Types of Bariatric Surgery Used in Obesity Treatment and the Role of the Dietitian

What is bariatric surgery?

Obesity is a health problem resulting from excessive accumulation of body fat. Bariatric surgery, also known as obesity surgery, is a surgical method preferred to fight obesity. Surgical treatments (under the supervision of an endocrinologist, dietician, exercise specialist and  psychologist) may be preferred in inpiduals with obesity if they have unsuccessful weight loss experiences in their past.

Metabolic surgery

The difference in definition from bariatric surgery is that a metabolic disease is also treated surgically. For this reason, it is a surgery that aims to treat diabetes and other metabolic diseases by affecting different mechanisms as well as weight loss, and covers all interventions performed on the stomach and intestines. Thus, it has effective results in the treatment of many obesity-related diseases such as diabetes, hypertension and hyperlipidemia.

Types of bariatric surgery

Bariatric surgery, which is an option for the treatment of obesity, is a type of treatment that can be applied in inpiduals followed by a multidisciplinary team. Bariatric surgery techniques can be categorized as reducing the volume of the stomach, reducing food entry into the stomach, bypassing a part of the intestine or a combination of both methods. Today, laparoscopic methods are preferred in bariatric surgery. This reduces the risk of surgery and shortens the recovery period after surgery. According to the ASMBS (American Society for Metabolic and Bariatric Surgery) guidelines, Adjustable Gastric Band, Sleeve Gastrectomy, Roux-n-Y Gastric Bypass and Biliopancreatic Diversion/Duodenal Switch methods are the standard surgeries accepted worldwide. The weight loss aimed by the inpidual, treatment of related diseases, risk factors, the preference of the inpidual, the experience of the clinic should be determined and the most appropriate surgical technique should be preferred accordingly. The surgeries performed today are given below according to their types.

• Absorption-impairing technique: It is aimed to lose weight by shortening the size of the small intestine and bypassing the absorption area and/or preventing the combination with biliopancreatic secretions involved in absorption.
• Volume-reducing technique: These are surgeries aimed at weight loss by reducing the volume of the stomach and limiting the amount of food entering the body. There is no difference in absorption.
• Combined technique: surgical methods that use a combination of malabsorption and restriction of food intake.

Sleeve gastrectomy

It is the most preferred type of bariatric surgery today. In the sleeve gastrectomy procedure, an average of 80% of the stomach is removed and the remaining stomach is given a tube shape. In sleeve gastrectomy, which is a volume limitation method, the remaining stomach volume is 150-200 mL on average. In addition to being a restrictive method and reducing calorie intake, hormonal changes also occur with this method. Postoperatively, GLP-1, cholecystokinin and peptide YY levels increase; ghrelin levels decrease, resulting in decreased appetite and increased satiety. It is a surgical option for effective weight loss, treatment of comorbidities and technical simplicity. Since it is not a bariatric surgery method that disrupts absorption, the risk of malnutrition and vitamin-mineral deficiency is low. Despite all these advantages, it also has disadvantages such as being an irreversible intervention, limited long-term data and the risk of leakage in the stapler line. Weight loss is defined as 60-67% in the first year and 53-65% in the 5th year.

Roux-en-Y Gastric bypass

This restrictive and malabsorptive bariatric surgery is described as technically complex and difficult. In this procedure, the upper part of the stomach is pided to create a small proximal gastric pouch (>30 ml). The small intestine is separated from the distal portion and a gastro-jejunostomy is performed between the distal open end and the gastric opening. Thus, the amount of food passing through the gastric pouch is restricted by bypassing the proximal part of the intestine and being delivered directly to the distal part. This method, which is both malabsorptive and restrictive, limits food intake due to the formation of a small volume stomach, supports weight loss with malabsorption and appetite control with hormonal changes. Although there are disadvantages such as leakage in the stapler line, dumping syndrome*, vitamin-mineral deficiency, it is a surgical option applied due to effective weight loss, long-term results, low calorie intake, and treatment of accompanying chronic diseases. Weight loss is defined as 70% in the first year and 60% in the 5th year.

*Dumping syndrome: This is the name given to the rapid emptying of the stomach and inadequate nutrient absorption that often develops after surgery or with excessive sugary food intake.

Mini gastric bypass

This method, which is frequently preferred by surgeons in recent years, can be defined as an easier technique because it involves fewer anastomoses* and the anastamosis is performed distal to the long gastric pouch. Since it is a combined restrictive and malabsorptive technique, effective weight loss is observed in the long term. The biggest concern with this technique is the potential risk of gastric and esophageal cancer due to the possibility of bile reflux into the gastric pouch and gastroesophageal junction. Weight loss is 77% in the first year and 65-70% in the 5th year.

*Anastomosis: In surgeries performed to treat a disease, the stitching of hollow organs together to ensure the continuity of the organs. For example; after intestinal surgery, the remaining ends of the intestines are stitched together to ensure continuity.

Adjustable gastric band

With the gastric band technique, which is only a restrictive method, normal digestion and absorption are not disrupted. In this method, an adjustable silicone band is placed on the upper part of the stomach to narrow the lumen of the stomach, limiting the passage of food and creating a proximal gastric pouch with a narrower volume. If necessary, the width of the gastric pouch can be adjusted by injecting fluid through a port placed under the skin. Although this method has advantages such as being easy, reversible, adjustable and not requiring multivitamin supplementation, it has disadvantages and complications such as band slippage, spasm, reflux, port infection. It is a restrictive procedure that is technically simpler and has the advantage of being reversible. Weight loss rates are 40-50% in the first year and 30-50% in the 5th year. 

