What Is GLP-1 and How Does It Work?

What Does GLP-1 Stand For?

GLP-1 stands for Glucagon-Like Peptide-1. It is a hormone naturally produced in your gut after you eat. Its primary job is to signal your pancreas to release insulin, slow down how quickly your stomach empties, and tell your brain that you are full.

GLP-1 receptor agonists are medications that mimic this hormone — but with a much longer duration of action than your body's natural GLP-1, which breaks down within minutes.

How Do GLP-1 Medications Cause Weight Loss?

GLP-1 medications work through several mechanisms simultaneously:

Appetite suppression: They act on receptors in the brain — particularly in the hypothalamus — to reduce hunger signals and increase the sensation of fullness.
Slower gastric emptying: Food moves more slowly from your stomach to your intestines, meaning you feel full longer after meals.
Reduced cravings: Many patients report a significant reduction in food noise — the constant preoccupation with food and eating that makes dieting difficult.
Blood sugar regulation: By stimulating insulin release in response to meals, GLP-1 medications help prevent blood sugar spikes that can drive hunger and fat storage.

The result is that most people naturally eat less without feeling deprived — making it easier to maintain a caloric deficit consistently over time.

What Are the Main GLP-1 Medications?

The two most widely used GLP-1 medications for weight loss are:

Semaglutide — available as Ozempic (for diabetes) and Wegovy (for weight loss). Also available as compounded semaglutide through telehealth providers like CalyHealth.
Tirzepatide — available as Mounjaro (for diabetes) and Zepbound (for weight loss). Tirzepatide is a dual GIP/GLP-1 receptor agonist, meaning it activates two hormone pathways instead of one.

Both are injectable medications typically administered once per week. Doses are started low and gradually increased over several months to minimize side effects.

Who Are GLP-1 Medications Right For?

GLP-1 medications are generally appropriate for adults who:

Have a body mass index (BMI) of 30 or higher, or
Have a BMI of 27 or higher with at least one weight-related health condition such as high blood pressure, type 2 diabetes, or high cholesterol
Have not achieved adequate results with diet and exercise alone

They are not appropriate for people with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2), or those who are pregnant or breastfeeding.

A licensed provider will review your full medical history before prescribing to ensure GLP-1 therapy is appropriate for you.

Are GLP-1 Medications FDA Approved?

Yes — both semaglutide (Wegovy) and tirzepatide (Zepbound) are FDA-approved specifically for chronic weight management in adults with obesity or overweight with a weight-related condition.

Compounded versions of semaglutide — which CalyHealth uses — are prepared by licensed compounding pharmacies and are not FDA-approved as a finished drug product, though the active ingredient itself is FDA-recognized. Compounding is a legal, regulated practice used widely in medicine.

How Long Does It Take to See Results?

Most people begin to notice reduced appetite within the first 1–2 weeks. Meaningful weight loss typically becomes visible at weeks 4–8, with continued progress over 6–12 months as the dose is optimized.

Clinical trials have shown average weight loss of 15–22% of body weight over 68 weeks with semaglutide and tirzepatide respectively — substantially more than any previous non-surgical treatment.