Semaglutide causes impressive weight loss. But is it better than weight loss surgery?

The New England Journal of Medicine published a study on February 10, 2021 showing that an existing diabetes drug called semaglutide (brand name Ozempic—everybody has seen the TV commercials), is effective for causing weight loss when combined with diet and exercise. This study got a lot of press coverage after it was published – see the New York Times article, and the Medscape article.

This is a good study because it was large (1961 participants), randomized (drug vs. placebo), and double-blinded (investigators didn’t know which patients got drug vs. placebo). Participants were randomized to get either the drug and lifestyle intervention, or placebo and lifestyle intervention. Participants all had a BMI >30, or BMI >27 with other weight-related medical issues. Of those participants:

  • ¾ of them were female
  • Average age was 47 years old
  • Average weight was 231 pounds…
  • So the average BMI was 38

The results were quite good. At 68 weeks—one year and four months—average weight loss was 33.7 pounds, which is 14.6% of initial weight. It’s important to note that this describes average weight loss—some patients lost more than the average, and some lost less. 

The breakdown of weight loss ranges in the study are as follows: (remember, the average starting weight was 231 pounds / BMI 38)

  • 33% of patients did great and lost ≥20% of their weight…bringing their final weight to 185 pounds or lower
  • 31% of patients did poorly and lost <10% of their weight…bringing their final weight to 209 pounds or higher
  • 19% of patients lost 10-14.9% of their weight…bringing their final weight to 196-208 pounds
  • 17% of patients lost 15-19.9% of their weight…so, their final weight was 185-196 pounds

Given the lack of safe and effective weight loss medications currently available, these results are significant. 

The primary medication in use currently for weight loss in the United States is phentermine, which results in an average of 7.5% weight loss. Phentermine is only approved for short-term use, and when discontinued, weight regain tends to happen. Compared to that, semaglutide patients in the above study lost twice as much weight (14.6%). Likely this medication would have to be continued long-term to prevent weight regain. 

How do the semaglutide study results compare with weight loss surgery results?

The semaglutide results sound good. But how do they compare with the results of weight loss surgery, which is currently by far the most effective treatment for obesity available today.

The most common weight loss operation in the US is gastric sleeve (also known as sleeve gastrectomy), which accounts for 70-75% of all first-time weight loss operations performed. I’ll compare the semaglutide results above with my gastric sleeve patient results, for which I have a full demographics and outcomes database. 

Using a comparable group of surgery patients with the same average starting BMI of 38, average weight at 12-15 months after surgery is 169 pounds.* This is an average weight loss of 68 pounds, which is 29% of initial weight.*

Weight loss statistics for gastric sleeve surgery and semaglutide:*

gastric sleeve weight loss vs. semaglutide weight loss

So what do these numbers mean?

  • There’s twice as much average weight loss with surgery compared to semaglutide. 
  • The chance to lose at least 20% of initial weight is 2.5 times higher with surgery compared to semaglutide. 
  • The chance to lose less than 20% of initial weight is only 12% with surgery vs. 67% with semaglutide.  

Comparing the above results, surgery results in significantly better weight loss than semaglutide, hands down

How do the unwanted side effects of semaglutide compare with weight loss surgery?

The drawback of surgery, of course, is that it is invasive and because it’s invasive, there are risks. So let’s look at side effects after both semaglutide and sleeve gastrectomy— again using my own database of patient outcomes. 

The semaglutide study above reports that side effects occur in 74.2% of patients, the most common being nausea, vomiting, diarrhea, and constipation. 

In my sleeve gastrectomy patient population, I certainly don’t see anywhere near a 74% rate of side effects. The main long-term potential issue with gastric sleeve surgery is an increase in heartburn/acid reflux symptoms, which occurs in roughly 15-20% of patients. 

There are other potentially severe complications that can happen early after surgery, such as blood clots and leaks, but studies have shown that with high-quality programs and surgeons, the risk for these potentially bad complications is very low. Our blood clot and leak rate for gastric sleeve surgery is 0%.* 

How does the cost of semaglutide compare with the cost of weight loss surgery?

What about cost? Unfortunately, insurance companies generally don’t cover medications for weight loss. The most common drug for weight loss, phentermine, is now available in generic form, so it is reasonably affordable for patients to buy. Semaglutide is a patent-protected drug (owned by Novo Nordisk), and is priced very high. One month of semaglutide costs around $1000. Likely the drug would need to be continued long term to help prevent weight regain. 10 years of drug therapy would cost $120,000!

The cost for surgery is approximately $20,000. 

  • A significantly lower price
  • Twice as much weight loss for the average patient*
  • Lower chance for side effects

In my mind, the winner is clear. 

The key for a successful weight loss surgery is choosing a good program and good surgeon with a track record of good outcomes. That way, you can maximize your chances for an excellent weight loss result, and minimize chances for complications.*

Learn more

Learn more about Dr. Oliak and his Los Angeles and Orange County weight loss surgery program by visiting

* Outcomes vary after weight loss surgery. Past results may not be indicative of future results.

More Weight Loss Surgery Resources


David Oliak, M.D.

Dr. Oliak is a board-certified, fellowship-trained surgeon who specializes in minimally invasive (laparoscopic and robotic) weight loss surgery. He has been in practice in Orange County, California, since 2002, has completed more than 3000 weight loss operations, and has a track record of excellent patient outcomes.*

Dr. David Oliak is the founder of the Oliak Center for Weight Loss. He started the Oliak Center because he wanted to provide weight loss surgery done right. His commitment has always been to provide the kind of care that he himself would want to receive. Dr. Oliak is affiliated with only the best bariatric hospitals and surgery centers in Los Angeles County and Orange County.

* Individual patient results vary. Past performance is not a guarantee of future results.

Which weight loss surgeon is right for you?

Download this guide of questions to ask your weight loss surgeon to help make the best decision for you.