Do New Weight Loss Meds Mean the End of Bariatric Surgery?

Anne L. Peters, MD; Miguel A. Burch, MD


September 28, 2023

This transcript has been edited for clarity.

Anne L. Peters, MD: It's nice to meet you, Dr Burch.

It's going to be really interesting to discuss the role for bariatric surgery these days, given that we have these new, wonderful medications that help people lose weight, seemingly effortlessly, although I don't think anything is effortless.

But before I pick your brain on that, I wanted to begin with a case I just saw this morning. It's a woman whose body mass index (BMI) was around 40. She had poorly controlled type 2 diabetes. We put her on semaglutide, and she lost maybe 10 pounds. But more importantly, her diabetes just became amazingly better. Her A1c is now 7. She's come back to see us now, with her BMI at 38, and she wants to go for bariatric surgery.

What would you tell me to tell her? Would you want me to switch her to tirzepatide to see if she can get more weight loss that way? Or do you think she's a good candidate for bariatric surgery, which is what she wants? How do you decide these days about what should happen to which patients?

Miguel A. Burch, MD: Dr Peters, it's a pleasure to meet you as well.

You have opened a Pandora's box of questions, because I think that none of us are extraordinarily clear on what to do on any of these patients.

A few weeks ago, I was looking at some presentations I've given in the past 10 years. At one point in my career, I could say that the only proven durable treatment for obesity is weight loss surgery. This was in the context of patients who are morbidly obese requiring risk reduction, not for a year or two, but for decades. And I'm not talking about 10-20 pounds, but patients requiring between 40-60 pounds of weight loss.

That was a previous era; we are now in a new one. And it's wonderful, in fact, to have the opportunity to serve so many patients with something other than just surgery. That frames the context for my answer to your question, which is that we're not sure.

The National Institutes of Health (NIH) criteria for bariatric surgery had previously withstood what had been the test of time. Those criteria were determined in 1991, and the risk-benefit ratio was weighed around surgery that was then performed open. Now, the adoption of minimally invasive surgery in this country for both primary as well as revisional surgeries is greater than 97%. We are in the era of robotic surgery, which has also improved the possibility of doing minimally invasive surgery.

Looking back on those NIH criteria, they determined that any patient with a BMI ≥ 40 was at such high risk for cardiovascular disease, that even if they didn't have any disease at the time (ie, no medical diagnoses, not taking any medications on a daily basis), they were still considered candidates for weight loss surgery at that point in time. The second group of patients are those with a BMI ≥ 35 who had high-risk comorbid conditions such as cardiovascular disease, diabetes, sleep apnea, etc. We've lived under those guidelines for a long, long time.

The patient you mentioned is diabetic, with a BMI that's come down from the 40s to 38 with utilization of medications. The question is, when do you decide to consider that patient for bariatric surgery vs continued medical therapy with the glucagon-like peptide 1 (GLP-1) receptor agonists? It's a difficult question.

A lot of the decision-making has to do with patient risk. If we have a slightly different patient — for example one who's had multiple abdominal surgeries and has heart failure — they probably are a bit better served by a lower-risk option with medications. A younger patient with no surgical risk factors may be better served with an operation. This is because one of the things that we think about a lot with the medications is their long-term, cumulative cost over years. It may actually eclipse the cost of surgery eventually.

The Limitations of New Weight Loss Medications

Burch: I think that's something you could help us understand. When people are on these medications, how long do they need to be on them for? What sort of cost is associated with the medication — not only the prescription, but also the monitoring of its possible side effects?

Peters: Cost is variable. Eventually some of these, maybe all of these, will become generic. But we'll also have newer agents that give you more and more weight loss.

This is evolving in the sense that, sure, I can get weight loss with semaglutide, but that generally doesn't get me to the target. The patient isn't where they really want to be at when they've experienced the medication's maximum benefit. Tirzepatide gives you somewhat more weight loss. But even still, I have patients who clearly are never going to reach a BMI < 40 who I think really would benefit from bariatric surgery.

