Gastric Bypass Surgery

Gastric Bypass Surgery – 14 Ways It Will Affect You

Gastric bypass surgery (“Roux-en-Y gastric bypass”) will make your stomach smaller and reroute your intestines. As a result:

  • You will feel full sooner when eating and eat less
  • Your body will absorb fewer minerals
  • You will lose up to 65+% of your excess weight within 1 year
    • For example: if you’re 5’ 4” and weigh 220 lbs, you will lose up to 50+ lbs within 1 year
    • If you’re 5′ 9” and weigh 300 lbs, you will lose up to 90+ lbs within 1 year
  • You will cure or improve your diabetes, asthma, sleep apnea, hypertension, and many other obesity-related health problems

Read and click below for everything you need to know about Gastric Bypass surgery.


How Gastric Bypass Surgery Works


  • Your stomach size will be drastically reduced, so you will not be able to eat as much
  • Your intestines will be rearranged, causing your body to absorb fewer minerals
  • If you eat unhealthy foods, you will suffer from dumping syndrome (unpleasant digestive issues)

The laparoscopic Roux-en-Y gastric bypass procedure takes about 4 hours to complete. Most patients remain in the hospital for 2 to 3 days following surgery.

The procedure serves 2 functions: it limits how much you can eat before feeling full (“restrictive”) and it prevents your body from absorbing as much food (“malabsorptive”).

To perform the procedure, your surgeon will:

  1. Cut your stomach into two parts, creating a small stomach pouch at the top
  2. Separate the bottom portion of your small intestine and connect it to your new stomach pouch
  3. Attach the top portion of your small intestines (which is still connected to the bottom portion of your stomach) to the bottom portion of your small intestines.

Weight Loss


  • You will lose up to 65% of your excess weight within 1 year
  • For example: if you’re 5’ 4” and weigh 220 lbs, you will lose up to 50+ lbs within 1 year
  • If you’re 5′ 9” and weigh 300 lbs, you will lose up to 90+ lbs within 1 year

Gastric bypass patients usually lose a lot of weight very quickly after surgery. Within 3 months, the average patient loses about one-third of their excess weight. By the 1-year mark, almost two-thirds of the excess weight will be gone.

Many patients reach “peak” weight loss between 1 and 2 years, then gain a little back (more about Weight Regain in the “Downsides” section below). But long-term results are still impressive, with the average patient keeping about 60% of their excess weight off after 5 years.

Keep in mind that these are averages – “middle of the road” results. Patients who eat the right foods, exercise regularly, and follow their surgeon’s advice can lose even more, while patients who veer off-track lose less.

Click Here to See How Much Weight You Could Lose

See our Gastric Bypass Before and After Pictures page to get a better idea of how you’ll look after surgery.

References: (1) (2) (3) (4) (5) (6) (7) (8)


Health Benefits


  • Gastric bypass surgery will cure or improve your diabetes, sleep apnea, hypertension, and at least 12 other obesity-related conditions

Most gastric bypass patients experience significant improvement in or a complete “cure” of obesity-related health problems.

Note that patients who have a strict follow-up schedule with their surgeon at 3-, 6-, and 12-months post-op see greater improvements in or remission of their diabetes, high blood pressure (hypertension), and high cholesterol than patients who skip these visits (9).

  • Mortality Reduction/Life Expectancy (5 year mortality): 89% reduction in risk of death vs obese patients who did not have bariatric surgery (10, 11)
  • Quality of Life Improvements: 95% of patients see an improvement (12)
  • Asthma: Completely resolved or improved in 80% to 100% of patients (13)
  • Cancer: Patients who undergo weight loss surgery have 33% less risk of developing cancer (14). Cancer rates are even further reduced for obesity-related cancers, including (15):
    • Colon cancer
    • Postmenopausal breast cancer
    • Endometrial cancer
    • Pancreatic cancer
  • Cardiovascular Disease: Up to 79% reduction in cardiovascular risks (16)
  • Degenerative Joint Disease: Complete resolution in 43% of patients (17)
  • Depression: Improvement for majority of patients (18)
  • Diabetes: 83% experience complete resolution by 1 year (19, 20)
  • Dyslipidemia hypercholesterolemia: 63% resolved (21)
  • Gastroesophageal Reflux Disease (GERD): Completely resolved or improved in 80% to 100% of patients (22)
  • High Blood Pressure (hypertension): Up to 69% of patients experience complete resolution by 1 year (23, 24)
  • Hyperlipidemia (high levels of fat in the blood): 73% experience improvement or complete resolution (25)
  • Joint Health: Gastric bypass weight loss improves joint health. For every pound of weight lost, there is a 4 pound reduction in pressure on the knee (26). This improves mobility and reduces pain in the knees.
  • Metabolic Syndrome: Up to 80% resolved (27)
  • Migraines: Up to 57% resolved (28)
  • Non-Alcoholic Fatty Liver Disease: 90% improved steatosis, 37% resolution of inflammation, 20% resolution of fibrosis (29)
  • Obstructive Sleep Apnea: Up to 98% resolved (30)
  • Polycystic Ovarian Syndrome: Improvement or resolution in nearly all women (31)
  • Pregnancy:
    • Obesity-related infertility resolved in up to 100% of women (32, 33)
    • Menstrual irregularities – reduced by 65%.
    • Gestational Diabetes: 25% less likely to develop
    • Pregnancy-Induced Hypertension: 73% less likely to develop
  • Pseudotumor cerebri: Up to 96% resolved (34)
  • Psoriasis & Psoriatic Arthritis: Significantly reduced risk and improved prognosis of psoriasis and psoriatic arthritis (35)
  • Stress Urinary Incontinence: Up to 88% resolved (36)
  • Venous Stasis Disease: Resolved in up to 95% of patients (37)
Click Here to See A Full List of Health Benefits

