Sarahj, thanks for the questions. Of course I am sure you know juicing is different than blasting. When using the Nutribullet you are getting 100% of the vegetables, fruit, nut, seed and grain. This means lots of fiber. With juicing you get some soluble fiber but no insoluble fiber.
To get rid of the sugar cravings you need to avoid simple sugars and high glycemic fruits and grains. Stick to berries, green apples, peaches, pears, oats and quinoa.
Yes you can add stevia but try to get use to having foods less sweet. When selecting stevia products make sure it does not have refined ingredients that have been added like maltodextrin.
If you are not accustomed to eating a lot of fiber (at least 30 grams per day) I would start with one a day for a week and then go to 2 blast a day. To much fiber too quickly can cause bloating and gas.
If you are not eating any other meals or snacks I would add a high quality protein to the blast even though leafy greens, nuts, seeds and grains do provide plenty of protein.
I hope this helps.
Wally Bishop C.N.C.