First water fast. I have questions!

Hello everybody,

I'm on day 4 of my first fast, a water fast. I'm doing well, I think - I've even gone to a party at a restaurant and resisted temptation. I'm a total novice at this, however, and could use some advice. I searched for an FAQ within this forum, but there doesnt' seem to be one.

First, I'm concerned about how long I should plan to do this. I currently intend to complete a 10 day fast, but should I do a 5 or 7 day, since I'm a beginner?

My physical situation: I am overweight, but have eaten a comparatively very healthy diet. Lots of whole grains, vegetables, daily fruit, no fast food... I do have hypothyroidism, however.

My second question: my fiance is supportive, but is a little concerned as he has not seen anyone fast before and does not know what to expect. I've tried to reassure him and show him the information I've found, but he's asked me to take a multivitamin daily for his peace of mind. So far I have, crushed with a mortar and pestle and mixed into water, but does that break my fast? I'm definitely in ketosis (what a taste, yeesh), so maybe not, but will taking a crushed vitamin have bad effects?

So far I've experienced only minor mood swings, one episode of strong nausea (without vomiting), and today I feel lethargic. I've experienced food cravings, but not much hunger. I feel like I could go the distance. What do you all think? Does anyone have just general advice?

Thank you all in advance for your help!