The Ob mouse is a breed of unhealthy and obese mice obtained by genetic mutation and intended for use in scientific research. No researcher had really asked the question of what made this animal obese. In 1994, Jeffrey Friedman discovered that this obese mouse lacked a hormone called leptin, a hormone that had been unknown until then.
He decided to inject these mice with leptin, which restored their vitality and health in the weeks that followed. In view of these results, big pharmaceutical companies were already imagining future treatments for obesity and of course the millions of dollars that this type of treatment could bring in on a large scale.
The pharmaceutical laboratories were quickly disillusioned, because contrary to the mice, the obese humans did not seem to be leptin deficient, on the contrary, the overweight people generally had excessive leptin levels and seemed to be "leptin-resistant". Supplementing them with leptin seemed to have a negative effect on their health.
The pharmaceutical industry and hospitals quickly lost interest in this substance, which again seemed to be of little physiological importance and difficult to patent. Despite this lack of interest, some researchers and scientists remain convinced that this is one of the most important key chemicals in the body and a determinant of health and life span.
Two essential hormones for optimal health.
Each human being is composed of trillions of different living cells. Life is possible thanks to a physiological balance maintained by the communication between all these cells. Health and life depend on the quality of information and intercellular exchanges. From birth, most of the physiological information is transmitted through hormones, the most important molecules for maintaining the body in good health. Metabolic functioning depends on the transmission of information by two essential hormones, insulin and leptin, which act in synergy.
The whole metabolism governed by these two hormones allows the transformation of food into energy useful for the functioning of the body. Insulin mainly regulates the use of sugars and leptin, that of fats. Digesting food provides the body with enough energy to maintain and repair cells, as well as to produce new cells. Ideal cell function and reproduction are factors that determine the quality and duration of an individual's life. Leptin controls the amount of energy the whole body needs to ensure optimal communication between all the cells in the body and the brain.
What exactly is the role of leptin?
Leptin is not a hormone in the strict sense of the term because it is not produced by an endocrine gland, but by adipocytes (fat cells). However, it works like a hormone and regulates fat reserves in the body through an action on the hypothalamus. It decreases or increases the amounts of fat stored in the tissues and acts on the feeling of satiety.
It also influences the thermoregulatory system, increasing or decreasing body energy expenditure according to temperature variations and needs. Metabolically, a large amount of fat mass induces a greater secretion of leptin and will cause lipolysis, thus eliminating fat. A leptin deficiency will increase the storage of fat mass and the desire to eat. It seems that for the same amount of fatty tissue, leptin secretion is three times more important in women than in men.
Leptin, a new approach to weight problems
The discovery of leptin has changed the way some scientists look at nutrition, weight problems and metabolism in general.
In the past, fat was considered a useless and unsightly deposit that had to be removed. After the discovery that fat itself produces leptin and in view of the very important role of this substance as an information carrier, the way scientists look at fat mass has changed considerably. Thus, fat is currently recognized as an endocrine organ, in the same way as the ovaries, the pancreas, or the pituitary gland, glands or organs that all perform essential functions in the body in general, and in the brain in particular.
Science has become aware of the essential regulatory role played by leptin and lipids, since they inform the brain, which in turn gives the body the signal to be hungry or full. So leptin regulates the amount of food to be taken in based on the body's vital needs and with the goal of achieving an ideal weight. Everyone knows that most diets are difficult to follow, but more importantly, it's hard to keep the weight off. Very often the person puts on more weight than he or she has lost, if he or she is not constantly "careful" about what he or she eats.
The important role of fatty tissue
In earlier times, the stored fat was very useful for protection against the cold or to face periods of famine. Currently, although this is no longer the case, this fat storage process is probably still in our genes. A few centuries ago, man led a less sedentary and more active life, which is no longer the case and overweight tends to spread in our populations.
As soon as overweight appears, the body, benefiting from an optimal functioning of the hormonal system, should trigger a production of leptin, signaling to the hypothalamus that the quantity of stored fat is sufficient, that it is time to stop eating and probably time to eliminate the excess by physical effort. This information from the most ancestral part of the brain is phenomenally powerful and makes it very difficult to not eat and voluntarily limit calories when you are hungry.
It seems that the only way to succeed in eating less and to anchor this result in the heart of the body's cells is to act on the hormones that regulate this feeling of hunger. Thus, by acting on the leptin level, the researchers found that not only the brain chemistry is changed, but also the connection circuits used by the neurotransmitters responsible for triggering this hunger process. In the current state of knowledge, it seems that in the body no other substance than leptin can accomplish this miracle.
