLP-1 belongs to a family of hormones called incretins, which is called this because they enhance the secretion of insulin.  This is one of the fastest and shortest-lived satiety hormones and increases the feeling of fullness during and between meals.

It has been suggested that if you have too little GLP-1, it could lead to or worsen obesity, as you may eat more during a meal and are more likely to snack between meals.  There is also a theory that dieting or natural weight loss may decrease GLP-1, which can then result in an increased appetite and then regaining the weight. 


6.  Adiponectin


This is a hormone that is secreted by the adipose tissue (commonly known as body fat), and it is crucial for health.  Adiponectin improves the body’s sensitivity to insulin and helps to protect against developing type 2 diabetes.  It does this by regulating the metabolism of lipids (fatty acids) and glucose. 

Research has shown that adiponectin levels are low in obese people.

Hormones that tell your body that you are Hungry:


1.     Ghrelin


Ghrelin is considered to be the main hunger hormone! 

It is produced in the stomach and it is secreted when the stomach is empty, as well as by the pancreas when it detects low blood sugar.  The liver also secretes ghrelin when its glycogen storage runs low (and glucagon is high).  The hormone triggers the hypothalamus in the brain to stimulate the appetite.  It also plays a role in promoting fat storage!

Ghrelin levels typically increase before a meal and decrease after you have eaten.

What is interesting, is that ghrelin levels increase when you go on a diet (the typical calorie-restriction diet), regardless of your body’s fat composition.  This is a natural response from the body – it senses starvation due to food restriction, and then goes into preservation mode.  This is to protect you against starvation.  The ghrelin levels will increase, and you will be hungry.  It also seems that the longer you diet, the bigger the spike in your ghrelin levels. 

Studies have shown that the ghrelin levels in obese people only slightly decrease after a meal.  The message that the brain receives is that they are not quite full, which can then lead to overeating.  This can make it very difficult for people to regulate their food intake. 

Last, studies have suggested that ghrelin also inhibits insulin secretion, leading to higher glucose levels in the blood.


2.     Insulin


Insulin is also known as the fat-storage hormone, and for good reason! 

Insulin is made in the pancreas, and the main job of insulin is to take sugar (glucose) out of the bloodstream when the blood sugar levels are too high and escort it to the muscle cells where it can be used for energy.  It is like being the sugar police!

When you eat, your glucose levels in the blood increases. The pancreas springs into action and releases insulin to remove the glucose from the blood.  This is great, but when there is too much sugar in the body all the time, the muscles become resistant and the insulin cannot put the sugar away into the muscles.  The problem is that now you have this large sugar load in your blood, and it must go somewhere. The extra sugar is then stored in the fat cells, and you start to gain weight.  But if you continue to eat sugar, the fat cells can also become resistant to the sugar load, and now you have high insulin and high blood sugar.  This is not good, as you are moving closer and closer to diabetes. 

One of the other problems when you are insulin resistant is that you feel hungry after a meal.  Even though this is not real hunger, it can lead to overeating.


3.     Cortisol


Cortisol is one of the main stress hormones, and it plays a key role in regulating your metabolism and hunger. 

When you are stressed, you need energy and you need it fast.  Cortisol is one of the hormones that stop the secretion of insulin (which stores nutrients).  The other hormones that are also involved are epinephrine (adrenalin) and glucagon.  So when insulin drops, the glucose can now be used as part of the stress-response, namely the fight-or-flight response.

As part of the body’s stress response, cortisol also stimulates your appetite!  This is to replace the energy you have just used (in fighting or running away).  When the stress is finally over, it takes a few minutes for cortisol levels to return to normal.  The big problem with cortisol, is that it increases the desire to eat foods high in fat and sugar. 


4.     Glucagon

Glucagon is a hormone that is released by the pancreas when it detects low blood sugar levels and instructs the liver to convert the stored energy (known as glycogen) into glucose and release it into the blood ( a process called glycogenolysis).

There is also growing evidence that suggests that glucagon plays a role in controlling food intake and feelings of fullness, through signaling the body to reduce levels of appetite hormones like ghrelin. 

Unfortunately, it also seems to lose its ability to induce feelings of fullness in obese people.


5.     Neuropeptide Y (NPY)


Neuropeptide Y is a hormone produced in the brain and the nervous system.  It is higher during times of stress.  Research has found that this hormone is highest during periods of fasting or food deprivation.

