Leptin – The Appetite Controller

Introduction and background

The life changing hormone, Leptin, is a protein that plays a key role in the regulation of energy consumption, body weight and energy expenditure, including appetite control and metabolism of your body. The name “leptin” was derived from the Greek word “Leptos” which means “thin”. Leptin is mainly produced by fat cells, intestinal cells and placenta and normally released in response to a meal or an increase in fat reserves. This reduces hunger and increases fat burning, all leading to gradual weight loss.

Why leptin is important?

If you are thin and have very little body fat, leptin helps regulate weight by controlling appetite and the use of stored energy. However, if you are overweight, you could have a problem with the blood level of leptin, a problem that may be the main cause of anorexia (lack of appetite), bulimia, obsession with food, and slow metabolism.


What affects the levels of leptin in the blood?

Studies show that the fatter you get, more leptin is released into your blood to signal the brain to stop eating and burn off excess fat. Similarly, when you have less body, less leptin is released to let your brain know brain that it’s now time to eat. Leptin levels are increased just before a meal and are decreased when your stomach is full.


Functions of leptin

Generally speaking, leptin plays a crucial role in regulating food intake, energy balance and body weight. Leptin is also directly involved in regulating the functions of other hormones e.g. hormones from adrenal, pancreatic, thyroid gland and sex hormones.
Leptin also helps control the brain in areas that monitor thyroid levels, and sympathetic nervous system responsible for blood pressure, diabetes, osteoporosis, heart disease, and aging.
The main function of leptin hormone in your body is hunger or appetite control.

Hunger control: Leptin basically acts on your hypothalamus, the part of the brain that controls appetite and satiety. Leptin tells the hypothalamus to decrease hunger (because fat stores are high), which leads to reduced food intake. That’s why; leptin is also called as an ‘anti-starvation hormone’ because its low levels lead to enhanced appetite. In other words, the higher the leptin levels in your body, the less hungry you feel.
Likewise, when your body fat stores are low (e.g. after dieting), blood leptin levels are decreased. This causes the hypothalamus to increase appetite which leads to over eating and a subsequent rise in your body fat. This more body fat results in more leptin being released, which then tells the hypothalamus to reduce appetite, leading to a reduced food intake. This is a classic negative feedback mechanism.
Maintenance of body temperature: Leptin also partially regulates your body temperature by affecting metabolism based on thyroid gland communications.


The leptin-obesity connection

For the reasons stated above, leptin has an indirect but important role in the development of obesity.

However, obesity, itself, is not the result of a lack of leptin. Instead, it is a lack of response to leptin that causes people to become obese, and obese individuals tend to have more and larger leptin-producing fat cells than thinner people, their leptin levels increase substantially with every pound of additional weight gain.
In other words, this is due to obese people becoming resistant to leptin’s signal, a condition commonly called as leptin resistance.


Defining leptin resistance

Leptin resistance is a condition in which leptin is unable to function properly in the body, so the body becomes unable to burn fat as fuel or does not respond to signals from leptin. In this condition, your brain loses sensitivity to leptin due to high levels secreted by excess fat and does not know when to stop eating. Hence, leptin resistance leads to progressive weight gain.
In other words, when you become leptin resistant, it takes more and more leptin to tell your brain that it is satisfied and that you don’t need more food. Therefore, it takes more and more food for you to feel satiated.

What causes leptin resistance?

It has been suggested that in obese people, leptin may have difficulty crossing the blood-brain barrier and, hence, cannot then stimulate the receptors in their brain.
Abnormal sleeping habits may also stimulate leptin resistance as the ‘sleep hormone’; melatonin is closely linked with leptin. Leptin resistance can also result due to high consumption of high fructose corn syrup, sugar, high fat foods, refined carbohydrates and deep fried / junk food.


How to prevent Leptin resistance

You can help prevent ‘leptin resistance’ by following some time-tested strategies such as:
Avoid ‘bad fats’ & excess sugar: One should consume healthy, well-balanced and natural foods and avoid the fatty or junk food and soft drinks that contain plenty of high calorie sugar.

Do regular physical workouts: Regular physical workouts can cause leptin levels in your body to drop, thus allowing you to feel hungry.

Improve your sleep: You should sleep at least for 6 to 8 hours in a day.

Use the natural supplements: Consuming natural supplements rich in melatonin, L-carnitine, CLA and omega-3 fatty acids have been thought to play an important role in normal leptin function and regulation.