Diet Guidelines Post Op Gastric Bypass

Medically Reviewed by Katelyn J. Mock, US-Registered Dietician (R.D.)

After gastric bypass surgery, your small intestine has been re-arranged, and your stomach is surgically reduced, restricting calorie consumption. You are required to stick to a diet that adjusts to your smaller stomach size. Below are the diet recommendations –

(This is general information that is based on suggestions by our Mexico Bariatric Program. It has to be customized for each individual)

Post-op Diet Right After Gastric Bypass

  • Stick to clear liquids.
  • You can have broth, low-calorie juices, and sugar-free Jell-O.
  • Around 64 ounces of fluid per day will keep you well hydrated.
  • You are made to progress to thicker liquids- cream soups, decaf beverages
  • The introduction of chicken and beef should not be hasty.

Phase – 1 (A Few Days after Gastric Bypass Surgery)

The prime focus of the post-op diet is on sugar-free clear fluids.

Your surgeon may guide you as to how to go about choosing the right liquids for post gastric care. Some of the healthiest choices are listed below:

  • Clearwater and teas (herbal and decaf)
  • Broth, soup (chunk free)
  • Fruit juices (diluted)
  • Diet drinks such as diet Snapple, Crystal Light juice, etc.
  • Diet gelatin, Ocean Spray, etc.


  • Sip or drink liquids slowly. Begin with 1 oz per hour and move to 6 oz per hour.
  • Avoid carbonated, caffeinated, or alcoholic drinks. These may cause nausea.
  • DO NOT use straws, as the additional air may cause gas, discomfort, and bloat.

It is important to maintain a fluid intake of about 64 ounces or more per day. This will help maintain the appropriate body levels of fluids and replace the losses from weight loss.

Phase – 2 (Full Liquids and Pureed Food)

After having developed tolerance to clear and thicker liquids, you can now move slowly to build your tolerance towards soft and pureed foods two to four days after the surgery. Follow these guidelines to prevent malnutrition after gastric bypass surgery.

  • Lactose-free, sugarfree, and low-fat diet must be followed.
  • Pureed protein-rich egg whites with refried beans and roasted chicken/ turkey breast.
  • Mash potatoes, cottage cheese, lean meats (ground or blended), etc.
  • Non-chunky soups and broths, skimmed milk, and sugar-free juices.
  • Blended solid foods that have a paste-like consistency.


  • Chew your food thoroughly and take no more than 2 bites per minute.
  • Have a 30-minute gap between a meal and a drink.
  • Add spicy or dairy foods slowly to suit your sensitive digestive system.
  • STOP EATING at the first sign of fullness.
Why is the pureed diet phase in the gastric sleeve longer than in the bypass?
Difference Between Diets for Gastric Sleeve and Bypass

Our Bariatric Dietitian Katelyn Mock Answers:

Gastric sleeve patients generally require a pureed diet longer than Roux-en-Y gastric bypass, gastric banding, or other surgical weight loss patients.

The reason

In Gastric Sleeve there is a longer suture line where a large portion of the stomach (almost 75%) of it is cut away. This internal suture line needs more time to heal and purees are easier for the stomach to tolerate than softer foods.

Phase – 3 (After Eight Weeks)

  • Fat-free/Low-fat cream soups made with 8 ounces skim milk.
  • Scrambled liquid egg substitute (Egg Beaters, Scramblers).
  • Light Yogurts (14 grams sugar or less per serving).

Suggested Foods

  • Oatmeal without added flavors Diet after Gastric Bypass Surgery
  • Pureed chicken, tuna fish, and eggs
  • Cooked and blended carrots and beans
  • Diet pudding
  • Bananas, watermelons, cantaloupe (avoid seeds)
  • Yogurt (plain), tofu, low-fat cheese
  • Steamed Fish with Yogurt Dill Sauce


  • Get used to be full after small portions of food
  • Eating past your capacity can potentially lead to stomach pouch stretching.
  • Space your meals not more than 4 hours apart
  • Try to reach 50-70 gm of protein per day
  • Do not eat raw fruits or vegetables
  • Keep a check on constipation, try to meet fluid goals, and have a fibrous diet

Quick tips

  • Inculcate mindful eating
  • Practice portion control
  • Read labels on packaged food, so you know what’s going in your stomach
  • Surgery success depends upon your willingness to stick to a healthy lifestyle
  • Add raw fruits or vegetables and fibrous meats only after 6 to 8 weeks of surgery.
  • DO NOT take additional iron supplements with calcium.
  • Check on food intolerances, and wait for a few weeks before reintroducing them to your diet.
  • Add one new food at a time to check what your new stomach can tolerate!
  • Keep your daily food record: or Bariatastic app

Note that nutritional deficiency is standard after gastric bypass, and you may have to take supplements for the rest of your life. As per Obesity Action [1]Addorisio, Denise. “The Post-Surgery Diet for Bariatric Patients: What to Expect.” Obesity Action
View in Article
malabsorption can cause a shortage of the following:

  • Vitamin B12
  • Iron
  • Calcium
Diet After Gastric Bypass
Diet After Gastric Bypass

Bypassing foods after the Gastric Bypass

According to Mayo Clinic [2]Mayo Clinic Staff. “Gastric bypass diet: What to eat after the surgery.” Mayo Clinic, 2015,
View in Article
, individuals should avoid eating the following items post gastric bypass surgery:

  • Popcorn
  • Carbonated drinks
  • Sturdy meats
  • Fried veggies

This Post Addresses

  • How much weight can you lose after gastric bypass surgery?
  • What foods should not be eaten after gastric bypass surgery?
  • Can you stretch your pouch after gastric bypass?
  • What happens if you gain weight after bariatric surgery?


  1. Addorisio, Denise. “The Post-Surgery Diet for Bariatric Patients: What to Expect.Obesity Action
  2. Mayo Clinic Staff. “Gastric bypass diet: What to eat after the surgery.Mayo Clinic, 2015

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