References: (38) (39) (40) (41) (42) (43)


How to Qualify


  • 35+ body mass index (BMI) required
  • If your BMI is under 40, you must have at least one obesity-related health problem

Most surgeons and insurance companies follow the guidelines of the National Institutes of Health (NIH) which state that you must fall into one of the following categories in order to qualify for gastric bypass surgery:

  • Have a body mass index (BMI) of 40 or more (“morbidly obese” or “super obese”), OR
  • Have a BMI between 35 and 39.9 (“severely obese”) and have a serious obesity-related health problem
Click Here to See Your BMI

Serious obesity-related health problems most commonly include:

  • High blood pressure
  • High cholesterol
  • Type 2 diabetes
  • Sleep apnea

Other qualifying health conditions related to obesity are listed in the Health Benefits section above.

If you do not meet either of these BMI requirements, you still might qualify for one other type of weight loss surgery called Gastric Balloon. See our Gastric Balloon Patient Guide for more information.




  • Your insurance will pay for gastric bypass surgery if your policy includes bariatric surgery

If your specific policy covers bariatric surgery, gastric bypass surgery will be covered.

Whether your policy covers bariatric surgery depends on what kind of plan you have:

  1. If you purchased your own plan or got it through a small business (under 50 employees) – The Affordable Care Act (Obamacare) requires insurance companies in many states to include coverage for bariatric surgery. Click here for an updated list of states required to cover bariatric surgery.
  2. If you got your plan through a large business (50+ employees) – Whether bariatric surgery is covered by your insurance is completely up to your company to decide. Talk with your HR department or contact your insurance company to find out if it’s covered.
  3. If you have Medicare or Medicaid – Both cover gastric bypass surgery, although not all surgeons accept them.

If Your Policy Covers It: Ask for Free Insurance Check

Before your insurance company will cover gastric bypass, it will require you to submit documentation from your doctor or surgeon confirming that a medically supervised weight loss program was unsuccessful.

Many surgeons offer a free insurance check and have a staff that is highly trained and experienced at working with insurance companies. Rather than figuring it out on our own, talk with a surgeon’s office about doing the legwork for you.

Click Here to Check Your Insurance

If Your Policy Does NOT Cover It: Seek Partial Coverage

You’ll most likely be able to get some of your gastric bypass expenses covered, even if bariatric surgery isn’t a covered benefit.

For example, there are many non-bariatric surgery reasons for your doctor to recommend:

  • Lab work
  • Psychological exam
  • Cardiology exam
  • Sleep study
  • Medically supervised diet program

For more about how to get gastric bypass surgery covered by insurance, see our Bariatric Surgery Insurance page.


Cost Without Insurance


  • The average gastric bypass patient pays $500 to $5,000 with insurance, $20,000 to $25,000 without insurance
  • If you get a medical loan, the loan payment is $556 a month, on average
  • You can usually get discounts &/or tax savings

According to our annual surgeon cost survey, the average total cost of gastric bypass surgery in the United States is $24,000, although we came across surgeons who charge as low as $16,000. Your local costs will be based on:

  • Surgeon and hospital fees and discounts – these can vary widely, even in the same town
  • How much your insurance will pay – even if your insurance company does not cover gastric bypass surgery, they may cover some of the related services like pre-op testing and lab work
  • Tax write-offs available to you – whether you qualify for tax write-offs depends on your total out-of-pocket medical costs for the year relative to your annual income
  • Whether you apply for a loan to help cover the costs

To get a free local gastric bypass cost quote and discuss financing options, click here to contact a local surgeon.

Click Here to See How Much Gastric Bypass Will Cost

For more information, see our Gastric Bypass Surgery Cost page.


