How GLP-1 receptor agonists work for weight loss: Exploring facts and myths

You’ve probably heard about Ozempic and how it’s helped people lose a lot of weight. But you might still be curious about what it actually is and why it works so well. Plus, with all the buzz around it, you might be wondering who it’s good for and if it could potentially work for you.

On a recent podcast episode from Noom Vibe (the new free wellness community app from Noom) Dayo Akinrinade, founder and general manager of Noom Vibe, sought answers to these questions. She was joined by Dr. Adonis Saremi, Noom’s Chief Medical Officer, for a deep dive into Ozempic and other GLP-1 receptor agonist medications. Together, they dug into the science behind how these medications work, debunking popular myths and separating fact from fiction. 

What are GLP-1 receptor agonists?

To understand what a GLP-1 receptor agonist is you first need to know what GLP-1 stands for. GLP-1 is short for glucagon-like peptide-1, a hormone made in your digestive tract after eating. GLP-1 acts like a tiny messenger that tells your stomach and brain you are full. 

“It kind of slows your gut down,” Dr. Adonis tells Akinrinade. “And then, actually, it acts on the brain, and we’re finding that it actually could play a role in reducing your appetite.” This effect prevents you from overeating on both a physical and mental level.

GLP-1 receptor agonists, often just referred to as GLP-1s, are medicines that act like super-powered versions of GLP-1. 

“The GLP-1s are a newer class of medications that we call highly effective anti-obesity medications,” says Dr. Adonis, “They can trick your body into feeling full and keep blood sugar levels in a healthy range, which is why they are prescribed to people with diabetes and to people trying to lose weight.” 

How GLP-1 receptor agonists affect weight loss

GLP-1 agonists help manage weight and improve metabolic health in a few ways:

• Making you feel full: GLP-1s are like little switches in your brain that help you control your hunger. When GLP-1 medications turn on these switches, signals are sent that make you feel full. This helps you eat less because you don’t feel as hungry. “It acts on the brain, and we’re finding that it actually could play a role in reducing your appetite,” explains Dr. Adonis. 
• Keeping food in your stomach longer: They also act directly on your stomach. GLP-1s slow down how quickly food moves from your stomach to your intestines. “It kind of slows your gut down, essentially,” says Dr. Adonis. This makes you feel full for a longer time after eating.
• Regulating blood sugar: GLP-1s also help your body release the right amount of insulin to balance blood sugar. When your blood sugar is balanced your hunger levels are more stable.

In short, GLP-1s help you feel full and less hungry, keeping your hunger in check. “Through these mechanisms, patients will experience a suppressed appetite, and then if they do eat, and when they do eat, they’ll feel fuller quicker, and thereby they’re going to lose weight naturally,” says Dr. Adonis.

Myth: I don’t need to watch what I eat while using a GLP-1 receptor agonist

“GLP-1s are being referred to as a miracle drug,” says Akinrinade. “Pretty much implying that lifestyle habits, healthy habits, like eating and exercise, are becoming less important. And is that the case?” 

Dr. Adonis says definitely not. While they may seem miraculous, any weight loss effort that includes a GLP-1 agonist medication must also include healthy habits. 

“Lifestyle measures, such as eating healthy, staying active, are really, really important,” says Dr. Adonis, “In fact, the drug label for GLP-1 medications says the medication should be used as an adjunct to diet and exercise.”   

Part of the problem, notes Dr. Adonis, is that GLP-1s are highly effective at reducing appetite, opening up the potential for muscle loss if you don’t eat enough protein or incorporate movement into your plan. 

“You can lose up to 30% or even 40% of weight due to muscle mass,” says Dr. Adonis, which he notes is similar to the levels seen with bariatric surgery. To counteract this people need to eat enough protein and to incorporate movement and exercise. This doesn’t necessarily mean weightlifting. “Although resistance training is particularly helpful in maintaining muscle mass, physical activity such as walking could also be extremely helpful,” he says.  

Noom is set up to help you successfully build these habits over time in an effective and personalized way. If you’re already prescribed a GLP-1, you can add the GLP-1 Companion to your experience. It will help manage side effects and build a healthy eating and strength training program to complement the medication. 

