Gastric Bypass Surgery

Gastric Bypass Diet: What You Can (& Can’t) Eat

You will have to change your diet after you have gastric bypass surgery in order receive the maximum benefits from your procedure. The gastric bypass diet that results in the most weight loss and highest cure rate of obesity-related health problems is described below.

  • You need to start practicing your new long-term diet at least 3 weeks before surgery
  • You will gradually transition from clear liquids to solid foods after surgery
  • You must eat primarily “whole foods” with limited snacking
  • You should eat at least 60 grams of protein per day
  • You need to drink at least 2 liters of low-calorie fluids per day
  • You will have to follow a strict vitamin regimen

Read the sections below for detailed information about your short- and long-term diet after gastric bypass surgery.


Click on any of the topics below to jump directly to that section

  1. Pre Op Diet
  2. Post Op Diet
  3. Long Term Diet
  4. Your Vitamins & Supplementation After Gastric Bypass Surgery

Your Diet Just Before Gastric Bypass Surgery


  • Begin practicing your new, long-term diet at least 3 weeks before surgery
  • 2 weeks before surgery you need to transition to a diet high protein, low sugar, low carbs (details below)
  • Stop or change your medications 1 week before surgery (details below)
  • You can only consume clear liquids 2 days before surgery (no food!)
  • You cannot eat or drink on the day you have surgery

There are three big reasons to start your pre-op gastric bypass diet at least 3 weeks before surgery:

  1. Lower risk of complications – Eating a healthier diet will cause you to lose weight, and the lower your body mass index on surgery day, the lower your risk of complications. For example, a healthier diet will shrink your liver and reduce your intra-abdominal fat, making it easier for your surgeon to to perform surgery.
  2. Quicker recovery – Eating healthy during the weeks leading up to surgery will optimize your body’s immune system and lead to a quicker recovery.
  3. Ease the transition into your new life – Recovering from surgery and adjusting to your new life will be challenging. Establishing good diet habits as early as possible will simplify the rest of the changes that are coming your way.

Pre-Op Food List & Guidelines

Your gastric bypass pre-op diet should begin at least 3 weeks before surgery, but the sooner, the better. Your surgeon’s guidelines will include the following.

As Soon As Possible Before Surgery (at least 3 weeks before)

  • Eat as healthy as possible (primarily “whole” foods; avoid processed foods)
  • Eat your protein first, and shoot for at least 60 grams of protein per day. For example:
    • 3 hard boiled eggs + 4 ounce chicken breast = ~60 grams of protein
    • ¾ block of extra-firm tofu + 6 ounces of tempeh = ~60 grams of protein
    • 4 ounces of ground beef + smoothie with 1 scoop of whey protein = ~60 grams of protein
  • Eat small portion sizes (using small bowls and plates will help)
  • Cut food into small pieces
  • Eat slowly, chew thoroughly (chew 25 to 30 times with each bite)
  • No more than 3 small meals per day
  • Limit snacking (no more than 2 small snacks per day)
  • Limit high-fat foods
  • No fibrous foods like asparagus, celery, or broccoli
  • No starchy foods like rice, pasta, or bread
  • No greasy or spicy foods
  • No whole milk products
  • No sugar
  • Take a daily multivitamin

2 Weeks Before Surgery

To reduce your risk of complications, start the following 2 weeks before surgery:

  • The entire 3+ Weeks list above
  • Stop all over-the-counter herbal supplements

1 Week Before Surgery

In addition to the pre-gastric bypass diet guidelines above, your surgeon will ask you to stop certain medications to reduce the risk of bleeding and stomach problems after surgery. Medications to stop or change may include:

  • Any arthritis medications
  • Time-released medications (switch to non-time-released)
  • NSAIDs (nonsteroidal anti-inflammatory drugs), such as:
    • Acetaminophen (Tylenol)
    • Aspirin (many brands)
    • Ibuprofen (Advil, Motrin)
    • Naproxen (Aleve)
  • Other anticoagulants, such as:
    • Enoxaparin (Lovenox)
    • Clopidogrel (Plavix)
    • Dipyridamole (Persantine)
    • Ticlopidine (Ticlid)
    • Warfarin (Coumadin)

2 Days Before Surgery

It’s time to clear out your digestive system in preparation for surgery:

  • No food

Midnight Before Surgery

  • No food or drinks of any kind

Your digestive system must be completely free of food or liquids during surgery.