More than that, these drugs do reach a plateau. People can and do start out-eating them and start regaining the weight because their sense of hunger comes back. But they also need to take these medications for life. There are all sorts of disruptions as to why people can and can't get medication. I often have people who come back and say, "I ran out of my Ozempic," "There was a supply problem," or "I went on vacation and lost it." There's an inherent problem with something that you have to do every week. I think that might make the effect of the medications to some degree less durable. Yet, if someone takes them and gets to a weight that is healthy for them, I think that's probably a win-win.

My other question is, how often do you combine a GLP-1 receptor agonist in patients after they have bariatric surgery? I have patients who have had bariatric surgery and may have lost 100 pounds, but they're still not at target. This isn't to say that their target is a BMI of 20. I'm saying that with a target BMI in the mid-20s, I will add in a GLP-1 receptor agonist to help with further weight loss. Even though they do slow gastric emptying to some degree, I by and large haven't seen a problem in patients who've already had bariatric surgery. What is your feeling about that?

Identifying Patients Who Benefit From a Multidisciplinary Approach

Burch: It's a really interesting proposition. I think that we have to change the way we look at obesity management as being either surgery or medicine and start thinking about it more as a multidisciplinary approach to a chronic and potentially relapsing disease, similar to cancer. For cancer, we totally think it's normal to have surgery plus chemotherapy plus radiation plus targeted therapies. I think obesity needs to be managed more like that as well.

In terms of how we deal with patients after surgery, it's been well recognized for a long time that endogenous GLP-1 goes up fairly significantly after bariatric surgery, both sleeves and bypasses.

Part of the outcome measures of whether bariatric surgery has been successful or not are fairly well defined in the surgery literature. We expect that patients who have bariatric surgery, whether that's sleeve or bypass, would have adequate weight loss at 1 year if they've lost 50% of their extra weight. When it comes to this issue, we talk in different numbers: excess weight loss vs total body weight loss. This can be confusing. To date, we've really used excess weight loss in the bariatric surgery literature. So, 50% of your extra weight has to come off at 1 year to be considered adequate weight loss.

We can start identifying patients who are looking like they're not going to hit that number probably within 6 months of their surgery. You can think of it like a growth curve that we use in pediatrics, where we talk about what percentile the child is in, but this is in terms of patients' weight loss.

We also look at patients' weight through the year and see whether they're coming off a trajectory.

For example, we're noticing that Mrs Jones, who should have been at 50% excess weight loss by the sixth month, is only at 30%. That's an opportunity that we haven't had before. Usually it was, "Mrs Jones, you have to talk to our dietitians, you have to become more active, etc." And Mrs Jones is saying she's feeling hungry again. Until the new medications came about, there was no option for Mrs Jones. But now we work with the medical bariatrician in our practice and talk about starting medications then, with the goal of salvaging the weight loss or hitting that 50% excess weight loss before the first year.

That's one bucket of patients who I think we can work as a multidisciplinary group to ensure long-term success.

The other group of patients who can benefit are those who have had bariatric surgery and are 2, 3, 4, or 5 years out, and have now returned having gained some if not all of that weight back. For those patients, it's multifactorial why they've gained weight back. Sometimes it's the anatomy. It can be psychosocial events. But all of them together can be helped by decreasing hunger.

Those are the two buckets to think about in terms of augmentation of surgical outcomes: the patients who are heading toward inadequate weight loss within the first year, and those patients who come back after a long period of absence from the program and their weight loss can be spurred with the use of a GLP-1 receptor agonist.

Peters: I love the way you're thinking about this, because I hadn't thought about it in quite this way before.

I also hadn't thought about the notion of the trajectory of weight loss. You can tell at 6 months if someone's going to be at their goal by the end of the year. Is it really true that this is predictable?

Burch: As predictable as it can be. There's been a couple of publications, one from the group at Duke, that looked at the weight loss curve to predict weight loss over a period of a year. The American College of Surgeons, through their Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP), has a publicly available calculator to predict weight loss over the span of about a year. We've been utilizing that at Cedars-Sinai to estimate weight loss throughout the first 12 months. When we start seeing a real divergence from those numbers, that's when we act.