This hormone stimulates appetite,  specifically for carbohydrates, which can lead to overeating and abdominal fat gain. 

When these hormones are out of balance


All of these hormones play important roles in regulating the need to eat as well as digestion.  Many of them influence other functions of the body, like regulating blood sugar levels, interacting with the immune system, and controlling inflammation.   

When these hormones are not working as they are supposed to, it can create havoc in your body, including weight gain, exhaustion, blood sugar irregularities, inflammation, and even thyroid function. 

How to keep your hunger hormones in check


Let go of the idea of dieting, especially if you have been yo-yo dieting in the pastThe notion of restricting calories will immediately send your body into preservation mode and start to save food in your body fat. 

Avoid inflammatory food.  Certain foods can trigger inflammation in the body, including sugar, gluten, dairy, soy, coffee, alcohol, legumes, nightshades (including peppers and potato), and seed oils.  Most processed foods (and this includes most fast foods) are inflammatory, so aim to avoid anything that comes in a box or is premade.  I recommend you start cooking meals at home and use healthy oils such as olive oil and coconut oil.  Chronic inflammation has been linked to lower GLP-1 production (which helps with feelings of fullness).

Eat a variety of fresh, whole foods that is high in fiber, both soluble and insoluble fiber.  You obtain fiber from plants, so eat more veggies and fresh fruit.  If you are struggling with eating more vegetables and fruit, you can include fresh, raw juice to help you.  Aim to drink a green juice each day (you can use a juicer or a blender) and limit the fruit-based smoothies to the occasional treat.

Eat more soluble fiber.  Soluble fiber is food for the good bacteria in your gut, which may reduce NPY levels (one of the hunger hormones).  Juicing is a great way to increase your intake of soluble fiber.  Other foods include avocados, sweet potatoes (in small amounts), flax seeds, guavas, apples, pears, hazelnuts, broccoli, and carrots. 

Get 7 to 8 hours of quality sleep.  Sleep is vital for health and helping to keep ghrelin and leptin hormones in check.  Skimping on sleep also has an impact on stress hormones and resistance to insulin, both of which contribute to weight gain.  Aim for 7-8 hours each night, consistency is important! 

Eat enough protein. Eating too little protein has been shown to increase NPY (one of the hunger hormones), which leads to hunger.  Protein also helps to increase GLP-1 (one of the satiety hormones) which helps to make you feel satiated.  Focus on eating more protein, especially at breakfast.  A 2006 study published in the American Journal of Clinical Nutrition found that a high-protein breakfast was more satiating than a high-carbohydrate breakfast “through suppression of postprandial ghrelin concentrations”.

Mitigate the impact of stress.  We cannot get away from stress, so it becomes important to act each and every day to reduce the impact of stress on our bodies.  Figure out what works for you to reduce stress.  Some suggestions include meditation, mindfulness, breathing techniques, using essential oils, moving your body, and listing to music.

Exercise, specifically HIIT and strength training.  Strength training helps to increase muscle mass, which in turn is associated with lower levels of ghrelin.   HIIT (high impact interval training) manipulates ghrelin and leptin levels.  A study done by the University of Bath (U.K.) showed that total ghrelin concentrations declined after high-intensity sprinting, and were significantly lower after 30 minutes of recovery compared to pre-exercise. 

Supplements can help. 

  • Magnesium supplements can improve insulin sensitivity. Magnesium is not toxic (it is safe up to 800 mg a day), it’s cheap and easy to find. There are seven different forms of magnesium, so it may be worthwhile to find the form that works for you.   
  • Zinc has been found to be low in obese individuals. Zinc plays a role in appetite regulation, improving insulin resistance and shows possible anti-inflammatory effects.  A word of warning: zinc supplementation can lead to a depletion in iron levels.  If you suspect a deficiency in zinc, speak to your doctor about checking the levels with a blood test.  It is also possible that a zinc deficiency can lead to a copper deficiency. 
  • Alpha-lipoic acid and fish oil may be beneficial, but more studies must be done to confirm the efficacy of alpha-lipoic acid and fish oil. If you do take a fish oil, opt for a high-quality fish oil that contains both EPA and DPA.  But a word of warning – if you are taking blood thinners such as warfarin, or if you have a bleeding disorder, please speak to your doctor first before you start supplementing.

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