A special diet will be prescribed for you following gastric bypass and sleeve gastrectomy surgery.  It has been designed to be gentle on your new stomach, to ensure proper healing of the staple line and to help you avoid overeating.  The average stomach can hold approximately six cups of food at a time.

Immediately after surgery, your stomach will only be able to handle ¼ to ½ of a cup of food. Life-long you will not be able to eat more than approximately 1 cup of food. It goes without saying that you will need to alter your eating habits quite a bit.  You will need to get into the habit of taking 20 to 30 minutes to eat each meal.  Eating too fast can lead to nausea or pain.

It is important to recognize when you are satisfied and stop eating.  The goal is not to finish your meal, it is to learn that you only need 4-6oz of food at a given meal.  Your operation will make this possible by altering the way your body manages food and energy.

While surgery will trigger significant weight loss, you must also do your part to maintain the weight loss by making lifelong changes in your eating habits.  It would be counterproductive to eat high calorie and high-fat foods after surgery.  You need to make healthy choices and eat low-fat, nutritional foods that will provide essential vitamins, minerals and protein to keep you well nourished.  Exercise is also critical to maintain muscle mass and an active metabolic rate.

Dumping Syndrome

After Gastric Bypass surgery only, many patients experience a phenomenon known as dumping syndrome after eating concentrated sweets, fatty foods, salty foods and/or drinking fluids with meals.  This happens when food exits the stomach rapidly and dumps into the intestine.  It can cause nausea, lightheadedness, diarrhea and stomach cramps.

To prevent this, you need to avoid eating sugar and foods containing sugar.  It is useful to read food labels.  Avoid products which list any of the following as one of the first three ingredients:  sugar, maple syrup, honey, molasses, corn syrup, corn sweeteners, glucose, lactose, maltose dextrose, fructose, sorghum, sorbitol and mannitol.  Somewhat unfortunately, this does not mean that you can never have sugar again but instead just occurs when patients have over 12 grams of sugar with a given meal.  When eating appropriately, one should not   After sleeve gastrectomy, some patients have also been known to experience a milder form of dumping syndrome.

Nutra Sweet, Splenda and other artificial sweeteners are acceptable substitutes for real sugar.  They will not cause dumping and will help with weight loss and maintenance since they contain only four calories per pack.  You can also prevent dumping by taking in the majority of your liquids between meals.  It is also important to remember to chew thoroughly before swallowing, to eat and drink slowly, and to stop when you feel full.

Protein Requirements

Protein is essential for wound healing and repair of staple lines, maintenance of muscle mass and prevention of hair loss.  You will need to include an adequate amount of protein in your diet after surgery (65-75gms).  Some patients may find they are unable to achieve adequate protein intake immediately after surgery and therefore may require protein supplements for a limited time period.  Ultimately, all patients should be able to achieve the required protein intake with directed diet modification and should not take protein supplements once they have met their requirements.  If you eat your protein first and stop eating when you feel full, it should not be necessary to count calories.  Hair loss, cracked nails and defective healing and immunity are just some of the side effects of inadequate protein consumption (not to mention difficulty losing weight).

Fluid Requirements

It is important to drink at least 64 ounces of non-caloric liquids between meals to prevent dehydration.  These liquids should be sipped slowly and consumed 30 minutes after eating to prevent bloating and excess calorie consumption.  However, be sure not to fill up on liquids before first meeting your food requirements which may mean you need to stop drinking 30 minutes before your meals. Your fluid intake should be increased by 10 to 20 percent when the weather is very hot and humid to prevent dehydration.  If your urine is dark or your mouth is dry, you are not drinking enough.

Milk is a great source of protein and hydration during the post-operative period and Lactose free milk is recommended for people who have intolerance to regular milk.  Milk can be used as a snack and also counted towards your daily fluid goal but once meeting your protein and fluid requirements, it should be faded out of your diet as milk is a liquid calorie that could lead to excessive caloric intake if used regularly once 6-8 weeks post-op. You should be aware that high protein diets are more prone to cause constipation and potentially kidney failure, if fluid intake is inadequate.

The dietary plan following weight loss surgery is broken into phases. Please refer to the post-operative diet phases for more information. If after advancing to the next phase, you develop problems, go back to liquids and advance only after you have tolerated liquids without any problems for 48 hours.


For Gastric Bypass, sleeve gastrectomy, and Gastric Banding it is also critical that you take a multivitamin/mineral supplement containing iron and zinc EVERY DAY FOR THE REST OF YOUR LIFE!  This is not optional!  You will not be eating enough to meet your daily requirements of vitamins and minerals.  You will also need to take 600mg of Calcium Citrate two to three times a day to meet your calcium needs.  A B12 taken beneath the tongue at least three times a week or a shot once a month is also required to prevent deficiencies.  Menstruating women will also need to take iron fumarate, iron gluconate or iron citrate each day along with vitamin C.

Required Supplements PDF

Exercise Regimen

Successful weight loss surgery patients have two things in common – they follow their dietary recommendations closely, and they initiate a regular exercise program.  It is essential that, immediately following surgery, you begin a regular exercise program as recommended. This will guarantee not only good weight loss, but will also improve your stamina, energy level and overall health.  Simple maneuvers such as parking farther away and taking the stairs instead of the elevator can make a difference.

Medication Changes after Gastric Bypass and Sleeve Gastrectomy


Do not take any of the following drugs without notifying the doctor. They may increase your likelihood of bleeding, ulcer formation or leakage.

  • Bayer
  • Advil
  • Ibuprofen
  • Vioxx
  • Goody’s
  • BC’s
  • Excedrin
  • Celebrex
  • Anacin
  • Naprosyn
  • Alleve
  • Nuprin

If you are unable to control your arthritis or pain without these medications, you will need to be placed on an antacid medication such as Nexium, Prilosec or Protonix.


Many diabetics will find that their disorder improves dramatically immediately following surgery, so you will likely be discharged on a lower dose of medication.  Additionally, you will need to monitor your blood sugars carefully during the first few weeks following surgery to make sure your meds are being titrated appropriately.  Most patients will be asked to check their blood sugars at least twice a day for the first couple of weeks to months.

High Blood Pressure

Roughly 60 to 80 percent of patients will have resolution of their high blood pressure within one year of surgery.  You need to be aware of symptoms of low blood pressure such as light-headedness or dizziness when standing.  If you experience these symptoms, contact your primary care physician or our office to discuss lowering your current dosage of medication.

Extended Release and Enteric Coated Medications

The reduction in the size of your stomach will interfere with your body’s ability to dissolve sustained release, extended release, or enteric coated medications (i.e. XR, SR, EC, etc.).  Therefore, you may need to have your medication changed to a regular formulation that will need to be administered two to three times a day instead of the sustained release formula that is usually only given once a day. Lap-Band patients should not need to change their sustained release or extended release formulations, because their stomach is not bypassed. Medications that are not formulated for sustained release are usually absorbed effectively and seldom require dose changes post-operatively.

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