Mounjaro (tirzepatide) is a once-weekly weight loss injection designed to target natural gut hormones that regulate appetite and blood sugar, helping support steady, clinically-meaningful weight loss over time.
Mounjaro reduces appetite, helping you feel full and eat less
Weight loss builds gradually
Check if the weight loss treatment is right for you
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All content on this page has been medically reviewed by: Hassan Thwaini, Clinical Pharmacist and Copywriter, Master of Pharmacy (MPharm) on 16 February, 2026. GPhC Registration: 2221320View profile
If you’re starting Mounjaro, one of the first questions you’ll have is: what should I actually expect? How quickly will it work, how much weight might you lose, and what changes will you notice in the first few weeks?
Rather than relying on willpower alone, Mounjaro works with your body’s natural gut hormones to reduce hunger and help you feel full for longer, supporting gradual, sustained weight loss as part of a structured, clinician-led programme.1
Tirzepatide works by acting on two natural gut hormones, GLP-1 and GIP, which help to control blood sugar and appetite. Together, these signals help the body release insulin more effectively after meals, reduce hunger, and support feelings of fullness.1
Because it stays active in the body for several days, it’s taken just once a week. In clinical studies, people taking tirzepatide lost a significant amount of weight over time, alongside improvements in markers linked to insulin sensitivity and metabolic health.2
Who can access Mounjaro depends a lot on whether you’re going through the NHS or a private provider.
On the NHS, access to Mounjaro follows strict NICE guidance and is being rolled out in phases. In practice, this means treatment is currently limited to people with more severe obesity and multiple weight-related health conditions, and waiting times can be long.
At present, or over the next few years, NHS eligibility generally requires:2
A BMI of 35 kg/m² or higher, plus at least one weight-related condition, such as high blood pressure, abnormal cholesterol, sleep apnoea, cardiovascular disease, or type 2 diabetes
In many cases, a BMI of 40 kg/m² or higher, often alongside multiple weight-related conditions
Lower BMI thresholds (by around 2.5 kg/m²) apply for people from South Asian, Chinese, other Asian, Middle Eastern, Black African, or African-Caribbean backgrounds
Even if someone meets the criteria, NHS access may be delayed due to phased funding and service capacity. Treatment is also reviewed closely, and continuation usually depends on achieving meaningful weight loss (typically at least 5% within six months at the highest tolerated dose).
Private providers may offer access outside NHS funding criteria, subject to clinical assessment.
With Numan, Mounjaro may be suitable if you:
Are 18 years or older, and
Have a BMI of 30 kg/m² or above, or
Have a BMI of 27 kg/m² or above with at least one weight-related condition (such as high blood pressure, high cholesterol, insulin resistance, or pre-diabetes), and
Complete a medical assessment reviewed by a qualified prescriber
This approach recognises that earlier intervention can reduce long-term health risks, rather than waiting until obesity becomes more severe.
Mounjaro isn’t appropriate for everyone. It may not be suitable if you:
Don’t meet the BMI or clinical criteria
Have certain medical conditions or medication interactions
Are pregnant, breastfeeding, or planning pregnancy
Are seeking a short-term or cosmetic weight-loss solution
Most people don’t lose a large amount of weight in the first week or two. Early changes are often subtle as your body adjusts to the medication and appetite begins to settle. Often, people notice reduced hunger first, before the scales move in a meaningful way.3
Over the first few months, weight loss usually becomes more noticeable and more consistent. In clinical studies, the majority of people taking tirzepatide lost at least 5% of their starting weight over time, with steady progress rather than rapid drops. This slower pace is expected and is generally safer and easier to maintain.3
As treatment continues and doses are gradually increased, weight loss tends to build. By around a year to a year and a half, people taking tirzepatide in the SURMOUNT clinical trial, lost, on average:3
Around 15% of their starting weight on lower maintenance doses
Around 19-21% of their starting weight on higher maintenance doses
Importantly, many people achieved substantial results, with roughly half of those on higher doses losing 20% or more of their body weight. Alongside weight loss, improvements were seen in markers linked to heart and metabolic health.3
Like other appetite-regulating medications, Mounjaro can cause side effects, particularly as your body adjusts. Studies show that most people experience mild effects, if any, and they tend to be temporary, easing as treatment continues or once a dose has settled.
