One in eight US adults reports that they have taken a GLP-1 medication either to manage diabetes, support weight loss, or lower the risk of heart disease. These medications are incredibly popular and their use is only expected to increase. But, what are these medications and how do they work?
What is GLP-1?
Glucagon-like peptide-1 (GLP-1) is a hormone naturally produced in the intestine. GLP-1 Agonists are a class of medications that mimic the effect of GLP-1 in the body, but while they are similar in structure and function, they are not identical to the naturally occurring GLP-1 peptide.
Let’s start with the GLP-1 peptide, a type of hormone that is naturally made by your body. A peptide is a short chain of amino acids (the building blocks of proteins) linked together. A peptide hormone is different than steroid hormones, like sex hormones, in that they are made from amino acids and are water-soluble. Peptide hormones play a variety of important biological functions in the body including, metabolism, stress, growth, and reproduction.
GLP-1 is produced in the intestine and released after eating. It plays many roles related to digestion, blood sugar regulation, and appetite. Its actions in the body include:
- Stimulating insulin secretion to help support glucose metabolism.
- Slowing down how quickly food leaves the stomach.
- Reducing appetite after meals.
- Inhibiting secretion of glucagon, a hormone that increases blood sugar.
What are GLP-1 Agonists?
A GLP-1 agonist is a version of the GLP-1 hormone that is made by either modifying the human peptide or is a synthetic version. Examples of GLP-1 agonists include Ozempic, Rybelsus, Trulicity, and Wegovy. They can be taken as injections or tablets.
The GLP-1 medications differ from what your body makes in specific ways. Naturally occurring GLP-1 has a short half-life of just two minutes. But GLP-1 medications are modified to extend their half-life so they stay in your system longer. The amino acids in GLP-1 may also be modified to help improve stability or increase potency.
While these medications may seem “new” because they are increasingly popular for weight loss, they have been approved for the treatment of type 2 diabetes since 2005.
Read more about the history of GLP-1 here.
How do GLP-1 Medications Work?
GLP-1 medications were initially used for the treatment of Type 2 Diabetes. Their main effect is triggering the release of insulin from your pancreas. This allows your body to utilize sugar from food more effectively, lowering your overall blood sugar.
Another hormone that plays a role in blood sugar regulation is called glucagon. This hormone is used to raise blood sugar levels. GLP-1 blocks the secretion of glucagon, so it is unable to trigger a rise in blood sugar.
GLP-1 medications also slow down digestion, affecting how quickly food leaves your stomach. This means you stay full longer after eating, so you don’t feel hungry as often.
Finally, they also impact the areas of your brain that trigger hunger and satiety. Many people on these medications report a reduction in “food noise” or obsessive thoughts about food.
For those with Type 2 diabetes, these medications can help manage blood sugar via the effect it has on insulin and glucagon. The slowed digestion also helps decrease blood sugar spikes.
The satiety effect of GLP-1 helps you decrease food intake more easily and better control your appetite and hunger. These combined effects often result in weight loss.
Types of GLP-1 Medications
There are several GLP-1 medications on the market, most are used for the management of diabetes. Most of these medications are available via injection either daily or once per week. A few of the GLP-1 medications approved for diabetes are available in tablet form.
These include the following:
- Dulaglutide: TrulicityⓇ
- Exenatide: ByettaⓇ
- Exenatide extended-release: BydureonⓇ
- Liraglutide: VictozaⓇ
- Lixisenatide: AdlyxinⓇ
- Semaglutide: OzempicⓇ
- Tirzepatide: MounjaroⓇ
The FDA has approved three of these medications for weight loss in people without diabetes. The weight loss versions have different brand names, although they are the same medication.
- Liraglutide: SaxendaⓇ
- Semaglutide: WegovyⓇ
- Tirzepatide: ZepboundⓇ
Side Effects
Like many medications, there are side effects you should be aware of. Always speak to your healthcare provider before starting one of these medications.
The most common side effects are gastrointestinal symptoms. These include:
- Nausea
- Vomiting
- Diarrhea
- Constipation
- Acid reflux/heartburn
You may also experience:
- Injection site reactions
- Headache
- Fatigue
- Nasopharyngitis
Less common but serious side effects:
- Acute gallstone disease
- Pancreatitis
- Serious allergic reactions
- Blood sugar levels dropping too low
- Increased heart rate
- Mood swings and depression
- Intestinal blockage
Rare but potential risks:
- Thyroid C-cell tumors, only seen in animal studies to date
- Kidney function impairment, particularly in those with pre-existing kidney conditions
- Increased aspiration risk during anesthesia due to delayed gastric emptying
While these medications are popular and many are having success with them, GLP-1 agonists are not without side effects. It is essential to have an open discussion with your healthcare provider regarding potential side effects and risks. Regular check-ups and monitoring are crucial to catch any early signs of complications.
Who Should Take GLP-1 Medications?
GLP-1 medications are used for the treatment of diabetes or obesity that has not been managed with lifestyle changes.
For those with diabetes, GLP-1 medications are used to manage blood sugar when other medications like metformin are not enough or are contraindicated. They are often used in combination with other treatments and lifestyle changes.
When it comes to weight loss, the FDA has approved the medications for adults with a BMI (body mass index) of 30 or higher or those with a BMI of 27 or higher with at least one weight-related health condition, like high blood pressure or elevated cholesterol. While you may have heard rumors that celebrities are using GLP-1 medications to “lose the last 5 pounds” it is not indicated to help you lose a few pounds.
GLP-1 medications are not indicated for pregnant or breastfeeding women, those with gastrointestinal or kidney disease, or those with a family or personal history of certain types of cancer, particularly medullary thyroid cancer.
If you are interested in learning more about these medications, start by speaking to your healthcare provider about your options and what is best for you.
About the Author
Ana Reisdorf, MS, RD
Founder, Lead Registered Dietitian
Ana Reisdorf has been a registered dietitian for over 15 years. When she first started her career, all she wanted to do was help people lose weight and live their healthiest lives. Over the last 10 years she has worked as a content creator helping spread the message of healthy eating on a larger scale.
