Many think that hunger is merely a "lack of willpower," but in reality, it is a sophisticated and highly potent biological mechanism. One of the central players in this system is a hormone called ghrelin, also known as the "hunger hormone." Ghrelin is secreted primarily by the stomach when it is empty, and is sent through the bloodstream to the brain to deliver a clear message: The body needs food.
But it does not end there. In recent years, it has become clear that ghrelin has far broader roles. It not only increases hunger, but also affects metabolism, fat storage, the secretion of additional hormones, and even the likelihood of successfully maintaining a diet over time.
How does the hunger hormone work? When the stomach empties, ghrelin levels in the blood rise. The hormone reaches the areas of the brain responsible for regulating hunger and satiety, primarily the hypothalamus, where it amplifies the sensation of hunger and encourages the search for food. This is not just a "thought about food." For many, it is a genuine physical sensation: A decrease in concentration, irritability, weakness, fatigue, and sometimes even mild abdominal pain. Studies have shown that ghrelin levels rise before meals and drop after eating, especially following meals rich in protein.
Why is it so difficult to diet? One of the primary reasons many people find it difficult to stick to a diet is that the body treats a sharp drop in weight as an emergency situation. When fewer calories are consumed over time, the body responds in several ways designed to protect itself from “starvation.” One of these is an increase in ghrelin levels.
In other words, the more weight one loses, the more the body may actually increase the sensation of hunger in an attempt to restore the lost weight. Concurrently, there is also a certain decline in the metabolic rate. The body attempts to “save energy,” and therefore burns fewer calories. This is the reason many people feel that in the initial stage of a diet, weight loss is relatively rapid, but later on, stronger hunger, fatigue, and difficulty maintaining the routine appear.
A large study published in the New England Journal of Medicine found that even a year after significant weight loss, hunger hormone levels still remained higher compared to the starting point, which explains why maintaining the new weight is so difficult.
Not just hunger – fat storage too: Ghrelin apparently has an additional role: To encourage the body to preserve energy stores. Studies have shown that the hormone may stimulate fat storage and influence the way the body utilizes energy. From an evolutionary perspective, this actually makes perfect sense. In periods of food scarcity, the body needed to protect itself from prolonged starvation. The problem is that in the modern era, where food is available everywhere, this same survival mechanism can work against us.
The link between ghrelin and blood sugar levels: Ghrelin also has an effect on the regulation of blood sugar. In states of hunger, the hormone helps ensure energy supply to the brain and muscles, among other things, by influencing insulin secretion and other mechanisms related to sugar metabolism. This is one of the reasons why, for some people, prolonged hunger also causes irritability, weakness, or difficulty concentrating.
When do ghrelin levels rise particularly? There are several known situations in which hunger hormone levels tend to rise: Skipping meals and prolonged fasting when the stomach remains empty for a long time, ghrelin rises and increases the sensation of hunger.
Extreme diets: The sharper and faster the weight loss, the more the body intensifies its defense mechanisms.
Lack of sleep: Studies have found that short or poor-quality sleep raises ghrelin levels and simultaneously reduces satiety hormones. This is one of the reasons tired people tend to eat more.
Stress and mental tension: In some people, stress increases emotional eating and also affects hunger and satiety hormones. After significant weight loss, even after the diet ends, the body may continue to “fight” to regain the previous weight.
Is it possible to reduce the hunger hormone? It is impossible to "turn off" ghrelin completely, and it is a good thing too. This is an essential mechanism for survival. However, it is possible to reduce its extreme fluctuations and help the body achieve a better balance.
More protein in the menu: Meals that contain sufficient protein generally contribute to more prolonged satiety and reduce the rapid rise in hunger. Eggs, yogurt, cheeses, fish, chicken, legumes, and tofu can help in this context.
Good sleep: One of the most important things for appetite regulation is sleep. Even a few nights of relatively short sleep can raise ghrelin levels and increase cravings for sweets and snacks.
Regular physical activity: Exercise improves sensitivity to satiety hormones and contributes to a better metabolic balance. In addition, for some people, physical activity also reduces emotional eating.
Moderate weight loss: A gradual and moderate decrease is generally easier on the body hormonally compared to extreme and rapid diets.
The bottom line: If you feel very hungry during a diet, it does not necessarily mean you lack willpower. In many cases, it is simply the biology of the body operating exactly as it was designed over millions of years of evolution. Ghrelin is a reminder that our body does not always "want" to lose weight. As far as it is concerned, it is primarily trying to protect itself from starvation.