Avi Rosengard asked:
What if youre about to faint but you know you aren't extremely ill and it would not be life threatening?
Avi Rosengard, San Diego, California, United States
The Kollel replies:
It would depend on which of the fasts it is. If it was Yom Kippur, and the person doesn't think he needs to break his fast, nor does a knowledgable doctor, then he would keep fasting (see OC 618:1). If it was any other fast - including Tisha b'Av - he would probably be best advised to stop the fast (see OC 550:1).
Kol Tuv,
Yonasan Sigler
This is not a Psak Halachah