It's important to note that medication intervention has not yet been indicated in the first 12 months after surgery because the GLP-1 levels should be high. We're currently designing a clinical trial to answer that question of whether or not intervention makes sense and, if so, at what time points.

Peters: It does make you wonder about all the factors that go in to having a person become overweight or obese, particularly obese. It seems to me that they're so multifactorial, because the responses to treatment are so multifactorial. But again, you're thinking of this like cancer or some other chronic disease that requires multiple modalities to treat. I think it's great.

I would argue that we can never forget lifestyle in all of this, because I think people need to do the things that hopefully can keep them healthy, like exercise and eating higher-quality food while they're going through surgery and medication management.

Remaining Vigilant to the Risks Associated With Significant Weight Loss

Peters: How do you look for and treat any kind of nutritional deficiencies. What's your focus when dealing with that?

Burch: That's an important question, particularly when you talk about large amounts of weight loss.

We can now say these medical interventions are causing significant weight losses — 20%-30% total body weight loss, which are numbers that had previously been reserved for only bariatric surgery. So, the possibility for nutrition issues now really encompasses both medical management and surgical management.

The Obesity Society, the American Society for Metabolic and Bariatric Surgery, and others have all gotten together to discuss the best way to screen for vitamin deficiencies, etc. They have a position statement that's been updated a number of times.

Essentially though, we look for deficiencies in the vitamins every 6 months in the first year after bariatric surgery. Previously that had been every 3 months, but we realized that we were getting a lot of labs that were normal. So, as a society position statement, it's been changed to labs twice a year in the first year if everything is going normally, and once a year thereafter. We especially look for vitamin B12, fat-soluble vitamins, and vitamin D.

Anemia is something that's popped up as being really important. As many as 25% of patients who have bariatric surgery will become anemic at some point in the first 2-3 years after surgery. This has to do partly with absorption, but also as a result of the change in diet. That's something we look after pretty carefully.

With the tremendous success of the medications, I think we're also going to start looking for those things in these patients as well.

Peters: That's important and probably should be studied, because people are losing a lot of weight. I've seen deficiencies in a number of micronutrients, especially if people really experience an effect. I had somebody have a tremendous vitamin B12 deficiency after he lost a lot of weight on tirzepatide. We need to think more like you think, which is, this has happened to a person, so let's see if there's anything we need to correct or worry about.

There has been some concern about increasing the risk for suicide with either bariatric surgery or these GLP-1 receptor agonist–type drugs. I don't know how much it's caused by losing weight itself or the other factors that go along with it, but I certainly think it's important to consider the mental health of patients. As their bodies change and they have to adjust to a new way of eating and being, they need all the help that they can get.

Is that something you've noticed or been concerned about in your bariatric surgery patients?

Burch: For a long time, there's been a lot of correlations between surgical treatment of obesity and the rearing up of a lot of psychosocial issues that maybe led to the obesity to begin with. Like all change, positive change can still be stressful. If you take away some of the adaptive behaviors that have been previously utilized to control anxiety, stress, and depression, things really have a tendency to present themselves again.

Because of the degree of weight loss that's being seen with these medications, I think it's going to be very clearly an analogous situation in the medical management of weight. Some patients are going to feel like something is taken away that helps them cope with emotions.

As a lot of bariatric centers do, we have a psychologist, a social worker, and support groups are run pretty routinely for the patients. If you're going to run a support group for patients, that should be monitored by a health professional, not run entirely by patients. That's because it's important to keep people on track and identify warning signs that somebody is decompensating, whether that's with suicidal ideations, self-harm behaviors (eg, alcohol and drug utilization), or other high-risk behaviors that we've seen in patients. It's really important that these interventions happen early on.

Support groups are a great way to build a community among the patients so that they can help each other. But having it monitored by a health professional allows it to serve as a bit of a screening tool as well to identify patients who are at risk.