Preparing for Gastric Bypass Surgery


  • If you properly prepare for surgery, it reduces your risks during surgery, leads to more weight loss, & saves you money

During the weeks leading up to gastric bypass surgery, your surgeon’s team will do the following:

  • Pre-procedure health assessment, where you will be asked questions about your medical history, medications, and surgical history
  • Order certain tests like an ECG, x-ray, and blood tests
  • Establish a pre-surgery diet regimen, including:
    • Two weeks before
      • No sugar
      • Lower carbs
      • Increased protein
      • Increased veggies
      • Plenty of fluids
    • 2 Days Before
      • Clear liquids, broth, one protein shake per day only
      • Talk with your surgeon about whether you should stop taking any medications
    • 2 Hours Before
      • No food or drink, or tobacco

Losing as much weight as possible prior to surgery is also critical because:

  • The more weight you lose pre-op, the more weight you will lose after surgery
  • The lower your pre-op weight, the lower your risk of complications
  • Gastric bypass surgery will not work over the long-term if you slip back into old habits. For about 70% of gastric bypass patients, eating unhealthy foods also lead to vomiting, diarrhea and other uncomfortable symptoms. The sooner you can start establishing good diet and exercise habits, the more likely you will be to maintain them after surgery

See our Preparing for Weight Loss Surgery page for more information.




  • Hospital Stay: You will be in the hospital for 2 to 3 days
  • Time Off Work: You will need to request 1 to 3 weeks off
  • Full Recovery: It will take 4 to 6 weeks to fully recover
  • Pain: It is managed with medication, just like any laparoscopic surgery
  • Diet & Activity: You will slowly transition to your “new normal” diet & lifestyle

Your gastric bypass surgery recovery will include:

  • Timeline: 4 to 6 weeks to full recovery
    • Hospital Stay: 1 to 3 days
    • Time Off Work: 1 to 3 weeks
  • Pain: Same as experienced after any laparoscopic surgery, managed with medication
  • Diet: Slow transition from clear liquids to solid foods
  • Activity: Slow transition back to regular activity and exercise
  • Challenges: Dumping syndrome, digestive issues & weight regain if you “cheat” on your diet, potential dental issues, gallstones, kidney stones, & short-term hair loss, and sagging skin from rapid weight loss
  • Follow-up with surgeon: Patients who follow-up their surgeon as directed have a greater improvement of obesity-related health problems (diabetes, hypertension, sleep apnea, etc.) than those who don’t (44). In other words, make and attend all appointments that your surgical team recommends after surgery.

See our Gastric Bypass Recovery page for an in-depth recovery timeline and details about each aspect of recovery.


Diet & Life After


  • Your diet will be restricted to mainly healthy foods and beverages
  • You will take prescribed vitamin and mineral supplements for the rest of your life eating
  • You will feel full sooner while eating and each much less as a result
  • You will establish a weekly exercise routine
  • Your personal relationships may change

Gastric bypass leads to impressive weight loss and health improvement, but what will day-to-day life be like? What are the tradeoffs?

Your surgery is only a tool, and long-term success requires diligence and sometimes difficult change in other areas.

Following is what to expect…

Food & Drink: Significant Changes

Following surgery, it will take about 6 weeks to transition into your new long-term gastric bypass diet which includes significant restrictions.

Most of your diet will consist of “whole foods,” including meat, vegetables, fruits, and grains. You will need to eat at least 60 grams of protein per day.

Your body won’t be able to tolerate much, if any, processed foods, high-fat foods, sugar, greasy foods, fibrous foods, starchy foods, whole milk products, or alcohol.

You will eat 3 small meals per day and no more than 1 small snack. Your portion sizes will be much smaller and you will need to eat slowly and chew thoroughly.

Click here to expand your diet transition schedule.
Timeframe Range Diet Requirements
2+ Weeks Before Surgery Practice your post-bypass diet
2 Weeks Before Surgery High protein, low sugar, low carbs
1 Week Before Surgery Stop or change some medications
2 Days Before Surgery Clear liquids only
Midnight Before Surgery to 7 Days After Surgery (Varies by Surgeon) Nothing to eat or drink
In Hospital (1 -2 Days) thru Day 7 After Surgery Clear liquids only
Day 1 to Week 2 After Surgery (Varies by Surgeon) Add thicker drinks & smooth foods (no chunks)
Day 2 to Week 3 After Surgery (Varies by Surgeon) Slowly test pureed & soft solid foods
Day 3 to Weeks 4+ After Surgery (Varies by Surgeon) Slowly test solid foods (avoid alcohol)

For more detailed information, see our Gastric Bypass Diet page.

Vitamins You Will Take: Lifelong & Crucial

Since gastric bypass is a “malabsorptive” procedure by nature, it carries a high risk of malnutrition. Patients must be extremely diligent about taking prescribed vitamins and supplements or risk serious vitamin deficiency.

Your daily vitamin regimen will include:

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

For more information, see our Bariatric Vitamins page.

Exercise: 2.5 hours per week, spread out over 2 to 4 days

Exercise is almost as important as what you eat after gastric bypass surgery for two big reasons:

  • Patients who exercise regularly lose more weight over the long-term
  • Physical and mental health benefits make you much more likely to keep your new lifestyle requirements in line

How much exercise do you need to for noticeable results?

