Korean juice diet is also called detoxification diet. I think this is it.

This diet has basically no side effects, but it will if you drink too much. It is best not to exceed 200cc a day, twice a day is the most effective. That is to say, it is good to drink 100cc twice a day. The side effect of drinking too much is dizziness.

Addendum: The side effect is that the number of exhaust (fart) will increase.