As an Amazon Associate, BariBuilder earns from qualifying purchases.

Constipation After Gastric Bypass: Causes, Recognition, Treatment

Constipation After Gastric Bypass: Causes, Recognition, Treatment

Weight loss surgeries are very popular and are known to be a relatively safe approach to tackling weight loss. As with any surgery, there is a risk of complications, and patients may experience many side effects after the surgery. However, that fact does not outweigh the benefits of the surgery.

Among a long list of side effects, constipation is one of the most common experiences after a gastric bypass procedure. Fortunately, doctors have studied the mechanisms causing constipation post-procedure, so it is completely controllable with adequate care and prevention.

What is Gastric Bypass Surgery?

Gastric bypass surgery is a fairly common and safe procedure that bariatric surgeons perform on the patients who are suffering from severe obesity. In medical terms, it is called a Roux en Y gastric bypass.

What a pre-operative digestive tract looks like.

In the gastric bypass procedure, the stomach is cut open into two parts and sutured, making two pouches and two pathways.

The smaller pouch, in simple terms, is the food pouch, almost the size of a kiwi fruit. It performs two functions:

  1. Its smaller size restricts the food intake so that you feel early satiety
  2. It bypasses food directly into the latter part of small intestine (jejunum), avoiding highly absorptive lining of duodenum so you absorb fewer calories.

The bigger pouch is the blind pouch containing the remaining part of the stomach and duodenum, connected to the new conduit by the jejunum.

  • As our gut requires digestive juices (stomach acid and pancreatic enzymes) to break down food, this blind pouch functions to provide these important components that help to digest food.

This alteration of normal anatomy helps to reduce weight significantly and control the diseases associated with obesity like Type 2 Diabetes, Metabolic syndrome.

Constipation after Gastric Bypass

The most common symptoms after gastric bypass surgery are satiety and constipation.

There are multiple symptoms patients may experience after a gastric bypass, such as the following:

  • Tummy pain
  • Bloating
  • Constipation
  • Diarrhea
  • Satiety or feeling full

But the most common among these symptoms are satiety and constipation. Early satiety is desirable as it limits the food intake and helps preventing binge eating behaviors.

How do I recognize constipation after gastric bypass?

Before digging into constipation, we should acknowledge what normal pooping is. In general, everyone has their own normal frequency from 3 times per day to 3 times per week. That can be totally normal, assuming it is your regular pattern. Constipation is defined as “any change from the normal bowel pattern.”

After surgery, your bowel pattern may change such that you may recognize new normal bowel habits. Your bowel frequency and consistency might change at the start, but it gets better as you recognize the new routine. Therefore, differentiating between normal bowel movement and constipation is important.

If you are experiencing the following symptoms, then you can suspect that you have constipation:

  • Passing fewer than normal stools
  • Having hardened or pallet like stools
  • Straining to have bowel movements
  • Feeling as there is a blockage in your rectum that prevents bowel movements
  • Feeling as you cannot empty the stool completely
  • Maneuvering with your fingers to evacuate the stool
  • Bloating or feeling of gas
  • Stomach-ache or rectal pain

Although constipation after surgery tends to be transient, persistent constipation may have serious health consequences. After surgery, your abdomen is vulnerable to excessive straining. Excessive abdominal pressure can potentially lead to weakening and delaying the abdominal scar formation, incisional hernia, bowel blockage, hemorrhoids and so on.

So, if you are experiencing these symptoms, do not overlook them. You should seek advice from a medical professional.

How to treat constipation after gastric bypass?

To know how to treat constipation after gastric bypass, we need to address the mechanism and causes of constipation.

Because the gastric bypass procedure changes the normal anatomy by rerouting the digestive tract, it disrupts the normal hormones, nerves, and bowel transit times. That can lead to constipation. Additionally, with a smaller stomach, you have less room for water and fiber, so you need a regular supply of it. As the stool remains stagnant in the bowel, the remaining water in it gets absorbed, resulting in hardening of the stool that is not only difficult to evacuate, but also causes abdominal pain and discomfort.

What causes constipation after gastric bypass?

In the majority of cases constipation after weight loss surgery is caused by the following:

  • A reduction in fiber intake
  • Iron and calcium supplements
  • Medications such as chronic pain killers, antidepressants
  • Weak abdominal muscles
  • Not drinking enough water
  • Avoiding diuretics such as caffeine
  • Lack of physical activity
  • Inadequate fiber intake

Treatment and tips

First of all, you need to express your concerns regarding constipation to your doctor. Your doctor might advise you or may prescribe you medicine at the beginning to help with constipation. Since some treatments for constipation may not be right for a person who underwent a gastric bypass procedure, so you must ask your doctor before starting any regimen.

