Calorie deficit for too long?

Hi Marc,

Question for you around length of being in a cut.  I am coming from a higher body fat percentage and have been in a calorie deficit now for just over 12 weeks.  I cut my calories back off my maintenance level and added in cardio after my lifts 2 or 3 times a week to help with a 1 to maybe 2 pound loss per week. 

My main question more revolves around time in a caloric deficit though.  I know I will need to be in a caloric deficit longer to get down to the body fat percentage I want to be at.  But, are there potentially any drawbacks to being a caloric deficit for this long or longer periods of time?