Purpose of Gastric Sleeve Surgery

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Gastric sleeve surgery is a type of weight loss procedure. During the surgery, a surgeon inserts small tools through multiple incisions (cuts) in the abdomen. The surgeon removes about 80% of your stomach, leaving a long tube-shaped stomach about the size of a banana.

Decreasing the size of the stomach limits the amount of food you can eat, which helps you lose weight quickly. The surgery may also lead to hormonal changes that make you feel hungry less often.

This article takes a closer look at the purpose of gastric sleeve surgery, the criteria you must meet to be eligible for it, and tests and labs to expect.

Woman consults with doctor about gastric sleeve surgery

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Diagnoses Related to Gastric Sleeve Surgery

The main goal of gastric sleeve surgery is to aid weight loss to prevent or improve medical conditions associated with obesity. Here are some examples of medical conditions that may be affected by obesity and weight:

Weight loss surgeries are usually not the first-line treatment option for treating obesity and obesity-related conditions. It is considered major surgery and carries risks for both short- and long-term side effects.

Typically, weight loss surgery is recommended after failed weight loss attempts through diet and lifestyle changes.

Research suggests a weight loss of as little as 10% of total body weight may help improve health outcomes in overweight and obese individuals for many of these health conditions.

Criteria for Gastric Sleeve Surgery

There are specific criteria a patient is expected to meet to be considered a candidate for gastric sleeve surgery. Often, your healthcare team will want you to attempt weight loss through diet and exercise changes.

They use these failed attempts to determine whether surgery is necessary because it’s better to maintain a healthy weight without altering your gastrointestinal system if possible.

The classic criteria used to determine eligibility for bariatric surgery include:

  • Body mass index (BMI) greater than or equal to 40 or BMI greater than or equal to 35 with at least one obesity-related health condition
  • Unsuccessful weight loss attempts
  • Passing mental health clearance
  • No medical conditions that would interfere with surgery

Recently, the criteria have been updated to include patients with a BMI between 30 and 35 if they have uncontrollable type 2 diabetes or metabolic syndrome.

Some people may not be eligible for weight loss surgery if they have conditions such as:

  • Severe psychiatric illness
  • Uncontrolled blood clotting problems
  • Barrett’s esophagus (changes to the lining of the food tube that increase risk of cancer)
  • Severe gastroesophageal reflux disease

Tests and Labs

Before being approved for surgery, patients undergo several different tests and evaluations. These may begin weeks to months before receiving bariatric surgery. Healthcare professionals included as part of most bariatric surgery teams include:

  • A bariatric physician or surgeon
  • A registered dietitian or nutritionist
  • A psychologist or psychiatrist

Some bariatric teams will include both physicians and surgeons to work with you before and after surgery. Both types are medical doctors. They just have different specializations. Both physicians and surgeons may help with pre-operative screenings like:

The dietitian or nutritionist will help you prepare for your new diet plan after surgery and help you along the stages of the bariatric diet. They will help answer any nutrition-related questions you have about eating a healthy diet.

The dietitian can also guide you through the stages of the post-bariatric surgery diet, such as clear liquid, full liquid, soft, and a balanced diet.

Another essential evaluation before and after weight loss surgery is the mental health screening done by a psychologist or psychiatrist. Eating can be connected with mental health, like stress, emotions, anxiety, depression, and other mental health conditions.

Talking with a mental health professional can help you feel ready to make changes to your diet and support you in the significant changes that happen with bariatric surgery.


The goal of gastric sleeve surgery is to make it easier for people to lose weight. It is usually done to prevent and improve obesity-related health conditions, like heart disease, diabetes, and metabolic syndrome.

To be considered a gastric sleeve surgery candidate, you must have a BMI over 40, pre-existing conditions, failed weight loss attempts, and pass a mental health screening.

Before your surgery is scheduled, a healthcare team will review your medical history, current health, and mental health and prepare you for the changes that develop after surgery.

A Word From Verywell

Weight loss surgery is a big decision and may help your overall health and well-being. Discuss all of the potential benefits and risks of bariatric surgery to learn if it is the best option for you. Weight can be an emotionally-charged subject. Stay kind to yourself and focus on the overall goal of improving your physical and mental health.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kheirvari M, Dadkhah Nikroo N, Jaafarinejad H, et al. The advantages and disadvantages of sleeve gastrectomy; clinical laboratory to bedside review. Heliyon. 2020;6(2):e03496. doi:10.1016/j.heliyon.2020.e03496

  2. National Cancer Institute. Obesity and cancer.

  3. Ryan DH, Yockey SR. Weight loss and improvement in comorbidity: differences at 5%, 10%, 15%, and over. Curr Obes Rep. 2017;6(2):187-194. doi:10.1007/s13679-017-0262-y

  4. Wolfe BM, Kvach E, Eckel RH. Treatment of obesity: weight loss and bariatric surgery. Circ Res. 2016;118(11):1844-1855. doi:10.1161/CIRCRESAHA.116.307591

By Ashley Braun, MPH, RD
Ashley Braun, MPH, RD, is a registered dietitian and public health professional with over 5 years of experience educating people on health-related topics using evidence-based information. Her experience includes educating on a wide range of conditions, including diabetes, heart disease, HIV, neurological conditions, and more.