I never got the 'carb flu' when I was switching to Paleo, I had already gone through the metabolic shifts through IF.... read on to see what I mean.
I did serious intermittent fasting (eating omnivore, mostly from local farmers (but still eating grains and cheap dairy) far about 4 years before I went to a PrimalBlueprint / Paleo / PaNu way of eating.
I had a really rough 2 weeks of adjustment to IF.
The first week or so I was following the adaption suggestions in the Fast5 free eBook, slowly moving the 5-hour eating window further back into the evening. About 1 week in I 'suddenly' did not feel like I HAD TO EAT NOW, and waited until the next morning to eat.
The next morning, I lept out of bed and ate an entire 4 person salad and 4 fried eggs.
(Heh, in 20/20 retrospect that might have been my secret first step onto the paleo path.)
During the rough 2 week period, I had wicked headaches, malaise, odd energy dips, and some acne.
Then I jumped to feeling amazing!!!
My weight started falling off, and new muscle galore was mine. Here are some supporting pics as evidence: http://paleohacks.com/questions/7058/share-your-paleo-before-and-after/17739#17739
After about 3-4 of IF years I hit a fat-loss plateau, and when I went looking on the web for more variations on IF (which had worked so well for me) I found Mark Sisson's website, was !inspired! and dropped most sugars and grains.
This let me drop 21lbs and 4% bodyfat and feel EVEN BETTER.
All of the above was my background for why I did not get any carb-flu when I went paleo... I had already activated my fat-using metabolic pathways through IF, and had 'paid the price' then.
Now, I've got better composition than I have ever had in my life, and I've just gone back to strict IF/EOD this week. This is a fasting day, today, and I shan't be consuming any calories till tomorrow.
My EOD Fasting = no calories on Sunday, Tuesday, and Thursday. I make sure to eat to satiation on the other Feasting days.
Maybe this will help me to my springtime goal of seeing my abs for the first time since I was in my teens.
My abs are getting nearer, I can see the outline of them, but not the creases.