Period of time. I want to get down on weight for summer and this is working like a dream. I'm thinking I may just do it once or twice a year to get my body back in check. I've been having a lot of back pain too and my doctors agreed that strengthing my lumbar and losing a couple pounds would help tremendously.
As for cutting out tortilla, there are other options and fruit is just moderation. I had a cup of raspberries this morning... 6 carbs.