Definition and Overview

A weight loss operation, which is also referred to as weight loss or bariatric surgery, is a sensitive medical procedure that aims to treat people who are suffering from potentially life-threatening obesity. Although it can lead to dramatic weight loss, it is not recommended for cosmetic reasons alone as it comes with serious risks and complications. The procedure works by limiting the body’s ability to take a significant amount of food by removing a part of the stomach. This is usually used as a last resort if the patient fails to lose weight through other non-surgical and less invasive means.

Who Should Undergo and Expected Results

Patients must meet the following criteria to be considered for any type of weight loss operation;

  • Have a BMI or body mass index of 40 or higher. For women, this means that they should be about 80 pounds overweight while men should be about 100 pounds overweight.
  • Have a serious health problem associated with their obesity such as high blood pressure, diabetes, gout, and breathing problems, among others.
  • Have tried other ways to lose weight and has failed
  • Are committed to drastic lifestyle changes following the surgery (eating a healthy diet, doing regular exercises, etc.
  • Know and understand the risks of the surgery

How Does the Procedure Work?

There are different types of weight loss operations and each is performed using different techniques. The main types of operations are divided into three main approaches:

  • Restrictive surgery – As implied by the term, this form of weight loss surgery aims to restrict the body’s ability to take in a specific amount of food; this is achieved by shrinking the size of the stomach. This limits the amount of food that the patient can consume from a normal rate of 3 pints to as little as 2 or 3 ounces. This surgery also effectively slows down a person’s digestion to lengthen the feeling of being full.

  • Malabsorptive surgery – This form of weight loss surgery aims to change the way the body takes in food. Like restrictive surgery, malabsorptive surgery also shrinks the size of the stomach. However, it also removes or bypasses a certain part of the digestive tract. This does not only limit the amount of food consumed but also limits the body’s ability to absorb calories. This type of operation is also called an intestinal bypass.

  • Electrical device implantation – This is a relatively new technique that works by interrupting the nerve signals running from the stomach going to the brain. The electric pulses help suppress hunger.

The different types of surgeries are:

  • Gastric bypass surgery – Gastric bypass is the most common type of weight loss operation that combines the restrictive and malabsorptive techniques. The idea is to create a shortcut leading from the upper region of the stomach to the lower section of the intestines, completely bypassing a part of the stomach and the small intestine. This restricts the body from absorbing too many nutrients from food, leading to a dramatic weight loss.

  • Adjustable gastric banding – This is a specific weight loss surgery that uses the restrictive technique. It works by placing an inflatable band that squeezes the stomach into a smaller pouch, forcing the patient to consume significantly less food. This is a commonly preferred method of surgical weight loss because of its smaller scarring, faster recovery, and the fact that it can be reversed; even if the band is already in place, patients can have it adjusted or even removed in the future if they decide to change their minds. The weight loss, however, is not that dramatic, and there is also the risk of the band slipping out of place or leaking.

  • Sleeve gastrectomy – Also a restrictive surgery, sleeve gastrectomy is the surgical removal of about 75 percent of the patient’s stomach. The remainder is simply a narrow tube connected to the intestines. In some cases, it works by itself, but in others, it is followed by other surgeries after 12 to 18 months. This is, however, a simple and low-risk surgery that is an excellent choice for patients who are severely obese or are suffering from a major health condition that makes other surgeries very risky. The good thing about this surgery is that, since the intestines are not affected, the body can still absorb the optimum level of nutrients.

Possible Complications and Risks

All surgeries have risks, but these differ based on the specific type of weight loss operation a patient undergoes. Malabsorptive surgeries are known to cause numerous side effects, so doctors do not widely recommend them. Gastric banding, on the other hand, is also a risky procedure, as it can cause vomiting if a patient eats too much too fast; patients also sometimes require a secondary operation to repair a band that has slipped out of place or become loose. In addition, all types of weight loss operations also come with a risk of infection and blood clots.


  • Lamond KG, Lidor AO. Morbid obesity. In: Cameron JL, Cameron AM, eds. Current Surgical Therapy. 11th ed. Philadelphia, PA: 2014.
  • Mechanick JI, Youdim A, Jones DB, et al. Clinical practice guidelines for the perioperative nutritional, metabolic, and nonsurgical support of the bariatric surgery patient - 2013 update: cosponsored by American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic and Bariatric Surgery. Endocr Pract. 2013;19:337-372. PMID 23529351
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