Malabsorptive vs Restrictive Weight Loss Surgeries: What’s The Difference?

Malabsorptive vs Restrictive Bariatric Surgery

For some people, particularly those living with obesity and serious health challenges, bariatric surgery may be the answer.

Bariatric surgery, which is also known as weight-loss surgery, aids weight loss and reduces the risks of obesity-related diseases. The surgery falls into two categories: Malabsorptive weight-loss surgery, and restrictive weight-loss surgery.

Malabsorptive weight-loss surgery limits the amount of nutrients your body absorbs, while restrictive weight-loss surgery restricts the amount of food you can consume. 

Goals of Malabsorptive and Restrictive Weight Loss Surgeries

Malabsorptive and restrictive surgeries facilitate weight loss in different ways.

The goal of malabsorptive weight-loss surgeries is to limit the amount of food (i.e., calories) your body absorbs by shortening or bypassing a portion of your small intestine. 

The goal of restrictive weight-loss surgeries is to reduce the amount of food you can eat by making you feel full more quickly. Surgeons reduce the size of your stomach, thereby physically limiting the amount of food your stomach can actually hold.

Early Weight Loss Surgeries 

Dr. A.J. Kremen is believed to have performed the first metabolic surgery in 1954, the jejunoileal bypass. The procedure, which kept the stomach intact but bypassed most of the intestines, is no longer performed today because too many patients developed complications.

Other weight loss surgeries that are no longer performed are the jejunocolic bypass, and the vertical banded gastroplasty (VBG).

The jejunocolic bypass, which had severe side effects, involved cutting across the small bowel and connecting it to the colon. The other end of the small bowel would be closed.

The VBG procedure involved stapling the upper part of the stomach vertically to create a pouch. A band would restrict the outlet of the pouch to the rest of the stomach. Long-term studies suggested the procedure would worsen severe heartburn, and had a notable rate of patients regaining weight.

Types of Malabsorptive Weight-Loss Surgeries

There are different types of malabsorptive weight-loss surgeries. Gastric bypass surgery is the oldest and most commonly performed bariatric surgery in the U.S.

A less common malabsorptive procedure is biliopancreatic diversion (BPD). In this surgery, the surgeon removes part of your lower stomach.

In a laparoscopic sleeve gastrectomy, also called “the sleeve,” “gastric sleeve surgery,” and “vertical sleeve gastrectomy or VSG,” a surgeon removes about 80% of your stomach, including the part that produces the “hunger hormone,” ghrelin. The stomach that remains is the size and shape of a banana. 

Types of Restrictive Weight-Loss Surgeries 

Restrictive weight-loss surgeries vary, just like malabsorptive surgeries. A common procedure is gastric banding (also known as lap band) surgery. This is different from a gastric bypass, in that it’s purely restrictive

The gastric band is made of soft silicone. It’s an inflatable and adjustable tube. The surgeon places the band around the top part of your stomach to limit the amount of food it can hold. How full you will feel after eating depends on the size of the opening between the pouch and the rest of your stomach. 

Newer restrictive procedures include gastric plication, sleeve plication, and endoscopic sleeve gastroplasty.

In gastric plication surgery, the surgeon folds your stomach in on itself, and stitches it to make it shorter and smaller. 

Related: Compare Bariatric Procedures

The surgeon folds over the upper part of your stomach and secures it with stitches or staples in sleeve plication. The remaining stomach pouch resembles a tube or sleeve.

In an endoscopic sleeve gastroplasty, an endoscopist inserts a suturing device into your throat and down into your stomach, where it is stitched to make it smaller. 

Another restrictive – and this one is non-surgical and temporary – weight-loss procedure is intragastric balloon placement. A bariatric specialist places a silicone balloon filled with saline into your stomach. It aids weight loss by limiting the amount of food your stomach can contain, and makes you feel full faster. 

Combination Malabsorptive and Restrictive Weight Loss Surgeries

All gastric bypass surgeries are malabsorptive, though some are also a combination of malabsorptive and restrictive. Roux-en-Y gastric bypass is one such surgery.

