How To Lose Weight After A Gastric Bypass

Annually, more than 200,000¹ Americans undergo bariatric surgery to help them lose weight. Gastric bypass surgery is a common type of bariatric surgery and is usually recommended for patients who have tried and failed to lose weight by adopting a healthier lifestyle.

Regaining weight after gastric bypass surgery can cause disappointment, confusion, and frustration. There are several reasons why you might regain weight after a gastric bypass, and it is actually fairly common. However, there are strategies you can implement to prevent weight regain, and if you do find you have regained weight, you can take steps to lose it again.

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What is a gastric bypass?

A gastric bypass, also known as a Roux-en-Y, is a type of bariatric surgery in which a small stomach pouch is created at the top of the stomach using surgical staples. This pouch is then connected to the small intestine, bypassing the rest of the stomach.

You might receive a gastric bypass if you are overweight and other weight-loss strategies like diet and exercise have not worked. A gastric bypass is usually performed on patients whose health is at risk because of their weight.

A gastric bypass is designed to help you lose weight efficiently and quickly. You will feel full after consuming less food, and you will absorb fewer calories.

Is it common to regain weight after a gastric bypass?

In the first three to six months after your surgery, you will likely see your weight decrease rapidly. After this time, you may notice your weight loss leveling off, suggesting you have reached a weight loss plateau. This is common and shows that your body is healing and getting used to your new food and calorie intake.

If you start to notice the scales rising again after this point, you may feel very disappointed and confused. Unfortunately, weight gain in gastric bypass patients is relatively common. A 2008 study² that examined weight gain in 782 gastric bypass patients over five years found that, despite significant weight loss within 18 months of surgery, 50% of participants had regained some weight within 24 months of surgery.

These findings reflect those of an earlier 2006 study³ that tracked patients’ weight at five and ten years after surgery. The study concluded that weight gain was common in obese and super obese patients in the time between reaching their nadir weight (lowest weight after surgery) and five and ten years after the gastric bypass.

Why you could regain weight after a gastric bypass

So why do so many patients regain weight after having gastric bypass surgery?

Diet and exercise

After your surgery, you may slip back into old lifestyle habits that could result in weight gain. For example, you might eat unhealthy foods and follow an unbalanced diet. If you had an unhealthy relationship with food before your surgery (if you used to binge eat for example), you may be more likely to gain weight after surgery.

You may also be at risk of gaining weight after gastric bypass surgery if you return to an inactive lifestyle.

Changes in your stomach and intestine

Your gastric bypass surgeon will make changes to your stomach and intestine to help you lose weight, but your body may change again in the months and years following surgery. These changes may result in weight gain.

For example, the opening between the stomach pouch and the intestine may get bigger over time⁴, which may reduce the effectiveness of the gastric bypass and result in weight gain. Another rare cause of weight gain after gastric bypass surgery is a gastro-gastric fistula⁵, a connection that develops between the stomach pouch and bypassed stomach which could make the surgery ineffective.


Alcohol is recognized as a cause of weight gain and may cause gastric bypass patients to regain weight after surgery.

A 2018 study⁶ reported that gastric bypass patients were more likely to consume alcohol in an unhealthy way. The study suggests that this is caused by changes in the way the body processes alcohol since the level of alcohol in the blood rises much faster than normal and takes longer to leave the body. According to the study, problematic drinking could also be caused by changes in the brain that make gastric bypass patients like alcohol more after surgery.

Drinking alcohol can disrupt your daily life and make it difficult for you to stick to healthy habits. Alcohol also contains empty calories that contribute to weight gain. Ultimately, gastric bypass patients should avoid or limit alcohol consumption after surgery to avoid developing alcohol abuse issues and weight gain.

How to avoid regaining weight after a gastric bypass

Although many people experience weight gain after gastric bypass surgery, the following tips may help to minimize the risk.

Join a bariatric support group

If you are finding it difficult to keep up with the lifestyle changes recommended for gastric bypass patients, consider joining a bariatric support group. At a support group, you will be able to speak to others who have had gastric bypass surgery and share any challenges you are facing.

Joining a bariatric support group could motivate you to stick to healthy lifestyle habits and keep the weight off. It’s also a great opportunity to get advice from other people who are in the same boat. For example, you might share healthy living tips, recipes, exercise plans, suggestions for staying on track, and much more.

Improve your mental wellbeing

If you don’t take care of your mental health, you will be more likely to return to unhealthy habits and gain weight after your gastric bypass surgery.

You may feel a lot of pressure after your surgery to lose weight or look a certain way. Be easy on yourself and put strategies in place to give yourself the best chance of success. Surround yourself with people who support and uplift you, and practice mindfulness to reduce stress and anxiety.

Address bad eating habits before surgery

There is evidence to suggest that the results of gastric bypass surgery are less positive in patients with a history of binge eating disorder (BED). A 2007 study⁷ and a 2014 review⁸ suggest that gastric bypass patients who had BED before surgery may lose less weight than non-BED patients and face more risk of regaining weight.

This certainly isn’t possible for everyone, but you should try to minimize any problematic eating habits before you have gastric bypass surgery to give yourself the best possible chance of success. You may want to consider therapy — which is recommended before and after surgery — to help you if you have BED or any other eating disorder.

How to restart weight loss after gastric bypass

Follow these recommended steps to help you restart weight loss if you have regained weight after gastric bypass surgery.

Follow your recommended diet

In the months and years following surgery, you are recommended to follow a specific diet to help your stomach and intestines heal, provide the nutrients your body needs, and reach and maintain a healthy weight. Your medical team will give you recommendations and guidelines, so be sure to follow them carefully.

Below are some of the guidelines you might be asked to follow:

  • Avoid high-calorie drinks

  • Drink lots of water

  • Consume several small meals instead of large ones

  • Cut down on sugar

  • Avoid snacking

  • Limit alcohol and caffeine consumption

Keep active

A gastric bypass is a major surgery, so it might take a while for you to feel like you can exercise again. However, once you feel able to and when your doctor has given you the go-ahead, try to introduce exercise back into your life.

Inactivity is one of the leading causes of obesity. It means you are unlikely to be burning as many calories as you are consuming. Keeping active is a great way to keep your mind and body healthy and kick-start weight loss after gastric bypass surgery.

When to see your doctor

Obesity is a chronic and complex condition. Do not feel ashamed if you regain weight after gastric bypass surgery as this is relatively common. The key is to assess why you are gaining weight and make changes to help you lose it.

Your doctor will be able to identify the cause of your weight gain and help you get back on track. For example, they may refer you to a nutritionist who will be able to advise you on your diet. If something has changed in your stomach or intestine and you need corrective surgery, your doctor will be able to refer you to a specialist.

The lowdown

For many patients, gastric bypass surgery is not enough to prevent weight regain. It’s important to remember that this surgery is a tool that may help you lose weight, but it is not a magic wand.

Many people lose weight at first, then gain weight when they return to unhealthy habits. Another cause of weight gain after gastric bypass surgery changes in the stomach and intestine. A medical professional will be able to diagnose this and they may suggest corrective surgery.

If you’re wondering how to restart weight loss after gastric bypass, you must commit to making lifelong changes in your everyday life. Eating a healthy, nutritious diet is essential, as is keeping active and avoiding alcohol and drugs.

Addressing problematic eating behaviors before surgery and taking care of your mental health will give you the best chance of success. It is also recommended to join a bariatric support group to help you overcome challenges and stay on track.

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