One study found that exercising 2.5 hours per week leads to 5.7% more weight loss (54). Another showed that gastric bypass patients who exercise at least 30 minutes a day, 3 days per week have a 4+% lower body mass index (55).

Further, regular exercise leads to quicker improvement in obesity-related health problems following surgery (56).

See our Exercise After Bariatric Surgery page for more information.

Your Brain: Less Hungry, Careful About Food Addiction, New Mentality Will Change Behavior & Relationships

gastric bypass surgery

Ghrelin Hormone & Hunger

The big diet changes reviewed above may be easier than they sound for two reasons:

  1. You may permanently feel less hungry following surgery since the production of a key hunger-causing hormone, ghrelin, will be reduced
  2. Your stomach will be much smaller, causing you to feel full much sooner after eating

Food Addiction

If not addressed prior to surgery, food addiction can lead to long-term weight regain for gastric bypass patients. If you struggle with food addiction, talk with your surgeon before moving forward with surgery.

To find out if you may be suffering from food addiction, take our Food Addiction Quiz.

Relationships After Weight Loss

gastric bypass surgery

Gastric bypass leads to rapid and significant weight loss, and people will start treating you differently within a couple of months after surgery. Following are positive experiences reported by most patients:

  • Treated with more respect
  • More romantic interest from others
  • No more obesity discrimination
  • Deeper relationships as a result of being able to physically keep up with kids and more physically fit friends
  • More compliments from others
  • Increased self-confidence
  • Improvements in quality of sexual life (57)

However, being “newly thin” may carry unforeseen negatives as well:

  • How will overweight friends or family members feel when you’re losing weight but they are not?
  • If they’re not making diet and lifestyle changes as well, will your friends or family make it more difficult for you to stay on track?
  • How will your coworkers react? Should you even tell them you are having surgery?
  • Will your new healthier diet and smaller portion sizes make meals with others awkward?
  • Could intimacy with your spouse or partner be affected?
  • Could your spouse or partner become jealous now that others are noticing you more?

The way you view people and relationships may change as well. Common thoughts include:

  • “Would this person be treating me the same way if I hadn’t lost all of this weight?”
  • “How do I handle obesity discrimination now that I’m on the “other side”?”

For real life experiences and advice from other gastric bypass patients, see our Relationships After Weight Loss surgery page.




  • Moderate risk of non-serious complications
  • Side effects may include digestion issues, dental problems, & sagging skin
  • Some weight regain is possible after you reach your low weight

Like all bariatric surgery procedures, the mortality rate for gastric bypass (the risk of dying) is extremely low. It has a survival rate of 99.8%.

However, complications are more common, with about to 1 out of 7 patients experiencing one or more over the long-term (58, 59).

Preventing Gastric Bypass Complications

Follow these steps to reduce your risk of gastric bypass complications:

  1. Select the surgery that is most appropriate for your situation. Different surgeries carry different risks for different people. Our Types of Bariatric Surgery page compares and contrasts the safest and most effective procedures.
  2. Choose an experienced surgeon, since more experienced surgeons tend to have better outcomes(60). Most surgeons offer free seminars that teach you about your weight loss surgery options, their practice’s experience, total procedures performed, and specific results. The seminars also allow you to get to know the surgeon prior to a one-on-one consultation.

    Click here to find and schedule a free in-person seminar or one-on-one consultation with a qualified weight loss surgeon in your area.

    You can also review our Bariatric Doctors page to learn how to interview multiple doctors and choose the best one.

  3. Eat and exercise as directed by your surgeon before, during, and after surgery. Your behavior before and after surgery directly and significantly impacts your gastric bypass complication risk. Read the other sections of this page for more information.

Possible Gastric Bypass Complications

The most common complications, which occur in greater than 1% of patients, include:

Stomal Stenosis – About 5% of patients
A narrowing or constriction of the diameter of a bodily passage or orifice. Results from a build-up of scar tissue between your intestine and your reduced stomach or at an intestine-to-intestine connection (anastomosis).
Wound Infection – About 3% of patients
When incisions are contaminated with a disease-producing substance or agent (such as bacteria). Much more common in open surgeries than in laparoscopic surgeries due to the size of the external incisions. Usually treated with antibiotics.
Bowel Obstruction – About 3% of patients
Also called an “internal hernia”, it occurs when the intestines twist and prevent the flow of food and digestive fluids. Patients with this condition usually experience abdominal pain, abdominal swelling, or vomiting. A doctor will confirm the diagnosis with a CAT scan or through surgery, and surgery may or may not be needed to treat it.
Leak – About 2% of patients
Occurs when sealed or sutured (stitched) openings leak digestive contents into the abdomen. This can cause infection and abscess. Can be repaired as long as it is caught early. Symptoms include fever, severe pain and a high heart rate. In order to prevent leaks, your surgeon should check the surgical connections a number of different ways, including (1) blowing air into the connection and observing whether any gets through and (2) using a dye to check for a leak. Leaks not discovered right away are usually treated by resting the stomach (being fed through an IV), but sometimes surgery is required to fix them.
Gastrointestinal bleeding – About 2% of patients
A copious discharge of blood from the blood vessels. After the surgeon determines the type and severity of internal bleeding, it can be resolved in a number of ways: on its own, replenishing bodily fluids, stopping the use of all anticoagulation drugs and (rarely) by transfusion or reoperation (61).