In the Roux-en-Y procedure, the surgeon staples your stomach to create a small pouch to hold less food, and shapes the small intestine into a “Y,” which is attached to the smaller stomach pouch.

Related: Compare Gastric Bypass vs Gastric Sleeve

In Long Limb Roux-en-Y gastric bypass, a surgeon increases a section of your small intestine to 150 centimetres, compared to Roux-en-Y, where the surgeon uses less than 100 centimetres of the small intestine for the Y-shaped section. The longer length results in greater weight loss.

A newer procedure that combines both malabsorptive and restrictive methods is SADI-S. In this procedure, the surgeon makes your stomach smaller and creates an intestinal bypass, resulting in a shorter route for digested food (i.e., calories) to travel through. 

Related: Compare Gastric Bypass vs Duodenal Switch

Another technique that decreases the size of your stomach and reroutes your intestines is duodenal switch surgery

Typical Weight Loss Results From Malabsorptive and Restrictive Surgeries

Malabsorptive and restrictive weight-loss procedures can lead to substantial weight loss. When they are completed in combination with a healthy lifestyle, you can achieve significant long-term weight loss (20-40 per cent of your body weight). 

Another benefit is the control, or, in some cases, the remission of obesity-related diseases, including hypertension, sleep apnea, fatty liver disease, and Type 2 diabetes.

In general, the success of weight-loss surgery is defined as achieving a 50 per cent loss or more of excess body weight, and maintaining it for at least five years. Gastric bypass patients could maintain a 50-60 per cent loss of excess weight 10 to 14 years after surgery. 

Weight-Loss Timeline After Bariatric Surgery

Studies suggest that following surgery, most patients lose weight quickly and continue to do so until 18 to 24 months after their procedure. 

You may lose 30-50 per cent of your excess weight in the first six months, and 77 per cent of excess weight as early as one year after surgery.

Related: Gastric Sleeve Weight Loss Timeline

Bariatric surgery outcomes do vary from person to person, because of factors such as age, initial body mass index (BMI), ethnic background, surgical technique, metabolic disorders, and whether an eating disorder is present. 

Nutrient Absorption and Deficiency Concerns After Malabsorptive Surgery

A consequence of malabsorptive weight-loss surgeries is nutrient deficiencies. Nutrients now pass through a shortened intestine that provides a smaller opportunity for nutrient absorption. 

One study suggests that post-surgical complications, particularly those related to malnutrition, “are widespread and often prone to misdiagnosis or inadequate treatment.” Bariatric surgery can also exacerbate pre-existing nutritional deficiencies in patients living with obesity. 

Another concern is whether patients will follow dietary recommendations after their surgery. If they fail to do so, they may develop nutritional deficiencies.

Nutrient Absorption and Deficiency Concerns After Restrictive Surgery

Malabsorptive weight-loss surgeries tend to have a higher risk of nutritional deficiencies than restrictive surgeries, which leaves the intestinal tract intact.

Surgeries that involve both restrictive and malabsorptive components carry an increased risk of malnutrition complications because of altered post-surgical anatomy.

To mitigate these risks, lifelong monitoring after surgery enables early intervention to prevent and address any deficiencies. 

Eating Habits and Lifestyle Changes After Bariatric Surgeries

Post-operative weight loss following malabsorptive or restrictive surgery largely depends on you managing a new lifestyle that includes diet, exercise, and behavior modification. 

Immediately after surgery, you will probably be on a liquid diet for a few weeks. Then you can slowly start eating soft foods before progressing to solid foods. Drinking plenty of fluids is also important to avoid nausea, constipation, and fatigue. 

Your doctor may also tell you to focus on consuming foods that are high in protein. Protein malnutrition is the most severe complication associated with malabsorptive weight-loss surgery, causing weakness and loss of muscle. It’s also likely you may need to take vitamin and mineral supplements for life.

Your healthcare providers may also encourage you to exercise moderately up to 30 minutes a day, which promotes and maintains weight loss. Some patients start walking within just a few hours after surgery. Yet, each patient is different, so check with your surgeon before you start exercising more intensely. 

