I can safely say that for ‘regular' skinny guys with fast metabolism, this guide is more then enough to pack on massive amounts of muscle in very minimal time compared to what the average guy achieves in the gym.

Current research indicates that three primary mechanisms are involved in exercise-related muscle growth: muscle tension, muscle damage, and metabolic stress (Schoenfeld 2010). Tension exerted on muscles during resistance exercise is generally considered the most important factor in muscle development.

Up to a certain point, greater muscle tension leads to a greater anabolic stimulus—a classic case of adaptation. Perhaps the most intriguing factor associated with muscle development is exercise-induced metabolic stress.