Ketosis makes me feel good and more energetic. Hard to say if it is all ketosis or some of it was absence of fruit. But in the lowcarb community, where some still eat processed food as long as it is still lowcarb, it's common knowledge that ketosis is typically associated with feeling good and full of energy. So my money is on ketosis as the prime generator. Fat is a very powerful fuel.

Personally, I think it is much easier to segway from paleo higher carb to paleo low carb, that it was to do go straight from SAD to paleo lowcarb. I think once you are eating healthier foods in general, the body tends to become much less sugar dependant and more capable of shifting to fat burning mode. Which I think makes a later shift to lowcarb much more natural.

However I am continuing to experiment with the macronutrient profiles. Lately, I've been cutting back on the carbs and will run that way a few weeks and then I am thinking I will try a bit more starch but no fructose and see how that goes. I am intrigued by someone else's post here recently that the starch only thing works for him for weightloss. I don't think I've read or heard much about that tactic so it makes me curious. Plus I like potatoes so it shouldn't be too unpleasant. (But if, on the other hand, it was an eat tons of Kale every day type plan, than I wouldn't be quite so eager LOL!)

I would bet that it's not a coincident at all. I went from a high-carb SAD, with lots of pasta, bread, etc. to less than 20gms of carbs literally overnight...no easing into it or anything...and I began to feel better right away. The thing that impressed me most, besides the rapid weight loss, was how much better my mood and mental functioning became.

I started from the low-carb side, after reading Good Calories Bad Calories, and it was amazing how much of a difference in weight and energy it made. To me paleo is the "to" solution after I figured out what I needed to run "from" (carbs).

It was especially clear after I got a blood glucose tester (I'm very enthusiastic about how useful these are!) and realized I probably was pre-prediabetic at best. So for me eliminating carbs was 90% of the solution and paleo is the icing on the cake.

are you sure that the problem was not in carbs per se but rather in "nuts and fruit" - personally for me those fellows are the surest way to binge and feel awful

Nuts and fruit make me immediately bloated and generally "blah" even in moderation. I stay away from them. Some people are just sensitive to them. After I cut them out completely, I was happy to find I had no desire to snack between meals anymore.

I get an immediate energy boost when going strict low carb which lasts a few weeks. I had so much energy that I started to work out every day instead of every other day! This did fade over time, but in general I have a lot more energy and more even moods/energy on low carb.