A recent study reveals that individuals using tirzepatide injections experienced greater weight loss and were more likely to achieve specific weight loss targets compared to those using semaglutide.
Researchers from Truveta, a health data analytics firm, analyzed electronic health records of over 18,000 adults with overweight or obesity who used these medications between May 2022 and September 2023. The results were published in the JAMA Internal Medicine journal on Monday.
Key Findings:
Effectiveness: Both medications proved effective, with most users losing at least 5% of their starting body weight after one year. However, 82% of tirzepatide users reached this benchmark, compared to 67% of semaglutide users.
Significant Weight Loss: 42% of tirzepatide users lost at least 15% of their starting weight, more than double the 18% of semaglutide users achieving this level.
Average Weight Loss: After three months, tirzepatide users lost an average of 6% of their body weight, while semaglutide users lost less than 4%. At six months, weight loss averaged 10% for tirzepatide and 6% for semaglutide. By one year, tirzepatide users saw over 15% average weight loss, nearly double the 8% for semaglutide users.
Mechanism of Action:
Tirzepatide and semaglutide both mimic the gut hormone GLP-1, which boosts insulin production and slows stomach emptying. GLP-1 also signals the brain to control appetite. Tirzepatide further stimulates a second gut hormone, GIP, potentially enhancing its effects.
FDA Approvals:
The US Food and Drug Administration (FDA) has approved tirzepatide and semaglutide for treating type 2 diabetes and obesity. Eli Lilly manufactures tirzepatide as Mounjaro for diabetes and Zepbound for weight management. Novo Nordisk produces semaglutide as Ozempic for diabetes and Wegovy for weight management. The study focused on doses approved for type 2 diabetes treatment.
Study Demographics and Comparisons:
Half of the study participants had type 2 diabetes, while the rest likely used the medications off-label for weight management under their doctors’ guidance. Novo Nordisk previously criticized the study’s comparisons, noting that the semaglutide doses examined were not intended for chronic weight management and that no direct trials compared Wegovy and tirzepatide.
Weight Loss in Diabetic vs. Non-Diabetic Participants:
Participants with type 2 diabetes experienced less significant weight loss compared to those without diabetes, but tirzepatide users still lost more weight on average.
Side Effects and Discontinuation Rates:
The study did not extensively track mild gastrointestinal side effects like nausea and vomiting, which may be inconsistently reported. Serious side effects, such as bowel obstruction, gastroparesis, or pancreatitis, were similar for both medications. High discontinuation rates were noted, with over half the participants stopping treatment before the study’s end, but rates were similar for both drugs.
Conclusion and Future Research:
The findings align with clinical trial results, but the study authors call for more research to compare tirzepatide and semaglutide on other health outcomes, such as heart-related events.
