Excess weight increases the risk of numerous health problems and negatively affects a person’s quality of life. Dropping a few pounds requires simple diet modifications and regular exercise. However, some obese men and women may find it difficult to slim down with lifestyle modifications only. Many need weight loss surgery to aid this process. The main focus of this post is weight loss surgery, different types of procedures, ideal candidates, and more.

Weight Loss Surgery

Weight loss, or bariatric surgery, is an umbrella term that refers to surgical procedures involving making changes to the digestive system in order to lose weight. The surgery is performed in cases when diet and regular exercise are ineffective or when a person has serious health problems due to excess weight.

Even though bariatric surgery is associated with a modern-day rise in obesity, the history of this procedure started centuries ago. In fact, historical reports claim the first weight loss surgery was performed in Spain in the 10th century. The legend says a king of Leon was so obese he couldn’t even walk, pick up a sword, or ride a horse. He even lost his throne due to his obesity. The king was escorted by his grandmother to Cordoba where a Jewish doctor treated his condition. The doctor sutured the king’s lips so he wasn’t able to eat proper food. Instead, he was fed a liquid diet through a straw. The king managed to lose half his weight then returned home and took his throne back. 

Now, this isn’t the classic weight loss surgery but it does paint a picture of a procedure being performed solely for the purpose of losing weight. 

Despite the fact, various weight-loss interventions have been reported in the second half of the 20th-century literature, they were quite scarce until the 1990s. 

The very first metabolic weight loss surgery is attributed to Dr. A. J. Kremen in 1954. In 1966, Dr. Mason (a surgeon from the University of Iowa) noted the patients with subtotal gastrectomy for cancer lost a significant amount of weight. He proposed the first bariatric surgery – the first gastric bypass. The surgery evolved greatly over the years, became less invasive, and with fewer complications (1). Nowadays, there are different approaches to bariatric surgery. 

Who is An Ideal Candidate for Bariatric Surgery?

Not every person with excess weight is an ideal candidate for bariatric surgery. To undergo this procedure a patient needs to meet several criteria. These include (2):

  • BMI ≥ 35 and, at least, one obesity-related co-morbidity such as hypertension, type 2 diabetes, non-alcoholic fatty liver disease, sleep apnea, lipid abnormalities, osteoarthritis, gastrointestinal disorders, and heart disease 
  • BMI ≥ 40 or more than 100lbs overweight
  • Inability to achieve a successful weight loss and maintain it for a period of time with prior efforts to slim down including diet and exercise. In most cases, you need to have at least six months of supervised weight loss attempts (3)

Bariatric surgery is recommended to adults primarily. But adolescents may be able to undergo this procedure if they have BMI ≥ 40 and any obesity-related medical condition or BMI ≥ 35 and a severe obesity-related medical condition. 

You can calculate your BMI here.

A suitable candidate should still be healthy enough to have surgery under general anesthesia. In patients with BMI ≥ 50, bariatric surgery may be considered without the patient needing to try lifestyle-related weight loss methods first (4).

The best way to learn whether you’re a suitable candidate for bariatric surgery is to schedule an appointment and see your doctor.

Types of Bariatric Surgery

Contrary to the popular belief, bariatric surgery is not a single procedure. As mentioned above, bariatric surgery is a term for several operations that work to jumpstart a patient’s weight loss. The main types of bariatric surgery include (5):

  • Gastric bypass (Roux-en-Y)
  • Biliopancreatic diversion with duodenal switch (BPD/DS)
  • Sleeve gastrectomy 
  • Adjustable gastric band

Below, you can learn more about each procedure. 

Gastric bypass (Roux-en-Y)

Gastric bypass, also known as the Roux-en-Y procedure, is considered the gold standard in weight loss surgery. The restrictive-malabsorptive procedure was first introduced in 1966 by Mason. Gastric bypass accounted for 60% to 70% of all bariatric procedures in the United States since 2003 (6). However, the latest statistics show Roux-en-Y has become the second most common weight loss procedure, right after gastric sleeve (7).

This procedure is generally performed after a person has tried slimming down naturally, but wasn’t successful. 

The procedure includes two main components:

  • A surgeon creates a small stomach pouch, 1oz or 30ml in volume, by dividing the top of the stomach from the remainder of the stomach area
  • Then, the surgeon divides the first portion of the small intestine. The bottom end of the divided small intestine is, then, connected to the newly created stomach pouch. The top portion of the divided small intestine is connected to the small intestine further down to allow digestive enzymes and stomach acids from the bypassed stomach and the first portion of the small intestine mix with food

Like other bariatric procedures, gastric bypass features a significantly smaller stomach pouch that requires smaller meals. This automatically lowers the number of calories consumed. To some degree, gastric bypass lowers the absorption of calories and nutrients. That happens due to decreased digestion of food in the smaller stomach pouch. The food doesn’t go through a part of the small intestine where calories are usually absorbed.

