[Adeniinteme]

According to what I learned from searching the web about this topic:

According to researchers, diets especially very low calorie diets, cause a rapid decrease in leptin levels circulating in the bloodstream. This lack of leptin is responsible for the increase in appetite often found when we drastically reduce our calorie intake.

However, if leptin can regulate fat mass, why is obesity still prevalent? The 2 possible reasons are leptin resistance and calorie intake.

Most of the obese and overweight people have leptin resistance in which case the body doesn't respond to signals from leptin. The brain loses sensitivity to leptin due to high levels secreted by excess fat and doesn't know when to stop eating. Therefore, leptin resistance is often linked to weight gain or obesity.

High leptin levels are inflammatory and increases our risk of diabetes, heart disease, arthritis, osteoporosis and other chronic diseases. Leptin resistance is often caused by excessive consumption of high fructose corn syrup, sugar, high fat foods, refined carbohydrates and processed foods.

Now how does calorie intake impact our leptin levels? Most dieters try to lose weight by drastically cutting down on their calorie intake. Reducing our calorie intake in is not a problem. What is wrong is prolonged calorie restriction that is not sustainable because it causes leptin levels to fall. Low leptin levels have negative impact on energy homeostasis and certain hormones. As the body goes into starvation mode, low leptin levels signal to the brain that the body needs feeding. Energy expenditure is reduced to compensate for the lack of food intake, thus lowering metabolism. This creates a hormonal environment conducive for storing fat. The combined effect of these hormonal changes are lower metabolism and increase in appetite and fat storage.