This is effectively the opposite of gastroparesis: the stomach contents are
propelled too quickly into the small intestine before they have undergone the necessary digestive processes.

It is an uncommon condition, usually seen after gastric surgery (which may
damage the system that controls digestion) or in a rare condition,
Zollinger-Ellison syndrome (extreme peptic ulcer disease and gastrin-secreting
tumours of the pancreas).

Excessively rapid delivery of a meal into the small intestine (jejunum) stimulates an exaggerated hormonal response (e.g. insulin and others)

Early dumping

begins during or right after a meal

Late dumping

1-3 hours after eating

• symptoms due to a reactive low blood sugar  and sudden diversion of
  blood to the gut (low blood pressure results)
• weakness, sweating, dizziness.
  

Both types may be seen together in some patients.

Diagnosis is made using blood tests, provoking the symptoms with oral loading
dose of glucose.

Treatment includes changing eating habits: eating several small meals a day,
(low in carbohydrates), drinking liquids between meals not with them.

Medication such as Ocreotide to slow the gut down may be needed in severe
cases. (but it has side effects such as diarrhoea)