Shakiness from Exercise. Thoughts?

I get extremely shaky during exercise and have difficulty focusing. Everything I've read says eat well before exertion to avoid this, but that doesn't seem to work. I've gone as far as to play around with ratio of simple/complex carbohydrates, as well as the timing of consumption in relation to exertion. Doesn't seem to help. Interestingly, if I don't eat at all for several hours before the shakiness is not as severe (but persists), likewise if I eat no carboydrates at all. Have not measured glucose during exercise. Labs are all within normal parameters (consistent w/multiple tests). Neg reactive hypoglycemia (single test). I'm 245lbs (111kg), 6'2 (188cm). I play ice hockey for 1-hour 3x per week + weights & cardio (elliptical) at the gym. Worth noting that I seem to have a propensity to gain weight, so I am constantly worried about overeating. I generally do not consume more than 2400 calories in a day - eating more doesn't seem to help me but adds fat. Thoughts?