Satiety: how hormones control our hunger

How does it actually come about that we feel hungry? What determines when we are full? And why can we sometimes simply not stop eating? You will learn all of that in this article. We also explain what role our hormones play in it and which way of eating lets you influence your feeling of satiety. All in all, a really tasty morsel of knowledge that definitely fills you up!

Have you ever thought about why we eat at all? The answer seems obvious: hunger. We are hungry, so we eat, full stop. That could make this the shortest article ever. But since that is not all there is to it, this is not the end of the article either. If you look at Western countries in general, our eating habits today have very little to do with hunger. We eat for emotional reasons, out of stress, out of habit… There are many reasons why we eat. But let us set those aside for now and look at the whole thing from a physiological point of view. Why do we eat?

Eating means energy. Through food we supply our body with the energy it needs to maintain the structures of the body, for example the structure of our cells or the organisation of the tissues. We also need energy for the basic functions that keep us alive, such as breathing, heart activity or digestion. Energy is also required for growth, which is of great importance above all in children, for the work our muscles do and for producing heat to maintain our body temperature. The energy requirement is covered by the three basic nutrients protein, fat and carbohydrate. In addition, our body needs a minimum amount of certain minerals, trace elements, essential amino acids and vitamins, as well as enough water and fibre. Taking in these essential food components is important for our health and our wellbeing, and intake and consumption should be balanced so that neither a deficiency nor an excess arises. Energy intake should also match energy turnover so that body weight is held at an individual set point. What determines this set point has not yet been clarified precisely. Current thinking is that 70% is determined by genetic factors and 30% by environmental factors.

Satiety plays a decisive role in our daily life and has an influence on various factors.

But how does it actually come about that we are hungry or full? The stomach is empty and, whoosh, we are hungry? Unfortunately it is not that simple, because a series of complex interactions comes with the feeling of hunger or satiety.

Briefly explained: when food comes in, the stomach first expands, which is registered by the so-called mechanoreceptors. The various nutrients that enter our body are picked up by so-called chemoreceptors. As the nutrients are digested and absorbed, various hormones are then released. All this information is passed on to the brain, which is what finally brings about the feeling of satiety.

Decisive for the regulation of hunger and satiety is the hypothalamus, a vital part of our brain that regulates body temperature, circulation and the salt and water balance, among other things. This is where the satiety centre and the hunger centre of our body sit. Both centres are regulated by certain messenger substances. These can be assigned either to the group of orexigenic substances or to the group of anorexigenic substances. Orexigenic substances increase food intake by stimulating the hunger centre and inhibiting the satiety centre. Anorexigenic substances do exactly the opposite: they inhibit the hunger centre and stimulate the satiety centre, which limits food intake.

Do we even know this natural feeling of satiety today? Are we ever really full? Many factors can lead us to eat even though our body does not actually need any fresh supply of energy. With that we throw our natural feeling of satiety out of balance. Which factors these are and how they act on our satiety is what you will learn now.

Naturally the way we eat plays an important role. It is already known that highly processed foods lead to excessive consumption, which in turn promotes overweight. A small study was also able to show that with a diet rich in highly processed foods the hunger hormone ghrelin was raised, while the satiety hormone PYY occurred in a reduced amount. In this way hunger is driven on further. That is why at Foodpunk we rely on natural and fresh foods. Exactly what your diet should look like so that you can rely on your feeling of satiety again is something we reveal in section 5.

