In order to gain weight, one has to consume additional calories on top of what you expense. Generally what you eat on a regularly maintains your weight if your weight is constant. Therefore by increasing your calories daily will lead to weight gain.Gaining weight is made easy by taking mass gainer daily as fluid is easier to consume after food. Best to take 1/2 serving of mass gainer after each meal to see fast results. The quality of mass gainer will affect weight gain vs muscle mass.