In this episode of PodMD, Gastroenterologist Dr Matt Kitson will be discussing the topic of weight-loss injectables and gastroenterology. We discuss what weight-loss injectables are, how they work, why these medications are increasingly relevant to gastroenterology practice, as well as conditions they can improve, and their potential side-effects.
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Today I’d like to welcome back to the PodMD studio Dr Matt Kitson.
Dr Matt Kitson is an experienced Gastroenterologist and Hepatologist providing care in the Eastern and Southeastern suburbs of Melbourne, and also in Gippsland.
You can read more about Matt on his profile page on our PodMD website.
*Please listen to our disclosure at the end of this podcast
Today, we’ll be discussing the topic of weight-loss injectables and gastroenterology. Matt, thanks for talking with us again on PodMD today.
Matt: Thank you for having me.
To begin, can you briefly explain what we mean by “weight‑loss injectables,” particularly GLP‑1 and related agents, and how they work?
Matt: By weight loss injectables, really we’re referring to GLP-1 receptor agonists, which is a glucagon-like peptide-1 receptor agonists, which are injectable drugs generally given once a week.
So the two most commonly prescribed medications are semaglutide, which branded as Zempic for diabetes and Wegovy for management of weight. And the other one is Tizepatide, which is branded as Mounjaro, which is used for both diabetes and for weight management.
These medications have multiple actions in glucose and appetite regulation, which is specifically mediated by these GLP-1 receptors, which are present in lots of organs, but specifically in the pancreas, the gut and the brain. for the action of weight loss. They cause early satiety and also delay gastric emptying and promote insulin sensitivity and release. So overall this ends up in resulting in a negative energy balance and this results in weight loss.
Why are these medications increasingly relevant to gastroenterology practice?
Matt: So as many people will be aware over the last couple of years, the prescription of these medications is becoming increasingly common and often the most common side effects are gastrointestinal in nature given how these medications work. So from a gastroenterology point of view, we’re both prescribing these medications more and seeing more side effects as well.
The other thing to be aware of is that Semaglutide or Wegovy and Ozempic have recently been TGA approved as a treatment for more severe fatty liver where steatohepatitis is present, and this is probably one of the most effective treatments we have for this, and it’s a very common treatment we see in both primary care and as gastroenterologists. There’s also implications of patients being on these medications in preparing for endoscopy, which I’ll address later.
What types of GI-related conditions can improve with weight-loss injectables, and what conditions may worsen?
Matt: So specifically steatohepatitis will improve, so the presence of quite significant fatty liver disease by the loss of fat and specifically the visceral fat present in the liver. But there’s other things. So if a patient has underlying delayed gastric emptying or nausea, this may worsen. And also if there’s underlying chronic diarrhea or constipation, this may get better or it may worsen depending on which side effects are experienced.
What is your most important advice to patients and prescribers with regards to GLP-1 therapies?
Matt: So whilst these medications are often used in primary care for a short-term period, maybe 6 or 12 months, these medications have really been designed and studied as long-term therapies. And I tend to advise patients prior to starting that they may need to be on them in the long term, although cessation might be possible after a period. But recent studies have shown there’s a really high incidence of weight gain in the first 12 months after cessation.
The other thing that is a very important point to be aware of that in addition to loss of visceral and subcutaneous fat with these medications, muscle loss occurs whenever we lose weight. And really concerted efforts need to be made to try and minimise this, as muscle is a metabolically active tissue. So if we lose muscle mass, it results in a lower basal metabolic rate and can have long-term negative health consequences.
The other thing to be aware of is that if a patient loses weight and they lose both significant amount of muscle and fat, if they stop it and then they regain weight, they’re going to be regaining that weight as fat, not as muscle, and it’s actually going to be harder to lose weight again down the track. So really important advice is… Because patients on these medications are going to have a reduced appetite, they really need to prioritise dietary protein intake, aiming for 1 to 1.5 milligrams per kilo per day. They need to make sure they’re getting adequate fibre to try and minimise gastrointestinal side effects, especially such as constipation and a fibre supplement may well be needed. And the other thing is this needs to be seen as part of long-term lifestyle changes, not just taking the medication for a period of time and other things such as regular exercise should really be put in as part of these lifestyle changes.
What are the most common GI side‑effects to weight-loss injectables such as GLP-1 therapies, and how can GPs manage these practically (eg. dose titration, dietary changes, managing nausea or constipation)?
