Leptin: The Role of Leptin in Weight Loss
Do you know that Leptin, also known as “the life changing hormone” is a protein that plays a key role in regulating your energy intake, body weight and energy expenditure, including appetite and metabolism? Leptin leap into the headlines when it was identified in 1995 as a protein that triggers weight loss in mice. It is produced primarily by fat cells, but cells in the gut and placenta also make leptin. It circulates in the blood and acts on different tissue including the hypothalamus, skeletal muscle, and liver. Leptin is normally secreted in response to a meal or in response to increasing fat stores. It reduces hunger and increases fat burning. Its production is primarily attributed to adipose or fat cells in the body.
Importance of Leptin in weight control
When you are lean and have very little fat stores, leptin helps to regulate your weight by controlling appetite and the use of stored energy. However, if you are obese there is a problem with the leptin levels, troubles occur and this could be the primary reason for food cravings, overeating, an obsession with food, and a slow metabolism.
How leptin controls our appetite?
Leptin's primary function is to act on the hypothalamus, the part of the brain that controls appetite and satiety. It tells the hypothalamus to reduce appetite (because fat stores are high), which results in decreased food intake. For the same reason, it has been also called as an 'anti-starvation hormone' because low levels lead to increased hunger. The higher the leptin levels in your body, the less hungry you feel.
On the other hand, when fat stores are low, for example, after dieting, leptin levels are reduced. This causes the hypothalamus to increase appetite. An increased appetite obviously results in greater food intake and a corresponding increase in body fat stores. More body fat results in more leptin being produced, which then tells the hypothalamus to decrease appetite, leading to a reduced food intake. This is a classic negative feedback mechanism.
The link of Leptin with obesity
Leptin has been proposed to prevent obesity because it acts in a feedback loop between peripheral fat deposits and the brain: increased body fat leads to elevated leptin levels that, in turn, reduce feeding and, at least in rodents, increase energy expenditure. According to the recent research, defects in leptin signaling lead to obesity, overeating, and decreased energy output.
Normally, when leptin levels in the blood go up, the brain signals us to stop eating. 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. When the brain fails to sense the leptin hormone's signal correctly, it thinks that more fat is required, even though we have enough. and fat begins to accumulate while metabolism slows down. Therefore, it is possible that 'leptin resistance' may result from over-eating. It is likely that you have become leptin resistant if your fasting serum leptin levels are high (similar to diabetes and insulin).
What is leptin resistance?
Leptin resistance is a condition in which leptin is not working properly in the body, so the body becomes unable to burn fat as fuel. In fact, the body doesn't respond to signals from leptin. The brain has lost sensitivity to leptin due to high levels secreted by excess fat and does not know when to stop eating. Hence, leptin resistance is often attributed to weight gain and obesity. When our body is in optimum calorie balance, it can communicate these messages efficiently. But if our diet is filled with starches and sugars, our fat will metabolize sugar releasing surges in leptin. Thus, these chronically high leptin levels cause our cells to become "leptin resistant" just as when our cells are chronically exposed to insulin promoting its resistance. When a person becomes leptin resistant, it takes more and more leptin to tell the brain that it is satisfied and that we don't need more food. Therefore, it takes more and more food to feel satisfied. As a result, the brain, not responding to leptin, frantically signals for more and more fat to be stored.
Causes of leptin resistance
Some scientists think that leptin may have trouble crossing the blood-brain barrier in obese people, which means it can't then stimulate the receptors in the hypothalamus. Leptin's reduced ability to cross the blood-brain barrier is thought to be due to the fact that obese people have a cerebrospinal fluid (CSF) to plasma ratio much lower than non-obese individuals. Poor sleeping habits may also exacerbate leptin resistance because the 'sleep hormone', melatonin, appears to have a close relationship with leptin.
Leptin resistance is also caused by excessive consumption of high fructose corn syrup, sugar, high fat foods, refined carbohydrates and processed foods.
How to prevent Leptin resistance
In order to prevent or overcome 'leptin resistance' the following strategies should be employed:
1- Avoid excess sugar and 'bad fats': Everyday more and more people become leptin and insulin resistant due to the Standard Diet, which is full of processed foods, refined grains, sugar, and not much else. The solution is to consume foods that focus on healthy fats and avoid blood sugar spikes. Without going into a complete hormone healthy diet, you will want to emphasize eating vegetables, lean meats, eggs, dairy, and other healthy fats, while limiting sugar and grain consumption.
2- Exercising can cause leptin levels in your body to drop, thus causing you to feel hungrier.
3- Improve sleeping habits (Sleeping at least 6 to 8 hours in every 24 hours is highly recommended).
4- Use some good, time-tested and recommended weight loss supplements.
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