How often can I fast in a year and why?

Hi there! I'm on day 22 of my first 30 day juicefast. I was going for thirty but I'm being called out of town on business several times next month so I'm going to end it early.

It's been tough but great (I've lost about a pound a day ave. and feel really good!) I was thinking I would do another month after going as close to raw food diet for the month I'm traveling HOWEVER...

I read that you should only do a 30 or 60 day fast once per year and 5-10 day fasts quarterly. Is that accurate? Could someone explain why? I'm kinda bummed, it would be great to get through this travel and go fast for one more month but I don't want to risk it if there's a risk.

Thanks everyone!