Bariatric Surgery vs. GLP-1 Meds: 2-Year Weight Loss Study

Obesity is a chronic, progressive disease that affects millions of Americans. For people struggling with significant excess weight—especially those with a BMI of 35 or higher—there are more treatment options than ever before.

Many patients today ask us at New York Bariatric Group:

“Should I try weight loss medications like Wegovy or Zepbound first, or is bariatric surgery better?”

This is an important question. New medications in the GLP-1 class (semaglutide, tirzepatide) have gotten a lot of attention for their ability to help people lose weight. At the same time, bariatric surgery—like sleeve gastrectomy and gastric bypass—has been proven over decades to offer major, durable weight loss and health benefits.

But how do these treatments compare in real life, outside of the ideal conditions of clinical trials?

A new study from NYU Langone Health and NYC Health + Hospitals helps answer that question. It analyzed over 50,000 real-world patients to see who actually lost more weight over two years. The results provide important insights for anyone considering their options.

Let’s look at what this study found, what it means for patients, and how you can make an informed decision about the best approach for you.

About the Study

This was one of the largest real-world comparisons of its kind. Researchers reviewed medical records for 51,085 adults with obesity (BMI ≥35) treated between 2018 and 2024.

They compared two groups:

• Patients who underwent bariatric surgery (sleeve gastrectomy or gastric bypass)
• Patients who received prescriptions for GLP-1 medications (semaglutide or tirzepatide)

Unlike controlled clinical trials that select only certain patients, this study reflected the messy reality of daily clinical practice: different insurance coverages, varying adherence, diverse patient populations, and all the challenges people face in sticking with long-term treatment.

Why Real-World Data Matters

When new weight loss drugs were first approved, they showed impressive results in clinical trials: semaglutide (Wegovy) delivered average weight loss of 15–21% of body weight.

But real-world patients often don’t get those same results. Why?

• Insurance may deny or limit coverage.
• Many patients can’t tolerate the side effects.
• Adherence drops over time because of costs or tolerability.
• Dose escalation might be inconsistent.
• Patients in the real world often have more complex health conditions.

That’s why studies that look at real-world outcomes are so valuable. They show what actually happens to typical patients, not just ideal trial participants.

Key Findings of the Study

Here’s the bottom line from this analysis: bariatric surgery delivered approximately five times more weight loss than GLP-1 medications after two years.

Average results after two years:

• Bariatric surgery: ~24% total body weight loss (~58 pounds average)
• GLP-1 medications: ~4.7% total body weight loss (~12 pounds average)

Even among patients who stayed on GLP-1 medications continuously for at least a year, weight loss averaged only ~7%. This gap is striking, especially given the high expectations people often have for weight loss injections.

Why Were GLP-1 Results Worse Than Expected?

Clinical trials for GLP-1 medications showed weight loss averaging 15–21%. But in this real-world study, it was only 4.7%.

Why?

High Dropout Rates

• Up to 70% of patients stopped GLP-1 treatment within a year.
• Insurance approvals often expire or change.
• Side effects (nausea, vomiting, diarrhea) lead many to quit.

Cost Barriers

• Even with insurance, co-pays can be high.
• Some insurers require repeated re-authorizations.

Dose Escalation Challenges

• Reaching effective doses often takes months.
• Patients who can’t tolerate high doses see less weight loss.

Real-World Complexity

• Patients may have other medical conditions that interfere with treatment.
• Social, economic, and behavioral factors make adherence harder.

For many patients, these challenges mean GLP-1s don’t deliver the dramatic results they hope for.

Why Does Bariatric Surgery Deliver Better Results?

Bariatric surgery works differently than medication alone. It’s not just about restricting how much you can eat—it also changes the biology of weight regulation:

Anatomical Changes

• Smaller stomach size reduces intake.
• Changes gut hormone signaling (e.g., GLP-1 naturally increases).
• Slows gastric emptying.

Metabolic Improvements

• Improves insulin sensitivity.
• Can lead to remission of type 2 diabetes.
• Reduces inflammation.

Durability

• Weight loss tends to be maintained long-term.
• Relapse rates are much lower than with lifestyle or medications alone.

Safety Record

• Minimally invasive laparoscopic techniques.
• Very low mortality risk (similar to gallbladder surgery).
• Short hospital stays.
• Rapid recovery for most patients.

These features make bariatric surgery the gold standard treatment for people with severe obesity.

Clinical Implications: What Patients Should Know

This study has important takeaways for anyone deciding between medication and surgery.