Additionally, gastric bypass reroutes the food stream thus changing gut hormones that suppress hunger, promote satiety.

Advantages of this procedure include induction of significant weight loss, lower food/calorie consumption, increased energy expenditure, and favorable changes in gut hormones.

Disadvantages of gastric bypass include potential vitamin/mineral deficiencies especially in vitamin B12, calcium, iron, and folate. The procedure is more complex than the adjustable gastric band and laparoscopic sleeve gastrectomy. For that reason, it may involve a longer hospital stay than an adjustable gastric band for example.

Biliopancreatic diversion with duodenal switch (BPD/DS)

A biliopancreatic diversion with a duodenal switch (BPD/DS) is not as common weight loss procedure as others on this list. Studies show, however, BPD/DS produces the most significant weight loss with amelioration of many obesity-related co-morbidities compared to other bariatric surgeries (8). Why is it performed less frequently then? You see, BPD/DS is more complex and has a higher complication rate than other procedures.

For the purpose of the procedure, a surgeon removes a portion of the stomach to create a small, tubular stomach pouch. More precisely, the procedure involves the removal of about 80% of the stomach in the process (9). Basically, this part of the process is similar to the above-described gastric bypass. Then, the large portion of the small intestine is bypassed.

The pyloric valve, the valve whose role is to release food to the small intestine, remains along with the duodenum, a limited portion of the small intestine that attaches to the stomach. The procedure involves connecting the duodenum to an end portion of the small intestine near a patient’s stomach. 

Similar to other weight loss procedures, BPD/DS limits food intake and lowers the absorption of nutrients such as fats and proteins. Over time, the effect lessens and a patient is able to consume a near “normal” amount of food. Unlike other bariatric procedures, BPD/DS involves bypassing a significant amount of small bowel. 

It’s also useful to mention the food doesn’t mix with pancreatic enzymes and bile until far down a person’s small intestine. 

Advantages of BPD/DS include favorable changes in gut hormones, greater weight loss than other procedures, reduced absorption of fat, and it is the most effective against diabetes. Disadvantages of the procedure higher complication rates and mortality risk, longer hospital stay, greater risk of nutritional deficiencies. 

Sleeve gastrectomy 

Laparoscopic sleeve gastrectomy (LSG), often called the sleeve, is a weight loss procedure where a surgeon inserts small instruments through multiple incisions in the upper abdomen. During this process, about 80% of the stomach is removed thus leaving a tube-shaped stomach pouch that looks somewhat like a banana. 

Initially, LSG was used as a bridge to definitive surgery in high-risk patients recently it has been forwarded as a standalone procedure. While technical details of laparoscopic sleeve gastrectomy vary, the main premise is to remove a great deal of stomach and leave only a gastric tube between the duodenum and esophagus (10).

The mechanism of action through which sleeve gastrectomy works is simple. The new stomach pouch holds a significantly smaller volume than the normal stomach. As a result, it reduces the amount of food and the number of calories a patient consumes. The impact of surgery is also observed through favorable effects on gut hormones.

Advantages of sleeve gastrectomy are similar to those of other procedures e.g. lower intake of food, rapid and significant weight loss, and unlike other procedures, it also involves a shorter hospital stay. 

Since it doesn’t involve a bypass like other surgeries, sleeve gastrectomy is a nonreversible procedure thus increasing the risk of long-term nutritional deficiencies. The procedure could have a higher early complication rate than the adjustable gastric band. 

Adjustable gastric band

An adjustable gastric band (AGB), also known as the band, is a bariatric procedure that relies on placing the inflatable band around the upper area of the patient’s stomach. As a result, a small stomach pouch is created above the band while the remainder of the stomach is below it. 

The procedure works in a similar manner as others of this kind. A smaller stomach pouch limits food and calorie consumption by making a person feel full and satiated. The feeling of fullness depends on the size of the opening between the pouch and the rest of the stomach created by the gastric band. It is possible to adjust the size of the stomach opening. For that purpose, the band is filled with sterile saline injected through a port located under the skin. Reduction of the stomach opening is performed gradually over time with repeated “fills” or adjustments.

Advantages of the procedure include a decrease in the amount of food the stomach can hold, successful weight loss of about 40% to 50%, and it is less invasive than other procedures. Since it’s not as invasive, AGB requires a shorter hospital stay and has the lowest risk of complications and mineral deficiencies. This procedure is reversible and adjustable. 

