early dumping can occur early after surgery and usually with 15 to 30 minutes of eating foods high in sugar, and is caused when rapid entry of food and fluids directly into the small intestine, producing decreased blood pressure and increased blood flow to the intestines. Food high in fat can also cause dumping.

symptoms of early dumping include: nausea, vomiting, abdominal pain, cramps, diarrhea, dizziness, lightheadedness, bloating, belching, fatigue, heart palpitations, rapid heart rate. 

late dumping causes low blood sugar caused by excess insulin produced in response to sudden dumping of food and fluids, such as sugar or carbohydrates, into the intestine two hours after eating and can occur much later, 1 to 3 years after weight loss surgery.

symptoms of late dumping include: sweating, weakness, fatigue, dizziness, lightheadedness, shakiness, feelings of anxiety, nervousness, heart palpitations, rapid heart rate, fainting, mental confusion, diarrhea, low blood sugar (hypoglycemia).

Sometimes, hypoglycemia or (late dumping) occurs after meals because the body produces more insulin than is needed. This type of hypoglycemia, called reactive or postprandial hypoglycemia, is not uncommon in people who have had gastric bypass surgery. However, in rare cases, hypoglycemia can be severe (if not corrected by diet) should be reported to your doctor for treatment.

Dumping is painful and very unpleasant—to say the least. Dumping can be avoided by limiting or avoiding sugary and refined foods (white flour, bread, and pastries), and high sugar fruits and juices. Once you have experienced dumping, you will want to avoid it at all cost.