Tomorrow is my last day (day 15)...how to carefully boost my metabolism??

I have lost 10 lbs, and am eager to keep it off. I have gone running (4 miles) a few times during the fast, and I walk about 10 miles a day (I don't have a car) and go swimming several times a week, so I would consider myself to be someone who exercises regularly. I could really use some good advise on how quickly I can up my calorie intake. I figure I have been averaging 600-700cal/day on the cleanse and prior to the cleanse, I needed 1800cal/day to maintain (which would explain the 10lb loss!).

Can I start with 700cal/day for a week, then move to 800cal/day for a week, and so on? Or is that too slow? I want to avoid making my body think I'm never going to eat again. I would really like to get back to an 1800cal/day maintenance level before doing another fast in December.

Thanks in advance for all your help!

Oh, if it's useful, I am a 27 y/o female and this is my first fast. Tweet