I assume that your main goal is to learn how to build muscle fast and not how to get skinny fast, but many of you are actually encouraging weight loss as opposed to weight gain.  Fortunately it's simple, and you don't need a physical therapy assistant in order to pack on some pounds, as it's quite simple. Too much weight training and not enough food will literally make it impossible to gain weight, and it's safe to say that if you are losing weight or seeing no results at all, it's time to step back and make some major changes.  Start to eat more food and train less, and I can almost guarantee that you will start seeing some great results.