The knowledge base for dealing with this is there already in bariatric surgery. I think it's important to share it and really come together with the medical bariatricians to establish a multidisciplinary approach to the problem.

Peters: That's a great answer. I think you and your colleagues have the advantage in that you seem to be so organized around this. As a diabetologist, I'm not used to seeing lots of weight loss except in the setting of bariatric surgery, where they have the services and resources you're talking about.

In my little clinic, I say, "Wow, look at that, your blood sugars are better, and you've lost some weight," but I have to start thinking about it differently too. I have increasing tools that are going to allow my patients to lose more and more weight medically. How do I support my patients in this journey and make sure they're kept safe and healthy?

I think these were really good points. I love talking with you about this and hope we get to work together on some patients and take good care of them.

Predicting Which Patients Are Most at Risk for Weight Regain After Ceasing Medication

Burch: That makes two of us who hope that. I have a couple of questions for you. A lot of studies have shown that people, when they come off the medications, tend to gain their weight back. But does that happen at the same rate for all the patients? Have you noticed, or has it been reported in the literature, that there are groups with certain BMI or comorbidities that are more at risk for weight regain after coming off the medications? How do you decide which patients need to be on it for life or which patients are at high risk for recurrence of their weight?

Peters: There is no organized literature around this because all of the big clinical trials look at putting you on the drug and what happens; they don't look at taking you off the drug.

In my own practice, I have lots of patients who are on these agents. I've seen so many different responses to these agents, just as I've seen so many different causes for obesity. I've seen patients who can cut back. If I instruct them to take half the dose every week or the whole dose every other week, they'll manage to maintain their weight on less. But, in my experience, almost no one has weaned off of it and kept the weight off. And I can't tell you who will gain the most weight back. In most cases, people gained between 50% and 80% of the weight back. With semaglutide, I think I've seen less weight loss than with tirzepatide, which gives you even more weight loss.

I'm not sure, as I start getting to know what happens in people who have even more weight loss, what the weight regain looks like. But certainly, with semaglutide, people just say their hunger comes back, and if they stop it fast, they're just ravenous. So, I always help people taper it if there's a cost or access issue. I'll reduce the dose, because some of it is better than none of it.

We don't have good data characterizing who's more at risk for the weight regain. But I bet most people will regain the weight to some degree if they stop their agent.

Burch: Interestingly, in bariatric surgery, we've spent a long time trying to standardize approaches to the surgery. That's why the American College of Surgeons has a standardized approach to the accreditation of bariatric centers, which strives to enforce quality delivery and outcomes.

Despite all those efforts, nationally, we've never seen the utilization of bariatric surgery increase above 2% of those eligible. Another way to say that is, of all the patients who would qualify for bariatric surgery in the United States, only 2% of patients seek it out. That means that 98% of patients who really need help aren't seeking it out.

How do you believe that's working when it comes to these medications? Medication has a side-effect profile, but it also has a cost issue. Are there any studies looking at utilization of medications in the people who can qualify for it?

Peters: You ask such good questions. I don't think we look at the world the way you look at the world, which is why this is such a fascinating conversation to me.

In my world, we're giving these drugs for the treatment of obesity and type 2 diabetes. That's easy, because I say, "This is going to help reduce your cardiovascular risk. It's once a week. It isn't bariatric surgery. It doesn't mean that you have to go to the operating room. It really is pretty simple."

If you're talking about using a weight loss drug like semaglutide, that's a different conversation because it's just about weight loss. The barrier there, I think, is cost, because a lot of the insurance plans don't cover weight loss treatment, at least in terms of medication. It's hard to figure out how many people who would qualify on the basis of weight alone would or wouldn't take these agents.

I can tell you that side effects are common. I certainly have patients who can't take them. In fact, I hear a lot about side effects. I had one clinic day not that long ago where I saw three patients in a row who were on either tirzepatide or semaglutide. Some were suffering from having lost too much weight, and one had been hospitalized for a gastrointestinal problem they felt was due to the medicine and required help.