Besides the foods we consume, there are further factors that influence our satiety. The purely physiological factors we have already looked at above work closely together with so-called hedonic factors. These have nothing to do with supplying the body with energy and much more to do with the pleasure of eating. And that starts before we have even taken the first bite. The smell, the look or just the thought of food can be enough to make us “hungry”. But between us, that is not really hunger, is it? The colour and presentation of the food play a part in this too. It also matters what surroundings we eat in. Both the place and distractions, from the television for example, influence how much and how long we eat. If we are distracted, we take in our food only unconsciously and ignore the fact that we are actually already full. Interestingly, the room temperature and the outside temperature also influence what and how much we eat. In colder surroundings we tend to eat more than in warmer ones. A slight rise in body temperature can also curb appetite. And portion size matters in so far as a portion is usually eaten up, whether it is large or small and whether or not we have long since been full. It is the same with a wide variety of different foods. If at a buffet of many different dishes we can take as much as we like, we usually eat beyond our hunger, because we want to try as much as possible.

Have you ever noticed how your eating behaviour changes as soon as you eat together with other people? One study showed that meals which are not eaten alone are about 44% larger than meals eaten on your own. That is mainly because we eat for longer in company. The other way round, though, eating can also become more restrained when others are present. That always depends on who we are eating with. What is known as mimicry is interesting too: we adjust our eating speed to the person opposite us, which then leads us to eat either more or less. In this way as well we ignore our feeling of satiety and eat as much as happens to be “appropriate” in the social situation.

We probably all know this: eating is tied to emotions. Whether it is grandma’s stew that takes us back to our childhood or the chocolate we simply treat ourselves to as a reward. We all have our own individual relationship with food, our own associations that we link with particular foods. And so our eating behaviour does not only change our emotions, our emotions also influence our eating behaviour. The same emotion can have quite different effects on eating behaviour in different people. In some, negative emotions tend to lead to increased food intake, while in others they inhibit food intake. Our choice of food is also steered by emotions. If we have positive feelings at the sight or the smell of a particular food, we are more likely to eat it. The other way round, negative feelings tend to lead to food being avoided. You have surely come across the term “emotional eating”. The theory of emotional eating behaviour is about negative emotions being reduced or managed through eating behaviour. So, for example, that stress tempts us to eat something sweet in order to ease the stress. At this point it is important to mention, though, that emotion-driven changes in eating behaviour can differ greatly from person to person.

Physical activity is of great value for our health and our wellbeing. But can exercise also influence our hunger and satiety hormones? On the current state of research this question cannot be answered with a clear yes or no, because the evidence is too uncertain. Some studies show that the hunger hormone ghrelin falls after exercise, while other studies were unable to observe any change. The findings on the satiety hormone PYY are similar. In some studies a rise in PYY was observed after exercise, while in other studies no changes occurred. Studies on the satiety hormone GLP-1 show that it rises after exercise. Directly after exercise the CCK levels also appear to rise for about two hours, so that no feeling of hunger arises during that time. In the studies, the response of most of these hormones to movement depended on the intensity and duration of the training. Different responses were also observed depending on whether a person was of normal weight or overweight. To be able to confirm the effects, though, further research is needed.

In the end exercise has many advantages, it gets the metabolic response going, helps with weight reduction and can under certain circumstances also reduce cravings and appetite. However, you should not rely on exercise alone. A healthy long-term change of diet always forms the basis for a good hormone balance. And even with exercise you should not eat like mad with the excuse that you have been working out.

The female sex hormones also play a role in regulating our appetite, our eating behaviour and energy metabolism. In women, food intake can change during the different phases of the menstrual cycle. Some studies showed that the least is eaten during the fertile phase, when oestradiol levels are high. By contrast, more is eaten in the phase shortly before bleeding, when progesterone levels are high. The effects of the menstrual cycle on hunger and satiety can vary greatly from woman to woman, though, because not all women show the same hormonal changes. And even with hormonal influences, conscious food choices and balanced eating behaviour can help to regulate hunger and satiety better.

The term microbiome refers to all the microorganisms that colonise our gut. These microorganisms are bacteria which, among other things, support the breakdown of our food or have an immune-modulating effect. Through the so-called microbiome-gut-brain axis there is a direct connection between our brain and the gut, in the form of a complex communication system that works in both directions. This communication is influenced by the gut microbiota. Current animal studies point to a link between the gut microbiota and the regulation of satiety and energy intake, a link that runs along many direct and indirect routes. It remains unclear, though, how these complex processes work in humans. The various bacteria probably influence the release of the gastrointestinal hormones in different ways, which in turn influences hunger and satiety.

