Intermittent Fasting

I've heard intermittent fasting several times before. I'd tried it, but I gave up shortly. I couldn't continue it.

I wonder; 

• How often intermittent fasting is the best way to lose weight and become healthy? Once a week, once 2 weeks, or once a month?

• How long intermittent fasting is best for me? 14hrs, 16hrs, or 18hrs? 

• Can I drink water in the fasting period? 

Thank you in advance for your answer.