I've been tinkering with different variants of intermittent fasting protocols for a little over a year now, settling on a slightly modified version of Martin Berkhan's Leangains. I fast daily for about 17-18 hours and keep carbohydrate relatively high on both workout/rest days as I live near the equator, am frequently active, and am still very much on the younger side.
With that said, I think you have three options that I'd recommend when it comes to fasting:
- A Leangains-style approach in which you fast daily between 14-20 hours.
- A 24 hour fast several times a week, in the vain of Brad Pilon's Eat Stop Eat.
- A very unstructured set up in which you just skip different meals on different days based on convenience and personal preference.
If you're attempting to lose weight, I would recommend the 1rst approach over the other two, as it will give your body a chance to adapt ghrelin release at specific meal times. If that's the case, I find 2-3 meals within 8 hours works best.
If you're just attempting to maintain your weight, pick whichever option you so desire. Play around with them all if you like, but make sure to eat enough food.
If performance beyond strength training is your primary goal, I wouldn't be fasting at all if I were you.