Limited fadting is supposed to be good for you, although it doesn't much appeal to me. But I don't believe we are talking of days at a time though. More a case of most or all of a day on some days. I know there's a diet going around that advises 2 days fast a week. Personally that sounds excessive to me, but there again a few hours fast does too. As for what you choose, that's up to you. If you try it then I think it should be more for health reasons than weight loss. Make sure you get sufficient nutrition whatever you choose.