Will a juicing fast cause me to lose weight? Is a nutribullet better?

I am planning on going on a 2 week or 3 week juicing fast where I drink nothing but vegetable juice made with fresh vegetables using a juicer / nutribullet. I am a 15 yearold male. This is healthy because there's a documentary called "fat sick and nearly dead" 2 men lost over 100 pounds and 1 lost 200. My goal is 20 or 30. Which better a juicer or nutribullet for weightloss? Also will I lose 20 pounds in 2 weeks?