Leptin is an endocrine hormone that’s produced by adipocytes (fat cells) to suppress feelings of hunger and optimize the efficiency of energy expenditure in the liver. In general, the production of this hormone is dependent on the number of fat cells the body has. In other words, the more fat you have, the higher serum levels of leptin.
However, researchers found that many overweight individuals have leptin resistance, where the actions of the hormone are ineffective.
This pathophysiology is now believed to be a driving factor of obesity. In this article, we will briefly discuss the action of leptin on the brain and how it should be a focus for people who are trying to lose weight.
The physiology of leptin
To understand the action of leptin, I first need to tackle an important structure that’s found in the brain. The hypothalamus is a complex neuroendocrine gland that’s located in the base of the brain and is responsible for the regulation of numerous physiological functions, including body temperature, metabolism, immune reactions, and appetite. The last function is the main target of leptin, as high serum levels of hunger-suppressing hormones will trigger the hypothalamus, and eventually, the entire central nervous system (CNS) to induce feelings of satiety (fullness).
Conversely, leptin deficiency removes the brakes from this system, which leads to constant feelings of hunger and increases the caloric intake. As a result, you will consume calories that get stored as adipose tissue instead of using your current energy storage (e.g., fatty acids, glycogen). This condition is referred to as congenital leptin deficiency.
As the name implies, leptin resistance refers to the ineffective action of leptin on a cellular level. This abnormality gained a lot of traction over the past few years, and experts believe it might play a key role in obesity. One of the consequences of leptin resistance is the difficulties people face when trying to follow a calorie-restricted diet since their hunger signaling pathways are unchallenged. Consequently, you will be in a constant state of hunger, which makes you consume more calories, preventing the body from using fatty acids stored in your belly and love handles.
Another factor that exacerbates this situation is rapid weight loss! That’s right; losing weight might make it more difficult to pursue your fitness goals. As I mentioned above, the amounts of leptin in the body are proportional to the adipose tissue. When you lose weight, the volume and number of adipocytes will inevitably decrease, which will be interpreted by the brain as a state of starvation. Therefore, the CNS will release more powerful signals, making it extremely difficult to stick to your diet.
Some of the consequences of leptin resistance include:
- Weight fluctuation, especially after rapid weight loss.
- Difficulties sticking to a calorie-restricted diet.
- Getting stuck in a Yo-Yo diet (rapid weight loss followed by rapid weight gain).
Leptin is a crucial hormone that regulates feelings of satiety and hunger. The deficiency and/or resistance of leptin is extremely challenging to deal with, especially without the proper guidance and management plan. For more topics about nutrition and fitness, don’t hesitate to check my other posts by clicking this link.
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Disclaimer: This information is provided as an educational service only, and is not intended as a substitute for medical advice. Anyone seeking specific medical advice or assistance should consult his or her doctor or orthopedic surgeon.