Working out and the Band.

I have worked out through my entire band journey and have found no problems when I work out however, I have really gotten to a point where I can't eat very much and I fear that my workouts are draining me of energy and I get dizzy when I stand up fast. Just wanted to know if anyone else has had this problem and is it normal. I do more weight lifting now than cardio (15 min) because I am at a good weight as of right now. I have lost 84 lbs. In a little over a year in a half. I do take my multi-vitamins and I eat about 1/4 cup to 1/2 a cup of food when I do eat.