Nutritional Support for Bariatric Surgery

Nutritional Support for Bariatric Surgery

Bariatric Surgery Nutritional SupportBariatric surgery, also known as weight loss surgery, is a general term used to describe various procedures that may help severely obese people to lose weight fast. These procedures are usually recommended for those who cannot lose a significant amount of weight, simply by maintaining a weight loss diet, exercising and/or other non-surgical means of weight loss. They may also be recommended for obese patients who have other existing medical conditions, such as heart disease or high blood pressure, for which significant weight loss is necessary.

Effects of Bariatric Surgery

There are three general effects of bariatric surgery, depending on the procedure done:

  • Restrictive surgeries, such as vertical sleeve gastrectomy and gastric banding, dramatically reduce the capacity of the stomach to receive and store food, so that one is not able to tolerate eating large quantities of food. This results in reduced calorie intake and subsequent weight loss.
  • Malabsorptive surgeries, such as biliopancreatic diversion and jejunoileal bypass surgery, create diversions in the gastrointestinal tract that result in reduced absorption of certain nutrients, such as fat. This results in weight loss, since absorption of nutrients is limited.
  • A combination of restrictive and malabsorption techniques, such as gastric bypass surgery, reduces the size of the stomach and creates a diversion in the gastrointestinal tract.

The overall effect of these surgeries on weight loss depends not only on the success of the surgery, but also on the adherence of the individual to his diet after surgery for the rest of his life. Although most patients are able to dramatically reduce excess weight and reduce their risk of chronic disease associated with obesity, they will need to pay attention to their diet and their lifestyle thereafter to avoid some of the side effects of the surgery and to maintain a healthy weight.

Common side effects of weight loss surgery include nutritional deficiency, constipation, dumping syndrome, and gallstone formation. Dumping syndrome is a condition characterized by a group of symptoms that include nausea, vomiting, severe diarrhea, abdominal cramps, sweating, and rapid heatbeats, which occur after eating sugary meals. Soda, fruit juices, and other sugary food cause water to rush through the stomach, leading to these symptoms. Gallstone formation is common (up to 50% of patients) when one loses a lot of weight quickly. Gallstones may be harmless, but may also cause nausea, vomiting, and abdominal pain. Many patients may need gallbladder surgery after gastric bypass surgery.

Nutrition After Bariatric Surgery

Right after surgery, patients will be instructed to go on a fast for one or two days, and then proceed to a liquid diet to allow the gastrointestinal tract to heal. Then, after a few days, they shift to a diet consisting of pureed foods for about two to four weeks. Soft, solid foods are later re-introduced to the diet, which may be taken for eight weeks, or until one can tolerate solid foods. High protein foods are recommended. However, certain foods are not allowed, such as nuts, seeds, dried fruits, highly fibrous fruits and vegetables, tough meats, breads, fatty foods, sugary foods and beverages, and spicy foods.

To avoid nausea, vomiting and other complications, doctors advise eating slowly, chewing food thoroughly, eating in small amounts, and drinking fluids about 45 minutes to an hour after eating.

If a portion of the small intestine is bypassed during surgery, the body will not be able to absorb enough nutrients from ingested food. To avoid nutritional deficiency, patients are advised to take a daily multivitamin supplement and other necessary health supplements for the rest of their lives.

Nutritional support after bariatric surgery is very important to maintain health and to avoid complications. Doctors advise patients about the foods they can and cannot eat. Doctors and nutritionists usually advise patient to eat well cooked vegetables, soft and canned fruits, tender meat, fish, poultry, eggs, breads and pasta made from white or refined flour, low fat milk, yogurt, cheese, and caffeine-free and sugar-free beverages.

Common nutritional problems include deficiencies in iron, calcium, vitamin B12, thiamine, folate, and fat soluble vitamins, especially common after malabsorptive surgical procedures. Daily health supplements required to prevent nutritional deficiency include:

  • Multivitamins, especially for patients who have undergone gastric bariatric surgery, to be taken daily, for the rest of their lives.
  • Iron, for women who are menstruating, to be taken daily.
  • Calcium, for patients who had gastric bypass surgery, especially women, in the form of calcium citrate, to be taken daily, for the rest of their lives.
  • Protein, in the form of liquid protein supplements, for people who have difficulty eating meat, to be taken daily, until they are able to eat meat.
  • Other vitamins, such as vitamin B12, C, and folate, and minerals, as recommended by the patient’s physician.

Health supplements will become the mainstay of the patients’ diets to prevent nutritional deficiencies arising from reduced intake of food as well as reduced absorption of nutrients.

The long-term success of weight loss surgery depends not only on the surgical outcome, but also on one’s careful adherence to a healthy diet and lifestyle, which include limiting the intake of high calorie foods, regular exercise and good health habits.


This information should not take the place of medical advice. We encourage you to talk to your health care providers (doctor, registered dietitian, pharmacist, etc.) about your interest in, questions about, or use of dietary supplements and what may be best for your overall health.


WebMD. What Happens During Weight Loss Surgery

Mayo Clinic. Gastric bypass diet: What to eat after the surgery

NJBariatrics. Nutrition Following Bariatric Surgery

American Dietetic Association. Gastric Surgery Nutrition Therapy.

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