Bariatric surgery: Understanding the risk of malnutrition

For purposes of weight loss and improved overall health, many individuals turn to bariatric surgery as an intervention to manage obesity. While bariatric surgery may offer a positive outcome in terms of weight reduction and metabolic health, it also carries a variety of challenges and considerations, including the risk of malnutrition. It is important to understand the risks involved to help prevent malnutrition and, in the event malnutrition occurs, understand treatment strategies to mitigate the severity. 

What is bariatric surgery?

Bariatric surgery refers to several different types of procedures that assist individuals in losing weight by surgically changing their digestive system. It is recommended for those who have tried to lose weight in more conventional ways without success. The surgery may also be recommended for those who have obesity-related co-morbidities that will improve if weight loss occurs.

The goal of all types of bariatric surgeries is to reduce the size of the stomach or limit the amount of food the stomach can hold. This results in less overall oral intake, which can ultimately lead to weight loss.

Types of bariatric surgery

Roux-en-Y Gastric Bypass (RYGB) – Often called the “gastric bypass,” RYGB is one of the most common operations to treat obesity and obesity-related diseases. This procedure divides the stomach into a smaller pouch while the small intestine is reconnected in a “Y” shape. With this procedure, more vitamin and mineral deficiencies may occur, and there are risks for small bowel complications and ulcers. Dumping syndrome can result after eating or drinking, especially when consuming large amounts of food and/or high-sugar foods.

Sleeve Gastrectomy – This procedure is performed laparoscopically and referred to as the “sleeve.” In this procedure, 80% of the stomach is removed which leaves the remaining portion the size and shape of a banana. The sleeve is a non-reversible procedure and can cause or worsen reflux and heartburn.

Adjustable Gastric Band (AGB) – This procedure involves a silicone device placed around the top part of the stomach that creates a small pouch. This small stomach pouch typically makes individuals consume less food, resulting in weight loss. While this procedure has the lowest rate of complications early after surgery, the results are often slower and less extreme than other procedures. Unlike several bariatric surgeries, this procedure is reversible. Complications of AGB can include problems with swallowing and enlargement of the esophagus.

Biliopancreatic Diversion with Duodenal Switch (BPD/DS) – This surgery first requires the creation of a tube-shaped stomach pouch before the first portions of the small intestine are separated from the stomach. Following this, another part of the small intestine is connected to the outlet of the newly created stomach so that when a person eats, the food goes through the sleeve pouch and into the latter part of the small intestine.

This procedure has slightly higher complication rates than the others and can result in the highest malabsorption occurrences. Reflux and heartburn both have the potential to develop or worsen.

Single Anastomosis Duodenal-Ileal Bypass with Sleeve Gastrectomy (SADI-S) – SADI-S is the most recent procedure endorsed by the American Society for Metabolic and Bariatric Surgery. This procedure starts similarly to the sleeve gastrectomy, but in addition to decreasing the size of the stomach, part of the small intestine is bypassed as well and then reconnected to the stomach. After SADI-S, the small intestine’s surface area decreases, which can affect the absorption of vitamins and minerals. This is a newer operation with only short-term outcome data; however, there is a known risk for reflux to develop or worsen.

Malnutrition after bariatric surgery

Malnutrition is a common concern following bariatric surgery procedures. It can occur due to several factors related to surgical alterations to the digestive system and/or changes in a person’s dietary habits. The following are the most likely ways that malnutrition can occur:

Dietary restrictions and changes in eating behaviors – Some patients struggle to adhere to recommendations advising them to follow a low carbohydrate, high protein diet. It’s not uncommon for patients to develop eating behaviors that result in avoiding certain food groups or adopting a diet that is heavy on processed foods or low-nutrient convenience foods which can contribute to nutrient deficiencies associated with malnutrition.

Reduced oral intake – Procedures such as gastric bypass and sleeve gastrectomy significantly reduce the size of the stomach, leading to a decreased amount of food intake, which can also mean a limited amount of essential nutrients if a healthy, balanced diet is not consumed.

Changes in nutrient absorption – All bariatric procedures can result in changes in how vitamins and minerals are absorbed, especially fat-soluble vitamins such as A, D, E and K which can lead to deficiencies over time.

Preventing malnutrition after bariatric surgery

Signs of malnutrition following bariatric surgery vary depending on the cause, but commonly, symptoms may include:

• Fatigue/Weakness
• Dry Skin/Hair/Eyes
• Weight loss and loss of subcutaneous fat
• Loss of muscle mass
• Poor wound healing
• Edema
• Bleeding gums

Main steps to prevent malnutrition after bariatric surgery:

1. Follow recommendations for a diet high in nutrients and whole foods as advised by your physician and registered dietitian.
2. Take the daily vitamins and supplements as recommended by your physician, which may include Thiamine (B1), Cobalamin (B12), Folic acid, Iron, Vitamin D, Calcium, Zinc, and Copper.
3. Consume adequate fluids for proper hydration (approximately 2 L of fluid daily after the initial recovery period, or as specified by your physician).
4. Avoid empty calories from sugar, processed foods and alcohol.

Treating malnutrition after bariatric surgery

The best option for treating malnutrition after bariatric surgery is to work with a registered dietitian to develop a personalized nutrition plan. A dietitian will help you identify nutrient deficiencies, make dietary modifications and optimize your nutrition to prevent further complications associated with malnutrition. In addition to nutrition counseling, behavioral management is imperative to address emotional or behavioral challenges to help the patient develop healthier eating habits and strategies to manage malnutrition. Dietary modifications such as adding nutrient-dense foods, adjusting meal timing or using oral nutrition supplementation may be suggested. Finally, in some cases, medical interventions may be needed if malnutrition is severe. This may include the use of IV nutrition therapy such as IV fluids and/or total parental nutrition (TPN).

Conclusion

By understanding the different types of bariatric surgery and their risks for malnutrition, we can prevent and manage any adverse outcomes following bariatric surgery. Patients working with a registered dietitian as part of their healthcare team can take a proactive approach to reducing their risk for malnutrition and other complications following bariatric surgery.

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References:

Bariatric Surgery Procedures. Available at https://asmbs.org/patients/bariatric-surgery-procedures/. Accessed on 5/13/24.

Bariatric Surgery Malnutrition Complications. Available at https://www.ncbi.nlm.nih.gov/books/NBK592383/. Accessed on 5/13/24.

Malnutrition in Obesity Before and After Bariatric Surgery. Available at https://www.sciencedirect.com/science/article/abs/pii/S0011502919300884?via%3Dihub. Accessed on 5/13/24.

Malnutrition after Weight Loss Surgery: Understanding the Causes. Available at https://www.ibihealthcare.com/bariatric/malnutrition-after-weight-loss/. Accessed on 5/13/24.

Malnutrition After Gastric Bypass Surgery. Available at https://www.verywellhealth.com/malnutrition-after-gastric-bypass-surgery-3156876#:~:text=Treatment%20Options,-The%20treatment%20of&text=Prevention%20is%20key%2C%20but%20when,IV%20nutrition%20may%20be%20used. Accessed on 5/13/24.