For a full list of potential issues, see our Gastric Bypass Complications page.

Gastric Bypass Side Effects: Digestion/Diet Issues, Dental Problems, Sagging Skin, & Others

Click below for more information about each gastric bypass side effect:

Digestion & Diet Issues
  • Dumping syndrome is experienced by 7 out of 10 gastric bypass patients, although for 95% of these patients, symptoms are relatively minor (62). Symptoms may include weakness, dizziness, flushing and warmth, nausea and palpitation immediately or shortly after eating. They are caused by abnormally rapid emptying of the stomach especially in individuals who have had part of the stomach removed.

    While this sounds like a bad thing, many patients view it as a “blessing in disguise.” The symptoms of dumping syndrome are completely avoidable by eating a proper bariatric diet… can you think of a more convincing way to keep you on track? In fact, some patients who do not suffer from dumping syndrome often comment that they wish they did, as “dumping” removes some of the choice involved in food selections. See our Dumping Syndrome page for more details.

  • Dehydration – an abnormal depletion of body fluids. You will need to drink a lot of water in the months following surgery – as much as 2 liters per day. Not doing so can lead to nausea and vomiting which can lead to even worse dehydration and other problems. In severe cases of dehydration patients may need to return to the hospital for IV fluids and vitamins.
  • Difficulty swallowing (also called dysphagia) can be caused by eating too quickly, too much or not chewing food enough and can usually be fixed by avoiding these issues.
  • Indigestion (also called dyspepsia) is the inability to digest or difficulty in digesting food, the incomplete or imperfect digestion of food or a case or attack of indigestion marked especially by a burning sensation or discomfort in the upper abdomen.

    Treatment is usually as simple as changing your diet, such as avoiding greasy foods or limiting liquid intake to certain times of day. Alcohol, aspirin and other drugs are also causes. If diet changes don’t work, antacids and H2 blockers are sometimes prescribed.

  • Intolerance to certain foods, beverages and drugs – With a changed stomach size and digestive system, there will be certain foods, beverages and drugs that you’ll need to avoid and certain diet habits you’ll need to maintain (63). It is important to talk with your doctor before taking ANY drugs, as they can damage your stomach pouch after gastric bypass surgery and cause ulcers (including over the counter pain relievers – Motrin, Advil, aspirin, Aleve).

    Regarding alcohol, a little may still be okay, but it will have a profoundly different effect on your body than it used to. First, it’s bad for your diet due to the large amounts of calories found in many alcoholic beverages. Second, you will become intoxicated more quickly following surgery which could lead to a number of problems.

    Finally, following surgery the effects of alcohol on your system could make liver disease more likely. As for smokers, you must stop now. If you smoke after gastric bypass surgery, there is a good chance that you will get an ulcer in your pouch.

  • Nausea and vomiting is one of the most common gastric bypass side effects and is experienced in up to 70% of patients. Following your doctor’s bariatric diet recommendations exactly will typically fix or improve the problem. While in the hospital, receiving a larger amount of IV fluids at a faster rate may make you less likely to feel nauseous or vomit (64). Keeping a food journal for a couple of days may help you to pinpoint the foods which seem to cause nausea and vomiting.
  • Change in bowel habits – bowel function after bariatric surgery may change in a number of ways, including (65)…
    • Diarrhea or loose stools – usually completely dependent on diet – you will need to figure out and avoid foods that “trigger” diarrhea. It could also be the result of lactose intolerance (not a side effect of surgery, but surgery can make you more sensitive to a problem that you didn’t know you had) which would require dairy products to be removed from the diet.
    • Constipation – usually fixed by increasing the amount of water you are drinking and by taking fiber supplements.
Dental Problems

Some gastric bypass patients experience problems with their teeth after surgery due to:

  • Malabsorption
  • Not taking proper vitamins in the right amounts
  • Potential pH changes in the saliva after surgery
  • Poor dental hygiene
  • Not addressing significant reflux or vomiting issues (stomach acid in the mouth is bad for the teeth)

See our Dental Problems After Gastric Bypass Surgery page for a dialogue between several patients, dentists and bariatric surgeons about the issue.

Sagging Skin

Gastric bypass surgery causes most patients to lose weight fast, and your skin simply can’t keep up.

Sagging skin can cause several mental and physical issues including:

  • Difficulty getting dressed
  • Difficulty exercising, which may impact long-term weight maintenance and health
  • Embarrassment with or without clothes on
  • Skin fold rashes or breakdown of skin
  • Skin fold infections

Options for addressing sagging skin include:

Alcohol Abuse

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 (66). 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 (67). 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.