This will reduce the risk of inhaling stomach contents which can cause problems like serious infection or pneumonia.

A clean digestive system is especially important for patients with gastroesophageal reflux disease (GERD) or gastric paresis (paralysis of the stomach) (1).

Pre-Op Drink List & Guidelines

Your gastric bypass pre-op liquid diet should begin at least 3 weeks before surgery.

3+ Weeks Before Surgery

  1. Plenty of low-calorie fluids (64+ oz [2+ liters] per day)
  2. Sip fluids, don’t gulp
  3. Do not drink anything 30 minutes before, during, or after meals
  4. No sodas or sugary drinks
  5. Limit caffeine

2 Weeks Before Surgery

Start the following to reduce your risk of complications:

  • The entire 3+ Weeks list above
  • No caffeinated drinks
  • No carbonated drinks

2 Days Before Surgery

To clear out your digestive system before surgery:

  • Drink only sugar-free clear liquids (no thick or pulpy drinks, no caffeinated drinks, no carbonated drinks, and no sugary drinks)

Midnight Before Surgery

  • No food or drinks of any kind

Pre-Op Meal Plans

2 Weeks Before Surgery

  • Breakfast: Low-carb, low-sugar protein shake
  • Lunch: Lean meat and vegetables
  • Dinner: Lean meat and vegetables

2 Days Before Surgery

Drink only clear caffeine-free, sugar-free fluids, such as

  • Clear broth (beef, chicken, or vegetable)
  • Jell-O (sugar free)
  • Juice without pulp or added sugar (such as apple juice or pulp-free orange juice)
  • Popsicles (sugar-free)
  • Tea (caffeine-free, unsweetened)
  • Water

Midnight Before Surgery

  • No food or drinks of any kind

3 Habits of Successful Patients: Diet Journal, Support Groups, Exercise

The most successful gastric bypass patients do more than just change their diet before surgery. They also adopt routines that keep them on track for the long-term, including:

  1. Start a diet journal
  2. Join a gastric bypass support group
  3. 30 minutes of exercise, 5 days per week

Click the links above for more information.

Addressing Food Addiction

Gastric bypass surgery helps with food addiction by reducing the size of your stomach which will make you feel full sooner while eating.

But for some patients, the addiction still remains strong after surgery. If food addiction is not addressed ahead of time, it may cause you to overeat or to eat the wrong foods which can lead to all sorts of problems including weight regain, dumping syndrome, and others.

First, find out if you are addicted to food by taking this Food Addiction Quiz.

If you suffer from food addiction, start to address it before moving forward with surgery, including:

  • Start a food addiction diet
  • Talk with your doctor about appropriate prescription drugs
  • Start a medically supervised weight loss program
  • Seek professional counseling
  • Join a support group of others who suffer from food addiction

See our Food Addiction Treatment page for more information.


Your Diet Stages After You Have Gastric Bypass Surgery


  • Stage 1: You can drink clear liquids only (no food)
  • Stage 2: You will add thicker drinks & smooth foods (no chunks)
  • Stage 3: You will need to slowly test pureed & soft solid foods
  • Stage 4: You can slowly test solid foods
  • It can take anywhere from 3 days to 4 weeks to start eating solid foods post-surgery (it varies by surgeon)

There are 4 distinct gastric bypass surgery diet stages:

  • Stage 1: Clear liquids only
  • Stage 2: Add thicker drinks & smooth foods (no chunks)
  • Stage 3: Slowly test pureed & soft solid foods
  • Stage 4: Slowly test solid foods

Every surgeon has a different philosophy about how much time each stage should last. Some feel that a quicker transition will speed up recovery, while others believe that giving your digestive system time to rest is a better approach. Both methods are effective, so talk with your surgeon about which they feel is right for you.

