Tirzepatide and Weight Management

Tirzepatide (Zepbound® for weight management; Mounjaro® for diabetes) is a once-weekly injectable medication that helps with significant and sustained weight loss. It works by targeting key metabolic pathways that control hunger, insulin response, and fat metabolism. The medication is administered subcutaneously, usually in the lower abdomen, thigh, or upper arm.

Mechanism of Action

Tirzepatide is a dual incretin receptor agonist that activates both the GIP and GLP-1 receptors. This dual mechanism leads to decreased appetite, delayed gastric emptying, improved insulin sensitivity, and better glucose control — all contributing to weight loss and improved metabolic health.

Clinical Benefits & Metabolic Impact

In clinical trials published in the New England Journal of Medicine, tirzepatide has shown superior weight loss outcomes compared to semaglutide. Participants achieved up to 20% reduction in baseline body weight over 72 weeks. Additionally, tirzepatide significantly improved A1c, triglyceride levels, and waist circumference.

Tirzepatide vs Semaglutide

Metabolic Benefits

Injection Guidance

Tirzepatide is injected once weekly under the skin using a prefilled pen. The preferred sites are the lower abdomen, upper thigh, or upper arm. Rotate injection sites each week to avoid irritation or lipohypertrophy. It can be taken with or without food, at any time of day.

Side Effects & Safety

Common side effects include nausea, vomiting, diarrhea, constipation, and decreased appetite. These are typically mild and improve as the body adjusts. Do not use if you or a family member has a history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN2).

Key Takeaways

• Tirzepatide offers dual hormone pathway activation for greater metabolic impact.
• Demonstrates superior weight loss versus semaglutide in clinical trials.
• Improves glycemic control and cardiovascular markers.
• Administered as a simple weekly injection with lifestyle modification for best results.

References

1. Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022.
2. Frias JP, et al. Tirzepatide versus Semaglutide in Type 2 Diabetes. N Engl J Med. 2021.
3. UpToDate: GLP-1 receptor agonists for weight management.
4. FDA Prescribing Information for Zepbound and Wegovy.