Mounjaro (tirzepatide) in the treatment of obesity

What is Mounjaro?

Mounjaro contains tirzepatide, an active substance representing a new generation of treatments for overweight, obesity and type 2 diabetes. Unlike earlier GLP-1 analogues, such as semaglutide, tirzepatide acts on two hormone receptors – GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide) (1,2).

How Mounjaro works

GLP-1 and GIP occur naturally in the body and are released after a meal. By mimicking or enhancing their effects, treatment with Mounjaro contributes to:

• Reduced appetite: by influencing the brain’s appetite centre, satiety increases, leading to quicker and longer-lasting fullness and reduced calorie intake.
• Delayed gastric emptying: food leaves the stomach more slowly, supporting prolonged satiety, reduced appetite, steadier blood glucose levels and reduced calorie intake.
• Improved blood glucose control: by stimulating insulin release when blood glucose rises and suppressing glucagon production, Mounjaro contributes to more stable glucose levels.

The combination of these mechanisms makes Mounjaro an effective treatment option for promoting healthy and sustainable weight loss (1,2).

Clinical effect

In the randomised SURMOUNT-1 study (72 weeks), average weight loss was –15.0% (5 mg), –19.5% (10 mg) and –20.9% (15 mg) compared with placebo (4). Tirzepatide at 10 mg and 15 mg has shown substantial weight reduction and a safety profile similar to other incretin-based therapies (3). Other data show that tirzepatide can lead to continued and maintained weight loss with long-term treatment — whereas weight may return if treatment is discontinued (4).

Dosage and use of Mounjaro

Mounjaro is administered as an injection once weekly or as prescribed by a doctor. The injection is given into the subcutaneous fat of the abdomen, thigh or upper arm using a pre-filled injection pen.

Treatment usually begins with 2.5 mg weekly. The dose may then be increased gradually every four weeks (e.g. to 5 mg, 7.5 mg and up to 15 mg), depending on how the body responds and on the physician’s recommendation. Gradual dose escalation allows the body to adapt and reduces the risk of side effects. It is not always necessary to titrate to the highest dose; treatment continues at the dose that provides effective results (1).

Who can be treated with Mounjaro?

Mounjaro is a prescription medicine approved for the treatment of type 2 diabetes and for chronic weight management in adults with obesity or overweight with at least one weight-related condition. It may be an option for patients who have attempted weight loss through diet and exercise but have not achieved or maintained a healthy weight.

Treatment must always take place under medical supervision, and the physician and patient will jointly assess whether Mounjaro is appropriate based on the individual’s needs and health status (1).

Side effects

Like other medicines in this class, Mounjaro may cause gastrointestinal symptoms, especially at the start of treatment or during dose increases. The most common side effects are nausea, diarrhoea, constipation and gas or bloating. These symptoms are usually mild and resolve after a few weeks.

To relieve symptoms, patients may:

• eat smaller portions
• eat slowly and stop when feeling full
• avoid fatty, spicy or fried foods
• drink water often in small amounts
• avoid carbonated drinks
• engage in regular physical activity

Mounjaro may also cause other side effects such as increased heart rate. The risk of hypoglycaemia increases mainly when used in combination with insulin or sulfonylureas; dose adjustments may be necessary. In rare cases, more serious side effects such as pancreatitis or gallstone disease may occur, and patients should contact a doctor if severe or persistent symptoms arise (2).

Mounjaro compared with other medicines for weight loss

Compared with other medicines such as semaglutide (Ozempic, Wegovy), Mounjaro has shown slightly greater weight-reducing effects in studies. In a head-to-head study, tirzepatide demonstrated superior weight loss compared with semaglutide over 72 weeks (5).

Both medicines work by reducing hunger and increasing satiety, leading to lower calorie intake and weight loss. However, Mounjaro acts on two hormone receptors, which may provide enhanced effects on weight loss and blood glucose control.

Lifestyle changes for weight loss

For Mounjaro to provide the best possible weight-loss results, a comprehensive strategy is needed (6). This means combining the medication with healthy changes such as improved eating habits, regular physical activity, stress management and good sleep — ideally with support from healthcare professionals.

Diet for healthy weight with Mounjaro

Weight loss requires a calorie deficit, meaning energy intake must be lower than energy expenditure. Medication can support this by increasing satiety and reducing hunger, which often becomes more pronounced in a calorie deficit.

When energy intake is reduced, it is especially important that the diet remains nutrient-dense to meet needs for vitamins, minerals and protein. Adequate protein supports satiety, helps preserve muscle mass during weight loss and improves body composition — particularly when combined with strength training.

Treatment should always be individualised based on the patient’s current eating habits, preferences and circumstances (6).

Training and physical activity

Physical activity is a central component of weight-loss treatment (6). It enhances the effect of medicinal treatment, improves general wellbeing and helps prevent or reduce side effects. It helps maintain muscle mass, improves metabolism and supports mental wellbeing. Regular movement can also reduce stress, improve sleep quality and lower the risk of related health conditions.