Realistic Expectations for GLP-1 Medications

• GLP-1s can be a powerful tool.
• But real-world weight loss is often modest (~5–7%).
• Many people can’t stay on them long-term due to costs or side effects.
• Insurance coverage can be inconsistent.

The Role of Bariatric Surgery

• Delivers much greater average weight loss (~24% vs ~5%).
• More durable results over many years.
• Proven improvements in obesity-related diseases (diabetes, hypertension, sleep apnea).
• Strong safety profile in experienced centers.

Combination or Sequential Approaches

• Some patients benefit from GLP-1s before or after surgery.
• Using medications can help people qualify for surgery or manage weight regain.
• Personalized plans can combine tools to get the best results.

When to Consider Switching from GLP-1s to Surgery

GLP-1 medications are not “failures” if you don’t lose enough weight. They’re one tool—but not the only one.

Patients who should consider surgery include:

• Those with BMI ≥35 who don’t get sufficient weight loss on GLP-1s.
• Patients who can’t tolerate or afford long-term GLP-1 therapy.
• Those with obesity-related health problems that remain uncontrolled.
• Anyone wanting a more durable, long-term solution.

Addressing Common Misconceptions About Bariatric Surgery

“Isn’t surgery the last resort?”

Actually, surgery is the most effective treatment for severe obesity. Guidelines recommend considering it early for patients with BMI ≥40 or ≥35 with comorbidities.Waiting until all other options fail just prolongs health risks.

“Isn’t surgery risky?”

Modern bariatric surgery is very safe.

• Mortality rates are similar to gallbladder removal.
• Most surgeries are laparoscopic with small incisions.
• Hospital stays are often 1–2 nights.*
• Long-term risks are low, especially with proper follow-up.

Unlike most practices that keep patients waiting months for surgery , patients who start the process with NYBG are typically able to schedule surgery within a month of their first visit. Our patients also have the benefit of a one day clearance visit, instead of needing to take a week off work.     

An additional benefit to our patients is our ambulatory surgery centers where patients are able to go home the same day of their procedure. That way patients can recover in the comfort of their home instead of the hospital.

They also get personalized and private care form a team that is well versed in bariatric surgery and focused on their smooth and rapid recovery.

“Isn’t it cheating?”

Obesity is a chronic disease, not a willpower problem.

• Surgery changes the biology that makes weight loss so hard to maintain.
• It’s a medical tool, just like insulin for diabetes.
• Patients still need to make healthy choices, but surgery makes those changes sustainable.

“I heard you regain the weight anyway.”

Some weight regain over time is normal. But on average:

• Bariatric surgery patients maintain much more weight loss long-term than lifestyle or medications alone.
• Relapse rates are far lower.
• Surgery changes the body’s weight-regulation set point.

Setting Realistic Expectations

No treatment is magic.

GLP-1 Medications:

• Help many patients, especially those with BMI <35 or those not ready for surgery.
• Real-world weight loss averages ~5–7%.
• Require long-term use (often lifelong).
• Insurance and cost barriers can limit access.

Bariatric Surgery:

• Best results for BMI ≥35 with health problems.
• Average ~24% long-term weight loss.
• Lifelong commitment to healthy eating and follow-up.
• Nutritional monitoring is essential.

For many patients, the choice isn’t either/or—it’s finding the right sequence or combination that fits their health needs and life goals.

Advice for Patients Considering Their Options

If you’re living with obesity, know that you deserve real treatment—not blame or stigma.

Talk with a bariatric specialist about:

• Your weight loss goals
• Your medical history and risk factors
• How medications and surgery can work together
• Insurance coverage and costs
• What support you’ll get before and after any treatment

At New York Bariatric Group, we believe in personalized, evidence-based care. We work with you to choose the plan that will give you the best chance at long-term success.

Conclusion

• Obesity is a serious, chronic disease that needs serious treatment.

• The new NYU Langone Health study shows that in the real world, bariatric surgery consistently delivers far greater weight loss than GLP-1 medications alone.
• That doesn’t mean medications are useless. They remain an important option for many patients—but real-world results require realistic expectations.
• If you’re not getting the weight loss you need with GLP-1s, or if you can’t stay on them because of cost or side effects, bariatric surgery is a safe, proven, and durable alternative.

You don’t have to fight this battle alone.

Ready to learn more about your options? Schedule a consultation with New York Bariatric Group today. Let’s find the approach that works best for you.