GLP-1 receptor agonists are having a moment! You may know them as Wegovy, Ozempic, Trulicity, or Rybelsus. Mounjaro is also a GLP-1 RA but slightly different in that it targets both GLP-1 (glucagon like peptide) and another hormone, GIP (glucagon dependent insulinotropic polypeptide). GLP-1 receptor agonists are all over television ads, talked about constantly, and have become very popular prescription drugs. 

What is GLP-1?

Your body naturally produces GLP-1 in your gut with receptor sites all over your body- brain, bone, blood vessels, heart, and many other places throughout your body. It regulates your blood sugar, appetite and brain mechanisms that control your stress response and even your mood. This hormone was first identified in the 1990s and pharmaceutical drugs were developed shortly after to mimic its effects. The main difference between the natural GLP-1 and the medication is the synthetic hormone lasts considerably longer than the naturally occurring hormone- around 7 days.  Used since 2005 primarily for people with type 2 diabetes, GLP-1 RAs have been very effective at improving markers like Hemoglobin A1c (HbA1c). In 2022, GLP-1 RAs became available as weight management drugs. 

How do GLP-1 Receptor Agonists Work?

So how do they work? They trigger your pancreas to release insulin. At the same time, they block your liver from releasing glucagon. Glucagon is an antagonist to insulin so it raises your blood glucose levels. GLP-1 RAs also slows down your gastric emptying and sends signals to your brain that reduce your appetite so you feel full longer. 

Common Side Effects & Risks

GLP-1 RAs can come with some unwanted side effects. Nausea is most commonly experienced, followed by vomiting and decreased appetite. In rare cases, some people experience stomach pain, stomach paralysis, and pancreatitis. 

The medications are quite expensive and insurance will often not cover them after a year. They are currently in high demand and shortages are constant. The mechanism by which people lose weight is typically through a decreased appetite. What we know is people on GLP-1 receptor agonists eat on average up to 40% fewer overall calories (Christensen et al, 2024). When you are on the medications, your nutritional needs don’t change but adequate nutritional intake becomes much more difficult given the mechanism of how they work (slowing down gastric emptying, prolonged feeling of fullness) and some of the side effects. 

Perhaps the most alarming aspect is the significant muscle loss many experience while on the GLP-1 RAs.  A 2021 study found that individuals on a higher dose of GLP-1 lost an average of 15% (34 lbs) weight loss, with 44% of that weight loss (15 lbs) coming from muscle (Wilding et al, 2021). Even with that rate of weight loss, the rate of muscle wasting is much greater than would be expected. 

A 2023 study found on a lower dose of GLP-1, participants lost on average 4.8% of lean body mass in just 24 weeks (Jiang et al, 2023). That may not seem significant, however, consider that in someone not resistance training, generally 3-5% lean body mass is lost over the course of a decade. 

The ideal scenario is losing fat while keeping or even building muscle. Muscle uses more energy than fat, so people with greater muscle mass often have faster metabolisms that burn more calories. Likewise, if you lose some of your muscle mass, your metabolism will slow down. You have a higher likelihood of keeping weight off if you’re preserving your muscle and that’s why we emphasize fat loss that is slow, steady, and sustainable and doesn’t take your muscle mass with it. We want this to be the last time that you are trying to lose weight. 

In those that stop taking the medications, rebound weight gain is very common. It’s quite common because the appetite increases without the medication’s effects, along with lost muscle mass that has further slowed the metabolism.  In addition, with rapid weight loss, many haven’t yet been able to put the necessary lifestyle habits in place to be successful at weight maintenance. You need to have a sustainable plan in place while you’re on GLP-1 RAs that you can maintain in case you need to come off of the medications. We think macros is that sustainable plan!

We do have some clients in our community that are on GLP-1 RAs. You are welcome here! If your doctor has prescribed these drugs for you, know that this is one tool to help you. It is not the solution on its own. We think the lifestyle piece is perhaps the more important part for your long-term wellbeing. We are here to help you put those lifestyle habits in place that preserve your muscle and set you up to flourish in your health over your lifetime. 

I cannot emphasize enough- if you’re on a GLP-1 RA, you need to be vigilant to eat adequate protein, to resistance train regularly, and to get good sleep. If you are in our 1:1 coaching program, you’ll work with your coach to eat as close to your nutritional needs as possible. This includes your total overall calorie intake but especially adequate protein. We know eating an adequate protein around 1 gram per pound body weight or goal weight- even when your overall caloric intake is not optimal- insures that muscle is preserved (Longland et al, 2016). 

We also know that resistance training is one of the most protective things you can do because resistance training can help you maintain or even gain muscle even when you’re not able to consume an ideal amount (Donnelly et al, 1993). 

How to Naturally increase your GLP-1 Hormone

Finally, I do want to touch on the many ways to increase your natural GLP-1 hormone: 

• Eating protein-rich foods: protein is the most satiating macro because it has the highest effect on your GLP-1 levels
• Eating fat-rich foods like olive oil, avocado, nuts, fatty fish can boost GLP-1 levels
• Eating probiotic-rich foods or taking a probiotic supplement: improve gut microbiota which trigger GLP-1 secretion
• Eating fiber-rich foods like vegetables, legumes, and whole grains: your gut bacteria break down fiber in your gut which then triggers the release of GLP-1 into your bloodstream. This is one of the reasons fiber helps you stay full!
• Sleep: poor sleep quality or quantity can lower GLP-1 production leading to increased appetite
• Exercise: short and long-term training can increase GLP-1 secretion
• Stress Management: poorly managed stress raises cortisol levels which reduces GLP-1 secretion 

This is everything we emphasize at Stay Fit Mom because every factor truly is interconnected! In our 1:1 coaching program, clients track protein, fat, fiber, and veggies because these are the guardrails that steer you to the nutrient-dense food that regulates your hormones, including GLP-1. We ask about your exercise, your sleep, your appetite, your mood, and your stress level. So many of our clients who have previously been stuck in a binge-restrict cycle on our program are satiated and no longer have the urge to binge while eating appropriate overall calories and especially protein. It’s the “boring basics”, but whether you are on a GLP-1 RA or not, there is no way but doing the basics well if you want to achieve your fat loss goals while thriving in your health!