you may run the risk of compromised digestion and elimination due to low agni/digetive fire that is not noticed for many weeks or you may not even notice this detriment and suffer the illusion that it is ok.
the master cleans strengthens the liver gallbladder and kidneys by way of the lemon which has effect on those organs. The cayenne helps cleanse the blood and improve circulation and capillaries and to lesser extents it can be called a whole body cleanse. The Master Cleanse is not for everyone, those who have the ayurvedic dosha vata will find it detrimental at times and will require more syrup and cayenne as well as those who suffer from hypoglycemia and similar. If you are hardy and resilient the Master-Cleanse is good.