I am a 50 year-old male, very experienced at exercising both weight training and cardio/endurance training and am both very muscle but overweight. I then recently started my diet & was working-out hard on an empty stomach when I experienced really bad symptoms of light-headedness, especially when moving my head from low to high but no shortness of breath. It seemed to go away once I had something to eat. Any insight on this would be appreciated, thanks