Over the past few years, the injection that the public increasingly calls the dual-action weight-loss shot — sold under the brand name Mounjaro in pharmacies — has become one of the molecules I am most often asked about by patients dealing with weight problems and high blood sugar. Its scientific name is tirzepatide. In this article, as a cardiovascular surgeon, I will explain in plain language what it is, why it works differently from classical weight-loss injections, and what large studies in major medical journals have shown.
Disclaimer: This article is informational about a prescription drug; it is not medical advice. The decision to start this injection is always made together with the physician who examines you.
What is the dual-action weight-loss shot?
The active ingredient inside Mounjaro, tirzepatide, is a small protein fragment (39 amino acids long). Thanks to a fatty-acid tail that keeps it bound to albumin in circulation, it is injected once a week under the skin of the abdomen. With a half-life of approximately 5 days (116 hours), a single weekly dose maintains effective plasma levels throughout the week.
The U.S. Food and Drug Administration (FDA) approved this drug in stages:
- May 2022 — for type 2 (adult-onset) diabetes,
- November 2023 — under a separate brand name (Zepbound) for obesity,
- 2024 — for moderate-to-severe obstructive sleep apnea (OSA).
In other words, this injection is not just a “weight-loss shot”; it is a treatment whose effectiveness in diabetes, weight, heart failure, and sleep apnea is now scientifically established. (Knerr et al., Diabetes Therapy 2025; StatPearls / NCBI Bookshelf)
Why do we call it “dual-action”?
Classical weight-loss injections (for example Ozempic or Wegovy, both containing semaglutide) knock on a single door: the receptor for GLP-1, a gut hormone that delivers an “I”m full” signal.
Tirzepatide knocks on two doors at the same time:
- The GLP-1 door: boosts insulin release, suppresses appetite, slows gastric emptying.
- The GIP door: makes insulin work more efficiently and supports energy expenditure in fat tissue.
What is interesting is that tirzepatide does not knock on these two doors with equal force — it was engineered to activate GIP about 5× more strongly than GLP-1. This “imbalanced” design prevents the receptors from being internalised too quickly and helps the effect persist over time (Willard et al., JCI Insight 2020).
The result: compared with single-target injections, this one delivers a stronger profile for weight loss, blood-sugar control, and breaking insulin resistance. This difference becomes clinically meaningful, particularly in discussions about the weight-loss shot in lipedema patients.
What do the clinical trials say?
There are large-scale studies on this drug involving tens of thousands of patients, published in the world”s most respected medical journals — particularly the New England Journal of Medicine (NEJM). Here are the key findings, in plain terms.
1) Weight loss — up to 22%
In obese individuals without diabetes, tirzepatide given over 72 weeks produced sustained weight loss of 16.5% to 22.4% of body weight (SURMOUNT-1 trial). For a 100-kg person, that means an average of 22 kg lost.
2) Type 2 diabetes control
In patients with type 2 diabetes, HbA1c (the 3-month average blood-sugar marker) dropped by 1.73 percentage points. Compared with the older drug dulaglutide in the same class, tirzepatide produced about 2.5× greater weight loss (SURPASS programme).
3) Heart and vascular health: life-saving evidence
The SURPASS-CVOT trial followed 13,299 patients for four years. Results:
- All-cause mortality 16% lower (HR 0.84; 95% CI 0.75–0.94; p = 0.002)
- Cardiorenal events 16% lower
- Equivalent safety on classical cardiovascular outcomes (heart attack, stroke)
In other words, this injection does not only promote weight loss — it provides the first major evidence that it can prolong life over the long term (Nicholls et al., NEJM 2025;393:2409–2420).
4) Heart failure with preserved ejection fraction (HFpEF)
The SUMMIT trial followed 731 patients with both obesity and HFpEF for two years. Tirzepatide reduced the risk of cardiovascular death + worsening heart failure by 38% (HR 0.62; p = 0.026). Quality of life (KCCQ score +6.9 points), 6-minute walk distance (+18.3 m), and the inflammation marker hsCRP (37% reduction) all improved significantly (Packer et al., NEJM 2024).