Other Potential Side Effects
  • Gallstones are small stones of cholesterol formed in the gallbladder or bile passages. They can be created following rapid weight loss which leads to their development in as many as 1/3 of bariatric surgery patients. To prevent this, your surgeon may remove your gallbladder during surgery or prescribe bile salt supplements after surgery.
  • Hair Loss occurs to some degree for most patients and can be caused by nutritional deficiencies or as your body’s response to major surgery or extreme weight loss. Most patients stop losing and start regrowing hair within 3 to 6 months following surgery. Supplementing your diet with protein, vitamin B, magnesium, calcium and zinc, among other bariatric vitamins, will help prevent hair loss and improve hair growth.
  • Kidney stones are stones in the kidney related to decreased urine volume or increased excretion of stone-forming components such as calcium, oxalate, urate, cystine, xanthine and phosphate. The stones form in the urine collecting area (the pelvis) of the kidney and may range in size from tiny to staghorn stones the size of the renal pelvis itself. Drinking lots of water, which gastric bypass patients should do anyway, will help to dilute the urine and may help prevent kidney stones.

Weight Regain: Half of All Bypass Patients After 2 Years

About half of all gastric bypass patients start to regain weight after two years.

After five years, the average bypass patient gains back about 8% of their weight compared to their 18-month to 2-year “low point.” (68)

Another study found that up to 20% of morbidly obese patients (40 – 50 BMI) and up to 35% of super obese patients (BMI over 50) gained back more than 50% of their excess weight after 10 years (69).

Equally concerning, the more weight you gain back, the more likely your health problems are to come back. For example, one study showed that after gastric bypass surgery, all patients with Type 2 Diabetes experienced improvement or complete resolution. However, after 3 years, about 1 out of 4 of those patients saw their diabetes worsen or come back (70).

Why do patients gain back weight?

Usually it’s the patient’s fault. They veer off course and consume foods or beverages they shouldn’t, causing their stomach pouch or the connection between their stomach and small intestines (called the “stoma”) to stretch out (71).

If you start to gain back weight, contact your surgeon or dietitian immediately to assess your diet and exercise habits.

See our Weight Regain After Gastric Bypass Surgery page for advice on how to avoid weight regain after gastric bypass surgery.


Gastric Bypass Vs. 6 Other Weight Loss Procedures


  • Gastric bypass is one of the best procedures for weight loss & health improvement
  • It has similar higher risks than the other top procedures
  • It is 1 of 3 procedures that is not reversible

Gastric bypass was considered the “gold standard” procedure for several years, until gastric sleeve surgery took its place.

However, it is still recommended by surgeons for some patients for its unique combination of benefits.

Gastric Bypass Positives

  • Weight loss is usually in range of gastric sleeve and much better (on average) than after LAP-BAND® surgery, gastric balloon, or vBloc Therapy (but less than duodenal switch). The AspireAssist needs more research, but initial results show a weight loss potential less than gastric bypass.
  • Health Improvement is generally better than after gastric sleeve, LAP-BAND®, gastric balloon, or vBloc Therapy (but not as good as duodenal switch). Initial research shows AspireAssist will have similar health improvements to gastric balloon or vBloc Therapy, but more research is needed to confirm.
  • Short-term risk of gastric bypass is similar to that of gastric sleeve and lower than duodenal switch (but higher than LAP-BAND®, gastric balloon, vBloc Therapy, or AspireAssist).
  • Long-term risk of gastric bypass is lower than duodenal switch (but higher than gastric sleeve, and LAP-BAND® surgery; long-term data not yet available for balloon, vBloc, or AspireAssist).
  • There is no external device left inside the body as there is with LAP-BAND®, gastric balloon, vBloc Therapy, and AspireAssist, so there is no risk of device-related complications. While the risk of device-related complications is relatively low for vBloc Therapy, gastric balloon, and AspireAssist, it is a concern and should be considered for LAP-BAND®.
  • If you are on anticoagulation medication (blood thinners), compared with gastric sleeve, gastric bypass surgery is probably a better choice to reduce the risk of marginal ulcers.

Gastric Bypass Negatives

  • Not reversible – Unlike LAP-BAND®, gastric balloon, vBloc Therapy, and AspireAssist, gastric bypass surgery (along with gastric sleeve and duodenal switch) should be considered irreversible – once your stomach size is reduced and your intestines are rerouted, it is very it is very difficult and uncommon for the procedure to be reversed.
  • Weight loss (on average) is usually lower than duodenal switch (but higher or similar to all other procedures).
  • Health Improvement is generally not as significant as after duodenal switch (but is generally better than all other procedures).
  • While survival rate is extremely high at 998 out of every 1,000 patients, risk of gastric bypass complications is higher than all other procedures except duodenal switch. Early complications occur in about 1 out of 10 patients while late complications occur in about 1 out of 7 (72, 73).
  • The two primarily “malabsorptive” procedures, gastric bypass and duodenal switch, are more complicated to perform and include the rearranging your digestive system. As a result, they have a:
    • Longer recovery
    • Higher risk of vitamin deficiency (and therefore require more daily supplements)
    • Higher costs
  • Dumping syndrome is experienced by up to 7 out of 10 gastric bypass patients, although many patients report this being a “good thing” since it helps them keep their diet on track (see more in the Downsides section above).

