I don't know about the eating thing, it may be a factor, however I never go in to a workout without waiting at least 2 hours after I've eaten, otherwise it bothers me. I've never had a problem doing this. Now, squats and deadlifts, you're going very intensely I would imagine. If this is the case, it isn't all that out of the ordinary, simply due to the fat that both all basically total body moves, and they require a lot, especially from the CNS, and especially when going intensly. I used to use an offseason DL routine where after warm ups, you took about 90% 1RM did a rep, backed off, 10 seconds later another rep, back off, 10 seconds later a 3rd rep, took 5 mins break, and I needed it because there was dizziness. Then the second set was take off about 10% weight, and repeated the process with 3 reps, pause, 3 reps, pause 3reps, and another 5 mins. Some dizziness again, and the final set was back off a little more weight and get 9 reps. So you can see, with total body, going intensly, don't be too surprized if there is some dizziness. Just make sure you have spotters. I can remember reading Dr. Ken Leistner talking about the 20 rep breathing squats, where you jus keep on going rest pause with deep breaths, until you hit the "white buffalo", and that meant the old "seeing stars" thing.