Ive never been told you HAD to have them for any reason other than it was another drink option!I have always been told they have far too much salt by nutritionists.
Ordinarily they would be a very salty addition to a normal diet, but whilst doing the milk diet, you are taking in so much fluid, your kidneys are flushing out too much salt too quickly and it has to be replaced by having the salty drink.
I didnt do the milk diet either!