In the last 3-6 months when I workout I feel very nauseous or dizzy. It happens with both weights and cardio, although my weight work it almost exclusively circuit style so there is some cardio in there too. My workouts nor my eating has changed much if at all. My guess is either low blood sugar (although I eat regularly every 2-3 hrs and I eat higher protein, and complex carbs not simple ones) or overtraining and my heart rate is getting too high. Any other ideas out there and what I should do?