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What to Expect After Gastric Bypass: Post-op Side Effects and How to Manage Them

Gastric Bypass Side Effects

By Dr. Hugh Houston

Gastric bypass surgery may be accompanied by a range of side effects. It is vital patients be aware of these, so they can better prepare themselves for the journey. While there are many pleasant side effects associated with this procedure like loss of appetite and lack of desire to eat, these effects may lead to unwanted consequences if not properly managed in the beginning.

The following is an overview of some of the common post-op side effects and how to manage them.


A lot of people don’t realize how much water we get from eating food. Most foods have a high water content, so we are hydrating as well as nourishing when we eat. After gastric bypass surgery, the volume of food intake goes down dramatically due to the smaller stomach and decreased appetite. As a result, the amount of water intake from food goes down too. Our body requires 8 glasses of water a day (64 ounces), and, after surgery, all this water has to come from drinking. If patients weren’t big water drinkers before the surgery, then they really struggle post-op to maintain hydration.

Signs and symptoms of dehydration include:

  • Dry skin

  • Dry mouth

  • Dark urine

  • Decreased urine

  • Dizziness

  • Headaches

  • Lack of energy

It is crucial for patients to implement a daily hydration plan in conjunction with their post-op diet. Patients should make it a goal to keep fluids on hand and to drink at least 4-6 ounces every hour while awake. This may be difficult when they first get home, but it will become easier to drink as healing occurs and swelling is reduced.

When patients return home, they should aim to drink a MINIMUM of 64 oz of fluid per day!


I think the biggest surprise for my patients after gastric bypass surgery is how powerful the surgery is at eliminating appetite. Almost all patients have zero desire to eat food right after surgery and have to force themselves to stay nourished.

The main nourishment we get from food is protein, vitamins, water, and good fat. Patients have to work hard to get in these minimal nutritional requirements. It can be difficult in the beginning because patients are restricted in the consistency of their food due to healing of their stomach.

The surgery can also have a profound impact on smell and taste where many foods are no longer appealing and don’t taste good after surgery. This can lead to an aversion to eating and malnutrition.

To combat these side effects, we are a big proponent of protein shakes in the early post-op phase even when patients advance to solid foods. When things aren’t tasting or smelling too good it is much easier to drink a shake. They are also very convenient on the run when patients are too busy to slow down and cook a good meal.


After gastric bypass surgery, patients may discover that they have a heightened sense of smell. This can make them feel nauseated when certain foods are around. This nausea is usually transient, and patients are able to return to drinking or eating later on. We send everyone home with a prescription for anti-nausea medicine for instances when the nausea is prolonged and aren’t able to get in their fluids or protein.

Dehydration and malnutrition can also be causes of nausea, so staying on top of fluid and protein intake post-op is extremely important to avoid this unwanted side effect.


Contrary to popular belief, vomiting should not be common after bariatric surgery and could indicate a more serious complication. Granted, if patients are eating too fast or aren’t chewing their food well, then vomiting can occur. However, vomiting for any other reason in the early post-op phase should warrant a phone call to the office for further evaluation. I tell my patients vomiting for any reason in the first few weeks while on the liquid or full liquid stage is not normal and they should call the office immediately.

Emotional Changes

There are also emotional changes that may occur after gastric bypass surgery. At the end of a hard day, we look forward to eating something that tastes good or makes us feel good. Unfortunately, after the surgery, that feeling or relief is taken away.

Many patients come in 2-3 weeks out from surgery, and their mood is down because they are no longer able to deal with stressors in their lives with food. So patients have to learn how to manage stress in other ways, like going out for a walk, reading a book, buying something on Amazon, or discovering a new hobby. It is important to find other outlets for gratification.

We also put a lot of thought, time and energy into preparing a meal, eating a meal, and then planning the next meal. There are many hours in the day that revolve around food, and, if you take that away, it can leave a void. Some patients are pleased to find out the extra time allows them to focus on other aspects of their lives; while for others, finding new things to fill time can be a psychological struggle.

Our professionally led psychological Aftercare program gives patients the support they need to work through and cope with the different challenges they may face after bariatric surgery. Patients find a great deal of comfort in discussing their experiences with other people who are going through the same issues.

The Good News

Even though gastric bypass surgery is accompanied by a range of side effects, if properly educated and prepared before surgery, the effects should be minimized. Many patients come back to the office in the early post-op period saying how much better they feel and very surprised not to be sick. I tell them I don’t know who they talked to before surgery, but it wasn’t our patients. We work hard to make sure patients are well aware of what they are getting into and educated on post-op requirements to prevent side effects and complications.

After the first couple of weeks, patients say they have more energy than they’ve had in a long time. Well, our energy level comes from proper nutrition, hydration, and sleep, not Starbucks! Since patients are no longer taking in excess sugar, processed foods, or sodas, they are much more nourished and feel better than they have in a long time.

In addition to feeling better, patients start to see medical problems like diabetes, high blood pressure and sleep apnea disappear down the road after significant weight loss. As the weight falls off, most patients find that their self-image dramatically improves as well. Most patients also experience increased mobility, better mood, and a better outlook on life in general.

Despite what people say, gastric bypass is not an easy way out. It requires a significant life-style change and is a big commitment. However, if patients prepare themselves and work hard, the benefits far out weight any potential side effects or complications. I have never met a patient who wouldn’t do the surgery again and most say they wish they had done it a lot sooner.


Contact Nashville Weight Loss Solutions for more information on gastric bypass surgery.

Are you dieting and exercising on your own, but still not getting the results you want? Whether you need to lose 20 pounds or 200 pounds, Nashville Weight Loss Solutions offers a comprehensive range of proven weight loss programs to help. Contact our office today to schedule a consultation!

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