First check your diet. this has an effect on how your waist looks. You may increase the carbohydrate intake primarilty from simple sugars to starch (eg. sweets, rice, breads...etc) regulate your intake of foods which are hard to digest because it would take more energy to digest it. But do not over eat, it will never be a solution. just gradually change your eating habbits from daily basis it is like "adding an extra". for example: adding an extra slice of bread every morning or adding an extra slice of cheese or adding half cup of rice.
Check your lifestyle. you should be eating at a proper time and having regular-served meals and a balanced diet.
Next having get rid of a skinny waist needs a gain of weight. in order to attain this we should have a regular protein intake and daily exercise. Build your muscle and maintain it.
hope this helps
Eating and exercising and gradually gaining weight will give you a curvier figure. Although packing on a bunch of pounds at once may seem like the fastest way to go, it is not very healthy and can lead to some serious health problems in the long run. Having a good amount of food intake and exercise would be the best way to gain the body you want.
An efficient way to add more weight to your body in a healthy manner is to ensure you are eating not only enough (calories) but eating a balanced healthy diet. With this, exercise, especially in strength-training. Cardio tends to be a more slimming exercise form, whereas strength-training helps to build muscle up and can result in a gain of weight around your torso, but in a healthy manner. As muscles grow larger and the strength-training gets more intense or to a higher level, simply once again eat more calories as well as getting a good amount of carbs and protein before and after a workout.