GLP-1 and GIP medications, like Mounjaro/Zepbound (tirzepatide) and Wegovy/Ozempic (semaglutide), are the newest “game-changing” weight loss medications everyone is talking about!
What are they? What are the differences? Which one is more effective?
Both medications belong to a class of drugs called glucagon-like peptide-1 receptor agonists (GLP-1 RAs), which are used diabetes management and weight loss. They are both available as prefilled pens and administered once a week as a subcutaneous injection. Wegovy, Ozempic, Mounjaro, Zepbound, and Saxenda have all been shown to help with weight loss when used with other lifestyle changes such as a healthy diet and exercise.
What is Mounjaro or Zepbound (tirzepatide)?
Zepbound and Mounjaro are similar medications- they both contain the active component tirzepatide and are manufactured by Eli Lilly. The difference is that Mounjaro is FDA approved for diabetes whereas Zepbound is FDA approved for chronic weight loss. Tirzepatide is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. It works by activating both the GIP and GLP-1 receptors. GIP and GLP-1 are hormones that are released from the gut after eating. By activating these receptors, tirzepatide stimulates insulin secretion, inhibits glucagon secretion, slows gastric emptying, and promotes satiety.
What is Wegovy or Ozempic (semaglutide)?
Ozempic, manufactured by Novo Nordisk, is the trade name for semaglutide, an FDA-approved medication for managing type 2 diabetes. Conversely, Wegovy is FDA-approved for weight loss. Semaglutide is a glucagon-like peptide (GLP-1) 1 receptor agonist, distinguishing it from dual GIP and GLP-1 receptor agonists like Mounjaro and Zepbound. GLP-1 is a hormone that is released from the gut after eating, and it plays a crucial role in regulating blood sugar levels and appetite. Semaglutide mimics the action of GLP-1 in the body, leading to increased insulin secretion, decreased glucagon secretion, slowed gastric emptying, and increased feelings of fullness.
How Do These Medications Help with Weight Loss?
Illustration Credit: Saraiva, José & Sposito, Andrei. (2014). Cardiovascular effects of Glucagon-like peptide 1 (GLP-1) receptor agonists. Cardiovascular diabetology. 13. 142. 10.1186/s12933-014-0142-7.
Appetite Control: Both semaglutide and tirzepatide act on receptors in the brain that regulate appetite and satiety, leading to reduced feelings of hunger and increased feelings of fullness.
Delayed Gastric Emptying: They slow down the rate at which the stomach empties, which prolongs the digestion process and helps in controlling food intake and reducing overall calorie consumption.
Improved Insulin Sensitivity: By improving insulin sensitivity, these medications can help regulate blood sugar levels more effectively, which may indirectly contribute to weight loss.
Decreased Caloric Absorption: Semaglutide and tirzepatide may also reduce the absorption of calories from food in the intestines, further aiding in weight loss efforts.
Increased Energy Expenditure: Some research suggests that these medications may increase energy expenditure, which means the body burns more calories even at rest.
Fat Metabolism: GLP-1 RAs like semaglutide and tirzepatide may also enhance fat metabolism, leading to a reduction in fat mass over time.
Behavioral Changes: By helping to control cravings and feelings of hunger, semaglutide and tirzepatide may also support behavioral changes that contribute to long-term weight loss success, such as healthier eating habits and increased physical activity.
Which is More Effective for Weight Loss?
Mounjaro or Zepbound (tirzepatide): The SURMOUNT-3 trial evaluated the efficacy and safety of tirzepatide compared to placebo for 72 weeks after a 12-week intensive lifestyle intervention. The participants achieved a total mean weight loss of 26.6% (29.2 kg or 64.4 pounds) from study entry over 84 weeks.
Wegovy or Ozempic (semaglutide): In a 2021 study, non-diabetic patients reported as much as 20% weight loss. On average patents had a 15% weight loss (around 35 pounds). Some participants lost up to 46 pounds (over 68 weeks).
A study published in the New England Journal of Medicine in November 2023 found that Wegovy can reduce the risk of serious heart problems by 20%. The study also found that once-weekly Wegovy injections cut the likelihood of serious cardiac events such as heart attacks, strokes, and cardiovascular deaths among the study’s participants by 20%.
Both medications have been shown to lead to significant weight loss when combined with a healthy diet and exercise program. Weight loss results will vary based on individual factors such as body mass index (BMI), existing health conditions, diet, exercise, and adherence tothe treatment plan.
See Which GLP-1 is Right For You
The decision to start any weight loss medication should come after a comprehensive evaluation from a healthcare provider. A healthcare provider can assess your medical history, current health status, and weight loss goals to determine if these medications are an appropriate treatment option.
GLP-1 medications may not be suitable for everyone, and there are certain contraindications and precautions to consider before beginning treatment.
See if You Qualify Today
Dr. Jami Feltner
Internal Medicine Physician
MD by the Sea offers an online medical weight loss program that is physician-led by our Board-Certified Internal Medicine physician, Dr. Jami Feltner.
We offer weight loss medications, including the newest GLP-1 medications (if appropriate), a nutrition and exercise plan, as well as continued ongoing support by email, text, phone and/or video.
These medications when used in combination with other lifestyle including the support of a physician, can lead to dramatic weight loss and continued long term success.