Slow and sustainable weight loss with a balanced diet can help to regulate hunger and satiety hormones. But what if we lose a lot of weight in a very short time through some crash diet that has far too few calories and that we give up again after a few weeks? You might think that losing weight is good, no matter how. But that is by no means the case. Hypocaloric diets, that is, diets that have very few calories, put the body into an extreme situation. Our body notices that we are taking in too little energy and starts saving, by focusing on the functions that are essential for survival. That can also throw hunger and satiety out of balance. Calorie restriction leads, among other things, to a reduction in the GLP-1 level, so that we are hungry for longer. And the rise in CCK after eating is also smaller after weight has been gained too quickly. As a result satiety only sets in later, more is eaten and weight is gained again. Short-term hypocaloric diets can throw the metabolism out of balance in various ways and are not exactly harmless. We therefore advise against such diets and make sure that your individual nutrition plan brings sustainable, healthy weight loss that supports your metabolism.

Bad habits can also contribute to our feeling of satiety getting out of balance. These include, for example, eating too quickly, being distracted while eating, frequent snacks, unhealthy foods, and also insufficient sleep and stress. How we can learn to listen to our natural feeling of satiety again is something you will find out in the next section.

Various medicines can influence our hunger and satiety in the most varied ways, by stimulating or suppressing appetite. And diseases of the gastrointestinal tract, such as Crohn’s disease or ulcerative colitis, can also have an influence on our hormone balance. The underlying mechanisms are complex, though, and go too far at this point. If you take medication over a long period, or are affected by an illness, it is best to talk to your doctor about possible side effects and consequences.

As you have just learned, your natural feeling of satiety is influenced by so many different factors that it can sometimes be quite hard to stop feasting. But do not panic, even small changes in the way you live and eat can let you sense your intuitive satiety again and so avoid constant hunger. A small side effect: unwanted pounds will melt away as if by themselves.

Before we look in detail at how you can regulate your hunger hormones with the right diet and at the same time raise your satiety hormones, here first are a few tips that you can build into your everyday eating from now on!

Let us first look at protein. Proteins are vital nutrients and, as a source of amino acids, particularly important for many processes such as building muscle . But can protein in our nutrition plan really contribute to faster and longer lasting satiety? The answer: yes, absolutely! The body responds extremely sensitively to protein-rich foods, and even with a small intake of protein the hunger hormone ghrelin and with it the feeling of hunger is lowered. Through the secretion of CCK and GLP-1 the emptying of the stomach is also delayed. The release of the satiety hormone PYY is likewise stimulated more strongly with a protein-rich diet and the feeling of satiety increases. By contrast, skipping a protein meal can lead to increased NPY secretion and so to greater food intake. This favours the development of overweight.

Even so, your nutrition plan should not consist only of protein, protein and more protein. For a healthy balanced diet you should of course still pay attention to a good macronutrient distribution in your meal. But even a protein intake of 15 to 30% per day brings about a stronger leptin sensitivity of the body and therefore means that satiety sets in sooner. Very healthy, tasty protein sources that you can build perfectly into your diet are, for example, eggs, hemp seeds, meat and cheese. And of course in your Foodpunk nutrition plan we make sure that your individual protein requirement is covered in a healthy way.

Next we look at the much disputed subject of fat, because does fat not actually make you fat? Oh yes, who does not know that saying. It is still often assumed that fats are responsible for more body fat, but exactly the opposite is the case. Eating fats brings about an inhibition of NPY activity and therefore goes along with fewer cravings. The precondition is that it is healthy fat and not, say, a burger from the nearest fast food restaurant.

