How Does Weight Loss Surgery Work?

Weight loss surgeries use a variety of different approaches to achieve the same end goal: to help patients overcome chronic obesity by shedding significant excess body weight in a relatively short time frame.

By giving obese patients a jump start on their long-term weight loss journey, weight loss surgeries, also known as bariatric surgeries, effectively provide a new lease on life. The combination of rapid weight loss, improved quality of life and reduced chances of obesity-related health problems allow patients to assert control over their bodies and the course of their health in a way that is truly life-changing.

Yet, for all the well-known benefits of rapid, lasting weight loss for people suffering from chronic obesity, the reasons why weight loss surgeries work so effectively has more and more scientific basis.

For anyone who has wondered exactly how bariatric surgeries work, this guide will provide essential information and insight about how the most widely practiced weight loss surgery procedures help patients lose weight.

How Bariatric Surgery Causes Weight Loss

Broadly speaking, bariatric surgery procedures bring about weight loss through a combination of caloric restriction and intestinal hypo-absorption (diminished absorption).

1- Caloric Restriction

Certain bariatric procedures reduce the volume of the stomach, which leads patients to feel full after eating less food than they their bodies are accustomed to. By reducing food intake, this long-term caloric restriction drives weight loss and helps prevent patients from regaining lost weight.

2- Hypoabsorption

Other weight loss surgeries modify the way the digestive system processes food, which causes the body to absorb fewer calories from consumed food. Certain surgeries may also decrease absorption of fat, proteins, minerals and vitamins.

3- Changes in Gastro-intestinal Hormones

In general, weight-loss surgeries also decrease the hunger hormone ghrelin, and increases the satiety hormone GLP-1.

4- Microbiome Changes

Weight loss surgeries cause a change in the quality and quantity of the gut bacteria in the colon.

Popular Weight Loss Surgery Procedures

The following non-exhaustive list of bariatric procedures includes the most widely-practiced techniques. Many of these surgical procedures use a combination of intestinal hypoabsorption and caloric restriction to bring about lasting weight loss, but there are some that focus exclusively on one approach over the other.

Laparoscopic Sleeve Gastrectomy (LSG)

The mechanism of action behind this procedure is caloric restriction and hormonal changes. A laparoscopic sleeve gastrectomy, also called gastric sleeve surgery, is one of the most widely practiced procedures because it is minimally invasive yet highly effective.

Through a series of small incisions, surgeons permanently remove a portion (60-85%) of the patient’s stomach using long instruments in less than an hour, leaving the remaining portion of the stomach in a sleeve-like shape. It leaves digestion and nutritional absorption mildly affected, so patients do not have to radically alter their eating habits, as their portion sizes are naturally reduced. Ghrelin, the hunger hormone, is reduced by 70%.

Within one year of an LSG procedure, patients tend to lose anywhere from 55% to 75% of their excess weight.

Gastric Balloon

Gastric balloons are devices that reduce the available volume of the stomach that restricts caloric intake. This outpatient weight loss procedure does not alter the stomach or the digestive tract, so it is well suited for patients who are not yet candidates for surgery and offers a great option to complement a weight loss program built around diet and exercise.

By using an inflatable balloon to reduce the available space in the stomach, this procedure brings about weight loss because patients feel more full for longer periods of time after eating, allowing for longer periods between meals. Even though gastric balloons are only a temporary measure, as they are meant to be removed within a 6-month time frame, patients usually lose about a third of their extra weight over the course of this period. They are often combined with medications that increase satiety, to prevent weight gain after balloon’s removal.

Mini Gastric Bypass Surgery (MGB)

This bariatric surgery procedure draws on both gastric reduction and intestinal hypoabsorption by creating a small gastric pouch and re-routing parting of the intestine. After gaining popularity in Europe and Asia, the MGB procedure is relatively new to Canada and the United States.

Based on traditional gastric bypass techniques, this surgery requires less operative time because there is only one connection between the stomach and intestine (rather than two).

Roux-en-Y Gastric Bypass

This form of gastric bypass also combines gastric reduction and moderate intestinal hypoabsorption, but it takes a different approach than the MGB.

After creating a gastric pouch near the esophageal sphincter, the first part of the intestine is divided in two, with the lower section (known as the “Roux” limb) attached to the gastric pouch, while the upper section (known as the “Bilio-Pancreatic” limb) is attached further down the Roux limb. This new intestinal formation brings digestive juices into the Roux limb, which brings digestion and ingestion further down the digestive tract. Hormonal changes, like an increase of GLP-1, cause satiety.

Duodenal Switch

This procedure relies on optimal intestinal hypoabsorption, as well as gastric reduction, and it is sometimes performed in two stages at two different times for patients with a body mass index (BMI) over 60.

The first stage involves a gastric sleeve gastrectomy to reduce the volume of the stomach, while the second stage divides the intestines to change how the body absorbs nutrients. By separating the lowest part of the intestines (the ileum) from the rest and dividing the upper part of the intestines (the duodenum), the surgeon creates a new digestive path, where one intestinal limb is for food and the other is for digestive juices. The resulting change limits nutrient absorption to a small portion of the lower intestines (40-50%). Hormonal changes, including lower ghrelin and higher GLP-1, result in higher Type 2 Diabetes resolution.

Weight Loss Surgery Reduces the Risk of Serious Medical Conditions

Each year, more and more studies show that carrying a significant amount of excess weight is associated with a long list of medical problems. Over time, people struggling with chronic or morbid obesity, face far greater risks than the general population for medical issues, such as:

  • Congestive heart failure
  • Coronary heart disease
  • Type-2 Diabetes
  • Depression
  • High blood pressure
  • High cholesterol
  • Arthritis
  • Sleep apnea
  • Fatty liver disease
  • Kidney disease

Each of these potentially serious medical issues lowers life expectancy, due to the increased risk of death from heart issues, in particular.

Fortunately, obese patients, even patients with type-2 diabetes, can avoid these health problems by taking steps to control their weight with bariatric surgery and improving their physical fitness through consistent diet and exercise.

Necessary Lifestyle Changes Following Bariatric Surgery

For obese patients, achieving long-term weight loss is a turning point that leads to greatly increased quality of life and reduced health risks. In the years after surgery, patients must make physical activity a regular part of their lifestyles, and control their eating habits, to fight weight gain. Also, the recipients of certain malabsorptive procedures, must use vitamin and mineral supplements to maintain good health.

Clinique Michel Gagner - Renowned Weight Loss Surgery Clinic

If you are someone who is considering weight loss surgery to change the course of your health and improve your quality of life, the team at Clinique Michel Gagner can help.

Led by the internationally renowned bariatric surgeon, Dr. Michel Gagner, the team at Clinique Michel Gagner focuses exclusively on advanced bariatric surgery techniques and comprehensive patient care to help patients get the greatest possible benefits.

For questions or consultations, contact us to discuss your weight loss surgery options.