Thanks for your question.
There are some basic points to increase the weight; first you have to visit your physician to exclude you don't have any disease that reduces weight.
Then-
1) Eat adequate high calorie food powered with
carbohydrate, protein and fat.
2)Time schedule of eating-eat 2-4 hourly,
4) Incorporate health drinks-Along with food you need health drinks such as
protein shakes to build muscle mass while working out.
5) Track your calories-In order to successfully gain weight fast, you need to eat at least your weight into 20 kales. Therefore, include calorie dense foods into your diet.
A 100 gm of peanut, for example has more than 500 kcal and 100 gm white pasta is 380 kcal.
Make sure you know the calorie count of what you are eating so that you can eat more.
6) Exercise/workout basic-Never exercises on an empty stomach because it will hamper the process of weight gain. Have a protein shake and some fruits before hitting the gym. Also make sure that your trainer knows you are there to build muscle mass and not lose weight. Follow these basic rules to gain muscle mass easily:
Free weights are the best way to gain muscle mass. Start with lighter weights and then keep adding the weight as your resistance increases.
The most important thing to remember about gaining weight fast is to track your progress in order to keep yourself motivated. Take pictures to know the difference and/or keep a journal to write about you are going through in the process. A positive outlook about gaining weight will reap results.
Consult a nutritionist to prepare your everyday diet chart according to the calorie requirements and from them you will get a chart of all daily use food with calorie value that can help a lot.
Best wishes.