She was extremely skinny though during certain periods. She lost a lot of weight in 2011/2012 compared to before. She was a bit chubbier around 2007-2008 compared to then. I would say just after that period is when she really got thin. Perhaps around her pink hair era?
I recall she mentioned once in an interview that she did not eat for a good period of time (probably in the early 2000s) because she wanted to stay thin but since then she has realized that is healthy which is great~ I don't think she'll ever get that thin again unless maybe some extremely stressful event happens, but for now she's gonna stay her toned self which is probably best for her and her body.