This article looks closely at the purpose of gastric bypass surgery, the criteria you must meet to be eligible for it, and the tests and labs to expect.

The primary goal of gastric bypass surgery is to lose weight in order to improve or reverse medical conditions associated with obesity.

Examples of such obesity-related conditions include:

Heart diseases, such as high blood pressure (hypertension) and coronary artery disease Lung diseases, such as obstructive sleep apnea, obesity hypoventilation syndrome, and asthma Venous conditions, such as deep vein thrombosis and pulmonary embolism Metabolic conditions like type 2 diabetes mellitus, non-alcoholic fatty liver disease, and high cholesterol Reproductive conditions, such as infertility and polycystic ovarian syndrome (PCOS) Urinary conditions, such as stress urinary incontinence Gastrointestinal conditions, such as gallstones, gastroesophageal reflux disease (GERD), and esophagitis Musculoskeletal conditions, such as hernias and osteoarthritis Nervous system conditions, such as idiopathic intracranial hypertension

Criteria

There are certain criteria a patient must meet in order to be considered a candidate for a weight loss surgery like gastric bypass.

These criteria include a patient with:

A body mass index (BMI) higher than or equal to 40 A BMI of over 35 with one or more obesity-related health conditions A BMI of over 30 with uncontrollable type 2 diabetes or metabolic syndrome

Due to a higher prevalence of abdominal (truncal) obesity, weight loss surgery may also be considered for Asian patients who have uncontrolled type 2 diabetes and a BMI as low as 27.5.

That said, meeting one of the above criteria is simply the first step in determining who is an appropriate candidate for surgery. Patients must be able to prove that they have been unsuccessful in maintaining a healthy weight through non-surgical means, such as lifestyle changes and drug treatments.

Tests and Labs

To confirm candidacy and to prepare for the outcome of the surgery, patients will need to undergo several evaluations with various healthcare professionals, usually beginning several weeks to months prior to the actual procedure date.

These healthcare professionals include:

A bariatric (weight loss) physicianA bariatric surgeonA nutritionist or dieticianA psychologist or psychiatrist

The bariatric physician will review your medical history and order tests to either newly diagnose or monitor health conditions related to your obesity. Some of these conditions may need to be optimized prior to surgery in order to reduce the risk of surgical complications.

Examples of such tests include:

A comprehensive metabolic panel and liver function test to evaluate kidney and liver function A hemoglobin A1C to evaluate blood sugar control A series of blood tests to evaluate for malnutrition (e. g. , vitamin D, albumin, ferritin) An overnight sleep study to evaluate for obstructive sleep apnea An esophagogastroduodenoscopy (EGD) to evaluate for GERD An electrocardiogram (ECG) and echocardiogram to evaluate for heart problems Other imaging studies (e. g. , chest X-ray or abdominal ultrasound)

Your bariatric physician will also probably start you on a medical weight loss program, as losing some weight before surgery is typically recommended.

Your bariatric surgeon will review the pros and cons of the surgery with you and enroll you in a bariatric pre-operative education program. The purpose of this program is to learn about the nuances of the surgery, including what to expect in terms of the short and long-term recovery processes, as well as, the potential risks involved.

A nutritionist will prepare you for what your diet will look like after surgery. They will also help you adhere to a low-calorie liquid diet, which is often required beginning two to four weeks before surgery.

A psychologist or psychiatrist will discuss the mental and emotional stresses associated with the surgery and its aftermath. Since mental health conditions, especially depression and eating disorders, are associated with obesity, your mental health professional may also provide therapy or recommend/prescribe medication.

Finally, consultations with different specialists may also be needed before surgery. For example, women in their childbearing years undergoing gastric bypass may need to see an obstetrician to discuss birth control options after surgery.

This is because professional societies, like the American College of Obstetricians and Gynecologists (ACOG), recommend that women not become pregnant in the first 12 to 18 months after bariatric surgery.

A Word From Verywell

The possible benefits of undergoing gastric bypass surgery are vast. Besides improving (if not reversing) serious health problems, patients feel better about their appearance and often report having improved self-esteem and quality of life.

Still, undergoing this type of surgery is an incredibly big decision, one that requires deep consideration and thought. As you continue to educate yourself about gastric bypass or other weight-loss surgeries, do not hesitate to reach out to loved ones for support.

Also, remember to be kind to yourself during this long and arduous journey. A good piece of advice is to simply take one day at a day and remain focused on your ultimate goal of achieving a healthier life—something you truly deserve.