Hi there as per your weight and height you are underweight. Your weight should be 85-87kgs.. That means you are 20kgs under weight which is not good as it effects your immunity. Try to eat small frequent meals. Eat calorie dense foods like avocado,nuts,dates,cream,butter,peanut butter. Include 1-2 serving of proteins source in your meal like 2 whole eggs,fish,chicken,soyabean,Paneer.drink plenty of water.
Next Steps
would suggest to go with proper diet you can consult me through practo so that i can help you in better way.
Health Tips
do not walk after having meals.