Indeed, this is the first time I hear of an “all foods barred” type of fasting. Which would be especially strange for the Orthodox, considering traditionally, IIRC, around 2/3 of the year were actually various Lents, as Sviatogor said. Actually, my grandma’s currently fasting as well, but she eats fine – it’s just all vegan (if that can be called fine eating, of course).
Otherwise, I’ve seen (and practiced) the “no food allowed” type of fasting only in our Protestant community. And it was always voluntary and often for just a single day (though, of course, I’ve heard stories of people who’ve gone over a month). And I think the Muslims (and/or the Jews?) only fast during the day, but can eat after sunset.