For further comparison of gastric bypass surgery to other procedures, see our Types of Bariatric Surgery page.

These pages will help you better understand the differences between gastric bypass and other popular procedures:

Click here to review studies that compare gastric bypass to other types of weight loss surgery.

Summary of Findings When Comparing Gastric Bypass to Other Procedures Year of Study
LAP-BAND® Surgery vs Gastric Bypass
Roux-en-Y gastric bypass is associated with better weight loss, resulting in a better correction of some comorbidities than gastric banding, at the price of a higher early complication rate. This difference, however, is largely compensated by the much higher long-term complication and reoperation rates seen after gastric banding.O 2012
Weight loss outcomes strongly favored gastric bypass over LAP-BAND® surgery. Patients treated with LAP-BAND® had lower short-term morbidity than those treated with gastric bypass, but reoperation rates were higher among patients who received LAP-BAND® surgery. Gastric bypass should remain the primary bariatric procedure used to treat obesity in the United States.A
Editor’s Note: This study was published before long-term results had been published for gastric sleeve surgery.
Collectively, data clearly point to distinct changes in dietary habits after bariatric operations which markedly differ between gastric bypass and LAP-BAND® patients. Overall, it is tempting to conclude that gastric bypass operations lead to a healthier and a more balanced diet than LAP-BAND® implantations.B 2008
Gastric bypass seems to provide a stronger suppression of ghrelin in comparison with gastric LAP-BAND® procedure.These findings are consistent with the hypothesis that suppression of ghrelin is one mechanism by which gastric bypass can reduce body weight long term, more than LAP-BAND®.C 2003
Mini Gastric Bypass Surgery vs Gastric Bypass
Pending long-term evaluation, mini gastric bypass surgery seems a good alternative to gastric bypass, giving the same results with a more simple and reproducible technique.D 2008
Previous studies have demonstrated that hospitalization after gastric bypass increases remarkably (20% per year). The present study shows that hospitalization followingmini gastric bypass surgery instead of rising, as reported with gastric bypass, decreases by a third. Themini gastric bypass has been shown to be a short, safe successful weight loss surgery in previous work. The present study supports themini gastric bypass as a low risk procedure that decreases the need for hospitalization.E 2006
Both gastric bypass andmini gastric bypass surgery are effective for morbid obesity with similar results for resolution of metabolic syndrome and improvement of quality of life. Mini gastric bypass surgery is a simpler and safer procedure that has no disadvantage compared with gastric bypass at 2 years of follow-up.F 2005
Gastric Sleeve Surgery vs Gastric Bypass
Compared with gastric sleeve, gastric bypass had significantly better effect in resolving type 2 diabetes mellitus, hypertension, hypercholesterolemia, gastroesophageal reflux disease, and arthritis. However, gastric bypass had higher incidence of complications and reoperation, and longer operation time than gastric sleeve.P 2014
Overall complication rates among patients undergoing gastric sleeve (SG) (6.3%) were significantly lower than for gastric bypass (RYGB) (10.0%, P < 0.0001). Serious complication rates were similar for SG (2.4%) and RYGB (2.5%, P = 0.736). Excess body weight loss at 1 year was 13% lower for SG (60%) than for RYGB (69%, P < 0.0001). SG was closer to RYGB than LAP-BAND® (LAGB) with regard to remission of obesity-related comorbidities.Q 2013
PYY levels increased similarly after either procedure. The markedly reduced ghrelin levels in addition to increased PYY levels after gastric sleeve surgery, are associated with greater appetite suppression and excess weight loss compared with gastric bypass.I
(Editors’s note: both ghrelin and peptide YY effect appetite. See our obesity and genetics page for more details)
The gastric sleeve operation is able to achieve significant weight loss comparable to the gastric bypass and duodenal switch operations but with the low morbidity profile similar to that of LAP-BAND® placement.J 2007
Duodenal Switch (DS) vs Gastric Bypass
Compared with gastric bypass, duodenal switch may be associated with a greater risk of vitamin A and D deficiencies in the first year after surgery and of thiamine deficiency in the initial months after surgery.K (Editors’s note: See our Bariatric Vitamins page for more.) 2009
Although duodenal switch is associated with more bowel episodes than gastric bypass, the difference is not statistically significant. Bowel habits are similar in patients who achieve 50% estimated body weight loss with duodenal switch surgery or gastric bypass.L 2008
Direct comparison of Duodenal Switch toGastric Bypass demonstrates superior weight loss outcomes for DS. Importantly, the likelihood of successful weight loss (excess weight loss >50%) was significantly greater in patients following DS (12 months, 83.9% vs. 70.4%; 18 months, 90.3% vs. 75.9%; 36 months, 84.2% vs. 59.3%).M 2006
No patients reported dumping syndrome (after DS surgery), and marginal ulcers were not seen.N 2006

