I'm part of the 'spiritual bunch' lol - who at certain times of the year fast. For example in 'Ramdan' the ninth month of the Islamic Calendar, Muslims fast from sunrise to sunset for a month. Unfortunately, against popular belief you either maintain or put on weight lol during that month. Muslims do it for a variety of reasons such as, building will power, remembering the hungry, detoxing the body. But like somebody said - it is not sustainable as a weightloss method and will do a lot of damage over long period of times (for example two months without eating).
I'm sure u were wondering about the powder lol - I would assume that it means u drink nothing but the powder for two days and then you replace the meals with it? maybe to shrink ur tummy? Maybe? possibly? lol don't quote me on it.
Praise be to God, to Whom everything in the heavens and everything in the earth belongs, and praise be to Him in the Next World. He is the All-Wise, the All-Aware.(Chapter 34: Verse 1: The holy Quran)
The Ultimate Goal