I've been experiencing lightheadedness after eating for about 8 weeks. I'm 61, not overweight. The lightheadedness is followed by sweating, stiff neck and fatigue. The biggest trigger is refined sugars; it can be as long as an hour delay with other foods. Fruit isn't a trigger. I've tried smaller, more frequent low carb meals, which helps, but not entirely. The symptoms are milder on days when I do cardio.