Gastric Bypass Summary


  • 7 steps to long-term weight loss

01. Start Working with a Top Surgeon As Soon as Possible

Top surgeons will help you effectively navigate the various procedure choices, pre-surgery steps, financing, and insurance options:

  1. As a first step, many surgeons offer a free initial consultation or a free local seminar or webinar to give you a better understanding of what to expect.
  2. Many will also provide a free insurance check to help you figure out how much insurance will cover, and, if necessary, appeal any denials or find additional financing. Most insurance companies require you to complete a medically supervised diet and exercise program before they will approve your surgery, so your surgeon will set this up for you if you haven’t done so already.
  3. Your surgeon will also push you towards new habits that will be essential to long-term success after surgery. Many surgeons will recommend that you attend support group meetings so you can listen to feedback from actual patients.

02. Two Weeks Out: Prepare for Surgery

By 2 weeks out you will have completed your pre-op tests, physical, and any other necessary steps required by your surgeon or insurance company. You should have insurance approval (if applicable), and you should be well on your way towards developing your new long-term lifestyle and diet habits.

In the week or two leading up to surgery you’ll be seeing the hospital pre-surgery department for an EKG, blood work, and any last minute instructions or other pre-op tests. You’ll see the surgeon one more time for consents, a pre-operative physical, and any last minute details.

The night before surgery you’ll be asked to not eat or drink anything starting at midnight.

03.Surgery Day

You’ll be asked to arrive at the hospital at least two hours prior to surgery to allow for prep time. The gastric bypass procedure itself will take about 4 hours to perform. For the first few hours after surgery, you probably won’t be awake to remember it, but you’ll have one-on-one attention from someone on your surgical team to manage your pain and monitor your vitals. Click here for more about what to expect in the hospital.

04. Recovery

Most gastric bypass patients are in the hospital for 2 or 3 days total. You will probably not be allowed to eat or drink anything for at least 24 hours after surgery, and your surgeon will want you to get up and walk around as soon as possible to start the healing process.

You’ll be discharged as soon as your surgeon is confident that you are well on the road to full recovery. You’ll likely need someone to drive you home from the hospital and care for you for at least a few days following surgery. Full recovery generally happens within 4 to 6 weeks. Click here for more about the recovery process.

05. Adjust to Your New Post-Surgery Diet & Lifestyle

Over the course of the first 6 weeks following surgery you will slowly transition from a sugar-free clear liquid diet to your “new normal” gastric bypass diet. You should also continue your transition into a more active lifestyle.

You will feel full sooner, you may feel less hungry generally, and you should start to experience significant weight loss within a couple weeks. Your surgeon’s dietitian or nutritionist will help you determine an appropriate diet.

See the Diet & Life After section of this page for more information.

06. Attend Support Groups Regularly

Regular weight loss surgery support group participation has been found to lead to the following benefits:

  1. Reduce post-op recovery time
  2. Lead to as much as 12% more long-term weight loss

Your surgeon will be able to recommend an in-person group near you.

07. Ongoing Doctor Visits

For the first year, your surgeon will most likely schedule follow up visits. Shortly after surgery, they will be weekly then transition to every four weeks, and, later, once every few months to ensure that you are recovering well and to answer any questions you may have. Subsequent doctor visits will be scheduled on an as-needed basis along with annual check-ups.


Test Your Knowledge


  • Click here to take the gastric bypass quiz

Gastric Bypass: Test Your Knowledge

Well-educated patients are more likely to be successful over the long-term. Test your knowledge to ensure that you’re ready to take the next step!

Take the Gastric Bypass Quiz

Find a Top Gastric Bypass Surgeon


  • You can ask a local bariatric practice for a free insurance check or cost quote
  • You can attend a free in-person seminar or an online webinar offered by a local weight loss surgeon
  • You should schedule a phone or in-person consultation (both often free), if you are interested in learning more about weight loss surgery

Search the gastric bypass surgeon directory below to find a top surgeon by country and region:


To view references for this page, click here.

* Disclaimers: Content: The information contained in this website is provided for general information purposes and your specific results may vary depending on a variety of circumstances. It is not intended as nor should be relied upon as medical advice. Rather, it is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her existing physician(s). Before you use any of the information provided in the site, you should seek the advice of a qualified medical, dietary, fitness or other appropriate professional. Advertising: Bariatric Surgery Source, LLC has entered into referral and advertising arrangements with certain medical practices, original equipment manufacturers, and financial companies under which we receive compensation (in the form of flat fees per qualifying action) when you click on links to our partners and/or submit information. Read More