Purpose of Weight Loss Surgery

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Weight loss surgery (also referred to as bariatric surgery) is a procedure to help improve the health of someone who is dealing with obesity and the medical issues related to it. By using this surgical intervention to remove excess weight, patients may be able to reverse or improve conditions like type 2 diabetes, heart disease, and more.

Most patients who have weight loss surgery lose anywhere between 15% to 30% of their starting weight, but maintenance measures like establishing a healthy diet and exercise routine are needed beyond surgery to help keep the weight off and improve health long-term.

purpose of weight loss surgery
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Diagnosis Related to Weight Loss Surgery

The most common diagnosis that leads to weight loss surgery is obesity. That’s because carrying extreme excess weight on your body can lead to other serious medical conditions, including metabolic syndrome, sleep disorders, high blood pressure, high cholesterol, and others.

The World Health Organization (WHO) states that worldwide obesity has tripled since 1975 and currently most of the world’s population lives in a country where obesity kills more people than those who are underweight.

In order to be diagnosed with obesity, your healthcare provider will look at your past physical exams to check your body mass index (BMI), which is your weight divided by your height, as well as your waist circumference.

An obese adult will have a BMI of 30 or above, though to be qualified for weight loss surgery many healthcare providers require a BMI of 35-40. For women who are not pregnant, a waist circumference of 35 inches or more is considered obese and for men 40 inches or higher.

Aside from your weight and waist, your healthcare provider will look at any other health conditions you may have. This will help them determine if the side effects may include extra weight or vice versa—if the excess weight is causing these other health issues.

This may require additional tests, such as a blood test to rule out hypothyroidism or Cushing’s syndrome, or a pelvic ultrasound to determine if the weight gain is being caused by polycystic ovary syndrome (PCOS).

BMI is a dated, flawed measure. It does not take into account factors such as body composition, ethnicity, sex, race, and age. 

Even though it is a biased measure, BMI is still widely used in the medical community because it’s an inexpensive and quick way to analyze a person’s potential health status and outcomes


Not everyone who is obese is a candidate for weight loss surgery. In order to get approved for this procedure, a number of criteria must be met, including:

  • Past efforts to lose weight through diet and exercise have not been successful. Your healthcare provider may require you to document your efforts anywhere from six months to a year.
  • You have a body mass index of 40 or higher
  • You have weight-related health issues such as sleep apnea, type 2 diabetes, hypertension, heart disease,or gastrointestinal disorders and a BMI higher than 35.

Even if you meet the above criteria, your healthcare provider will still look at any aspects of your overall health to determine if this procedure is right for you. This will include your current nutrition and exercise habits (meaning you’ll want to start establishing or continuing these well ahead of any treatment), your overall medical health including age, and your mental health.

They may also want to speak with you about your desire for seeking out this procedure, which will help show them how likely you are to stick to their exercise and diet recommendations after the surgery to get the most successful outcome.

Tests and Labs

In addition to the tests and labs your healthcare provider will run to determine an obesity diagnosis, there are several tests you’ll get done as you move through the criteria checklist to make sure weight loss surgery is right for you. They may include one of several of the below:

  • Blood work
  • Chest X-ray to look at the heart, lungs, airway, and surrounding blood vessels.
  • Upper gastrointestinal testing (UGI) to examine the health of your digestive tract, as well as what changes the surgeon may make to it during the procedure.
  • Electrocardiogram (EKG) to check heart health.
  • Esophagogastroduodenoscopy (EGD) to examine the lining of the esophagus, stomach, and upper part of the small intestine.

These tests will flag any pre-existing conditions and show your healthcare provider how your body will hold up to the stresses of surgery, including how it will recover.

Once these tests are done you’ll get a psychological evaluation to discuss your at-home support system and make sure there aren't any mental health conditions including alcohol or substance abuse, which can make it difficult to maintain any success achieved from weight loss surgery.

You’ll also meet with a registered dietitian to go over your current diet and what modifications to make before and after surgery. They will take into account your lifestyle, including any time management obstacles you may have, family dynamics and the eating patterns at home, and more.

A Word From Verywell

If you’re concerned your weight may be affecting your overall health, it’s a good idea to speak to your healthcare provider about weight loss surgery. They will have the latest technology and information to share with you, as well as give insight as to whether or not you might be a candidate for the procedure.

It’s important to keep in mind, however, that getting weight loss surgery isn’t a magic bullet—there’s a lot of work and commitment that has to be done once the surgery is over.

Many of the lifestyle choices you may be asked to make will be a dramatic shift from your usual patterns, which is why a psychiatric evaluation is such a large part in determining if a patient fits the criteria to become a candidate for weight loss surgery.

Depending on what type of weight loss surgery the patient gets, such as a lap band surgery versus gastric bypass there’s a good amount of education required as to what to expect after the procedure and the possible complications.

Your healthcare provider will give you all the materials you need, but ultimately it’s up to you to make sure you understand the risks and rewards and seek more information or ask questions to ensure you’re making the best choice for you.

6 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. National Institute of Diabetes and Digestive and Kidney Diseases. Definition & Facts for Bariatric Surgery.

  2. World Health Organization. Obesity and overweight.

  3. National Heart, Lung, and Blood Institute. Overweight and obesity.

  4. American Society for Metabolic and Bariatric Surgery. Who is a candidate for bariatric surgery?

  5. MedlinePlus. Gastric bypass surgery.

  6. Northern Westchester Hospital Northwell Health. Preparing for bariatric surgery.

By Colleen Travers
Colleen Travers writes about health, fitness, travel, parenting, and women’s lifestyle for various publications and brands.