I'm interested in trying intermittent fasting by skipping a meal a few times a week. I wonder how many hours one needs to go food-free in order to reap the benefits of IF. Thanks everyone!
Martin Berkhan recommends 14 hours for women and 16 hours for men as the ideal window. I personally do a daily 16 hour fast and find that to be perfect where I actually feel real hunger pangs but also don't want to throttle anyone in hunger-induced psychosis.
I've been doing 16-18 hours off since February based on Martin's recommendations Erica also mentions (I'm a male). 7 days a week. Anything above 16 hours is pushing it for me hunger-wise, but I'm very tolerant to that. More than 16 hours also means your eating window is quite tight, and cramming all the calories might become a challenge on training days especially for those with poor appetite (me).
There's a period of a few days to two or so weeks when your body, hormones and metabolism gets used to IF, and I've heard some people have real problems adjusting.
There are many other ways to do IF, Dr Berardi did quite a bit of experimentation earlier this year on it, and wrote a very good introductory booklet to IF.
First, you shouldn't do it at all if you don't want to. I found it a very natural thing.
It was natural because I like a large meal--it's important to eat until I feel full. When I do that, though, I don't feel hungry again for a long time.
So, there's no clock involved. I let my body tell me when to eat again. It could be the same day, but usually not. It could be the next morning, but frequently not. Most often, it's late morning to early afternoon the next day but if I'm busy it's no biggie to wait until night-time.
So do what feels right for YOU. If it's stressful to wait, go ahead and eat. You may IF all the time or only once in a while.
For me, I experienced a noticable difference during the first day, espically if you train LISS (Low Intensity Steady State cardio @ about 65-75% of your MHR for 45 minutes +) in a fasted state.
I lowered body fat and for the following week after it seemed to have an effect on appetite suppression and cravings for dark chocolate (previous my first IF I craved dark chocolate every night).
Here's what my 24 hour fast proctocol (once a week):
Everybody is different; IF isn't recommended for anybody with eating disorders or people that are seriously obese or unhealthy(training during a fasted state can do kooky stuff to some). Basically for realitively fit people who are trying to fine tune their diet and give their stomach a break.
More good stuff:
Starting off by skipping a few meals is sensible. If you're already Paleo then you shouldn't have much to worry about with withdrawal, it's just a question of learning to understand the signals your body gives. I don't consider skipping a meal IF - I do it if I'm not hungry, and that's probably because I had a big meal in which case 8-10 of those 16 hours I was still digesting. I prefer occasionally going the whole day without food rather than having a routine, and find that to be most effective and easiest to stick to. But try different things and see what happens!
I try to make my IF window be at least 18 hours, but I don't feel the need to IF every day (since as mentioned elsewhere in the thread, a fasting window this long every day makes for a short refeeding window). I set it up so that MWF I have dinner but no lunch, and that usually nets me about 20-22 hours (less if I'm out having a drink the previous night). It took me a few months to really get used to it; I started in March this year, and later in the spring I was rather devoid of energy, but I adjusted and have had no problems since.
This is a great discussion. I tried IF for the first time on Sunday and skipped breakfast. I went about 18 hours. I felt weak, lightheaded and faint. I also did a hard workout (4 mile run/walk with sprinting intervals) and maybe I should have opted for more walking.
I can normally skip meals here and there and not feel the lighteadedness. Must be from the workout?
I was doing two full days a week, and now have been doing a daily 8 hour or less eating window for over a month. I prefer the daily window, it works better for my life and my body. Experiment! Find what works for you...there are so many schools of thought on this, my m.o. is to see what my body likes through trial and error...
The number I've seen range for 14 to 24 hours for benefits, with few deleterious effects up to 48 hours, all depending on what guru you listen to.
I used to IF once per week for 24 hours (usually after eating 3 squares a day over the weekend). I now do more or less a 8 hour feed window, simply by skipping breakfast (though my morning coffee is not completely calorie-free).