What do you think about juice fasts? Healthy or nah?

I'm watching this documentary on Netflix 'Fat Sick & Nearly Dead' where this guy does a juice fast for a few months. He lost sooooooo much weight, had more energy, and no longer requires medocation to keep his autoimmune disease at bay. Watching this has really motivated me to shed this baby weight and I think after Easter I'm going to try it for 10 days and see how I feel. I'm getting back on birth control on the 10th and my body stores a bunch of fat when I'm on hormonal birth control so I figure this will give me a head start to try to lose weight and help me be more active. It will also help me in my efforts to become vegan.