Disadvantages of the adjustable gastric band include slower weight loss compared to other procedures, the foreign device needs to remain in the body, and a smaller percentage of patients lose at least 50% of excess body weight than with other weight-loss surgeries. In some patients, the band can slip or erode into the stomach (11).

Benefits of Bariatric Surgery

Weight loss surgery can be life-changing for men and women with high BMI and failed attempts to slim down with diet and exercise alone. Benefits of bariatric surgery procedures include (12):

  • Reduced capacity of the stomach to suppress appetite and generate a feeling of fullness 
  • Weight loss 
  • Improved cardiovascular health
  • Long-term remission of type 2 diabetes
  • Depression relief 
  • Management of sleep apnea
  • Improved fertility
  • Joint pain relief and improved flexibility and range of motion
  • Improved general health and wellbeing

Studies confirm current bariatric surgeries generate substantial and durable weight loss (13).

Risks of Bariatric Surgery

Every surgery comes with certain risks and bariatric procedures are not the exceptions here. The specific risks depend on each type of bariatric surgery, but in most cases they include:

  • Infection
  • Excessive bleeding
  • Leaks in the gastrointestinal system
  • Lung or breathing problems 
  • Blood clots
  • Adverse reactions to anesthesia 

Long-term complications also depend on each type of procedure. But generally, they may range from bowel obstruction and gallstones to hernia, malnutrition, low blood sugar, vomiting, acid reflux, ulcers, a dumping syndrome that leads to diarrhea, and the need for revision surgery.

What Happens Before Surgery?

Before surgery, a patient usually meets a dietitian, internist, psychiatrist, and bariatric surgeon. The main point here is to help a patient establish a healthy lifestyle after the surgery. Bariatric surgery is not a finish line, but a start. 

What to Expect After Surgery?

Since most procedures are laparoscopic today, the hospital stay is shorter than it used to be. You can expect to spend two to three days in a hospital. Most patients can return to normal activities in three to five weeks. Open surgeries require a longer recovery time (14). 

Right after surgery, a patient starts with a liquid diet and moves to a soft diet over several weeks. Eventually, they may start consuming solid foods again. It’s important to stick to doctor-recommend recovery instructions to ensure proper healing and achieve the best results.

Do You Need to Exercise After Bariatric Surgery?

Physical activity after bariatric surgery can support the healing process and recovery. It improves blood circulation, reduces the risk of blood clots, and promotes bowel function. At first, you will be able to take short walks. As you recover and heal you will be able to engage in other activities. Advise your doctor about the right time to engage in regular workouts.

How much weight Can You Lose with Bariatric Surgery?

The amount of weight you can lose depends on the baseline weight (before the procedure) and the type of bariatric surgery. In one study, a year after gastric band, gastric sleeve, and gastric bypass patients lost between 38 and 87 lbs. Gastric bypass produced the most significant weight loss but had more complications. While most people regained weight over time, the number of pounds they put on was small compared to how much they lost (15).


Weight loss surgery is the last resort i.e. a solution for obese men and women whose prior attempts to slim down were unsuccessful. Several bariatric procedures are available today. Surgeons usually perform laparoscopic surgeries that are minimally invasive and have a shorter recovery period. The surgery is just beginning and a patient needs to make lifestyle adjustments to support weight loss. In other words, despite surgery, you still need to exercise regularly and eat a well-balanced diet.


  1. https://www.sciencedirect.com/science/article/pii/S2444866416300186
  2. https://asmbs.org/patients/who-is-a-candidate-for-bariatric-surgery
  3. https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/gastric-bypass-surgery/art-20046318
  4. https://www.nhs.uk/conditions/weight-loss-surgery/who-can-have-it/
  5. https://www.niddk.nih.gov/health-information/weight-management/bariatric-surgery/types
  6. https://pubmed.ncbi.nlm.nih.gov/31985950/
  7. https://asmbs.org/resources/estimate-of-bariatric-surgery-numbers
  8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3929999/
  9. https://www.mayoclinic.org/tests-procedures/biliopancreatic-diversion-with-duodenal-switch/about/pac-20385180
  10. https://pubmed.ncbi.nlm.nih.gov/19536054/
  11. https://asmbs.org/patients/bariatric-surgery-procedures
  12. https://health.clevelandclinic.org/7-bariatric-surgery-benefits-besides-helping-you-lose-weight/
  13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6320354/
  14. https://www.webmd.com/diet/obesity/what-to-expect-after-weight-loss-surgery
  15. https://pubmed.ncbi.nlm.nih.gov/30383139/

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