These medications aren't as simple as saying, "Here, just take this. You're going to be fine." It does take follow-up. There are side effects, and I don't think there is a one-size-fits-all approach. I do think acceptance of an injectable agent or maybe even an oral agent will probably be easier for most patients than bariatric surgery, because it's not surgery.

But I think it's complicated treating people who are overweight and obese because there's a lot of psychology behind it, as you well know. I try to move gently with people because I don't want them to feel badly about themselves, but I want them to be healthier. And we both know well the health consequences of obesity.

Protecting Patients Means Ensuring Careful Prescribing and Monitoring

Burch: I think you hit on something very important there, which is that it's interesting to me how when I talk to patients about their diabetes, hypertension, or something similar, they're very open to discussing it. But if you talk to people about obesity, there is a fairly emotional response many times that has to do with concerns about biased, prejudicial behavior they've experienced in the past. I think it's even more complex than talking to patients about things we think are hard, like cancer. There's a lot of emotional attachment to the term obesity.

Again, it's really important to advocate for the multidisciplinary approach to these problems. In our experience, we are a department of surgery, but we hired an internal medicine doctor into our department in order to ensure that we were approaching this as a multidisciplinary, comprehensive center. In addition to that, we've started utilizing occupational therapists who are trained specifically around obesity, behavior management, etc. I think the field is wide open.

As a bariatric surgeon, we're seeing a 20%-30% reduction in volume since the advent of these medications. That's a big reduction, but one I'm welcoming with open arms because of the impact it's going to have on our patients.

Peters: It's kind of a mixed blessing. You want people to be successful with weight loss no matter how they get there. Everybody's getting used to these agents, seeing how they work in themselves and what point of weight loss they'll get to, but my bet is that people will still need bariatric surgery, just like they need these medications. We'll find some balance to it.

I would love to work at the preventive end of all this and use these agents in people who are not yet significantly overweight and see if I can treat their diabetes and prevent obesity. My dream is to use this earlier rather than later to help patients avoid all these complications and issues down the line.

Burch: As you know, prescribing the medication when it's not for just diabetes is something anybody can do. That's important to talk about, because I've seen medical spas popping up and physicians prescribing the medications without any of the considerations we've talked about thus far — without goals around A1c if it's a patient with diabetes, but also not even looking at the nutritional impact on patients.

We as a society of physicians really need to talk about this, because the potential for abuse is significant. We're talking about a very vulnerable population of patients who are really willing to turn to anything to lose the weight. So, it's going to really be important over the next few years, or maybe even months, to think about how we as different societies are going to help manage this issue so that vulnerable patients are not getting taken advantage of by people who maybe shouldn't be prescribing the medication — because that is maybe all they're doing, writing a prescription and walking away.

Peters: We need to make sure that everyone takes good care of the patients, because I agree. Thousands of things have been advertised over time for weight loss, and this one actually works. But I believe it needs to be used in a controlled setting, because there are other side effects and things that need to be watched in patients who are on any of these treatments.

Do you have any closing comments you'd like to make?

Burch: The only thing in closing that I'd like to reflect upon is, again, the multidisciplinary approach that's required to take care of patients with a chronic relapsing disease that's going to be with them for their entire lifespan. We know that the improvement in comorbidities doesn't require a lot of weight loss. Really, 10%-15% of weight loss is enough to sort of improve all the health problems. But given the recidivism of that weight loss, surgery at some point may be an option for some patients. But I appreciate the fact that people like yourself, who are committed to ensuring good outcomes, are part of this group. Thank you very much for your time.

Peters: Thank you for your time. I really enjoyed this and hope we get to continue the conversation.

Anne L. Peters, MD, is a professor of medicine at the University of Southern California (USC) Keck School of Medicine and director of the USC clinical diabetes programs. She has published more than 200 articles, reviews, and abstracts, and three books, on diabetes, and has been an investigator for more than 40 research studies. She has spoken internationally at over 400 programs and serves on many committees of several professional organizations.

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