Leptin is a hormone that regulates the energy balance of the body. It is mainly produced from fatty cells of white fat, but certain amounts of it are also secreted by brown fat, skeletal muscle, stomach, liver, ovaries, placenta in pregnancy and other tissues.
Its name derives from the Greek word leptos, meaning "weak". And indeed, leptin takes care of being weak. He communicates with the hypothalamus in the brain and tells you when to stop eating, so he is also called the "satiety hormone."
In addition to controlling appetite, leptin performs several more important tasks. It is related to the regulation of metabolism, reproductive function, immune system, bone growth, regulation of blood pressure, blood sugar, body temperature, and others. Since leptin is mainly secreted by fat cells, women with very low body fat (below 7-8%) experience disturbances in their monthly cycle due to reduced levels.
Various factors may affect leptin production. Fasting, as well as very low intake of calories, lower leptin levels, thereby increasing appetite. Interestingly, in the case of termination of starvation and an increase in calories, the level of leptin is not normalized immediately. self-regulation of energy reception remains disturbed, resulting in permanent overeating and overweight. A good reason to avoid starvation and extreme diets.
Melatonin, a neurohormone sequestered during sleep, increases leptin production. In this way control over appetite at night. People who sleep poorly do not produce enough melatonin and violate this regulation, which increases their appetite. Leptin production is also inhibited by stress.
Leptin normally begins to rise during and after eating, aiming at pressing the Stop button on the feeling of hunger and stopping the meal. This "button" is the leptin receptor cell in the hypothalamus. However, if the receptors do not capture the signal, although leptin levels are high, it is a condition called leptin resistance.
What is leptin resistance?
Leptin resistance typically appears to be part of the metabolic syndrome, which also affects insulin resistance. Both conditions are similar in that the target cells for the respective hormones very hardly perceive their signals.
With leptin resistance, the brain does not normally recognize the leptin levels. This creates a deceptive sense of hunger and leads to over-consumption. Leptin also has the task of controlling the amount of adipose tissue. If fat stores increase, the leptin level increases, which not only reduces appetite but also gives the body a signal to burn more fat.
With leptin resistance, fat cells scream: "Hey, we're over!" But the brain "does not hear" and tells you to eat and store even more, although this is the last thing you need.
End of part 1