As this seems to be an ongoing issue for you irrespective of diets you've tried, it would suggest something deeper.
Have you had your thyroid levels checked?
Until you can feel energised on a good healthy diet I don't think trying to push your body into Ketosis is going to be very helpful, by leaning to fats you will probably be reducing your intake of a variety of micronutrients which may result in a negative outcome.
Keep the whole primal thing going, but rather than restrictions increase your intake of salad greens, vegetables & fruit, nutrient rich bone broths, additional solouble fibre, yoghurt & a good probiotic supplement. Unless your issue is a clearly defined medical condition then it is most likely poor gut health leading to poor nutrient uptake & restricting nutrients isn't going to help. Solouble fibre is not just for keeping the bowel movements regular, it also regulates the uptake of sugar and in a healthy bowel it is fermented to short chain fatty acids & other compounds which are not only taken up by the body, but many are used there and then to power the bowel itself, so this helps take the load off the liver & rest of body to supply energy there.
From experience (my partner) the Acetyl L Carnitine & CoEnzyme Q10 may well help with muscular fatigue and know of a number of individuals who had positive results with fatigue issues, but I think the focus should still come back to gut health.
Eat as much variety as possible and for a short period, say a month don't restrict, but eat when your body is asking for it, if you add a few pounds on the road to rectifying your fatigue issues, these will move easily when your body is healthy again.
Don't think I saw fish mentioned, get some Omega 3's in there as well.
Griff's cholesterol primer
bloodorchid: paleo and primal are not low carb
Winterbike: What I eat every day is what other people eat to treat themselves.
What do you do for exercise?
I have been battling fatigue issues for a great while now as well. I agree with the others that since changes in diet don't seem to effect the fatigue, there might be more at play. I would go get some bloodwork done to check your thyroid and adrenal glands. Adrenal fatigue seems to be more and more of a common thing.
Eat some sugar/fruit daily; eat enough; use coconut oil; walk daily; minimize/eliminate PUFA; drink milk.
My second guess would be to suggest that you might need to eat a little more. I weigh 120 lbs and eat like a freaking horse on primal. I frequently eat more than my fiance who is twice my size, and he wonders out loud where I put it. But, I'm very active, so your mileage may vary. It's worth a try though.
Welcome to the mystery fatigue club. Sorry you qualify.
I've had a diagnosis of CFS for years, though at least half of it turned out to be wheat related. Mono is a common initiator for CFS. The lack of response to exercise is also fairly typical, although fortunately you are at the mild end.
Because the diagnosis is a bit muddled, it's hard to make recommendations, but in general it's a good idea to not push yourself too much. Don't worry too much about fat vs carb burning. Primal should give your body plenty of building material if it has the ability to overcome this itself. And eat plenty. Eat when hungry, and I mean mildly hungry, not ravenous. Eat as nutrition dense as you can manage too. Make sure anything your body might need for repair is available.
Update: attempted 12-hour fast today, intending to go from 8:00 a.m. breakfast to 8:00 p.m. dinner. Total failure. Nausea hit me like a brick wall mid-afternoon. It got so bad I had exactly two choices: eat something or puke. I chose the former but of course had no food and could only scrounge up a single quarter so my choices were limited to the little spinning hand-crank vending thingie. Chiclets, sweet tarts, reece's pieces or M&Ms. I chose M&Ms. Sigh. Does this happen to anyone else??