Stage 1: Clear liquids only

Begins 1 day post-op to 7 days post-op (varies by surgeon)

Depending on your surgeon, Stage 1 of your gastric bypass post-op diet will last anywhere from 1 to 7 days and will include:

Drinks should include:

  • Water or Ice (since you can’t eat anything yet, chewing ice may be more satisfying)
  • Clear broth (beef, chicken, or vegetable)
  • Drink mixes (sugar-free), like Crystal Light or Kool-Aid
  • Jell-O (sugar-free)
  • Thin juice or drinks without pulp or added sugar (such as apple juice, Propel Water, Powerade Zero, etc.)
  • Popsicles (sugar-free)
  • Tea (caffeine-free, unsweetened)

When you return home:

  • Continue the same clear-liquid-only diet until your surgeon tells you it’s okay to transition to Stage 2
  • Take all vitamins and supplements recommended by your surgeon

Other Habits

Stage 2: Add thicker drinks & smooth foods (no chunks)

Begins 1 day post-op to 14 days post-op (varies by surgeon)

Your surgeon will confirm that you have no nausea or vomiting before allowing you to begin Stage 2 of your post-op gastric bypass diet. Stage 2 lasts from one day to 2 weeks, depending on your surgeon, and includes thicker drinks, pureed foods, and small “meals”:

  • Clear liquids list from Stage 1
  • Protein shakes
  • Clear broths (beef, chicken or vegetable)
  • Cream of Wheat
  • Cream soups (no chunks)
  • Carnation Instant Breakfast (sugar free)
  • Greek Yogurt
  • Natural applesauce
  • Sherbet (sugar-free)
  • Skim or Lactose-Free Milk Products
  • Thicker sugar-free juices like low-sodium V-8 or pulp-free orange juice
  • Vitamins and supplements

Remember: No soft or solid food and no drinks with chunks or seeds.

You can also drink clear liquids between meals.

While drinking anything:

  • Take small sips
  • Stop immediately as soon as you feel full or feel any pressure

Stage 3: Slowly test pureed & soft solid foods

Begins 2 days post-op to 3 weeks post-op (varies by surgeon)

Stage 3 of your diet after gastric bypass surgery will last from 1 to 7 days, depending on your surgeon.

This stage allows softer solids, but take it slow!

When you’re ready to start pureed foods, blend water, skim milk, broth, or sugar-free juice with one of the following:

  • Beans
  • Cooked vegetables
  • Eggs
  • Fish
  • Ground meats (lean)
  • Soft fruits

As soon as the pureed foods are going down without a problem, work your way into soft foods like:

  • Cooked vegetables
  • Ground meats (lean)
  • Soft fruits (no seeds or skin)

General post-gastric bypass diet guidelines during Stage 3 include:


  • Test one new food at a time to confirm you can tolerate it
  • Eat as healthy as possible, protein first
  • 60+ grams of protein per day
  • Small portion sizes
  • Cut food into small pieces
  • Eat slowly, chew food thoroughly
  • No more than 3 small meals per day
  • Limit snacking (no more than 2 small snacks per day)
  • Limit high-fat foods
  • No fibrous foods like asparagus, celery, or broccoli
  • No starchy foods like rice, pasta, or bread
  • No greasy or spicy foods
  • No whole milk products
  • No sugar
  • Take your vitamins


  • Plenty of low-calorie fluids (64+ oz [2+ liters] per day)
  • Sip fluids, don’t gulp
  • Do not drink anything 30 minutes before, during, or after meals
  • No sodas or sugary drinks
  • Limit caffeine

Other Habits

Stage 4: Slowly test solid foods

Begins 3 days post-op to 4 weeks post-op (varies by surgeon)

Stage 4 of your post-op gastric bypass diet will last anywhere from a couple days to 1 to 2 weeks, depending on your surgeon. During this stage you will complete your slow transition to your “new normal” long-term diet.