Blood leptin levels as a health measure
The influence of leptin on the process of satiety and hunger has therefore attracted the attention of the scientific community. And to come to the conclusion that the installation of cardiac pathologies, obesity, diabetes, osteoporosis, autoimmune diseases, reproductive disorders and even the aging process itself, would result from an inability of the body to capture or transmit correctly the signals emitted by leptin.
The impact of this substance is difficult to imagine as there are so many areas of the brain on which it acts. Thus, leptin levels also affect thyroid secretions and the sympathetic nervous system, which are responsible for such important physiological parameters as blood pressure, body temperature, adaptation to exercise and to the surrounding environment, and the levels of adrenaline, cortisol and all the other hormones that regulate most of the vital processes.
In the same way that we speak of insulin resistance, we can therefore speak of leptino-resistance as an original factor in many diseases. Currently, in the field of health, no one questions the importance of insulin in triggering certain diseases other than diabetes alone.
According to leading scientists, leptin levels are even more vital than insulin levels, since leptin still acts upstream of insulin. The researchers also linked high levels of leptin to the development of inflammatory processes, or the production of inflammatory substances. According to many current hypotheses, leptin could also be a determining factor in the aging process, since too much fat storage in the viscera would hinder the proper functioning of essential organs such as the heart, liver, stomach or intestines. Leptin levels are easily measured and should therefore be measured at least as often as cholesterol levels.
The Biology of Aging
Scientists interested in the aging process are beginning to investigate the role played by this hormone, leptin, which appears to have a critical impact on health. To maintain itself, since the dawn of time, life results from two programmed functions, reproduction and feeding, without which we would probably not be here. The main morphological and physiological characteristics have all been programmed to ensure these two activities. Nature doesn't care if the life of each man is long, healthy and comfortable, what is essential for her is that the chances of perpetuating the race are sufficient. However, nature hates to waste and the body has been programmed to perform these vital functions with the least amount of energy possible and to constantly maintain its balance or homeostasis.
The genetically programmed set of mechanisms regulating homeostasis allows for the maintenance and repair of DNA, the increase in the production and levels of antioxidants, the protection of proteins against major thermal shocks, etc. During the 1970's, it was demonstrated on animals that all these processes work optimally and significantly extend life when caloric intake is limited.
Link between leptin, insulin and longevity
There is a powerful link between reproduction, energy storage, and longevity. This link is largely the responsibility of insulin, low levels of which appear to promote maximum lifespan. Glucose is the body's primary fuel because it can be consumed within the tissues without direct oxygen supply, which is the case during intense but brief efforts. The second fuel is fat, which will be consumed later in the effort and only in the presence of oxygen.
Recall that the primary signal that indicates the amount of fat to be stored is leptin. Leptin has a direct impact on the entire metabolism through the thyroid gland. Among other things, the thyroid is a real thermostat on which the body temperature depends directly.
It is well known that low temperatures have a beneficial influence on longevity. This is not to be confused with hypothyroidism, but rather to allow the body to function as efficiently as possible with the least amount of energy possible.
However, we realize that in order to lose weight or to improve health, we generally advise people to exercise and therefore increase their metabolism and thermogenesis. According to this theory, which demonstrates the importance of leptin and insulin levels, it is not the intensity of the metabolism that should be increased, but rather the quality and deep functioning of the metabolism.
In conclusion, too low leptin levels, or insulin or leptino-resistance (too high levels) would have an inevitable impact on life span and optimal metabolic functioning.
Leptino-resistance and insulin-resistance, the keys to diet
Leptino-resistance would be established in the same way as insulin-resistance, i.e. by excessive hormonal stimulation. For example, it is known that repeated high levels of blood glucose lead to frequent insulin spikes, which gradually lead cells to insulin resistance, and often to diabetes. It seems that the mechanism is identical with leptin. That is to say, when excess sugar is transformed into fat, the adipocytes would release leptin in bursts, which would cause leptin peaks, in the same way as insulin peaks for glucose. These spikes emitted too frequently in a repeated manner would give rise to leptino-resistance.
To allow weight loss and prevent these sudden increases, there is only one way to act, by restoring appropriate leptin and insulin cellular information. It is necessary to get the brain to "rehear" the cellular signal emitted, which would allow not only a restoration of the ideal weight, but also a metabolic optimization and therefore a prolongation of life itself. This cellular reprogramming is essential in order to avoid superfluous cellular storage and feelings of hunger during a diet.
A smart, well-balanced diet that avoids blood sugar and fat spikes will restore your cells' sensitivity to insulin and leptin and retrain your brain to listen to their messages. All restoring harmonious metabolic functioning.