He's a joke -- uses injected synthol to inflate his muscles like a balloon.
I used to be into bodybuilding just as a hobby, enjoy working out so I tried to educate myself the best I could with it, and he's the brunt of many jokes in that community.
Obviously has some mental issues, I don't know how any sane person would think this looks good. If you notice his triceps they aren't even a muscle, not at least in any anatomy book I've seen, it's just an inflated mass under the skin. I'm not 100% sure but I read somewhere about a year ago that he literally popped one of his biceps and one arm looks normal again.