Sleeve vs. Bypass? Here Are 23 Pros & Cons to Consider

Article By: Whittany Gibson, RDN

Whittany is a Registered Dietitian Nutritionist who specializes in bariatric nutrition counseling, providing education and support prior to and following weight loss surgery.

Weight loss surgery can be scary. We know this. There are so many unknowns. You’ve heard success stories, and you’ve probably heard nightmare experiences as well. It’s hard to determine which surgery is the right option for you and which will offer the least amount of risk with the greatest reward. With bariatric surgery, the risks are minimal but definitely shouldn’t stop you from exploring your options.

After all, WLS could completely change your health for the better and add years to your life! Two common procedures you’ve likely heard of are vertical sleeve gastrectomy (VSG) and gastric bypass (Roux-en-Y). There are many things to consider before choosing a permanent procedure like either of these, and both will have their pros and cons. You should go into the WLS process with a complete understanding of what’s best for you long-term.

Sleeve gastrectomy has most certainly gained popularity in recent years as a result of fewer risks compared to gastric bypass. However, bypass is still an option for many people. Factors such as age, weight, and health conditions will be considered when you talk to your surgeon about which is right for you. Let’s break down the basics of these two procedures and review the pros and cons!

What is sleeve gastrectomy?

Also known as vertical sleeve gastrectomy (VSG), this procedure restricts your stomach size, removing at least 80% and leaving you with a stomach comparable to the size and shape of a small banana. It is usually performed laparoscopically via multiple small incisions in the upper abdomen.

Along with meal size restriction and other required eating behavior changes, you will also experience hormonal changes that aid in weight loss. Additionally, these hormonal changes help prevent future comorbidities and minimize or relieve current comorbidities associated with being overweight. These comorbidities include high blood pressure or other forms of heart disease, diabetes, high cholesterol, and sleep apnea among other health conditions.

Patients also report increased energy, improved mental health, increased confidence, improved fertility, and the list goes on... Sleeve gastrectomy is considered a restrictive procedure, not malabsorptive, therefore lessening the risk of malnutrition.


  • Performed laparoscopically
  • Restrictive, not malabsorptive
  • Reduced appetite from hormone changes, early satiety
  • Less concern with post-op multivitamin supplementation compared to gastric bypass
  • Reduced risk and complication rate compared to gastric bypass
  • Reduced risk of dumping syndrome
  • Improved comorbidities and prevention of other comorbidities


  • Risk of worsening or developing acid reflux or GERD symptoms
  • Stomach can stretch if not disciplined with meals and meal sizes
  • Lifelong multivitamin supplementation
  • While not necessarily common, surgical risks include excessive bleeding, infection, adverse reactions to anesthesia, blood clots, gastric leak, intestinal hernia, gastric sleeve stricture, gallstones, deep vein thrombosis (DVT)
  • Possible malnutrition or nutritional deficiencies
  • Slower weight loss compared to gastric bypass (which may not be considered a negative)
  • Patients may lose less weight compared to bypass

What is gastric bypass?

Also known as Roux-en-Y, gastric bypass was the hottest weight loss surgical option in years past and continues to be an option but, with its associated risks, has become more of an option based on necessity and individualized needs. With gastric bypass, a small gastric pouch (stomach) is created and is attached to the lower part of the small intestine, bypassing the upper portion. This aids in decreasing the absorption of calories and nutrients, which makes this surgery method “malabsorptive” in addition to restrictive.

Food is still digested but essentially takes the fast track. Bypass can be performed laparoscopically as well as through open incision. Weight, age, and health condition will determine whether you might be a good candidate for gastric bypass. One primary downside to gastric bypass is the risk of malnutrition. To help avoid this, patients have to be stringent with multivitamin supplementation, consistent with follow-ups with your surgical team and dietitian, be regimented with a healthy diet, and have labs drawn regularly to assess nutritional status.

Another drawback is dumping syndrome. Given the route of your foods and fluids, if your bowels aren't ready for what you consume, you can experience nausea, fatigue, lightheadedness, sweating, shakiness, irritability, rapid heart rate, abdominal cramps, and diarrhea. Making appropriate food choices and following guidelines can help you to avoid dumping syndrome and food intolerances. Let’s look at the pros and cons of gastric bypass.


  • Rapid and dramatic weight loss
  • Continued weight loss past one year up to 24 months
  • Reduced appetite from hormone changes, early satiety
  • Weight maintenance favorable even 10 years post-op
  • Improved quality of life, reduced or reversed comorbidities


  • Greater chance of dumping syndrome resulting in diarrhea, vomiting, or nausea
  • Long-term concern for malnutrition and nutrient deficiencies
  • Lifelong multivitamin supplementation
  • While not necessarily common, surgical risks include excessive bleeding, infection, adverse reactions to anesthesia, blood clots, gastric leak, intestinal hernia, gallstones, deep vein thrombosis (DVT)

What are some other details to consider when getting bariatric surgery? 

It is obvious that bariatric surgery can dramatically change one’s life. But it’s up to you to use this tool to your advantage and support it with lifestyle changes. With both VSG and gastric bypass, you must follow a regimented and healthy diet, practice mindful eating habits, and be consistent with exercise.

To maintain a good nutrition status you must take your bariatric multivitamin as directed and be consistent. It's imperative you follow up with your surgical team on a regular basis for the first year to minimize complications and to ensure you are on the right track with your weight loss.

Additionally, you should follow up with your bariatric dietitian on a consistent basis following surgery to ensure you are meeting your needs and optimizing weight loss with adequate nutrition. This is definitely not a decision to take lightly, so speak thoroughly with your surgeon and make sure you ask the right questions. Moreover, choose a surgery center that supports you, listens to you, and provides an adequate amount of education.

BariMelts provides general recommendations, not to be construed as medical advice. Please consult your doctor.

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