On the PB, no, I never had fatigue. I hopped straight into the exercise routine and was fine. Are you two doing the exercise? Specifically, are you getting in your walking? You might find it helps a little. However, a couple months before I jumped into the PB, I went on the Atkins diet for about a month and a half, and on that diet, yes, I had a lot of fatigue from week one to week two. Because the Atkins diet is so similar to the PB, I would assume many primal folk have experienced fatigue as well. I was off the Atkins diet for a good three months before I went on the PB, but I still didn't experience fatigue.
Are you two following the Primal Blueprint Fitness?