Some people it easier than others to put on weight and others struggle with having to put on even a lb. If you're naturally big its very easy to gain weight. But if you're small you may have to put in some effort. I think exercising for half hour daily (weighlifting or strength training) with a balanced diet helps to put on healthy weight. You may not gain alot that way , it'll definitely make you look and feel better and it has far more benefits than just increasing carb intake to go big for a short while.