It is recommended to combine different forms of physical activity (7):

• Everyday movement: taking the stairs, walking, cycling or standing more often
• Aerobic activity: such as brisk walking, swimming or cycling
• Strength training: 2–3 times per week, with particular focus on maintaining muscle mass

Recommendations should always be adapted to the individual’s abilities, limitations, health status and goals.

Sleep matters

Adequate sleep is essential for weight regulation and plays a key role in hormonal balance. Lack of sleep affects several hormonal systems that regulate appetite, satiety and energy balance, which may lead to increased hunger and cravings for high-calorie foods (8).

Reducing stress

Chronic stress can lead to elevated cortisol levels, which affect appetite regulation and metabolism. Stress perception is individual and influenced by life circumstances, personality and previous experiences. Support and treatment must therefore be tailored to each person’s needs.

For some, this may involve reducing external stressors; for others, improving recovery and developing coping strategies is more important. Regular physical activity, adequate sleep and stress-reducing techniques can be valuable tools (9).

What patients need to know before starting treatment

Mounjaro is not a quick fix, but part of a long-term plan for health and weight management. Stopping treatment without consulting a doctor may lead to rapid increases in weight or blood glucose again (4).

Patients should also be informed that Mounjaro is unsuitable or must be used with caution in certain conditions, such as type 1 diabetes or previous pancreatitis. It is not given to pregnant or breastfeeding individuals, nor to those planning pregnancy within one month. A careful medical assessment is essential before treatment begins.

Summary – Mounjaro

Mounjaro is a medicine that can support weight loss in patients with overweight or obesity. The active substance tirzepatide influences hunger and satiety signals through two hormone receptors, which may provide effective and sustainable weight reduction.

The medicine is administered as an injection as prescribed by a doctor, and is always combined with lifestyle changes such as diet and physical activity for best results. For many people, Mounjaro not only supports improved weight control but also reduces the risk of related health conditions and enhances long-term health.

Treatment must take place under medical supervision, and patients need to make the necessary lifestyle changes to maintain their health and weight over time.

References

1. European Medicines Agency. (2022). Mounjaro: EPAR – Product information. Retrieved November 12, 2025, from https://www.ema.europa.eu/en/medicines/human/EPAR/mounjaro
2. Sallam, M., Snygg, J., Ghandour, S. E., & Sallam, M. (2025). Efficacy and Safety of Tirzepatide for Weight Management in Non-Diabetic Obese Individuals: A Narrative Review. Obesities, 5(2), 26. https://doi.org/10.3390/obesities5020026
3. Jastreboff, A. M., Aronne, L. J., Ahmad, N. N., Wharton, S., Connery, L., Alves, B., Kiyosue, A., Zhang, S., Liu, B., Bunck, M. C., & Stefanski, A. (2022). Tirzepatide once weekly for the treatment of obesity. The New England Journal of Medicine, 387(3), 205–216. https://doi.org/10.1056/NEJMoa2206038
4. Aronne, L. J., Sattar, N., Bade Horn, D., et al. (2024). Continued treatment with tirzepatide for maintenance of weight reduction in adults with obesity: The SURMOUNT-4 randomized clinical trial. JAMA, 331(1), 38–48. https://doi.org/10.1001/jama.2023.24945
5. Aronne, L. J., Bade Horn, D., le Roux, C. W., Ho, W., Falcon, B. L., Gomez Valderas, E., Das, S., Lee, C. J., Glass, L. C., Senyucel, C., & Dunn, J. P. (2025). Tirzepatide as compared with semaglutide for the treatment of obesity. The New England Journal of Medicine, 393(1), 26–36. https://doi.org/10.1056/NEJMoa2416394
6. Konstantinos C Koskinas, Emeline M Van Craenenbroeck, Charalambos Antoniades, Matthias Blüher, Thomas M Gorter, Henner Hanssen, Nikolaus Marx, Theresa A McDonagh, Geltrude Mingrone, Annika Rosengren, Eva B Prescott, the ESC Scientific Document Group. Obesity and cardiovascular disease: an ESC clinical consensus statement. European Heart Journal. 2024;45(38):4063–4098. https://doi.org/10.1093/eurheartj/ehae508
7. World Health Organization (WHO). WHO Guidelines on Physical Activity and Sedentary Behaviour. Geneva: World Health Organization; 2020. Available at: https://www.who.int/publications/i/item/9789240015128
8. Chaput JP, McHill AW, Cox RC, Broussard JL, Dutil C, da Costa BGG, Sampasa-Kanyinga H, Wright KP Jr. The role of insufficient sleep and circadian misalignment in obesity. Nat Rev Endocrinol. 2023 Feb;19(2):82-97. doi: 10.1038/s41574-022-00747-7. Epub 2022 Oct 24. PMID: 36280789; PMCID: PMC9590398.
9. Lengton R, Schoenmakers M, Penninx BWJH, Boon MR, van Rossum EFC. Glucocorticoids and HPA axis regulation in the stress-obesity connection: A comprehensive overview of biological, physiological and behavioural dimensions. 2025. Available at: https://pubmed.ncbi.nlm.nih.gov/39623561/

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