Presumably, he stopped using "the cream and the clear" once he figured out they were illegal / banned / whatever, and once baseball started testing for them. So, if his weight-gain is everyone's big evidence that he's a user, why hasn't he lost weight in the last two years?
Does anyone realize how big Ken Griffey, Jr. has gotten in the last few years? He used to be just as skinny and wiry as Bonds was, and now, while he's not quite as big as Bonds, he's filled out a lot. Why hasn't anyone accused him of steroid use? (Do note that my point is not that Griffey's a user: it's an attempt to undermine the standard evidence presented that Bonds is only as big and strong as he is because of chemicals.)