Gastric Bypass Surgery: How to Prepare

Table of Contents
View All
Table of Contents

If you and a healthcare provider have decided you need gastric bypass surgery to improve your health, you’ll soon start the journey to prepare for surgery. But surgery won’t happen immediately.

Learn about where gastric bypass surgery takes place, what to wear and bring, and the adjustments you need to make in terms of food and drink or pre-operative medications.

Preparing for Gastric Bypass Surgery

RichLegg/Getty Images


Gastric bypass surgery is performed by a bariatric surgeon under general anesthesia in a hospital. On the day of your surgery, you will go to a preoperative room within the surgical unit of the hospital. Here you can expect the following:

  • You will change into a hospital gown.
  • A nurse will place a peripheral IV, start an antibiotic, and record your vital signs.
  • Your surgeon and anesthesiologist will come to say hello and briefly review the surgery with you.

Next, you will be taken to the operating room where you will be given anesthesia medications to put you to sleep. You will not feel any pain or remember anything from the surgery.

While asleep, and just prior to the surgeon making any incisions, an endotracheal (breathing) tube, urinary catheter, and an orogastric tube (to decompress your stomach) will be placed. Inflatable compression devices will also be placed on your legs to prevent blood clots.

What to Wear

Your surgeon will likely advise you to shower either the night before or the morning of the surgery using a special type of antibacterial soap. You may be asked to focus on washing your abdominal area (where the surgery will take place).

It's important to leave jewelry, credit cards, and other valuables at home. In addition, do not wear any of the following on the day of your surgery:

  • Makeup
  • Fingernail polish
  • Perfume
  • Deodorant
  • Moisturizers

Food and Drink

About one to four weeks prior to surgery, your surgeon will ask you to begin a low-calorie liquid diet. This diet generally consists of two or more protein shakes daily, along with eight glasses of zero-calorie liquids, such as:

  • Water
  • Crystal Light
  • Unsweetened tea

In small amounts, patients can also usually have the following:

  • Sugar-free jello or popsicles
  • Black coffee with no sugar
  • Broths

The purpose of this strictly liquid diet is to decrease the size and stiffness of your liver. This will help your surgeon avoid injury to your abdominal organs during the actual surgery.

One or two days before surgery, you will probably be asked to only consume clear liquids. Then, on the eve of your surgery, you will be told not to eat or drink anything after 10 pm or midnight.


Your surgeon and anesthesiologist will instruct you to stop various medications prior to undergoing surgery. For example, about seven to 10 days prior to surgery, you will be advised to stop any nonsteroidal anti-inflammatory drugs (NSAIDs) like Motrin (ibuprofen), or Aleve (naproxen).

Starting the day or night before your operation, you may be asked to begin a bowel cleansing preparation. Instructions may vary, so be sure to follow your surgeon's directions. Reach out to them if you have any questions.

What to Bring

For gastric bypass surgery, you can expect to stay in the hospital for approximately two to five days. To prepare for your stay, pack these items and bring them with you on the day of your surgery:

  • Your driver's license and insurance card
  • Comfortable clothes to leave the hospital in
  • Personal items for your hospital stay, such as underwear, toothbrush, comb, glasses or contact lenses (with container), and a cell phone charger.
  • One or more "comfort" items, such as a sleep mask or a small pillow
  • Sleep apnea mask (if you have one)
  • Entertainment materials such as an e-book reader, tablet, books, music, headphones, etc.

Pre-Op Lifestyle Changes

Prior to undergoing gastric bypass surgery, your surgeon will ask you to do the following:

  • Engaging in an education/lifestyle program: Most insurance companies require that patients undergo a six-month pre-operative program to learn all about the surgery, including the short and long-term recovery process.
  • Losing weight: Your surgeon may advise you to lose weight on your own before surgery by starting an exercise routine and restricting your calorie intake.
  • Stopping smoking: Your surgeon will ask you to stop smoking for at least three months prior to your surgery. Stopping smoking lowers your chances of developing serious surgical complications, such as impaired wound healing.
  • Avoiding caffeine: Some surgeons ask their patients to avoid caffeine for at least one month before surgery.

A Word From Verywell

Since the outcome of gastric bypass surgery is life-altering, preparing for it takes commitment and time on the patient's part. During this potentially challenging time, lean on loved ones for support and/or consider joining a bariatric support group. Take your weight loss journey one day at a time.

7 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. Lim RB. Laparoscopic Roux-en-Y gastric bypass. Jones D, ed. UpToDate. Waltham, MA: UpToDate.

  2. University of California San Francisco Medical Center. Your weight loss surgery.

  3. Edholm D, Kullberg J, Karlsson FA, Haenni A, Ahlström H, Sundbom M. Changes in liver volume and body composition during 4 weeks of low calorie diet before laparoscopic gastric bypass. Surg Obes Relat Dis. 2015;11(3):602-6. doi:10.1016/j.soard.2014.07.018

  4. John Hopkins Medicine. Roux-en-Y gastric bypass weight-loss surgery.

  5. UCSF Health. Recovery from bariatric surgery.

  6. University of Pittsburgh. Preparing for bariatric surgery.

  7. American Society of Anesthesiologists. Risks: Smoking.

By Colleen Doherty, MD
 Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis.