IF is just a fancy term for 'skipping a meal'.

Personally I don't eat breakfast anymore. This means my last eating is done around 7 or 8 pm in the evening and then I don't eat again until lunch the next day (11 am), so that means I go 15-16 hours typically for my 'fast'.

I will say that some days I go get a little hungry around 9 or 10 and then I just eat a hard boiled egg or two that I was going to have as part of my lunch.

As far as your questions go:

1- How long do you go between meals? (including sleep)

As per above overnight I generally go between 15-16 hours.

2- What kinds of progress have you seen in weight loss/muscle defn?

I started eating primal on Jan 1 of this year and have lost 50 pounds, 9 inches around my waist and seen my body fat % go from 40% to 28% and my lean body mass has gone up during this time. Now I didn't start IF until March or so but it just came about naturally as I really wasn't hungry in the morning anymore so I just stopped trying to eat a breakfast.

3- Ladies, do you find this interferes and/or causes curious symptoms with your "lady time"

Not qualified to answer.

4- How long have you been IF?

Since March, so almost 4 months.

5- Advice for those new to/considering incorporating IF?

I'd say it has made me pay more attention to my body's hunger signals. And free myself from eating because it's meal time. As I said earlier, I just kind of fell into it because I wasn't hungry when I woke up in the morning.

I've also heard that sometimes when you feel hungry what your body may really need is more water. So in the morning when I get up I do drink plenty of water.

I think you may need to ease into it by going longer and longer between meals until you have an IF time frame that makes sense for you.

I did try to IF during the day at work eating only breakfast and dinner but I found that much harder to stick with than just eating a lunch around 11 am and then dinner around 6 or 7.

Please note that when eating this way my lunch and dinners are generally bigger than they used to be when I ate three meals a day. My calories eaten during a day are pretty much the same although on some days I can be quite a bit under if what I've eaten has filled me up particularly well.

I usually eat from 11am until 5pm. Its difficult for me to eat in the morning because I am busy with an infant and try to do all my housework so IF works great for me and that is how it started, I have been doing it for probably about 5-6 weeks. I have lost 20lbs and would have lost more if I didn't cheat or include chocolate and dairy on a pretty much daily basis. I have not had a change in my cycle and no weird symptoms, I think IF makes me feel better in general. If you want to give it a try I would recommend just skipping breakfast for a couple days and see how it makes you feel. Also I believe some people drink a bullet proof coffee in the am when they are fasting and that keeps you from being hungry until well into the afternoon.

Well, I fasted 12 hours today between breakfast and dinner, not intentionally, it just worked out that way. And funny thing, I wasn't even really hungry for dinner, but figured I'd better eat as otherwise I'd have been below 1000 calories for the day.