Matt: Yeah, that’s a really good question. So side effects, and specifically gastrointestinal side effects, are common after commencement of the medication or after dose escalation. And often these side effects are mild to moderate and will settle with time. So one of the most common things that’s seen is nausea. due to the effects of delaying gastric emptying. So slow titration of dose upwards and having smaller meals more common will help and overall this should improve with time.
If patients are getting significant ongoing symptoms, then instead of having an injection every seven days, this could be pushed out to every eight or nine days. And with nausea, the other thing that needs to be considered are the patients on medications that may also delay gastric emptying and specifically opiates and certain other antidepressant medications can do this. With regards to constipation, having adequate fibre intake and a good amount of water, at least a litre and a half a day, as well as engaging in regular physical activity. Diarrhoea is often mild to moderate and can be managed as well.
Are there specific red‑flag GI symptoms in patients taking weight‑loss injectables that should prompt a GP to stop the medication and refer urgently?
Matt: So one of the really uncommon but severe side effects that has been noted with these medications is pancreatitis. So if a patient’s developing severe abdominal pain suspicious for pancreatitis, then this needs to be further investigated.
How should GPs approach prescribing these medications in patients who already have established GI conditions – for example, IBD, coeliac disease, or chronic constipation?
Matt: So in patients with either celiac disease or inflammatory bowel disease, these conditions need to be well managed and in remission prior to commencement of these medications, because if they do get gastrointestinal side effects, We want to know that this is a side effect and not related to a flare of disease, especially inflammatory bowel disease. With regards to constipation, it’s really common, but generally constipation associated with these medications can be managed and we’ve got lots of tools in our armamentarium to help there.
If a patient develops new or worsening reflux, nausea, or altered bowel habits, how can GPs distinguish between predictable medication effects and warning signs of an underlying pathology?
Matt: So I guess the key thing is if the onset of these symptoms relates to commencement of the medication or it’s related to an increase in the dose, then it’s much more in keeping with the side effect. And if withholding a dose improves those symptoms, again, that’s in keeping with the side effect. If it’s a more severe side effect that the patient’s getting that persists after withholding or ceasing the medications, then further investigation might be necessary. But by far and away, the most likely thing that’s going to be a side effect.
How should GPs structure follow‑up and monitoring for patients using weight‑loss injectables to identify GI issues early and adjust therapy safely?
Matt: So each pen has four doses and it’s a weekly dose, so it really lends itself well to four weekly follow-up initially after starting the medication and also to titrate the dose up if necessary and a check-in about side effects. And also efficacy as well is really important. And one of the key things is what we don’t want is particularly rapid weight loss. Half a kilo to a kilo a week is really the sweet spot of of weight loss and just also being aware that weight that is being lost is not just fat, but there’s also going to be an element of muscle loss there as well.
Do GLP-1 therapies have any impact on how you plan for gastroscopy and colonoscopy?
Matt: So that’s another really good question. So given that these medications delay gastric emptying, it can have an impact. on gastroscopy and colonoscopy. That’s in specifically with regards to gastroenterology, but it also does have an impact on other surgeries as well. So our approach with endoscopy tends to be to have all patients on clear fluids for 24 hours prior to ensure that there’s no retained food in the stomach. And the other thing is if a patient is just having a colonoscopy, then sometimes we might consider whether we need to do a gastroscopy as well, just to make sure that the stomach is emptying.
To sum up for us, could you please identify the three key take home messages from today’s podcast?
Matt: Yes, absolutely. So firstly, the GLP-1 receptor agonists are their safe and effective medications. And the other thing that’s going to be a game changer is the availability of oral semaglutide or Wegovy slash ozempics. This has been approved in the US in December, and no doubt it will probably be available in Australia at some point. So given the availability of an oral medication, it may well be there could be even higher uptake of these medications.
The second point is that it’s really important to prioritize adequately dietary protein intake, aiming for 1 to 1.5 milligrams per kilo per day, as well as fibre intake. This is so that we can minimise the risk of losing muscle mass as this has a long-term impact on health.
And the final point that I’d like to make is that weight rebound is common following cessation of these medications in the first 12 months and hence making long-term lifestyle changes is really important if it’s being used as a short-term medication.
Perfect. Well, thanks very much again for your time and insights and we look forward to welcoming you again to the PodMD studio.
Matt: Thanks very much.
*We do hope you enjoy this podcast but please remember that the advice here is of a general nature and is not intended as specific advice about a given patient. The views and opinions expressed in this podcast are those of the doctor, not PodMD. If you do have a patient on whom you require specific advice then please seek advice from a colleague with appropriate expertise in that area.
