Ozempic, Wegovy, and Mounjaro for Weight Loss: What Are They?
Ozempic, Wegovy, and Mounjaro, when it comes to weight loss, are classified as GLP-1 agonists. These are drugs that, when taken, mimic the action of an existing hormone that decreases appetite, slows the rate of digestion, and decreases blood sugar levels. Ozempic, Wegovy, and Mounjaro are the most popular prescription drugs for weight loss currently in use. According to the FDA (2023), both semaglutide (Wegovy) and tirzepatide (Zepbound, the weight loss version of Mounjaro) are officially approved for chronic weight management in adults with obesity or weight-related health conditions.
How GLP-1 Agonists Work in the Body
GLP-1 agonists, also called glucagon-like peptide-1 receptor agonists, activate GLP-1 receptors in the brain, stomach, and pancreas. It is a hormone. It is released by the gut after eating.
GLP-1 agonists work by:
- Reduces hunger and food cravings by signaling the brain.
- Slowing gastric emptying, making you feel full longer after meals
- Triggers the pancreas to release insulin following food intake.
- Reduces the release of glucagon (a hormone that raises blood sugar)
Ozempic, Wegovy, and Mounjaro: Key Differences at a Glance
What is Wegovy, and How Does it Differ From Ozempic?
Ozempic (semaglutide 0.5 to 2 mg) is a once-weekly injectable medication FDA-approved in 2017 for type 2 diabetes. Ozempic is frequently prescribed off-label for weight management in people with obesity.
- Starting dose: 0.25 mg once weekly for 4 weeks
- Maintenance dose: 0.5 mg to 2 mg once weekly
- Effectiveness: Average weight loss of 10 to 15% of body weight over 68 weeks, per the SUSTAIN trial (2021)
- Best for: Adults with type 2 diabetes who also need to lose weight, or people with a BMI of 27 or higher with weight-related conditions
What Is Wegovy and What Makes It Different From Ozempic?
Wegovy is a higher-dose form of semaglutide (2.4 mg/week) that received FDA approval in 2021 specifically for long-term weight management. The active ingredient is same as Ozempic, but is used at a much higher dose, which leads to greater weight loss outcomes.
- Starting dose: 0.25 mg once weekly, increased every 4 weeks
- Target maintenance dose: 2.4 mg once weekly
- Effectiveness: The STEP 1 trial (NEJM, 2021) showed an average weight loss of 14.9% of body weight over 68 weeks. Approximately 1 in 3 participants lost more than 20% of body weight
- Best for: Adults with a BMI of 30 or higher, or 27 or higher with weight-related conditions. FDA also approved Wegovy for adolescents aged 12 and older in 2022
What Is Mounjaro and Why Does It Produce the Most Weight Loss?
Mounjaro (tirzepatide) is a once-weekly injectable medication FDA-approved in 2022 for type 2 diabetes. Unlike Ozempic and Wegovy, Mounjaro activates both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors, making Mounjaro a dual-action medication. The weight loss version, Zepbound, received FDA approval in November 2023.
- Starting dose: 2.5 mg once weekly, increased by 2.5 mg every 4 weeks
- Maximum dose: 15 mg once weekly
- Effectiveness: The SURMOUNT-1 trial (NEJM, 2022) showed an average weight loss of 22.5% of body weight at the 15 mg dose. Approximately 57% of participants lost 20% or more of body weight
- Best for: Adults with type 2 diabetes seeking blood sugar control and weight loss (Mounjaro), or adults with a BMI of 30 or higher seeking weight loss (Zepbound)
Adverse Reactions: How Does the Body Respond to GLP-1 Medications?
Common Side Effects
- Nausea, especially during dose escalation
- Vomiting and diarrhea
- Stomach pain or bloating
- Fatigue and injection site irritation
- Burping or acid reflux
Serious Side Effects
- Pancreatitis (inflammation of the pancreas): Severe upper abdominal pain with radiation to the back
- Pancreatitis (inflammation of the pancreas): Severe upper abdominal pain with radiation to the back
- Thyroid C-cell tumours: These medications carry a boxed warning based on findings from animal studies that showed an increased risk of thyroid tumours.
- Gallbladder problems: Rapid weight loss can raise the chances of developing gallstones.
- Kidney injury: Ongoing nausea and vomiting may lead to dehydration, which can affect kidney function.
Who Should Avoid GLP-1 Agonists
- People with a personal or family history of Medullary Thyroid Carcinoma
- Those with Multiple Endocrine Neoplasia Type 2
- Individuals who are pregnant or breastfeeding
- Anyone with a history of severe pancreatitis or gastroparesis
Administering GLP-1 Injections Correctly
- Choose your injection site: abdomen (at least 2 inches from the navel), front of the thigh, or upper arm.
- Rotate injection sites each week to avoid skin hardening (lipodystrophy).
- Thirty minutes prior to injecting, take the pen out of the refrigerator.
- An alcohol swab should be used to clean the site. Let it dry completely.
- Hold the pen firmly against the skin and hold for 5 to 10 seconds after clicking.
- Needles must be disposed of immediately in a sharps container.
- Store all the unused pens at 2 to 8 degrees Celsius.
What Happens When You Quit GLP-1 Medications?
Most people regain two-thirds of the weight lost when they stop GLP-1 agonists. This was demonstrated in the STEP 4 trial, published in Diabetes Care in 2022. The trial found that people regained two-thirds of the weight lost after one year of stopping Wegovy. This is because the hunger hormones return to pre-treatment levels, and the weight set point has not been altered. More and more obesity experts are considering GLP-1 agonists as long-term medications, like blood pressure or cholesterol medications.
Conclusion
Ozempic, Wegovy, and Mounjaro are the most advanced drugs in the field of obesity treatment, as they provide the best possible results in the form of weight reduction, which cannot be achieved with the help of dieting and exercising alone. The best results are obtained with the help of Mounjaro, as it works by activating two receptors, while the best-tested drug is Wegovy, which is approved by the FDA for the treatment of obesity. Consult with a doctor to get the best possible GLP-1 drug according to your health conditions.
