Gastric umping syndrome, or rapid gastric emptying, happens when the lower end of the small intestine, the jejunum, fills too quickly with undigested food from the stomach. "Early" dumping begins during or right after a meal. Symptoms of early dumping include nausea, vomiting, bloating, cramping, diarrhea, dizziness and fatigue. "Late" dumping happens 1 to 3 hours after eating. Symptoms of late dumping include weakness, sweating, and dizziness. Many people have both types.