From almost the moment that Camp X-Ray opened, prisoners embarked on hunger strikes as the only means available to protest about the conditions of their detention: specifically, their day-to-day treatment, the treatment of the Koran, and the crushing uncertainty of their fate, as they remained imprisoned without charge and without trial, with the ever-present possibility that they would be held for the rest of their lives.
Andy Worthington has released the results of an important investigation he undertook on treatment of prisoners at Guantánamo, Guantanamo’s Hidden History: Shocking Statistics Of Starvation (PDF) (his article introducing it is here).