If you consume the recomended 12 drinks max (1 gallon +/-) of lemonade you'll be ingesting 1200 calories per day which is hardly "starvation mode". Your metabolism does slow down and if you go back to your old eating habits you will gain the weight back and possibly more.
To really address the M plaque issue you need to look into colon cleansing. You may also consider adding the PB shakes to the MC. I personally like to do the Master-Cleanse neat so it will do it's intended job unimpeaded but many folks have had good success clearing MP using the PB shakes while on the MC.
I have done 3 long MCs 40/28/21 and continued to exercise through all of them and have noticed little to no muscle loss. I consumed 9 drinks a day 3 qts +/-)