How Does Gastric Sleeve Work to Help People Lose Weight?
Why a smaller stomach leads to significant weight loss
Why a smaller stomach leads to significant weight loss
Imagine feeling full after a meal without eating nearly as much as you did before — and losing a lot of weight in the process. That’s the goal of gastric sleeve surgery, one of the leading types of weight-loss surgeries today.
Also known as vertical sleeve gastrectomy, gastric sleeve helps with weight loss by reducing the size of the stomach, limiting how much one can eat and lowering levels of hunger hormones. These changes help people feel full sooner and reduce their appetite.
Surgery isn’t the only option. New weight-loss medications, such as GLP-1 receptor agonists, are increasingly being used and offer a non-surgical option for some people. But results can vary, side effects are common and weight gain often occurs after stopping the medications.
For those with severe obesity or obesity-related health conditions, minimally invasive gastric sleeve surgery remains a widely used, long-term treatment option.
“Gastric sleeve surgery is one of the most effective treatment options for people with severe obesity — especially those with obesity-related conditions like type 2 diabetes, sleep apnea, high blood pressure, or high cholesterol — who haven’t had lasting success with diet, activity changes or medication alone,” says Mark Takata, MD a bariatric surgeon at Scripps Clinic Torrey Pines.
A bariatric surgeon can help you compare gastric sleeve surgery with other weight loss operations and weight-loss medications. They can also discuss combination approaches.
“Together, you can choose the option or combination of options that best fits your needs and supports your long-term health goals,” Dr. Takata says.
How does gastric sleeve work to help people lose weight?
Gastric sleeve surgery permanently reduces the size of the stomach. During the procedure, surgeons remove about 75–80% of the stomach. The remaining portion is reshaped into a narrow, sleeve-like tube.
With a smaller stomach, patients feel full sooner and eat smaller portions, which helps reduce calorie intake. The surgery also lowers hunger signals in the body by reducing hunger hormones.
“By removing the portion of the stomach that produces the majority of the hunger hormone ghrelin, gastric sleeve surgery can shift hormonal signals and significantly reduce appetite,” Dr. Takata says.
Gastric sleeve surgery is different from gastric bypass surgery because it does not reroute the intestines. This means there is a lower risk of nutrient malabsorption and certain long-term nutrient deficiencies.
Gastric sleeve surgery also differs from gastric banding, which uses an adjustable band to restrict the stomach without removing any portion of it.
Who benefits most from gastric sleeve?
Doctors usually recommend bariatric surgery for patients with:
- A body mass index (BMI) of 40 or higher
- A BMI between 35 and 39.9 with related health issues, such as type 2 diabetes, high blood pressure, high cholesterol, heart disease and severe sleep apnea
“These are often patients with severe obesity who haven’t had lasting success with diet, exercise or medically supervised weight-loss programs,” Dr. Takata says. “They’re ready to commit to long-term lifestyle changes and ongoing follow-up care. And, for the right candidate, gastric sleeve surgery can be a highly effective tool for long-term weight loss and better health.”
Pre-surgical evaluation: Why it matters
Before surgery, patients go through a pre-surgical evaluation to check if they are medically ready and prepared for lifestyle changes.
Patients meet with a dietitian. They review eating habits, portion sizes, protein needs and possible nutrient gaps.
A psychological assessment will also be included to help identify behaviors or mental health issues that could affect long-term success.
“These evaluation steps are not barriers. They are meant to support better outcomes and help patients build healthy habits for lasting weight loss,” Dr. Takata says.
How much weight can you expect to lose?
In the first six months to one year after surgery, many patients lose about two-thirds to three quarters of their excess weight. Long-term success depends on following recommended guidelines, including:
- Regular physical activity (about 150-300 minutes per week)
- Adequate protein intake
- Avoiding high-sugar and high-calorie drinks
- Limiting snacking and portion sizes
Health benefits beyond weight loss
In addition to weight loss, gastric sleeve surgery may improve or resolve several obesity-related conditions, including:
- Type 2 diabetes
- High blood pressure
- High cholesterol
- Obstructive sleep apnea
- Joint pain and mobility issues
- Fatty liver disease
Risks and long-term considerations
Gastric sleeve surgery, like any surgery, carries some risks. These can include bleeding, infection and blood clots. Some patients may also develop or have worsening acid reflux and may need lifelong vitamin and mineral supplements to prevent deficiencies.
Patients should follow a post-surgery diet, exercise, and take vitamins for long-term health and successful recovery.
“After surgery, the patient must follow a specific diet that enables the body to recover and get used to a smaller stomach," Dr. Takata says. "Thereafter, the patient must transition into a lifetime of healthy eating. Gastric sleeve surgery requires a commitment to living a healthier lifestyle.”
Gastric sleeve surgery vs. GLP-1 weight-loss medications
New weight loss medications, including GLP-1 treatments, are increasingly being used to treat obesity. These medications can help with weight loss by reducing appetite, increasing fullness and sometimes slowing digestion.
For some patients, GLP-1 medications can be a good first step, especially when combined with healthy eating and exercise. But results vary, side effects are common, and some people may not lose enough weight — or keep it off — with medication alone.
Weight regain is also common when GLP-1 medications are stopped. This can be a bigger concern for people with severe obesity or obesity-related health problems. In these cases, gastric sleeve surgery remains a proven option for significant, long-term weight loss.
Many bariatric programs now offer personalized plans that may include medication, surgery, or both.
“GLP-1 treatment can support weight loss before surgery or help with long-term weight management after surgery,” Dr. Takata says. “For others, especially those with severe obesity or obesity-related conditions, gastric sleeve may still be the most effective option for lasting results.”
Are you a candidate for weight-loss surgery?
If you’re considering weight-loss surgery, consult with a board-certified bariatric surgeon or member of a comprehensive weight management team. They'll assess your health history, review your options and explain the risks and benefits of surgery.
At Scripps, the bariatric surgery program offers a full team to support you through evaluation, surgery and long-term follow up