well 7 days is nothing...i am muslim...we fast usually in midd november-->midd december (about a month) from sun up to sun down...meaning you basically can't eat or drink ANYTHING (yes, even water) from like 4:30 AM (usually when the sun starts to come up) until ~6:20 pm (when the sun goes down in the season - it changes daily by a min or 2 mins) - i've just recently started lifting though...so i have yet to fast WHILE lifting and bodybuilding...so i imagine that would be hard since you need to "eat big to gain big" or whatever..
but it really does feel good when you do it...it gives you such control over your body when you're done and it's over...especially if you find it hard to be on a bodybuilder's diet...after fasting you're like i don't care WHAT i eat i just feel so lucky that i have food on the table...(so it makes eating the nasty-tasting food easier since it's better than having NO food/drink) and you won't give into temptations at all after fasting...your will power increases daily with your fast...
if this is the first time you're thinking of fasting, however, i suggest you take it slow...my first time i fasted it felt like such TORTURE and SUFFERING...my first day i was about 8 and i had to last from morning until like 6:30 PM...was crying my ass off by the end of the day for food/drink...i should have prepared in advance...since its an annual thing for me i've learned to prepare myself...a week before i start my fast i do this: day 1) no food/drink until noon 2) no food/drink until 1 pm 3) no food/drink until 2 pm 4) no food/drink until 3 pm 5) no food/drink until 4 pm 5) no food/drink until 5 pm 6) no food drink until 6 pm 7) no food/drink until 6:30 pm...
the first and last day will be your toughest...but after it's all said and done it feels GREAT...honest...my family usually has a large dinner to break our fast at 6:30ish (OF COURSE YOU WILL FEEL VERY HUNGRY so you need a big meal) then small meals to follow and LOTS of water mmmm for the rest of the night...
some people like to wake up at 2-3 AM for an early snack and then go back to sleep so they have something in their stomach so they dont feel VERY hungry during the day but i'm the kind of guy that cherishes sleep so much...not worth getting up...sleep the whole night and just handle it during the day like you should - don't give in
hard ass part of fasting is brushing my teeth
because while fasting we muslims can't drink water remember so you have to make sure you spit out like every little bit of toothpaste and water you use...which leaves your mouth dry as hell at the beginning of the day (which sucks hardcore)
but you get used to that as well...it's all about your body getting used to it's new routine...i like fasting because it makes me feel like i control my urges and my urges aren't controlling me
i hope something in this long post helps you...pm me if you have any other Qs - i'm sure i can help in some way or another...i'm a 9 year faster and it'll be my tenth come this november