Many of us hit a plateau when on a juice fast. And often it occurs in the middle of an extended fast... It's really nothing to worry about, because the metabolism will pick up again.
There could be some good reasons for this plateau, such as the body is using the energy to detox deep or to heal and rebalance an old health issue... The body knows exactly what it needs to do to perform at it's best. Often against what we think needs to be done, which is often why we are ill and unhealthy. We don't listen to the body and we exert our will on the body...
Remember, a juice fast (or any kind of fast) is not about weight loss. Weight loss is a by-product. Fasting is about detoxing and deep healing, so the body is going to be working very hard along those lines. If the weight comes off too, great! If it doesn't, the body has good reasons for that.
If, however, you are on this fast primarily for weight loss and not a health issue, there are ways you can rev your metabolism up, get it moving again and keep it on its toes.
EOD -- Every Other Day -- water fast. Today juice, tomorrow water fast, the next day juice, then water fast... But beware, the detox symptoms could become more profound. If they do and you find it's too much to deal with, just fix yourself a large juice with lots of greens and that will slow the detox down.
It helps to know which produce has more calories than others. All sweet fruits have more calories than veggies. Citrus is the least high calorie of the fruits. Carrots, beets and sweet vegetables such as these are higher in calories than the greens and the greens are lower in calories than the other veggies. The green Granny Smith apples have the least amount of sugar of all the apples, 'tis why it's so tart and one of the favorite apples of regular juice fasters.
Alot of people go on juice fasts primarily for weight loss without understanding that the body has its own (detox/healing) agenda and will pursue that agenda regardless of the wishes of the owner of that body. That's when fasting can become very difficult.