Your focus should be on eating your proteins first, in solid form (not protein shakes). Here’s why:

  • You need 60+ grams of protein to stay healthy, and getting that much can be tough if you fill up on other food first
  • Liquid protein is okay while you are in healing mode, but switch to solids after recovery. Solids make you feel full sooner while eating and reduce the risk of weight regain.

Other points to keep in mind include:

  • Stage 3 guidelines above
  • Test one food at a time to make sure you can tolerate it
  • Eat healthy “whole” foods (foods from the farm or water; avoid processed foods)
  • Eat slowly and chew thoroughly
  • No starchy foods like rice, bread, and pasta
  • No whole milk products
  • 64+ oz (2+ liters) of fluids spread throughout the day
  • No drinking 30 minutes before or after meals

Your Long-Term Diet After Gastric Bypass Surgery


  • Your body will have changed after having the surgery (read details below)
  • You'll have to eat certain types of foods and avoid others (see details below)
  • You can drink certain types of liquids, you must avoid others (see the list below)
  • Read the list of helpful hints to stay on track below

Differences from Before Surgery

Once you’ve fully transitioned into your new diet after gastric bypass surgery, you:

  1. Will feel less hungry – your smaller stomach will secrete fewer hunger-causing hormones
  2. Will feel full sooner while eating – your smaller stomach will hold much less food
  3. Will be much more diligent about healthy eating and drinking – Eating and drinking correctly will help you (1) avoid side effects like nausea, vomiting, and diarrhea and (2) prevent your stomach from stretching out and causing weight regain. See the sections below for more information about appropriate foods and liquids.
  4. May have difficulty swallowing if you eat too quickly – this is the result of food backing up into the esophagus after the stomach pouch has been filled. Chew your food thoroughly, eat slowly, and eat foods that are more easily digested. If you experience this issue, it should get better as your pouch stretches over time.
  5. May need to avoid dairy – If you are currently lactose intolerant, symptoms after surgery will probably become more prevalent. This is easily addressed by avoiding dairy products.

Foods You’ll Eat Or Avoid

About four out of every five gastric bypass patients experience dumping syndrome when they eat the wrong foods. Conveniently, the wrong foods are the unhealthy ones, so while dumping syndrome symptoms are unpleasant, they will help you keep your gastric bypass diet in check.

Generally speaking, following is what you should eat (and not eat) to lose the most weight, avoid side effects and dumping syndrome, and prevent weight regain. We’ve included sample gastric bypass diet plans further down the page.

Types of Foods to Eat

  • Eat protein first, then fruits and vegetables, then whole grains
  • Eat 60+ grams of protein per day
  • Eat whole foods (directly from the farm or water)
  • Limit processed foods
  • Limit high-fat foods
  • Take your vitamins (see the Vitamins section below)

Types of Foods to Avoid

  • No fibrous foods like asparagus, celery, or broccoli
  • No starchy foods like rice, pasta, or bread
  • No greasy or spicy foods
  • No whole milk products
  • No sugar
  • Limit seeds and nuts

How to Eat

  • No more than 3 small meals per day
  • Limit snacking (no more than 1 small snack per day)
  • Small portion sizes
  • Cut food into small pieces
  • Eat slowly, chew food thoroughly (25 to 30 chews with each bite of food)
  • Do NOT overeat – this will permanently stretch out your stomach and lead to weight regain. As a general guideline, eat until you feel 80% full.

Liquids You’ll Drink Or Avoid

Liquids are often overlooked as a part of the gastric bypass diet, but poor liquid choices can cause just as many problems as poor food choices, including dumping syndrome.

Types of Liquids to Drink

  • Plenty of low-calorie fluids (64+ oz [2+ liters] per day)
  • Limit caffeine

Types of Liquids to Avoid

  • No sodas
  • No sugary drinks

How to Drink

  • Sip fluids, don’t gulp
  • Do not drink anything 30 minutes before, during, or after meals


The physiological effects of alcohol are amplified following gastric bypass. This is supported by a study suggesting gastric bypass patients will have a higher blood alcohol content than control subjects after consuming the same amount of alcohol (2). Instances of individuals receiving Driving Under the Influence charges after consuming small amounts of alcohol have been reported.

