If you search through moreless' posts on this forum and the akaline/acid forum he covers why people have low body temperature.
If I recall correctly it is a mineral deficiency related to the ratio of potassium to sodium in the body.
Here is a link to a post by moreless where he talks about a comprehensive program to remineralize the body and to restore it to a better balanced PH.
I followed this program and saw significant results within 5 days and consistent improvement after that. I also added topical and internal UT. Before I started following his recommendations, low body temperature and feeling cold all the time was one of many of my symptoms.
God Bless you and guide you on the way to better heath,