Do you need to gain scale weight to gain muscle mass?
How do I put this nicely? Yes. If you want to gain 5kg's of pure muscle, don't feel that you have to smash the carb's & gain 15kg's thinking that you've done well. What I highly recommend is eating really clean carbs, oats, basmati rice, sweet potatoe et al, eating the right ammounts & quality protein...in the process you'll have to gain muscle...unless you 'cardio' it out, by doing a lot of cardio work. But if you eat clean, then you'll make some nice small gains which will more than likely be muscle.
How does that sound?