Possible Nutritional Complications After Weight Loss Surgery

Weight-loss surgery is effective in providing significant weight loss as well as improvements in comorbidities, like diabetes and sleep apnea. Many of the potential complications are caused by a deficiency in the proper nutrient intake or the lack of following the guided behavior changes that are recommended before choosing to have bariatric surgery.

Below are a few guidelines to assist you in avoiding nutritional complications after the operation.

Nausea and Vomiting

Nausea and Vomiting

Nausea, vomiting or abdominal discomfort are usually due to one of the following:

  • Taking bites that are too big (larger than the size of an eraser)
  • Eating too fast
  • Not chewing your food to applesauce consistency before swallowing
  • Eating foods that are dry or harsh
  • Drinking with your meals or too soon after you have eaten
  • Eating too much at one meal (Remember, your new pouch is about the size of a small egg.)
  • Lying down too soon after eating


Frothing and Dehydration

Frothing is a white mucous liquid that your pouch might produce when dehydrated or overstimulated. This is your body’s way of protecting itself, which may cause you to be nauseated as well.

This may occur when your body is preparing to vomit or attempting to release any food that is stuck in the pouch. If this is happening, your pouch is seeking to lubricate itself. Your nose may feel full after you eat, which is part of the frothing process. If this occurs, slowly sip a mildly acidic liquid, like tea with lemon.

The key to preventing this is to:

  • Stay hydrated by consuming a minimum of 48 ounces of fluids.
  • Take tiny bites (pea size).
  • Chew your food thoroughly before swallowing.

Read More: Signs and Risks of Dehydration After Gastric Sleeve


Constipation and Bowel Movements

It is normal for post-weight-loss surgery patients to have fewer bowel movements; less food intake means less waste. Constipation is common, especially when an iron supplement is added. To minimize the chances of constipation, you can:

  • Stay hydrated by drinking a minimum of 48 ounces of liquid and aiming for 64 ounces per day.
  • Incorporate fruits and vegetables into every meal.
  • Moving your body daily by being active or starting an exercise program.

Read More: Constipation After Gastric Sleeve? Here are 19 Home Remedies for Relief

Dumping Syndrome

Diarrhea and Dumping Syndrome

This is specific to gastric bypass surgery. Dumping occurs when the undigested food in your stomach is transported or “dumped” into your small intestines too quickly. Symptoms include feeling nauseous, vomiting, bloating, cramping, diarrhea, dizziness, feeling tired or weak, and sweating. You may feel like you have flu-like symptoms.

This can be avoided by avoiding high-sugar or high-fat foods. If you have had gastric bypass surgery, you need to follow a meal plan that omits simple sugars. You should not have more than 15 grams of total carbohydrates in one sitting.

Read More: Dumping Syndrome Guide: Symptoms, Diagnosis and Treatment Options


This is usually specific to gastric bypass surgery. If diarrhea is occurring, it may be a physiological response to the procedure itself as a result of malabsorption, bile salt diarrhea, or dumping syndrome. Most commonly, this is due to dumping syndrome following the consumption of sugars or processed foods.

If you are experiencing moderate to severe diarrhea steps to follow:

Trigger Foods to Avoid:

  1. All Fatty Foods
  2. All Dairy products
  3. Sugar substitutes
  4. Fruits, Berries or anything containing sorbitol

If changing your diet doesn’t work, here are your next options to improve diarrhea or dumping syndrome:

  1. Imodium or Lomotil at bedtime and if need mid-morning  to help minimize diarrhea
  2. Start taking a probiotic (Lactobacillus Acidophilus) to help restore natural bacteria
  3. If that doesn’t work, you may need to go to your Primary care physician  (PCP).