I try to fast from food (water is okay) for at least 3 days per month. I find that after 3 days there are no hunger pangs or desire to eat. So, basically, the first 3 days are full of temptation. After the 3 are past, I find fasting is really very easy as long as I keep busy. The longest I have ever gone is 40 days (more just to see if I could do it).
Intermittent fasting is supposed to be really more beneficial to the body, with 16 hours being optimal. It is much easier to do as well since not eating after 8 or 9 PM plus 8 hours of sleep will comprise much of that time.