Living things practice anabolism and catabolism through the whole time they are living and the balance between anabolism and catabolism is called metabolism. An example of catabolism is the breakdown of glucose into carbon dioxide and water, and an example of anabolism is the condensation of glucose molecules, which happens in liver cells and skeletal muscle.
By taking a meal contains protein and proper amount of carbonhydrate before the workout may reduce catablolism, and taking a meal after the work out may improve the anabolism which will eventually help to slow down metabolism thereby producing greater gains in muscle mass and weight.
Many experts have agreed on the fact that it is more important for hard gainers like ectomorphs have to focus more on muscle development than a cardio exercise, which is very true. However it doesn’t mean that you can skip the cardio day, because if you want to gain more weights, you have to increase the threshold of energy that your body currently have. In order to increase the threshold, you should teach your body that you need more energy by consuming more energy than before through high intensity exercise.
When your body realize that you are spending more energy, it will require for you to eat more foods which will be the source of energy for the exercise, then It will convert them into the energy and use them to accomplish whatever activity that you want your body to accomplish, and high intensity aerobic cardio exercise is a great way to teach your body a new level of threshold of energy that your body can handle. As a result, you will eventually get to eat more for your body to spend more energy which will eventually lead to gaining more weight. Therefore It is very important to do the high intensity cardio exercise at least once in a week, if you want to gain more weight.