Why leptin does not guarantee a health for everyone

Probably, each of us understands that a person cannot live without energy. Everything from growth of hair to the process of thinking is correlated by the energy potential in the cells of the human body. And the hormones that take part in energy metabolism and give signals about the level of energy in the body affect all our functions in some way. Leptin is one of them.


  1. Who count energy reserves.
  2. The role of leptin.
  3. Something went wrong.
  4. Deficiency of fats and its reverse side.
  5. The other side of the coin.


Who count energy reserves

There are a lot of counters of energy reserves, but the main ones, of course, are leptin and insulin. As for insulin, this hormone is familiar to almost everyone. Its role in the regulation of blood glucose levels and in the development or treatment of diabetes is absolutely clear. But few people know about leptin. This hormone is responsible for storing fat in the human body.

At the same time, insulin is produced by the pancreas after glucose enters the bloodstream, and leptin is a product of fat cells. With a high level of both hormones in a human body, the feeling of hunger is dulled, since they both imitate satiety and send a signal about this to the central nervous system.

The hypothalamus is responsible for eating behavior. It works on a «plus or minus» basis.

In other words, there are two types of cells:

  • the first group synthesizes substances that stimulate appetite, they are known as orexigenics;
  • the second one acts exactly the opposite, these are anorexigens.

The most frequent state for people given to us by evolution is being hungry or exhausted. In this case the hypothalamus produces hormones that activate appetite and make a person look for food. Hunger centers are stronger than satiety centers. But after satisfying his desires, a person is faced with the problem of high levels of glucose in the bloodstream. What does it mean? Only that insulin is connected to the process, which blocks the activity of appetite cells and helps the synthesis of anorexigens. As a result, the person feels full.

The role of leptin

Everything is clear: insulin does not play a major role in this complex process. It so happened that since the time of our distant ancestors of glucose the result of satiety was so small. Fat was the main source of energy. Our body was used to store it up for a rainy day. Fat was (and still is!) a key factor in appetite control. And it carried out its activities with the help of leptin.

The algorithm of actions is extremely simple:

  • the more we eat, the more extra calories we store in reserve in the form of local fat deposits;
  • the more fat is deposited in a body, the more leptin is synthesized by fat cells;
  • the more hormone in the blood, the more hunger centers are blocked and the more satiety hormones are produced.

Thus, the energy balance in the body is maintained. But why does nature help a person to forget about the feeling of hunger? That is because all people should not only eat, they must remember about other joys of life and their duties! If we have a lot of energy, as leptin tells us, we start thinking about procreation. To tell true, this applies more not to modern man, but to his distant ancestors. But this essence is still clear. For this aim, leptin not only removes the feeling of hunger, but also takes care of many other related biochemical processes. There is only one goal is to make healthy offspring.

Along the way, leptin stimulates the higher nervous activity of a person through a special hormone BDNF or intracerebral neurotrophic factor. How is this factor related to leptin? Everything is simpler than it seems to be: the brain that is the main consumer of energy. So if BDNF stimulates the growth of neurons, it should also take care of them. Energy is the first thing the cells of the brain tissue need.

Therefore, BDNF is like a person who has two hands:

  • one produces energy;
  • the other spends the energy to ensure optimal brain function.

So a person grows smart and beautiful, because the balance of energy metabolism not only makes the brain happy, but also reduces appetite, which prevents obesity and metabolic syndrome.

In addition, leptin increases fertility. It is a powerful immunomodulator, that supports the functioning of the circulatory system, respiration, and the bone skeleton. It is not just a hormone, it is a real dream. The control of leptin activity is very simple: accumulate extra pounds and have fun.

Something went wrong

Only one circumstance can confuse your body. Leptin stops working in a case of overweight. There is a lot of fat, a big concentration of leptin, and the appetite does not decrease in any way. As lipids become more and more, for some reason they extinguish all the wonderful functions that leptin is endowed with by nature itself. Why? The scheme worked for millions of years and suddenly the ideal mechanism just broke down?

It’s all about adaptation. All the ideal functions for leptin were invented by nature and designed for the nutritional conditions in which our ancestors lived. But the 20th century changed the situation dramatically. The age of abundance has arrived. Prior to that, protein was the main source of nutrition and energy, carbohydrates played a minimal role, and fats played a microscopic role. What about today? Fats and carbohydrates are on the first place, protein comes after them. This so-called «food revolution» played a cruel joke on a person.

Deficiency of fats and its reverse side

We are not very interested in carbohydrates, but let’s talk about fats in detail. Extra fat is a huge problem for modern man. It is almost foreign substances for our body. All previous generations lived in conditions of semi-starvation, so it was simply not possible to store fats. Now there is the time for abundance, and the body cannot rebuild itself at the click of a button and refuses to work normally in conditions of fat accumulation. Evolution did not help people to find such a mechanism.

First of all, this situation occurs in the central nervous system represented by the brain. A persistently high level of fat in the bloodstream dramatically changes the permeability of the blood-brain barrier. It is considered to be a filter for bioactive substances as they are transported from the bloodstream to the brain tissue. As a result, leptin simply does not have the opportunity to get to the center of appetite in the right amount.

The Omega fats

Omega fats play a special role. Today, we not only eat a lot of fat, but also this fat is represented in the «wrong» form. Therefore, the share of saturated animal fats, omega-6 fats from vegetable oil and lard is growing at the expense of the share of omega-3 fats. And here we are faced with the gangerous side of fat.

Some of the fats in our ancestors’ diets were bioactives. They were not a source of energy. They affected the functional state of the cells. Accordingly, if today they predominate in our diet, and even their biochemical balance will be changed, the work of the cells of the body will work, as it has been some time ago. An imbalance of omega-6/omega-3 provokes a change in the composition of the cerebral membranes and the center of appetite. And this is a sharp increase in the amount of inflammatory hormones, the source of which is omega fats.

Such situation causes the neuroinflammation developments. And this is a problem from which almost all disorders of brain activity grow from atherosclerotic disease to Alzheimer’s syndrome. All problems start at the center of appetite. Leptin resistance occurs and brain receptors simply stop responding to leptin signals. By the way, insulin resistance also develops.

So it turns out that neither leptin nor insulin is able to affect the cells that control appetite with a plus and minus sign. In the result, the hunger/satiety system works by default.

The other side of the coin

The saddest thing is that a long-term high level of leptin harms all vital processes, which normally the hormone has an extremely positive effect. Immunity is under attack, it ceases to calmly respond to infections and demonstrates an overreaction. It is familiar to everyone today as a cytokine storm during Covid, or autoimmune interest.

The positive effect of leptin on fertility with an excess of the hormone blocks the reproductive function, disrupts the balance of sex hormones. A high concentration of leptin is considered a risk factor in the development of breast cancer. It turns out that leptin resistance is in no way inferior to, and in many respects surpasses in its negative, insulin resistance. Only one thing can calm us down, we know how to deal with it. But not everyone has the strength and character to do so.

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