Eating like horse is not enough. The main thing is what you are eating. Carbs are the way to go to gain weight. Make sure you are eating enough of the other food groups too, but pick up on the healthy carbs for example, pastas, bread, oatmeals, milk shakes, etc. May be you should have to follow Arnold Schwarzenegger Old school workout. It will really help you to gain muscles. Here is the web address http://www.fatlosspot.com/old-school-new-body-review/