In Need of Moisture

I do not want to jump to any conclusions, but I have noticed a symptom that I fear may be a side effect of Diet Rehab.  

I warn you that the side effects are not pretty.

I have started to suffer from really, really dry skin. Additionally, I have noticed that both my finger nails and my toe nails are dry and a bit brittle. 

I wondered if these symptoms were related to the cold winter and artificial heating, but while my skin has a tendency to be dry, I’ve never had nails that break so easily (and I do not have long nails). Alas, I think the dryness is diet related.  

I must be missing something food-wise for this to happen. I thought it might be fat–specifically animal fat–but maybe it’s protein or calcium?  

Any advice would be appreciated.