How Long Does Mounjaro Take To Work?

Many people notice that their hunger decreases within the first few days after their first injection. Mounjaro (tirzepatide) delays gastric emptying (the process of food leaving your stomach), meaning you feel full for longer¹. Some users report:

• A reduced urge to snack between meals
• Feeling satisfied with smaller portions
• Less interest in high-calorie or sugary foods

However, the exact timing varies. Some people feel appetite suppression within 24-48 hours of their first dose, while others may take a couple of weeks before noticing a difference. It’s also important to note than suppression increases as the strength of the dose increases, so on lower doses the feeling of suppression may not be too strong².

Because Mounjaro slows digestion, some people experience:

• Fullness for longer after meals
• Mild nausea (especially at first)
• Changes in bowel habits (such as constipation or diarrhoea)

These side effects often appear within the first one to two weeks. They’re usually mild to moderate and tend to improve as your body adjusts to the medication³.

Most people start to see weight loss within the first 3 to 6 weeks of taking Mounjaro. However, weight loss will be gradual at first, as the medication starts to take effect. This is because your body is still adjusting to the medication, and the appetite suppressing effects may not be as strong at first.

Everyone is different, but a typical weight loss timeline can look like this:

• Weeks 1-4 → Some appetite suppression, minimal weight change
• Weeks 5-8 → More noticeable weight loss as higher doses take effect
• Weeks 8-12+ → Faster weight loss as your eating habits adjust

Many Medicspot members report losing 5-10% of their body weight within the first 3 months, especially when eating a calorie-controlled diet and incorporating regular movement into their lifestyle.

Clinical and real-world studies of tirzepatide have shown that people who remain on treatment typically lose around 12 % of their body weight after six months.⁴

The time it takes to reach your goal weight depends on factors like:

1. Your starting weight – the more weight you have to lose, the longer it may take
2. Your target weight loss percentage – Mounjaro has shown results of up to 26% in clinical trials, but this varies
3. Your lifestyle – a balanced diet and exercise can speed up progress

Everyone is different, but a typical weight loss timeline can look like this:

• 3 months: 5-10% body weight loss
• 6 months: 10-15% body weight loss
• 12 months: up to 20% body weight loss (in clinical trials)⁵
• 18 months: up to 26% body weight loss (in clinical trials)⁶

For some people, weight loss slows down after the first few months. Weight loss plateaus are normal, and can be overcome. Staying consistent with your habits is key.

If you’d like a more personalised forecast for your weight loss you can use our weight loss calculator (below) to help estimate your weight loss journey.

Here’s the typical weight loss achieved by Medicspot members on Mounjaro:

• Month 1 = 3.3kg
• Month 2 = 6kg
• Month 3 = 8kg
• Month 4 = 9.7kg
• Month 5 = 13.2kg
• Month 6 = 14.8kg
• Month 7 = 17.6kg

Your Mounjaro journey is unique, and it’s not a race.

You may feel changes in your appetite within a few days and see measurable progress after a few months.

The key is to stay consistent, communicate with your healthcare provider, and focus on all the ways your health is improving, not just the number on the scale.

Better energy, improved sleep, and more stable eating habits are all signs that Mounjaro is working for you.

If you’re ready to start your journey, or you’d like personalised guidance on whether Mounjaro is right for you, our team can help.

¹ Electronic Medicines Compendium (EMC). Mounjaro KwikPen 2.5mg solution for injection in pre-filled pen – Summary of Product Characteristics (SmPC). Last accessed November 2025. [https://www.medicines.org.uk/emc/product/15481/smpc]

² Heise T, DeVries JH, et al. Tirzepatide reduces appetite, energy intake, and fat mass in people with type 2 diabetes. Diabetes Obes Metab. 2023. Open-access summary. Last accessed November 2025. [https://pmc.ncbi.nlm.nih.gov/articles/PMC10154650/]

³ EMC Patient Information Leaflet. Mounjaro, INN-tirzepatide (PIL). Common GI side effects and cautions. Last accessed November 2025. [https://www.medicines.org.uk/emc/files/pil.15481.pdf]

⁴ Hankosky ER, Chinthammit C, Meeks A, et al. Real-world use and effectiveness of tirzepatide among individuals without evidence of type 2 diabetes. Diabetes Obesity & Metabolism. Last accessed November 2025. [https://pubmed.ncbi.nlm.nih.gov/39996368/]

⁵ Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). The New England Journal of Medicine. 2022;387:205-216. doi:10.1056/NEJMoa2206038. Last accessed November 2025. [https://www.nejm.org/doi/full/10.1056/NEJMoa2206038]

⁶ Wadden T. A., Chao A. M., Machineni S., Kushner R., Ard J., Srivastava G., Halpern B., Zhang S., Chen J., Bunck M. C., Ahmad N. N., Forrester T., et al. Tirzepatide after intensive lifestyle intervention in adults with overweight or obesity: the SURMOUNT-3 phase 3 trial. Nature Medicine. 2023;29:2909-2918. doi:10.1038/s41591-023-02597-w. Last accessed November 2025. [https://www.nature.com/articles/s41591-023-02597-w]

This article is for general information only and should not be used for the diagnosis or treatment of medical conditions. Medic Spot Limited has used all reasonable care in compiling the information but makes no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. In the event of an emergency, please call 999 for immediate assistance.

There is no guarantee of a specific weight loss medication being prescribed. Clinicians will review your online questionnaire and will recommend the most appropriate weight loss treatments for you based on your answers. In some cases the clinicians may contact you for additional information. See our Terms of Service for more information.