Giving up sugar and caffeine - feeling miserable?!?

hi, i plan on doing the same thing in a few weeks- i have some essays to write first. anyway i bought this book called 'how to quit without feeling sh*t' by Patrick Holford. ive only read the first few chapters so i cant you give much advice. but the book is about how to quit anything from sugar, caffeine to cocaine. he discuses how your brain becomes addicted to these substances and advises certain nuitritional supllements to ease withdrawal symtoms and cravings. good luck