How long does Mounjaro take to work?

Many people notice that their hunger decreases within the first few days after their first injection. Mounjaro slows down gastric emptying (the process of food leaving your stomach), meaning you feel full for longer. 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.

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 diarrhea)

These side effects often appear within the first one to two weeks and tend to improve as your body adjusts to the medication.

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 people 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.

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

✅ Your starting weight – the more weight you have to lose, the longer it may take
✅ Your target weight loss percentage – Mounjaro has shown results of up to 26% in clinical trials, but this varies
✅ 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)
• 18 Months: up to 26% body weight loss (in clinical trials)

For some people, weight loss slows down after the first few months, but this is normal. 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 to help estimate your weight loss journey.

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 alongside other independently validated medical information about you 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 Terms of Service for more information.