First of all, could you tell us why you are on this particular diet. Your diet of milk and bananas does not contain all the essential nutrients. Any other diet which does not provide adequate carbohydrates, proteins
, minerals and fibre does some amount of harm. Only a balanced diet can provide everything that is required by the body.
I do not know why you have been asked to take only milk and bananas, so i do not know if nescafe can affect the reason behind the particular diet and its supposed benefits. Kindly consult the person who advised you the diet. And once again, this particular diet will not meet the needs of your body and may do harm