Training on Ozempic - and other GLP- 1 Agonists

Training on Ozempic

It’s become a bit of a cliché to discuss how drugs like Ozempic/Wygovy (GLP-1 agonists) are game changers in managing obesity. So instead, I’m going to skip over that and get to something a bit more practical. What should you expect in the gym, while taking a GLP-1 agonist?

This won’t be a technical article on mechanisms of appetite regulation, or GLP-1 receptor binding, or even what it means for a drug to be a “receptor agonist”. Instead, I’ll focus on the practical implication of taking a GLP-1 agonist on how you feel in the gym, what side-effects to expect, and how to manage some of the discomforts associated with GLP-1 side-effects. Hopefully, this will reassure people that they’re not the only ones going through these things.

Heartburn While Exercising, Especially Lifting

Heartburn and nausea are common side effects of taking GLP-1 agonists and are documented in the scientific literature. This is likely the result of GLP-1 agonists slowing digestion, resulting in food hanging around in your stomach for longer after you eat. This isn’t the full explanation, but it’s enough for this article.

Unfortunately, this feeling of indigestion seems to be further aggravated by lifting weights. This isn’t a problem unique to GLP-1 agonists and there are a few things that might be contributing factors. Firstly, feelings of indigestions and heartburn are more commonly reported in people suffering from obesity (the primary population taking GLP-1 agonists). Secondly, exercise is frequently reported to aggravate chronic heartburn, independent of other factors such as obesity or medications. So, when you add to this the slowing of gastric emptying (i.e., the time it takes for food to leave the stomach) from taking a GLP-1 agonist, you can end up with significant heartburn.

As a quick aside, you might be wondering why exercise would make indigestion worse. When you lift weights or exercise vigorously there’s a brief increase in intra-abdominal pressure associated with your body “bracing” to safely lift or exert itself. This increase in pressure is unavoidable, and good. It’s a reflex your body uses to ensure you’re safe and prepared to do hard work. The thinking is that this increased pressure when lifting combined with food sticking around in your stomach results in small amounts of your stomachs acidic contents “leaking” into your esophagus and causing a burning sensation. In plain language, when you lift something heavy or strain against resistance the muscles around your abdomen squeeze hard to prepare you to lift, putting pressure on your stomach, which might leak a bit of acid into your esophagus, which puts the “burn” in heartburn.

The good news is that this seems to mostly go away on its own with time. It’s not totally clear why, but we can make some educated guesses. Firstly, the side effects of GLP-1 agonists seem to fade with time all on their own. Secondly, people taking GLP-1 agonists to directly treat obesity can expect significant reductions in obesity, addressing one of factors associated with heartburn.

Takeaway

The easiest thing to do here is to avoid large or slow to digest meals before exercise. Make sure anything you eat in the two hours before your workout is low in fat and fibre and ensure the portion is small. Some of my clients have reported that avoiding exercise that require lying down also helps; such as bench press or sit up variations.

Of course, if you experience persistent heartburn you should consult a physician, as there are often effective treatment options.

Fatigue

GLP-1 agonists make it easy to eat less. Appetite plumets and some people even “forget” to eat meals. This is great for losing bodyfat. However, just because you don’t feel hungry doesn’t mean you aren’t low on fuel. Normally, we tend to connect these things in our minds “I’m hungry and tired”, but GLP-1 agonists can break this connection.

This isn’t a huge deal, but it does catch people off guard. When you’re in a significant calorie deficit, which is the kind of the point with GLP-1 agonists, it’s going to make exercise harder. You’ll find that you run out of steam earlier in sets when lifting, and that conditioning and aerobic work start to become significantly more challenging. The important thing to remember is that this isn’t permanent, and when you do get to a stable bodyweight and are no longer in a calorie deficit your energy levels will come back up.

Takeaway

Something that my clients have found helpful is to try and add some easy to digest carbohydrates in the two hours leading up to their workout. This can be some light fruit, such as grapes, or even a bit of juice. These items don’t typically induce a feeling of fullness but give a few calories just when you need them. This can be a bit of a challenge if you’re experiencing symptoms of heartburn as described above, which is why I recommend light, easy to digest foods.

Muscle loss? Probably Not.

One of the results of the clinical trials on Ozempic was that people lost a significant amount of lean mass, in addition to fat mass. Many have interpreted that as meaning that GLP-1 agonists cause a disproportionate amount of muscle mass loss. Don’t panic though, this is a premature conclusion and I’m fairly confident you don’t need to worry about this. Here’s why.

First off, not all lean mass is muscle. Lean mass is all the weight in your body that isn’t fat. This includes water, connective tissue, visceral organs (liver, kidneys, intestines, etc.), and even skin. Whenever you lose weight you lose some proportion of lean mass, particularly if you lose significant amount of weight. This is a consistent finding in the research and not unique to GLP-1 agonist induced weight loss. While some proportion of lean mass loss is bound to be muscle a non-trivial amount is also skin, connective tissue and visceral organ mass. This is all normal and nothing to worry about.

This last point is important. Any time you lose a significant amount of weight you will lose some proportion on lean weight. Many trainers and influencers try to make a big deal out of this. Why? Because fear sells. I’m hoping that reassurance and facts also sell. Don’t panic!

Secondly, we know how to mitigate muscle loss to the extent that can almost completely prevent it. Quite simply, by strength training. It is well established that including strength training as part of a weight loss strategy almost completely prevents loss of muscle mass. In fact, you don’t even need to lift that much. The clinical trials cited to argue that GLP-1 agonists cause disproportionate muscle loss don’t include strength training as part of the intervention. This isn’t a critique of the research, but it does give context for its interpretation.

Given the exploding interest in GLP-1 agonists and their rapid adoption I don’t think it will be long before clinical trials combining GLP-1 agonist interventions with strength training regimes start getting published. In other words, we’ll soon have research results countering concerns about muscle loss with these drugs. Anecdotally, clients I know to be taking Ozempic don’t show signs of losing muscle or strength.

Takeaway

This one is simple. Adopt a well-designed strength training program that takes into consideration your goals and the potential constraints imposed by GLP-1 use such as low energy level.

Final Thoughts

Again, I won’t bore you with clichés about how GLP-1 agonists are game changers or whatever. Instead, I’ll just say that they’re proving to be a safe and effective tool in fighting obesity. While they’re not without side effects, my experience is that for most people it’s very manageable. If you’re currently taking a GLP-1 agonist or plan to in the future, I hope this article helps you navigate the experience a bit more smoothly.