He didn't only lose the weight he put on - he lost more. You can see the gaunt in his cheeks and to me he just looks too skinny here for himself.
Some people aren't built to be extremely thin. Kind of like Kelly Osbourne. Even at her lower weights, she was always kind of thicker and muscular. Now she looks like death. She was never meant to be as skinny as she is now. Not natural for her body type. Same for Jazz.
On the left is Jazz at his normal average weight before the weight gain. Right pic and op pic are now. He's just getting too thin and he keeps losing weight.
