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Your Diet Before Bariatric Weight Loss Surgery

It's important to follow your surgeon's pre-bariatric surgery diet and nutrition guidelines, which help prepare your body for surgery and improve results.

Updated December 16, 2020

Your surgeon may require that you start the following pre-surgery diet two weeks before surgery.

  • Begin protein supplements (protein powder or shakes)
  • Decrease all fats (fatty meats, fried foods, whole milk products, and others)
  • Decrease sugary foods and drinks (sweets and soda)
  • Decrease high-carbohydrate foods (white bread and white pasta)
  • Stop smoking
  • Avoid alcohol
  • Avoid binge eating
  • Don’t use certain over-the-counter medications and prescription medications. Ask your doctor for specifics, but this may include aspirin, ibuprofen (Advil/Motrin), naproxen (Aleve), acetaminophen (Tylenol/Excedrin). 

This is the purpose for following a pre-surgery diet:

  • Reduce body fat: Reducing fat in the abdomen and liver increases patient safety.
  • Preserve and protect muscle tissue: Increasing protein keeps the body from using muscle tissue as an energy source on a reduced-calorie diet. The body will burn fat instead.
  • Prepare the body for surgery and recovery: Eating healthy, increasing protein intake, and taking vitamin and mineral supplements will help the body heal and recover after surgery.
  • Prepare the patient for post-surgery diet: The pre-surgery diet is very similar to the post-surgery diet (reduced-calorie, high-protein, low-fat, low-carbohydrate) and will prepare patients for the new way they will be eating after weight-loss surgery.

Pre-surgery weight loss increases safety

Losing weight before surgery will lower the risk of complications and make weight-loss surgery safer.

The main purpose of losing weight before weight-loss surgery is to reduce body fat in the abdominal region, especially in and around the liver. In some instances, a bariatric surgeon must postpone surgery if the patient’s liver is too large. Reducing the size of the liver can shorten the operating time for laparoscopic surgery, and this makes the procedure safer.

For super-obese patients (body mass index greater than 50), losing sufficient weight before surgery allows the procedure to be performed using a minimally invasive surgical approach performed through small incisions (laparoscopic), rather than as open surgery.

Amount of pre-surgery weight loss

The amount of weight loss necessary before surgery can only be determined by your bariatric surgeon based on your health, weight, and bariatric procedure. Some patients are required to lose 10 percent of their weight before weight-loss surgery is performed. For other patients, losing just 15 to 20 pounds right before surgery is enough to reduce the risk of complications.

It’s important to follow your surgeon’s pre-surgery diet and nutrition guidelines. A pre-surgery diet helps prepare your body for surgery and improve the outcome. It also helps you adjust to the food and eating changes you need to make following weight-loss surgery—and for the rest of your life.