Karina is also a great character, and I loved the fact that she was interested in David for his personality and not his physique. Her own struggles with body image help her deal with David, and there is a fun interaction early on when David tells her how attractive he is in a way that highlights what a great guy he is. There is some young adult content concerning underage drinking (one boy tries rum and coke put spits it out under a table because it tastes bad) and there are several indications that Karina and David are sexually active, but there are few details.
Alpha's deep involvement in the "gear' culture, and David's complicity in it, are what make this book truly wrenching. Acevedo has a note at the end of the book that details his own experiences with taking steroids when young, which explains the vivid and horrifying details. This hit close to home for me; forty years ago, one of my high school classmates died of a heart attack during his freshman year of college, and it was attributed to steroid abuse.
While there is a level of profanity that makes this more of a high school title, it is a riveting story about a high school boy determined to make a difference in his life at any cost. It reminded me of Geoff Herbach's great novels, like Stupid Fast, and will be hugely popular with teen boys who are involved in high school sports or who are just concerned about their own bodies.