There isnt much in HY Biochem but it is what I used. In reality there arent many Biochem questions on the USMLE that dont have a clinical basis (duh... they are trying to make the test clinical). Thus you can get by just knowing the stuff in FA (you wont get 280 though). For me, the reason I turned to HY beyond FA is that I couldnt understand the Biochem as it was presented in FA, I needed more explanation. HY isnt meant to teach you FA, but I didnt really want to learn it, I just wanted to memorize and understand enough to answer the questions. If you want to learn the biochem get some other book (some of my classmates used Lippincott). But if you just want to get beyond this blasted subject and answer the questions reasonably well, FA and HY should be enough.