Studies also indicate that patients who’ve undergone gastric bypass have an increased risk of developing an alcohol use disorder after surgery (3). Researchers have not conclusively determined why, but some experts suggest it is related to changes in the “pleasure center” of the brain. Faster absorption and increased potency of alcohol after gastric bypass may influence reward circuitry in the brain, effectively increasing the likelihood of developing alcohol related issues.

For individuals with a pre-existing alcohol abuse disorder, surgeons may advise an extended period of sobriety prior to receiving gastric bypass. Patients with a history of alcohol abuse disorders may be at higher risk of additional alcohol related problems after gastric bypass.

Tips to Stay On Track

Successful gastric bypass patients need plenty of support and encouragement from family, friends, and other patients in order to maximizing weight loss and avoid side effects.

The most highly recommended tips from successful patients include:

  1. Start and maintain a diet journal to:
    • Set goals and record progress
    • Plan your meals ahead of time
    • Use as your guide at the grocery store – take your journal with you (or print your list) and only buy the foods that you have planned
    • Prevent gastric bypass post-op diet cheating
  2. Join and regularly attend a support group to address:
    • Weight loss – Regular weight loss support group attendees lose as much as 12% more excess weight than patients who do not attend support groups (4)
    • Fear before surgery
    • Questions about the future
    • Diet challenges
    • Temptations and how to overcome them
    • Impatience or frustration regarding how quickly the weight is coming off
    • How to interact with the world in your new body
    • Relationship changes at home and work
    • Depression relating to your new diet and changes to existing relationships

Other top patient tips for the best diet after gastric bypass surgery include:

  • Keep your blood sugar stable – stable blood sugar leads to stable hunger and stable relationships (no mood swings). In order to keep your blood glucose level in check:
    • Avoid simple carbohydrates. Foods with simple carbs include white bread, potatoes, white rice, corn, peas, and anything that is obviously full of sugar like candy, ice cream, or donuts.
    • Eat good carbs in small portions (along with high amounts of protein), including vegetables, apples, and the “brown foods” like whole-grain bread and brown rice. In addition to being good for your blood sugar level, good carb sources are often high in fiber which makes you feel full faster and helps to regulate your bowel movements.
  • Don’t snack – Snacking between meals is the quickest way to halt your weight loss progress and to gain back weight. Either don’t snack at all or limit it to one small healthy snack per day.
  • Grocery shop the right way:
    • Take your journal and only buy your planned healthy foods
    • Don’t shop while you’re hungry
    • Since healthier foods tend to cost more, don’t be afraid to shop in bulk and freeze the extras.
  • Measure your meals with a scale – Don’t guesstimate. Overweight people underestimate their calorie content per meal by as much as 22% (5), so use a food scale to ensure you are eating the proper amounts.
  • Use small plates and small utensils. At only 4 ounces per meal, using your old plates could lead you to add more just because the new portion sizes feel so tiny in comparison. Smaller plates and utensils will help train your mind to feel okay with the smaller portion sizes.
  • Avoid alcohol. Several problems can arise if you decide to drink alcohol after gastric bypass surgery (6). The sugar and carbohydrates found in alcoholic beverages can derail your daily goals, cause your blood sugar levels to get away from you, and cause you to gain back weight. Alcohol will also make you much more likely to give in to food cravings which can also lead to weight regain.

Sample Post-Op Meal Plans

After you’ve completed the 4 Stages above, a good sample gastric bypass diet plan may include:

Breakfast Ideas

  • Protein bar
  • Egg muffin
  • Greek yogurt
  • 1 egg and 1 slice of turkey bacon
  • Hard-boiled egg and string cheese
  • High-protein oatmeal
  • Omelet with bacon and vegetables
  • Low-sugar cereal with skim milk

Lunch Ideas

  • Low-fat chicken noodle soup
  • Baked beans
  • Chef salad
  • Omelet with sausage and vegetables
  • Pork chops and salad
  • Chicken breast and green beans
  • Lettuce wrap with deli turkey and low-fat cheese

