If losing some extra weight has become a mission impossible for you and it seems like your diet or exercising is not yielding the desired results, then leptin may be the problem that you need to fix instantly. Leptin is a very powerful hormone that has a major influence on energy balance and body weight. Leptin performs its function on two ways. The first is by sending signals to our brain when we need to stop eating and the other one is when it stimulates the fatty tissues to burn energy.
Our body releases more and more leptin into the bloodstream as we grow fatter to create a balance and to stimulate fatty tissue to burn the extra fat. By continuously overexposing to high levels of this hormone you are at the risk of becoming leptin-resistant.

this hormone is the reason why you can't lose weight
What is Leptin Resistance and How You Become leptin-resistant?
After long periods exposed to high leptin levels, some individual’s body loses its sensitivity to leptin. Therefore, the brain doesn’t listen to leptin when it tells it to accelerate metabolism or to stop eating. And this is the point where the weight loss problem appears. Leptin resistance makes people more prone to chronic diseases, causing excess stomach fat and increasing inflammation.
One of the reasons of developing leptin resistance can be crash diets. Some people often make mistake by reducing their calorie intake intensely in order to lose weight fast. But this becomes a problem because in that case leptin is telling the brain that it needs more food. That’s why the best thing is to avoid this kind of diets because they often give the opposite result.
You can also become leptin-resistant if your nutrition consists of processed foods like these below:
 Refined Carbohydrates
 Foods high in fat
 High fructose corn syrup
 Foods high in sugar