Whoever is compelled to break his fast for a valid reason, such as donating blood to save a life, and he or she does not have the strength to do so without food, the person is allowed to break his fast. Indeed, it is mandatory for him to break, because saving a life is mandatory.
As they say: Mala, yatimul wajib illa bihi fahuwa wajid. (An action necessary to accomplish a mandatory act is mandatory.) Similarly, the person who needs to break his fast to gain strength so as to participate in defending Muslim life and property should break his fast.
This book is an in-depth review of the most important rules and laws on the Fiqh of fasting, with the aim of explaining both the moral and physical meaning and uniqueness of this extraordinary act of worship to the reader.