It's not my body that likes blood sugar, it's my brain.

And, when I say "my brain likes blood sugar", I mean that it's happy when I'm grazing on bread-like carbs, which produce glucose, not sucrose/fructose/etc per se.

yes, your brain needs sugar to function - one of the reasons I find that low-carb diets are awful for my productivity - my brain shuts down If you're living on carbs that's not good for you either

oh, and serious cardio should combat the weight gain you speak of