Dumping Syndrome After Gastric Bypass Surgery

Dumping syndrome is a problem for many people who have had gastric bypass surgery. It happens when the solid parts of a meal get “dumped” directly from the stomach into the small intestine without being digested, thereby causing symptoms. This can feel uncomfortable and may even lead to malnutrition if it isn’t treated.

Doctors don’t really understand why dumping syndrome happens. Some doctors think it’s because the weight-loss surgery makes the stomach so small. Of course, this is the point of the surgery. A stomach that doesn’t hold much food helps people lose weight. But some people don’t tolerate this small capacity, and problems like dumping syndrome can result.

Facts about dumping syndrome

Some amount of dumping syndrome happens in at least 15 to 20 percent of people who have had a part of their stomach removed for some other reason. A small number of people can’t get rid of the syndrome once they have it.

Doctors divide dumping syndrome into two types. Early dumping happens 10 to 30 minutes after a meal. Late dumping happens one to three hours after eating.

The symptoms of dumping syndrome are different depending on which type you have. The majority of people with dumping syndrome have early dumping symptoms. About 25 percent have late dumping symptoms.

Late dumping is linked to hypoglycemia. Also, you are more likely to have dumping syndrome if you eat a meal heavy in starches or sugars. The sugars can be either fructose or sucrose (table sugar).


Early dumping syndrome causes symptoms because of the dense mass of food that gets dumped into the small intestine at an earlier stage of digestion. The intestines sense that this food mass is too concentrated. The body reacts by shifting fluid circulating in the bloodstream to the inside of the intestine. As a result, the intestines become fuller and bloated, and diarrhea often occurs 30 to 60 minutes later. In addition, certain substances are released by the intestine that affect heart rate and often blood pressure, causing many of the symptoms of early dumping. This can lead to lightheadedness or even fainting.

These are typical early dumping symptoms:

  • Bloating

  • Sweating

  • Abdominal cramps and pain

  • Nausea

  • Facial flushing

  • Stomach growling or rumbling

  • An urge to lie down after the meal

  • Palpitations and rapid heartbeat

  • Dizziness or fainting

  • Eventual diarrhea 

Symptoms of late dumping happen because of reactive hypoglycemia (a decrease in blood sugar level). Reactive hypoglycemia is low blood sugar caused by a large surge of insulin one to three hours before.

These are symptoms of late dumping syndrome:

  • Heart palpitations

  • Sweating

  • Hunger

  • Confusion

  • Fatigue

  • Aggression

  • Tremors

  • Fainting or loss of consciousness


Doctors typically diagnose dumping syndrome based on symptoms rather than tests. A glucose tolerance test and hydrogen breath testing can also help your doctor make a diagnosis.


The main treatment for dumping syndrome is changes in the diet. These include not drinking liquids until 30 minutes after a meal and dividing your daily calories into six small meals. Experts also advise lying down for 30 minutes after a meal to help control the symptoms. You should also choose complex carbohydrates like whole grains instead of simple carbohydrates like white breads and sugary sweets. Adding more protein and fat can help meet your energy needs.

Another step your doctor may recommend is to slow gastric emptying by making your food thicker. Some people add 15 grams of guar gum or pectin to each meal. But many people don’t tolerate the supplements that well.

When dietary changes don’t help, your doctor may give you some slow-release prescription drugs, but these work only rarely. In severe cases, when dumping syndrome causes major problems, and when diet and medicines have failed, your doctor may suggest tube feeding or corrective surgery.


Because what you eat can play such a large role in causing dumping syndrome, dietary changes after gastric bypass surgery are generally the best plan to prevent problems. These include avoiding liquids during meals and choosing complex carbohydrates over simple carbohydrates. Avoiding sugary or sweetened foods will help prevent late dumping syndrome. Some people may need to stop eating dairy products.

The most important advice for anyone with a small stomach capacity related to gastric bypass surgery is to eat small meals. If you overeat after having this procedure done, it may cause problems in the future.