Any medications you had been taking may also change after you have had surgery. Your doctor may decrease the dosages, or eliminate them altogether.

You may be asked to avoid alcohol for the first six months after surgery, because it will absorb into your blood stream more quickly after your procedure. Bariatric surgery patients will have higher levels of alcohol in their system for a longer period of time after drinking compared to before surgery. This is because of their altered metabolism.

Patients can still regain weight after surgery, so regular visits with your bariatric specialist, which may include additional treatment, medication, and advice on lifestyle changes, will help ensure you can successfully maintain your weight loss.

Potential Risks and Complications of Bariatric Surgery

Like any surgery, malabsorptive and restrictive weight-loss surgeries carry risks and potential complications. We’ve already discussed nutrient deficiency. Here are other risks and complications: 

  • Dumping syndrome. Nausea, diarrhea, abdominal cramping, and hypoglycemia can occur when the stomach dumps food into the small intestine too quickly. These symptoms usually fade with time. Dietary guidelines can help prevent or reduce them.
  • Bile reflux. Surgery that affects the opening between the stomach and small intestine (the pyloric valve) can cause it to malfunction, resulting in bile reflux. 
  • Gallstones. Rapid weight loss sends a large amount of cholesterol to the liver to process. Then, when the liver sends bile that’s laden with extra cholesterol to the gallbladder, it can build up and form gallstones. The good news is, you may receive a prescription for medication to prevent gallstones after surgery.
  • With Laparoscopic Adjustable Gastric Banding, the band can erode into the stomach or slip, blocking the flow of food through the band. The stomach pouch can also enlarge over time. 

Other risks include infection, blood clots, pneumonia, bleeding ulcer, obstruction or nausea when food isn’t properly chewed, abdominal scarring and adhesions that can lead to bowel blockage, and vomiting due to eating more food than the stomach pouch can hold or eating too quickly.

Patients may face other risks, depending on their individual condition, so it’s wise to discuss any concerns with a doctor before your procedure. Your doctor should also discuss all risks and potential complications with you, as well as answer your questions.

Pre-Operative Assessments and Post-Operative Care 

Another key to successful bariatric surgery is a thorough pre-operative assessment that evaluates and manages all aspects of the procedure. This can involve multiple appointments, and lab and diagnostic testing to ensure you are a good candidate for the surgery, and to identify and address any health issues before surgery.

An assessment includes a comprehensive patient evaluation, personalized treatment planning, continuity of care, and patient education. This also minimizes risks or complications. A whole team, from the bariatric surgeon to anesthesiologists to a registered dietitian, can be involved in your pre-operative assessment.

Post-operative care is just as important, to ensure a smooth recovery, and prevent complications such as pneumonia, blood clots, and constipation. 

Criteria to Determine Patients’ Suitability for Malabsorptive or Restrictive Surgeries

You may be a good candidate for bariatric surgery if: 

  • You have not been successful in losing weight through diet and exercise, and have a body mass index (BMI) greater than 35
  • You have not been successful in losing weight through diet and exercise, have a body mass index (BMI) greater than 30, and an obesity-related health issue, such as Type 2 diabetes, osteoarthritis, hypertension, coronary artery disease, or major depression
  • You fully understand the procedure and its implications 

Your age is also taken into consideration. Weight loss surgery for individuals less than 18 is controversial, yet the risk of developing obesity-related diseases increases the longer someone remains obese.

If you’re contemplating weight loss surgery, please consult with your healthcare provider. He or she will determine the most appropriate option based on your health profile.

The Last Word on Malabsorptive and Restrictive Weight Loss Surgeries

Malabsorptive or restrictive weight-loss surgery may be an excellent option if you’re struggling with obesity, have tried to lose weight through traditional diet and exercise methods, and if you’re living with obesity-related diseases.

Malabsorptive surgeries promote weight loss by limiting the amount of nutrients your body absorbs. Restrictive surgeries lead to weight loss because they reduce the amount of food your stomach can contain.

Please seek the guidance of a medical professional if you’re considering malabsorptive or restrictive weight-loss surgery. He or she will help you identify the best course of action for you! 

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