I'm the original author. I should have mentioned in my post that I've also been consuming very few daily carbs for a few years now. I experience the effects you describe now when I do indulge in a doughnut or the like. It's hard to tell now how much of my even mood is due to quitting caffeine and how much is due to steady insulin levels. I do feel that I benefit from being very cautious about consuming all of the above (caffeine, sugar, carbs).