Going on a 3 day juice fast any tips?

ok so I am going to start a 3 day juice fast tomorrow and am wondering if anyone else has done this before? what was it like? did you get tired? constipated? lose weight? feel better after? I'm hoping to lose a few pounds as well as detox my body. I weigh about 145 and have gained about 30lbs in 2 years dating my boyfriend, all we do is eat out. I'm going to start trying to get healthier and feel like a juice diet will help kick start it maybe making me not crave the bad food I have been. any one have experience with this?
Updates
+1 y
also I'm going to be at work 2 of these days.. do I have to drink all the juice in one sitting or can I drink it throughout the day and just drink some juice then some water and then a few more sips?
Going on a 3 day juice fast any tips?
Post Opinion