Generally, treatments for constipation are effective. However, if one treatment works for someone, it may not necessarily work for you. So, it is a trial and error process. You may have to try a couple of treatments in the beginning to know what suits you best.

Here are some steps you can follow to treat constipation as long as you consult your doctor first.

Increase fluid intake

You can try drinking a minimum of 6-8 glasses of water per day.

Drink plenty of water. You should drink a minimum of 6-8 glasses of water per day. If it feels too hard to intake such amount, you can start sipping small amounts and make it a lifetime habit. Avoid drinking fluids during meals because it can make you feel overfull and you may consume less nutrient-rich food that is essential.

If you get bored with drinking plain water then you can replace it with flavored, non-caffeinated beverages.

Fibers are essential for normal bowel activity

Dietary fiber has been proven to improve bowel movements and prevent constipation.

Dietary fiber has been proven to improve bowel movements and prevent constipation. In the early post-operative period, supplement any soft food you are consuming with fibers. Add fiber-rich foods in your diet such as oatmeal, sugar-free applesauce, a baked potato with skin, bran cereal, whole grain bread or unsweetened pureed prunes.

If you still feel like you are not consuming enough, you can buy over-the-counter fiber supplement powder and drink water mixed with it to treat and prevent constipation.

Keep yourself active

Exercise increases overall blood flow and improves bowel motility.

Early movement and exercise after surgery improves treatment outcomes. Exercise increases overall blood flow and improves bowel motility. Stick to a daily exercise routine. Even if you cannot get out of bed, move arms and legs when possible to improve circulation.

Multiple studies have shown that lack of exercise and sedentary behaviors has been correlated with constipation.

Start your supplements gradually

Some supplements may contribute to constipation.

After gastric bypass surgery, it is necessary to add certain supplements. Among these supplements, iron and calcium can act as culprits causing constipation.

Introduce these supplements gradually. You may temporarily hold them until your bowel movements resolve.

Take a bariatric form of calcium (calcium citrate instead of calcium carbonate), because calcium carbonate is not digested well after gastric bypass, and may cause constipation. Similarly ferrous fumarate or ferrous gluconate iron supplements cause less constipation after gastric bypass surgery than other forms of iron.

Magnesium is a good muscle relaxant and it is an essential component in most laxative medications. You can supplement it with the other minerals to prevent constipation.


Probiotics prevent certain vitamin deficiencies and compete with the bad bacterias from growing.

Probiotics are the good bacterias and yeast that play an important role in gut health. They prevent certain vitamin deficiencies and compete with the bad bacterias from growing. Antibiotics and surgery can disrupt the normal flora of the intestine. Adding these probiotics help with the formation of softer stools and thus bowel movements.

Avoid diuretics

Avoid coffee and caffeinated beverages containing excessive caffeine that can promote water loss and lead to dehydration. Dehydration promotes constipation.

Avoiding constipation causing foods

Foods like bananas can cause constipation.

Some foods tend to cause more constipation such as dairy, processed foods, bananas, cheese, rice, potatoes without the skin and peanut butter. Avoiding these foods can prevent constipation.

Laxative medications

Laxatives are an option for battling constipation.

If you are still suffering from constipation after trying all the above treatments, you might want to start laxatives. However, you should speak to your doctor about it as not all laxatives are suitable after gastric bypass surgery. Avoid taking these laxatives longer than needed, as your bowel may become dependent on it.

The over the counter laxatives, which include docusate sodium (Colace), draw water from the intestinal lining to soften the stool. Softer stools are easier to pass.

Bottom line

Constipation after gastric bypass surgery is treatable with adequate care and prevention. In the majority of cases, it lasts for a brief time post-operatively and is self-limiting. If it is persistent then following preventions and treatments are helpful:

  • Generous fluids intake
  • High fiber diet
  • Adequate exercise
  • Probiotics
  • Laxative medications
  • Magnesium
  • Avoiding foods that cause constipation

Hopefully, these treatments will cure the constipation if followed regularly.

Want to discuss this article or ask a question? Join our Facebook community of peers just like you.

Saad Javeed, MBBS, MD


Saad is in the process of starting his residency after graduating from medical school summa cum laude. He is interested in Neurosurgery and currently working on neuroscience and behavior research.

Gintas Antanavicius, MD, FACS, FASMBS

Medical Reviewer

Dr. G is a co-founder of BariBuilder. A US-based expert surgeon with over 10 years of bariatric experience, he regularly publishes research in medical journals like SOARD, Obesity Surgery, etc.