Biliopancreatic diversion and Duodenal switch

The Duodenal Switch technique with Biliopancreatic Diversion has two stages. First, a sleeve gastrectomy* is performed and a tubular cavity is left. Second, the small intestine is cut proximally just after the pylorus** and distally approximately 250 cm anterior to the ileocecal duct. The distal small bowel is fixed and the duodenum is anastomosed. Finally, the distal end of the middle section is anastomosed to the small intestine approximately 100 cm anterior to the ileocecal duct***. It is a technically complicated surgery and has a high risk of vitamin malabsorption and protein malnutrition in the long term. For this reason, doctor and dietitian follow-up is important. The aim of these surgeries is to minimize the contact of bile and pancreatic secretions with the food taken into the stomach and to cause malabsorption****. With gastric resection, food intake is also reduced. This technically difficult procedure is recommended to be performed in hospitals with appropriate infrastructure and by experienced surgeons. Weight loss is defined as 75% in the first year and 70-90% in the 5th year.

*Gastrectomy: Partial or complete surgical removal of the stomach.

**Pylorus: A muscle tissue called a sphincter between the small intestine and the stomach, located at the exit of the stomach and controlling the passage from the stomach to the intestines.

***Ileocecal canal: The name given to the region located at the end of the small intestine (distal ileum) and the beginning of the large intestine (cecum).

****Malabsorption: Impairment of nutrient absorption.

Situations in which Bariatric Surgery Can Be Performed

In our country, the age range of 18-65 years is specified as appropriate for bariatric surgery, but these criteria can be stretched or narrowed with the decision of the surgeon and multidisciplinary team. The eligibility criteria for bariatric surgery are listed below as stated in the Bariatric Surgery Guidelines.

• BMI; “40 kg/m2 and above”
• BMI; “35 kg/m2 or more” and at least 1 comorbidity* (type 2 diabetes, hypertension, dyslipidemia, sleep apnea, hypoventilation, Pickwick syndrome, non-alcoholic fatty liver disease/non-alcoholic steatohepatitis, gastro-esophageal reflux, asthma, pseudotumor cerebri, venous stasis disease, advanced urinary incontinence, arthritis affecting daily life).

*Comorbidity: In medicine, it is the situation where one or more disorders or diseases occur at the same time in addition to the main disease or disorder.

Situations in Which Bariatric Surgery Should Not Be Performed

According to the Bariatric Surgery Guidelines, some situations in which bariatric surgery should not be performed (contraindications) should be evaluated by a multidisciplinary team before surgery. Some of the contraindications for surgery are age restriction, untreated obesity-related diseases, pregnancy, various psychiatric diseases, alcohol or tobacco product addiction, inability to adhere to the diet after surgery, active cancer, severe reflux.

Complications

Bariatric surgery is an effective treatment for obesity and plays an important role in the treatment of many diseases along with weight loss. Nutritional, metabolic and gastrointestinal problems may also occur after surgery. Weight regain is also an important complication seen in recent studies. For this reason, postoperative follow-up of the patient is important. Some of the common complications:

• Weight regain
• Nutritional deficiencies
• Wernicke's encephalopathy
• Dumping syndrome
• Hypoglycemia
• Reflux
• Bowel problems
• Anemia
• Kidney failure
• Vitamin D deficiency

Role of the Dietitian

In bariatric surgery, dietitians play an important role in the nutritional management of patients in the pre- and postoperative period. This process involves improving patients' dietary habits before surgery and facilitating the transition to an appropriate diet after surgery. In particular, protein and micronutrient intakes need to be regulated in the postoperative period. It plays a critical role in preventing nutritional deficiencies and reducing postoperative complications. Dietitians are also responsible for ensuring the appropriate administration of nutritional supplements with an inpidualized approach and follow-up of patients. The support of bariatric surgical dietitians specialized in this field is of great importance in helping patients achieve their weight loss and healthy lifestyle goals.

Recent studies have shown that dietitians are effective in preventing nutritional deficiencies and increasing surgical success rates in follow-up after bariatric surgery.

Misconceptions

Although it is true that weight loss will occur after surgery, especially in the early period, a lifestyle change is essential to maintain and protect the inpidual. Weight regain, especially after the first year, is one of the most important complications. For this reason, the person should definitely pay attention to nutrition and physical activity level.

It is also a wrong approach to prefer surgery to achieve weight loss without dieting. The postoperative diet must be established by a bariatric surgery dietitian with follow-up. In fact, it is stated in the guidelines that dieting before surgery affects the success of surgery.

Summary

Bariatric surgery is a treatment method for inpiduals with obesity. A multidisciplinary team should be closely monitored before and after surgery. It is aimed to improve obesity and accompanying diseases and increase the patient's quality of life with the weight loss achieved after surgery and the inpidual's maintenance of this weight loss. For the success of bariatric surgery, it is important to provide lifestyle change, inpidualized bariatric nutrition follow-up and the use of daily necessary supplements. It is recommended to look at bariatric surgery as a tool in this bariatric journey. Depending on the type of surgery, it is aimed for inpiduals who have a new stomach with a reduced stomach volume or absorption-reducing method to learn to eat again and adopt healthy lifestyle habits.