Post Gastric Bypass Diet: A New Way Of Eating

Post Gastric Bypass Diet: A New Way Of Eating

A gastric bypass diet is specifically designed for people who are recovering from gastric bypass surgery to help them heal and improve their eating habits. Gastric bypass is basically surgical procedure used to reroute the digestive system and shrinking the size of the stomach.

This operation is recommended for treatment of morbid obesity (BMI >40). A gastric bypass surgery typically achieves dramatic weight loss in the initial stage, however the efficacy of this procedure can be greatly reduced if one does not follow a sound post gastric bypass diet.

It is crucial to follow a  gastric bypass diet to ensure:

  • Your stomach heals well and does not get stretched by excessive food intake
  • To get used to eating lesser foods and promote proper digestion post surgery
  • To maximise weight reduction and prevent weight gain
  • To reduce the risk of nutritional deficiencies, side effects and post surgery complication.

If you are considering a bypass or have already set the appointment to do a bypass surgery, here is a preview of how your way of eating and diet needs to change after the procedure. First you need to know that your stomach will be reduced to 10% of its original size. Also, the way food is being handled and digested will change. Overall, you will eat less food and your body does absorb lesser calories from food you have eaten.

 The Basics Of The Gastric Bypass Diet

  1. Ensure adequate fluids (6-8 glasses daily)
  •  Take small sips of fluid throughout the day
  •  Avoid fluids within 30-60 minutes of a meal
  •  Do not use a straw (increases air flow into the stomach causing distension)
  • Only calorie-free fluids are allowed e.g. water, herbal teas
  1. Avoid high calorie high sugar foods and beverages e.g. cakes and soft drinks
  2. A multivitamin and calcium (citrate form) supplement is recommended due to the decrease absorption of nutrients post gastric bypass. An additional B12 and iron supplement may also be needed.
  3. Eat and chew slowly. Food needs to be chewed to a very fine consistency before slowing to reduce the risk of intestinal blockage and obstruction.
  4. Eat 5-6 small meals instead of 3 heavy meals. Pay attention to your satiety cues, stop eating when you are full.

Signs of fullness are:

  1. a) a feeling of pressure in the center just below your rib cage
  2. b) nausea
  3. c) a pain or tightness in chest
  4. Always consume the protein component of your meal first to ensure you are achieving adequate intake of protein. If you are unable to eat a large serving of protein due to the feeling of fullness, try to incorporate 1-2 high protein snacks into your diet once you are allowed to be on solid foods.
  5. The gastric bypass diet will progress in phases from liquids to semi-solids and eventually full solids.

Phase 1: Clear liquids diet (immediately post surgery)

water-benefitsIn the first 3-4 days after your surgery, only clear liquids are allowed.

This includes:

  • Clear broths
  • Water
  • Herbal tea (no sugar)
  • Unsweetened fruit juices ( no red or brown juices to minimize possibility of undetected  post surgical bleeding)

Phase 2: Full liquid diet (1-2 weeks post surgery)

1-2 weeks after your procedure, your gastric bypass diet allows you to consume low-sugar full fluids. Full fluids includes:

  • Milk and Milkshakes (no added sugar)
  • Cream soups
  • Custards and yogurts (sugar free varieties)
  • Unsweetened smoothies

At this stage, digestive discomfort may occur.  Avoid high sugar fluids as this may provoke the ‘dumping syndrome’ which is classified as rapid movement of contents from the stomach into the intestine.  This causes severe diarrhea and malabsorption as the intestinal contents do not stay long enough your gut to be digested.

Phase 3: Puree diet (2 weeks post surgery)

This is the first step to introducing solids back into your gastric bypass diet. A puree diet can comprise of easily digestible foods such as potatoes, rice, oats, minced meat, vegetables (without stalk) and fruits (flesh only). Do incorporate high protein foods into the meals. Again stick to low sugar principle.

It is essential that you pay close attention to signs of fullness. The point of the surgery is to reduce your stomach capacity to contain food as a regulatory mechanism to control your food intake.

Eating to a point of being uncomfortably full will distend your stomach.  You also risk vomiting and various post surgical complications.

Phase 4: Soft diet (3 weeks post post surgery)

3 weeks into your gastric bypass diet depending on your tolerance to puree foods, you can progress to a soft food diet. Basically, foods that are soft enough consistency are those that can be easily mashed with a spoon. . Foods allowed include:

  • Soft fully ripen fruits (no skin and seeds)
  • Ground meat, tofu and baked beans
  • Cooked vegetables (leaves only)
  • Pasta,  rice, cous cous and oats (Avoid whole grains and multi-grain at this stage as they are difficult to digest)

Phase 5: Regular diet (after 1-2 months)

In the last phase of your gastric bypass diet, you can gradually resume solid foods.  Some individuals may not tolerate spicy and crunchy foods. The key is to experiment with small amounts of regular foods to gauge your tolerance level.

Foods To Avoid For A Gastric Bypass Diet

  • Dried fruits
  • Nuts and seeds
  • Popcorn
  • Carbonated beverages and alcohol
  • Granola
  • Stringy or fibrous vegetables, such as celery, broccoli, corn or cabbage
  • Tough meats with gristle

These foods are not very well tolerated months after surgery. However you can with time re-introduce some of these foods into your diet under the supervision of the dietitian.

Sample Meal Plan Of A Gastric Bypass Diet (Phase V)


  • 1/3 medium banana
  • 1 soft poached egg
  • 1 slice of white toast

Morning snack

  • 1 cup of non fat no added sugar yoghurt


  • 2 ounces of steamed chicken breast
  • 1/4 cup mashed peas
  • Garden salad, no dressing

Afternoon snack

  • 1 cup of mixed fruit cocktail, packed in water


  • 1/3 cup cooked pasta with tomato sauce and minced meat
  • 1/2 cup cooked green beans

Evening snack

  • 2 pieces saltine crackers with hummus dip

* And remember to sip water and no-calorie beverages throughout the day

Gastric bypass is a life changing decision. It can and will result in long term weight reduction. The success greatly depends on your dietary habits.  If you do return to unhealthy eating habits and overeat after weight-loss surgery, you may not lose all of your excess weight, or you eventually regain any weight that you have lost. So be compliant with the  gastric bypass diet, exercise regularly and you will be living a lighter and healthier life.

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