You should see a marked difference post-fast if your diet is plant-based and you only eat according to appetite.
The body will not allow complete healing and rejuvenation in such a short time frame-frame as 16 days, which has taken many months if not years to accumulate.
The fast has kick-started the healing and cleansing of your entire body and not just your skin.
Patience is a virtue here and healing is an ongoing effort by the body fasting or not, if you provide the right physiological conditions (including diet) for this to take place.