5) Sleep apnea — fewer pauses, more restful sleep
In obese individuals with moderate-to-severe OSA, tirzepatide reduced the apnea-hypopnea index by 25 events per hour; systolic blood pressure, hypoxic burden, and hsCRP also dropped meaningfully (Malhotra et al., NEJM 2024).
Why is this important from a vascular standpoint?
As a vascular surgeon, the conditions I encounter most frequently in my patients include varicose veins and venous disease, lymphedema and lipedema, chronic venous insufficiency, and peripheral arterial disease. Almost all of these conditions share two underlying drivers: excess weight and systemic inflammation.
The dual-action weight-loss shot may indirectly support vascular health in three important ways:
- Significant weight loss → reduces venous pressure in the legs, alleviates chronic leg swelling.
- Up to 37% reduction in hsCRP → slows endothelial damage (the inner lining of blood vessels).
- Reduced blood pressure → eases venous return load.
There are currently no randomised trials designed specifically for varicose veins or lymphedema. However, the HFpEF + obesity and OSA datasets clearly show that overweight patients carrying a cardiovascular burden gain a comprehensive clinical benefit. For this reason, obesity treatment in patients with vascular disease should always be planned multidisciplinarily (with input from several specialists).
Availability in Türkiye and the prescription process
In Türkiye, Mounjaro is available by prescription under the authorisation of TİTCK (Turkish Medicines and Medical Devices Agency), following an evaluation by an endocrinologist, cardiologist, or internal-medicine specialist. Approval status and reimbursement conditions can change over time, so the latest situation should be confirmed with your physician.
Obtaining the drug from the internet or from abroad without a prescription is strongly discouraged: this carries serious risks both in terms of drug safety (cold-chain storage, counterfeit products) and personal contraindications — for example a history of medullary thyroid cancer, MEN-2 syndrome, or severe pancreatitis.
Summary — Who might benefit?
Tirzepatide (the dual-action weight-loss shot), by simultaneously activating the GIP and GLP-1 receptors:
- improves blood-sugar (diabetic) control,
- delivers significant weight loss,
- lowers the risk of death from cardiovascular and renal events,
- improves quality of life in OSA and HFpEF.
However, like any medication, this is a personal decision. Your past medical history, the other medications you take, and your cardiovascular risk profile must all be evaluated one by one before starting. In patients with a vascular substrate — particularly with advanced varicose veins, lymphedema, chronic leg swelling, heart failure, or peripheral arterial disease — treatment should be planned multidisciplinarily.
For an evaluation tailored to your health needs, please feel free to reach out via the contact page or read more on the about page.
Scientific References
- Knerr PJ et al. Insights into the Mechanism of Action of Tirzepatide: A Narrative Review. Diabetes Therapy. 2025. link.springer.com/article/10.1007/s13300-025-01804-w
- Willard FS et al. Tirzepatide is an imbalanced and biased dual GIP and GLP-1 receptor agonist. JCI Insight. 2020;5(17):e140532. insight.jci.org/articles/view/140532
- Packer M et al. Tirzepatide for Heart Failure with Preserved Ejection Fraction and Obesity. N Engl J Med. 2024. DOI:10.1056/NEJMoa2410027 — nejm.org/doi/full/10.1056/NEJMoa2410027
- Malhotra A et al. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity. N Engl J Med. 2024. DOI:10.1056/NEJMoa2404881 — nejm.org/doi/full/10.1056/NEJMoa2404881
- Nicholls SJ, Pavo I, Bhatt DL et al. Cardiovascular Outcomes with Tirzepatide versus Dulaglutide in Type 2 Diabetes. N Engl J Med. 2025;393:2409-2420. DOI:10.1056/NEJMoa2505928 — nejm.org/doi/full/10.1056/NEJMoa2505928
- Tirzepatide. StatPearls. NCBI Bookshelf, 2024. ncbi.nlm.nih.gov/books/NBK585056