Fibre can also contribute to a faster and longer lasting feeling of satiety and should therefore be built into your nutrition plan. But what was it again? Fibre consists of plant substances that the body largely cannot digest. So they are not broken down in the small intestine at all but pass straight into the large intestine. They are often chewed more thoroughly, slow down the breakdown of carbohydrates and digestion, and contain many fibres that take up water in the stomach. This makes the food “swell” and gives it a larger volume despite fewer calories. So we stay full for longer, have a steady blood sugar and insulin level and fewer cravings. Fibre also brings many health benefits. It contributes, for example, to good gut health and a healthy cardiovascular system and is by no means just ballast!

You might assume that carbohydrates keep you full for a long time because they are so substantial, but that is by no means the case. Carbohydrate-rich meals, especially if they are rich in simple sugars, not only increase the desire for another dish but also make you want even more carbohydrates. Weight gain is then already on the cards. But why is that actually so? After we have eaten carbohydrates, the GLP-1 and the PYY concentration in the blood is extremely low and, compared with food rich in fat and protein, the ghrelin level is especially high. Satiety therefore only sets in briefly and, before you know it, hunger has taken the upper hand again. A low-carb dish, by contrast, keeps you full for longer. Because after a low-carbohydrate meal the ghrelin concentration stays pleasantly flat and the satiety hormones GLP-1 and PYY are stimulated ideally.

What conclusion can you draw from this? A low-carb diet with healthy fats and good protein sources can keep you full for a long time without your blood sugar riding a roller coaster.

A very healthy alternative to conventional ways of eating and strict diets is the ketogenic diet. This is a low-carbohydrate way of eating that places particular value on good fats and in which ketone bodies are formed from fatty acids in the liver. These lead to a very low insulin secretion and to few blood sugar fluctuations and contribute to optimal fat burning. The keto diet can not only stabilise blood sugar fluctuations, though, it can also bring the hunger and satiety hormones back into balance and really raise the feeling of satiety in the long term. Studies show what effects the ketone bodies have on hunger and satiety. In them, participants drank a ketone ester drink, and after 1.5 hours the ghrelin level and the desire for food were clearly reduced. Only after around 4 hours did the GLP-1 and PYY concentration in the blood slowly flatten off again. A ketogenic diet with a focus on more fats and proteins therefore raises the feeling of satiety, and the cravings and the constant thoughts about food can finally be kept in check.

If you want to get your hormone chaos under control but do not yet know how to build the keto diet into your everyday life easily, we have exactly the right thing for you. Because with your individual, science-based keto nutrition plan you no longer need to think about it, we take care of your nutrition, you enjoy the tasty dishes. And along the way your hunger and satiety hormones find their natural balance again.

Finally we dive a little into lovely sleep and sweet dreams. Oh yes, how nice it is to lie in your cosy warm bed, snuggled into lots of blankets and fluffy pillows, and lose a few kilos “as if in your sleep”.

Yes, you read that correctly, an effective and good sleep keeps you slim in the long run and brings the hunger and satiety hormones back into balance. Too little sleep, by contrast, can disturb the natural balance of hunger and satiety, contribute to increased food intake and insulin resistance and impair leptin regulation. Even a sleep deficit of just 4 hours a week, or less than 7 hours a night, reduces the leptin level by 18% and raises the ghrelin concentration by 28%. Lack of sleep is therefore, among other things, a common cause of strong cravings, obesity and type 2 diabetes. The optimal length of sleep to reduce the risk of overweight and further negative effects is between 7 and 9 hours a night.

Why sleep is so important and how it keeps us slim in the long run is something you can read in our really exciting blog articles!

Phew, that was quite a lot of input to digest! What is there to keep in mind, in short? While from now on you enjoy your tasty keto meal slowly and thoughtfully, with high-quality fats, proteins and healthy fibre, you bring your hunger and satiety hormones back into balance all by themselves and stay pleasantly full for several hours after eating. Enough sleep is important too: treat yourself to a long, lovely sleep at night.