Diets do not work! If they do, that is for short period of time, and then, after that, you gain the weight you loss because of your deprivation, caused by a diet! The more you deprive yourself from food, the more you will overeat after that. When you deprive yourself from food, the body gets into starvation mood, and it starts to conserve your fat, because your body thinks, that it is going to starve.
Go on a diet, only if you want to gain weight, not to loose it!
If you try to eat, only when you feel really hungry, your weight will become normal, not too skinny, and not too fat, in a few months. For some people, it can take 6 months, and for others 9 months. It depends on various factors and is very individual, but eventually, eating only when you are hungry, will help to become a normal weight. Of course, there is the genetic component, but this advice is general.
Also, each time you eat, try to eat portions, not bigger than your fist, because that is about the size of your stomach, when it is empty. That will be enough to keep you going and feel satisfied. When you eat, only when your are hungry, that is the time, when your brain sends signals to your stomach, to get ready for food and digestion. When you are hungry, that is when most digestive juices are produced. Hunger is the best cook. When you eat only when you are hungry, your body gets only the calories it needs for its functions and no more. Your body will be able to assimilate most of the food.