Bonds' face is fatter now then it was when he was younger, but that probably could be said of most people.
Is there any proof that his hat size is larger now? If there is, that would end any doubt for me (not that I really have any that he used some form of steroids). I could go by the photos, but photos don't always tell the truth. Besides, it would probably make more sense to use a photo of him a year before he started really mashing the ball for the comparison instead of when he was twenty.
My opinion (even though you didn't ask)? He knew, he made a conscious decision, he's a pr!ck, and he should be sent packing now, before there's any "asterisk" controversy when he passes Ruth and Aaron.
Yes, over time Bonds does get bigger and clearly heavier - but with age, most people do. But the increase in his head size and muscle mass are undeniable, and to me, a pretty good indication that he used steroids.
But the other thing about Bonds is that he has, for all of those seasons, put up 30-50 HR's almost every year. You can't explain that through steroid use alone - the guy is a great hitter with a good eye and a beautiful swing. However, that being said, the incredible numbers he's put up over the period from 2000-2004, definitely stretches plausibility unless you accept that he has been using steroids, particularly given his advancing age. Most baseball players see their performance peak from age 28-32 (or thereabouts). For Bonds to put up the most monsterous numbers of his career from age 37-42 is, to say the least, extremely suspicious.
You don’t need to look far for that. Look at his Giants 1997-98 picture. He is smaller then to, but a little bigger than when he was a rookie. He used HGH which is totally different than Roids. Why does everyone say he did Roids, HGH is totally different, clear in the system (would never fail drug tests), and much more pure than steroids and changes your DNA. Look up the facts, it also causes your head to grow.