well as far as i am concerned its been beer for me ! put on about six stone in the last three years !
seriously though, wouldnt suggest this. theres a much more sensible and healthier way to gain weight, and also gain the right type of weight/mass.
i have just started powerlifting/weight training the last couple of months and do a lot of cycling so my legs and thighs are huge(34") which together with the big (beer) gut, which is why my weight is around the 20-21stone mark.
i am also looking for ways to maintain the size and bulk. anyone recommend any good supplements that are not creatine based ?