Fasting During Elul

Question

Kavod Harav: I read somewhere that the Ari Hakadosh and his student, R' Chaim Vital would fast during the day and eat in the evenings during the whole month of Elul and during Aseret Yemei Teshuvah leading up to the Yom Kippur fast (similar, although G-d Forbid, I am not making any comparison, to the Ramadan fast in Islam). Is this an acceptable minhag or is it something that should be reserved for people on the level of kedushah of these tzadikkim? Todah Rabah, Yakov