I'm asking this question for my wife, who is severely (BMI ~60) overweight. We started Paleo two weeks or so ago. About four days after we started, my wife had severe diarrhea. She then came down with a non-specific viral infection that had her down for a few days. In that time, she "fell off the wagon", as it were. She's been feeling better, so she started back on the paleo diet four days ago. And again today, severe diarrhea. By comparison, I've been doing paleo for the same amount of time, and I feel pretty good.
Note that our meat / fat sources are all grain fed at the moment - we haven't switched to grass fed for budgetary reasons. Since we're getting a lot of omega-6 fatty acids with this diet, we've been supplementing with 1360mg fish oil (which says it provides 950mg omega-3) for the past few days.
She has done some research, and it suggests that this diarrhea could be the result of toxins stored in the fat being metabolized along with the fat she's burning. Alternatively, there are other sources that say it could be that her intestinal flora are out of whack. Does anyone have any suggestions to help her adjust? The diarrhea is debilitating to the point where she's having to miss classes (she's a college student) when it happens.