The juiced beets fad is just as much bullshit as the audio one.
The "energetic rush" people feel on a juice cleanse is likely just a sustained sugar high. "Cleansing juices" typically have 75-190 grams of sugar per serving, whereas a can of Coke "only" has 39 grams of sugar. The juices are also low in fiber and protein, which means a lot of the weight loss people experience is actually muscle loss, rather than fat. Honestly, if you want to stop eating food, lose a bunch of muscle, and burn money at the same time, just take up meth. At least your house will be clean.