Myth: Only celebrities can benefit from a prescription for a GLP-1 medication

Actually, more people can benefit from GLP-1s than currently use them, says Dr. Adonis. He wants to change the view of GLP-1 medications as a medication only for high-profile celebrities. “I’d really love to bring the conversation from talking about these unaccessible celebrities to us ordinary people,” he says.

Many people who have tried diet and exercise in the past and haven’t seen great results could find GLP-1s useful. This includes people with a certain BMI and those with medical issues relating to obesity. 

“GLP-1s are indicated in those that have a body mass index, otherwise known as a BMI, above 30, or in those with a BMI over 27 that also have at least one weight-related medical risk factor,” says Dr. Adonis. These can include diabetes, high blood pressure, sleep apnea, certain heart issues, or high cholesterol. 

Your doctor can determine which medication is right for you. You could also see if you qualify for Noom Med. If you do, our qualified clinicians will help you get a prescription for the right medication, coordinate benefits, and help you build a healthy eating and exercise plan. 

Fact: GLP-1s can have some uncomfortable side effects

Yes, GLP-1s can cause some side effects, but they are typically mild. 

“These are mostly gastrointestinal in nature, meaning you may experience nausea, for example, which is seen in about 50% of patients,” says Dr. Adonis, “These symptoms are generally mild, especially at low doses.” 

Other common side effects people have experienced include vomiting, diarrhea, stomach pain, constipation, and fatigue. Many of these side effects tend to lessen as your body becomes used to the medication.

“Anytime you’re considering treatment, you want to always weigh the potential benefits, risks, and alternatives,” says Dr. Adonis. 

Fact: Some people shouldn’t take GLP-1 receptor agonists

While GLP-1s can help people struggling with obesity, they do have their potential serious risks. People with certain conditions or those who are predisposed to them should skip GLP-1s. Serious side effects can include pancreatitis, kidney problems, gallbladder issues, and even an increased risk of thyroid cancer.

“Some contraindications for these medications would include a personal or family history of medullary thyroid cancer or a condition called MEN2 (Multiple endocrine neoplasia, type 2),” says Dr. Adonis. “Additionally, you know, in people with a history of pancreatitis, you would not want to take this medication.”

Your doctor will consider your complete help history before prescribing a GLP-1 and monitor you regularly. 

Myth: Ozempic is the only GLP-1 medication used for weight loss

Several different medications beyond Ozempic are considered GLP-1 agonists. Some are even FDA-approved for weight loss, unlike Ozempic which is approved to treat diabetes and prescribed off-label for weight loss. Those containing semaglutide or tirzepatide as the active ingredient are the most popular medications used for weight loss.

Medications containing semaglutide 

• Ozempic, probably the most well-known semaglutide, is administered as a once-weekly injection. It is FDA-approved for managing type 2 diabetes and can be prescribed off-label weight loss.
• Wegovy is FDA-approved for chronic weight management in adults with obesity or overweight conditions and can help improve metabolic health. It is also administered as a once-weekly injection.
• Rybelsus is taken orally once daily. It is FDA-approved for managing type 2 diabetes and can be prescribed off-label weight loss.

Medications containing tirzepatide 

• Mounjaro is administered as a once-weekly injection. It is FDA-approved for managing type 2 diabetes and can be prescribed off-label for weight loss.
• Zepbound is administered as a once-weekly injection. It is FDA-approved for type 2 diabetes management and weight management.

Aside from semaglutide and tirzepatide, other notable GLP-1 agonists are dulaglutide, liraglutide, and exenatide. Most of the medicines with these GLP-1 agonists are used for diabetes management, though Saxenda (liraglutide) is also approved for use in weight management. 

Fact: Combining medication and healthy habits is your best bet for lasting results

It’s important to remember that while GLP-1 agonists are highly effective medications, their use should always be tailored to your personal health needs and monitored closely by healthcare providers. Combining these medications with lifestyle changes—like those covered in the Noom program—can amplify their benefits and make the journey to better health more achievable and sustainable in the long term.

Noom pairs GLP-1 treatment with support focused on developing healthy habits, such as personalized coaching and peer encouragement through Noom Med and the GLP-1 Companion. By combining the physical and behavioral aspects of weight management, Noom offers a comprehensive approach to achieving and maintaining a healthy weight. 

Note: Ozempic is not FDA-approved to treat obesity or for weight loss.