Leptin: everything you need to know about the satiety hormone

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What is leptin? What is his role ?

The leptin is a digestive hormone that regulates fat reserves in the body as well as appetite. It is called “ satiety hormone » because it gives the feeling of being full. It's a anorexigenic hormone that is to say, which “suppresses the appetite” (as opposed to hormones which increase appetite such as ghrelin or cortisol). Leptin is released by white adipose tissue but also by the stomach.

Apart from its effects on energy metabolism, leptin is also considered to be a cytokine playing a role in immunity. Finally, it is involved in bone metabolism and reproductive function.

Structurally, leptin is a protein of approximately 16 kDa (kilodaltons), coded by the “OB” gene located on the chromosome 7 human. It was first discovered in 1973 in mice.

Physiologically, leptin levels are higher in women than in men (at equal weight, in relation to the difference in proportion and distribution of fat mass between the two sexes).

Leptin, a hormone that makes you lose weight?

Leptin is a hormone that limits weight gain.

After eating a meal, leptin, produced by the stomach, enters the bloodstream. By focusing on specific receptors of the hypothalamusit causes the feeling of fullness.

Also, released by adipose tissue, an increase in fat mass will have the effect of stimulating its synthesis and reducing food intake while increasing energy expenditure. Conversely, when adipose mass becomes scarce, leptin secretion decreases, the feeling of hunger appears, as well as a reduction in energy expenditure.

Leptin and obesity: what is leptin resistance?

Of the Elevated leptin concentrations are seen in obese people evoking resistance to the latter. This leptin resistance would worsen with weight gain. This mechanism would be similar to that of insulin resistance.

When the body develops resistance to leptin, satiety is no longer respected, which promotes weight gain. As weight increases, fat cells produce more and more leptin. The higher the level of circulating leptin in the blood, the more the brain no longer understands the message! Hunger is therefore greater and food intake increased… This is one aspect of the infernal cycle of obesity. Doctor Corinne Chicheportiche-Ayache, nutritionist.

These findings make synthetic leptin (in the form of medication or food supplement) an ineffective alternative for lasting weight loss in obese subjects. However, a leptin synthetic analogue is commercially available to treat leptin deficiencies in people with lipodystrophy.

We find food supplements based on leptin but no serious demonstration of effectiveness has been carried out. Furthermore, there is a treatment reserved for very specific indications such as lipodystrophies (rare congenital diseases). These medications are administered only under rigorous medical supervision and cannot under any circumstances be used in cases of overweight/obesity.

Metreleptin, a drug to increase leptin

The metreleptin (Myalepta®) is indicated to treat complications associated with leptin deficiency in patients with lipodystrophies (abnormalities in the distribution of fats in the body).

A well-known acquired lipodystrophy is notably a complication linked to taking old triple therapies against HIV. However, there are other causes of lipodystrophy whether acquired or congenital.

Lipodystrophies can manifest as a loss of fat in the legs, arms, face or buttocks or by an accumulation of fat in the stomach, breasts/chest or neck (buffalo hump). .

Leptin and insomnia: what is the link?

During sleep, leptin levels are usually so high that the feeling of hunger is not felt. However, if sleep is disturbed, this rate drops at night and you feel hungry, even though the body does not really need food.

“In the case of insomnia or reduced sleep time, leptin is produced less, which will promote the deregulation of satiety and therefore appetite. The inevitable risk is weight gain.”, underlines Dr. Corinne Chicheportiche-Ayache, nutritionist doctor.

People who suffer from insomnia or who work nightly hours must therefore be extra vigilant and monitor their measurements.

Note that conversely, sleep limits the production of ghrelin which produces the feeling of hunger.

To stay in shape, the first rule therefore consists of having a good night's sleep (increase in leptin levels and reduction in a hormone with opposite effects, ghrelin) and therefore in implementing all the hygienic and dietary measures intended to promote healthy good sleep (fixed schedules, no blue light…). Thus leptin will make it possible to better respect satiety and ghrelin will be less produced, the appetite will thus be reduced. Doctor Corine Ayache-Chicheportiche, nutritionist.

Leptin: what other effects on health?

Changes in leptin levels could have serious health effects.

Leptin and Alzheimer's disease

A 2009 study carried out among several hundred elderly people demonstrated that people with the lowest leptin levels are more likely to develop neurological diseases than those in whom the rate is high (source 1).

According to this work, leptin helps prevent the onset of senile dementias such as Alzheimer's disease. Scientists therefore believe that it is possible to use leptin levels to diagnose the disease and, above all, that this discovery will allow a breakthrough in the search for a treatment.

Let us add that this research shows that too low weight and low body fat (resulting in low leptin levels) could be associated with an increased risk of dementia such as Alzheimer's disease.

Leptin and osteoarthritis

Obese people are predisposed to suffering from osteoarthritis, not only because of mechanical overload, but also because of their elevated levels of leptin and other pro-inflammatory cytokines, which contribute to joint inflammation and destruction of cartilage.

Leptin and cardiovascular risks

A high leptin level finally seems to be correlated with a greater risk ofmyocardial infarction and this, regardless of the level of obesity (sources 3 and 4). Likewise, the risk of occurrence of a diabetes could increase for the same reason – at least in humans (source 5).

As you can see, generally speaking, high levels of leptin are associated with many diseases often associated with obesity. This is also the case for breast cancer, sleep apnea or even covid-19 pneumonia (sources 6,7,8).

Weight loss: how to activate this hormone naturally?

And healthy lifestyle is the key to optimizing leptin production and avoiding weight gain.

Foods: where to find leptin?

“To increase leptin production, you must increase the feeling of satiety through a diet rich in fiber in particular (fruits, vegetables, whole grains, vegetables or dried fruits) and water! Furthermore, physical activity helps fight against leptin resistance”, according to Doctor Corinne Ayache-Chicheportiche.

It is also recommended to incorporate sources ofproteins (in the evening, it is better to avoid animal proteins that are difficult to digest and risk disrupting sleep) as well as good unsaturated fatty acids (omega 3,6,9). So be sure to maintain a regular consumption of lean meats, eggs, legumes, fatty fish, virgin oils and oilseeds.

Let us add that the way you eat plays an important role: as the secretion of leptin in the stomach takes at least 15/20 minutes, if you eat too quickly you might think that you are still hungry (but that's just that). the leptin peak has not yet been reached). In eating more slowlyyou will have a synchronization between your diet and the production of leptin and you will thus feel the signal of satiety.

Sufficient sleep

In the event of disturbed sleep, leptin levels decrease significantly. The quantities and choice of foods eaten are increasing. A sufficient sleep is essential to activate leptin production in order to limit weight gain.

Manage stress

The cortisol is produced in greater quantities in situations of physical or psychological stress. Cortisol with its orexigenic effects (i.e. promoting appetite) opposes the anorexigenic effects of leptin. Therefore, even in case of satietyThe brain will receive a hunger message in stressful situations. It is therefore advisable to work on managing anxiety and to avoid intensive sports training.

Moderate and regular physical activity

Leptin sensitivity may increase during light to moderate athletic activity. You will not only burn your calories, you will enjoy a real feeling of satiety. This is why we often say that sport has an anorexigenic effect (except in the case of intensive training).

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