Small Snack Ideas

  • Hard boiled egg
  • Low-fat cottage cheese
  • Low-fat/diet yogurt
  • Sugar-free mousse/custard
  • Canned fruit
  • Low-fat rice pudding
  • Chopped melon
  • Reduced fat hummus with chopped raw veggies
  • Crackers with low-fat cream cheese
  • Low-sodium beef jerky
  • Edamame

Dinner Ideas

  • Grilled or blackened fish
  • Grilled or blackened chicken and asparagus
  • Grilled or blackened chicken, spinach, and feta salad
  • Roast and carrots
  • Stuffed zucchini
  • Soft (well-cooked) pasta or couscous
  • Mashed potatoes

Vitamins & Supplements


  • Multivitamin
  • Calcium
  • Folate (folic acid)
  • Iron
  • Thiamin (Vitamin B1)
  • Vitamin B12
  • Vitamin D

Due to the malabsorptive component of gastric bypass surgery, the post-op diet for gastric bypass patients includes a strict life-long vitamin regimen.

Your vitamin regimen is designed to offset:

  • Malabsorption that results from a portion of your small intestine being bypassed
  • The fewer nutrients you are getting from your smaller gastric bypass meals

Some surgeons offer specialized, gastric bypass vitamins. They are made to address common nutrient deficiencies post-surgery, including:

  • Iron
  • Vitamin B12
  • Vitamin D
  • Folate

Patients who take specialized vitamins after gastric bypass are less likely to have nutrient deficiencies three years after surgery (7). If your surgeon doesn’t offer a specialized vitamin, they will still recommend over-the-counter vitamins to address your nutritional needs.

Click below for more information about each vitamin you will take.

Multivitamin: Full Body Health

A daily multivitamin with mineral supplements will help prevent hair loss and general nutrition problems (8) (9).

  • 1 to 2 per day
  • Chewable and liquid versions are best
  • At least 200% of the Recommended Dietary Allowance (RDA) of iron, folic acid, thiamine, copper, selenium, and zinc

Calcium: Bone Health

Calcium citrate supplements will keep your bones strong after gastric bypass surgery (10).

  • Must be calcium citrate (NOT other forms of calcium)
  • 500 – 600 mg doses
  • Take 3 times per day forever
  • Chewable and liquid versions are best
  • Try to find one that includes Vitamin D

Folate (folic acid): Cardiovascular Health

  • Patients who don’t get enough folate are at a higher risk of anemia (low red blood cell count or hemoglobin) (11).
  • 500 – 600 mg doses
  • For some patients, the folic acid found in a good multivitamin is not enough. Many surgeons do not prescribe extra folate, so ask them to test your folate levels as time goes on to be on the safe side.

Iron: Cardiovascular Health

  • Patients low on iron are more likely to have a stroke, heart attack, or other blood-related problems (12) (13).
  • The iron found in a good multivitamin is not enough for some patients. Ask your surgeon to watch your iron levels to avoid any problems.

Thiamin (Vitamin B1): Full Body Health

Thiamin deficiency, also called Beriberi, can result in loss of appetite, headaches, nausea, weakness, irritability, depression, abdominal discomfort, pain in the limbs, shortness of breath, and swollen feet or legs.

Deficiency may occur after vomiting, skipped meals, or missed supplementation.

Vitamin B12: Brain/Central Nervous System

Your central nervous system relies on Vitamin B12, and not getting enough of it could lead to serious issues like numbness, memory loss or even paralysis.

  • 1000 mcg. under your tongue, 2-3 times per week (or 500 mcg. daily). Other options include nasal spray and shots from your doctor.
  • Must be taken forever

Vitamin D: Full Body Health

Without enough Vitamin D, you’re at risk of developing rickets (a weakening of the bones, muscles, and teeth) (14) (15) (16).

  • Chewable or liquid forms are best
  • 3,000 International Units per day
  • Take with food
  • Take 2 hours apart from any Iron supplement (including a multivitamin that contains iron)

Talk with your surgeon to be sure, but you may be able to find a calcium supplement that fulfills your Vitamin D requirements.


To view references for this page, click here.

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