Gastric Bypass Diet Portion Sizes: Eating After Bariatric Surgery

If you’re considering bariatric surgery, it’s vital to be aware of the dietary guidelines you should follow after undergoing the procedure. 

Designed to help in your recovery, this special diet will limit the number of calories you consume. The dietary guidelines set by your doctor will include portion sizes and supplements needed to help preserve muscle tissue and prevent nutrient deficiencies.

The diet is also created to:

  • Help you avoid weight gain or re-gain.
  • Avoid any complications or side effects of bariatric surgery.
  • Allow your stomach to safely and comfortably digest smaller portions of food.
  • Promote the healing of the stomach.

Bariatric Dietary Guidelines (Overview)

After bariatric surgery, it’s vital that you follow a new healthy diet as recommended by your doctor. 

As the surgery will reduce the size of your stomach drastically, it directly affects the way that food enters your intestines.

That’s why it’s essential that you follow these guidelines:

  • Make sure that you only eat small portions of food each day – one cup of food up to five times a day. Over time, you can then shift to a regular diet of three to four meals a day (although this should still be limited).
  • Only eat balanced meals.
  • Keep a diary detailing your intake of calories and proteins, as well as your food portions.
  • Cut up food into small bites and eat slowly. This will help you avoid ‘dumping syndrome’.
  • Do not chew ice or use straws. 
  • Drink plenty of water and calorie-free fluids after surgery – up to 8 cups a day.
  • Eat plenty of high-protein foods (up to 75 grams a day) – including eggs, meats, seafood, fish, soy milk, tofu, yogurt and poultry.
  • Take mineral supplements – as recommended by your doctor – crushed into eight small pieces so that they are easily digestible. These can include up to 2,000 mg of calcium, 1,000 mg of Vitamin D and 500 mcg of Vitamin B.
  • Take multivitamins – chewable and high in protein, you should take up to two tablets a day post-surgery.

bariatric pop op diet sample

Try To Avoid The Following Foods Post–Bariatric Surgery

The following foods should be avoided for a few months after surgery. With the guidance of your doctor, you will gradually be able to eat these again.

  • Rice
  • Bread
  • Fresh fruits 
  • Raw vegetables 
  • Pork and steak – alongside other tough meats. 
  • Carbonated beverages 
  • Sugar beverages or food – for example, fruit juices and sweets.
  • Caffeine 
  • Alcohol 

1-2 Weeks Post-Bariatric Surgery Diet Regime

Once you have undergone surgery, your bariatric diet will begin with you only consuming clear liquids – no solid foods. Once discharged from the hospital, you can gradually start adding thicker liquids to your liquid diet.

One week after your liquid diet, you can start eating mashed (pureed) foods. Mixing them well to avoid solid pieces, you can have up to six tablespoons of food a meal – making sure not to eat more in order to avoid nausea and vomiting. 

These can include cream soups, cooked vegetables, applesauce, soft fruits, scrambled eggs, cottage cheese, fish, poultry and ground meat that have been mixed with a liquid. The liquid can either be sugar-free juice, water or skimmed milk.

When following this diet, make sure that you eat slowly – only take three sips at a time and wait up to 10 minutes before taking any more. This will prevent vomiting or stomach pain. 

3 Weeks Post–Bariatric Surgery: Soft Foods 

At this stage,  will include small portions (up to half a cup) of small and easy to digest food. During this time, you can eat up to five meals a day. 

Soft foods will include the pureed foods that you’ve been eating blended during the previous weeks, but they can now be digested in their original form. 

8 Weeks Post-Bariatric Surgery: Solid Foods

After two months of the post-operative gastric bypass diet, you can start eating firmer, solid foods again. However, make sure that at this stage, you must chew solid food very well, eat slow and stop eating before you feel full. During this stage you can:

  • Eat three meals a day – this can vary, however, by the type of solid food and the reaction your stomach has to it. 
  • 1 cups of food per meal.

Up to 26 Weeks (6 Months) Post–Bariatric Surgery 

Up to 6 months post-surgery, it’s recommended that you only have 1 ½ cup of liquids and 1 ¼ cup of solids. This can include 3 servings of low-fat meat, 3 servings of low-fat dairy products and 1 serving of fruit.

For advice regarding other foods, it’s important that you consult your doctor.

What Are The Risks of NOT Following a Post-Operative Diet?

If you follow the correct post-surgery gastric bypass diet, you’ll be able to achieve your weight loss goals and have a healthy and balanced diet. If you don’t follow it, you could face the following risks:

  • Excess or re-gained weight
  • Dehydration – to prevent this, you must sip up to 48 to 64 oz of liquids a day. Just make sure that you don’t drink this all at once.
  • Dumping syndrome – if you overfill your stomach, don’t eat slowly enough, or don’t chew adequately, you could face vomiting, nausea, sweating, and diarrhea.
  • Constipation – due to a lack of fluid or physical activity.

Final Thoughts on Weight Loss Surgery Diet

Over time, it’s important to know that you’ll be able to increase the types of food you’re able to eat. Throughout the healing process, however, it’s critical that you focus only on eating low-calorie, low-sugar, and low-fat food and drink.

With a comprehensive gastric bypass diet plan consisting of smaller portions and counting your calories every day, you’ll have the best results possible from your bariatric surgery. 

This, along with staying hydrated and staying motivated, will help promote the healing process from the start and ensure that you’re on the right path.

Interested in learning about the difference in coming to Mexico to get your bariatric surgery done? Visit our medical tourism page here.

Or, schedule a free virtual consultation here.

More About Bariatric Surgery Post-Op Care



Dr. Gabriela Rodriguez specializes in General and Laparoscopic Bariatric Surgery. She brings to VIDA Wellness and Beauty a wealth of experience in bariatrics. Dr. Rodriguez is a founding associate of the Mexican College of General Surgeons. A world-class bariatric surgeon with double certification in the US and Mexico.