The most commonly reported side effects are digestive and include:1,3
Nausea
Diarrhoea
Constipation
Vomiting or acid reflux
Less commonly, some people may notice:1,3
A faster heart rate
Reactions around the injection site, such as redness or irritation
Symptoms linked to dehydration if fluid intake is low
Rare but important side effects, such as pancreatitis, gallbladder issues, or changes in blood sugar, are uncommon and would be monitored closely by clinicians. Please refer to the patient information leaflet for a more detailed list of side effects.
By working with the body’s appetite and metabolic systems, Mounjaro supports steady, clinically meaningful weight loss when combined with proper medical oversight and lifestyle support. The key is suitability, safety, and long-term thinking, which is why treatment should always start with a thorough assessment and ongoing clinician care, not guesswork or pressure to rush results.
Mounjaro is designed to work gradually. In clinical trials, weight reduction was already measurable by 20 weeks, and continued steadily over the full 72-week treatment period. The medication is started at a low dose and increased slowly to improve tolerability, so changes build over time rather than happening all at once.
Most people experience progressive weight loss as treatment continues and doses are increased.
In the SURMOUNT-1 trial (72 weeks):
People taking 5 mg lost an average of 15% of their starting weight
Those taking 10 mg lost about 19.5%
Those taking 15 mg lost about 20.9%
Placebo groups lost 3.1%
Importantly:
85-91% of participants lost at least 5% of their body weight
Around 50-57% on higher doses lost 20% or more
Up to 36% on the highest dose lost 25% or more
These are averages from clinical trials. Individual results vary.
Yes. Mounjaro (tirzepatide) is a prescription-only weight loss medication. Treatment must be given under medical supervision and combined with structured lifestyle support.
Yes, current NHS backlogs and strict weight loss eligibility criteria can make it difficult to acquire Mounjaro for free. Accessing weight loss programmes privately means you can usually be assessed sooner, receive a clinician-led evaluation, and, if appropriate, begin treatment without long waiting times. This will occur under proper medical supervision and with ongoing support.
In the most recent treatment guidelines, Mounjaro is recommended for people who:
Have a BMI of 30 or higher, or
Have a BMI of 27 or higher with at least one weight-related condition (such as hypertension, dyslipidaemia, obstructive sleep apnoea, or cardiovascular disease)
Results vary depending on each individual, but healthy weight loss happens gradually. Sustained weight loss is one of the biggest challenges when it comes to achieving weight goals, which is why Numan’s programme incorporates health coaching and behaviour change. The programme focuses on key areas of health, including nutrition, exercise, and mindset.
We offer a subscription service for our weight loss programme. You can expect to receive a delivery of Mounjaro every 28 days.
The price of our programme varies based on both the type of medication you are taking and the strength of the dose. The market price of the higher-strength pens of Mounjaro and Wegovy is higher than that of the lower-strength pens.
The following prices are per month, and exclude potential discounts:
Wegovy
0.25mg: £139
0.5mg: £159
1mg: £179
1.7mg: £209
2.4mg: £229
7.2mg: £359
Mounjaro
2.5mg: £229
5mg: £239
7.5mg: £289
10mg: £309
12.5mg: £329
15mg: £339
Alli
60mg: £139
Farzam K, Patel P. Tirzepatide. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2025.
Tirzepatide for managing overweight and obesity. NICE. [accessed 29 Jan 2026] Available from: https://www.nice.org.uk/guidance/ta1026
Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387(3):205–16.
Medically reviewed:
