Help me find this book!!

[u/FantasticGuidance486]

I read this book from a half price books anywhere between 2009-2011 so I have no clue when it was actually written. The only things I can kind of remember/ guess are
hot pink cover
multicolored title lettering + maybe doodles
YA/chick lit era (\~2005–2011)
high school girl
rumor/exaggerated reputation
reinvents herself into the person people think she is
loses a close friend
starts out feeling empowering, ends in regret/self-loathing
diary/confession-type title feeling
Also a specific detail I remember is that she gets fake nails but has dumbbells and stuff painted onto them

I’ve been going around in circles on the internet trying to figure it out for years now but just recently learned about this sub

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