I've been low carb Primal (paleo plus cream and cheese, and 50g or less of carbs) for a few weeks. Prior to that, I was mostly WAPF, with some sugar.
I've been feeling dizzy and lightheaded after I eat. Usually within 5 minutes of eating. I'm not feeling faint, but I can tell a difference.
It doesn't matter if it is more or no carbs, low or high fat, or morning or evening (thou, my afternoon eating doesn't cause it quite as bad as morning or evening.). I've gotten the same feeling from a chipotle meat salad as a 1 inch square of brownie (I work on a bakery and had to try the new flavor.)
(if it makes a difference, I have a partial gastrectomy, in which part of my stomach has been removed, but I have the natural and functional entrance and exit.)
TO UPDATE: I got a blood glucose monitor, which regularly recorded blood sugar readings between 85 and 100, even after meals. I started eating more carbs to attempt an oral glucose tolerance test, and found that I would get dizzy and/or nauseous when my blood sugar was rapidly changing (falling or rising). It never got higher than 140, and never lower than 79, even with higher carb meals.
EDIT Again: I did an Oral Glucose Tolerance Test. Fasting: 79. 50 grams of carbs (jellybeans). 30 minutes 124, one hour 81 (I felt bad), two hour 73. According to the Hypoglycemia book, it is a mild form of hypoglycemia.