The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Stopping And Restarting Mounjaro Weight Loss
If you're taking Mounjaro for weight management and wondering about stopping or restarting, it's important to understand what happens when you pause treatment and how to safely resume. Mounjaro (tirzepatide) is a prescription-only weekly weight loss injection that works through a dual GIP and GLP-1 mechanism. Stopping and restarting requires careful planning with your prescriber, as your body's response may differ from your initial treatment. This guide covers what to expect, how your GP or prescriber can help, and how Mounjaro's restart profile compares to Wegovy.
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Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
What Happens When You Stop Mounjaro
When you stop taking Mounjaro, your body gradually loses the appetite-suppressing effects of the medication. Weight regain typically begins within 1–2 weeks of your last dose, though the pace varies between individuals. Clinical trial data suggests that people who discontinue GLP-1 and dual GIP+GLP-1 medications regain an average of 50% of weight lost within the first year without ongoing treatment.
Key changes after stopping:
- Appetite and food cravings gradually return
- Nausea and stomach side effects resolve within days
- Blood sugar control may worsen if you have type 2 diabetes
- The medication clears your system within 4–7 days (one half-life)
Stopping abruptly does not cause harm, but many people find a gradual tapering approach easier psychologically. Your prescriber may suggest spacing final doses further apart rather than stopping suddenly.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
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Restarting Mounjaro: Dosing And Safety
If you restart Mounjaro after a break, you typically restart at the original starting dose of 2.5 mg, regardless of the dose you were on before stopping. This allows your body to readjust to the medication safely. Your prescriber will then escalate you through the dose titration schedule again, increasing every 4 weeks if tolerated.
The timeframe for restarting depends on why you stopped: health reasons, cost, side effects, or personal choice. Your prescriber will reassess your eligibility and suitability before prescribing again. If you're considering switching to Wegovy (semaglutide) as an alternative weekly injection, discuss this with your GP or licensed prescriber—both require clinical assessment and may suit different individuals based on your health history and previous experience.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Will I regain all the weight I lost after stopping Mounjaro?
Not necessarily. Weight regain depends on your eating habits, exercise, and individual metabolism. Clinical data shows approximately 50% of weight lost returns within a year without ongoing treatment. However, many people maintain at least 30–40% of their weight loss if they sustain healthy lifestyle changes. Your prescriber can discuss strategies to minimise regain.
How quickly can I restart Mounjaro if I stop?
You can restart as soon as you have a new prescription from your GP or licensed prescriber. There's no mandatory waiting period. However, you'll restart at 2.5 mg and go through dose escalation again, which takes 16–20 weeks to reach higher maintenance doses. Discuss timing and your reasons for stopping with your prescriber.
Does stopping Mounjaro cause withdrawal symptoms?
Mounjaro does not cause physical withdrawal. However, as the appetite-suppressing effects wear off over 1–2 weeks, you may experience increased hunger, food cravings, and mood changes related to this shift. These are not withdrawal symptoms but a return to your baseline appetite regulation. This can feel challenging psychologically.
How does restarting Mounjaro compare to starting Wegovy instead?
Both require restarting from a low dose with gradual escalation. Wegovy (semaglutide) is a GLP-1 agonist only, whereas Mounjaro is a dual GIP+GLP-1 agonist. Clinical trial data shows both support weight loss of approximately 15–21% body weight. Your prescriber will assess which suits you best based on your health, side effects experienced, and individual response to treatment.
What should I tell my GP before restarting Mounjaro?
Inform your GP of any changes to your health since you stopped, including new medications, blood sugar control, gallbladder or pancreas problems, or any side effects you experienced previously. Be honest about why you stopped—this helps your prescriber decide if Mounjaro remains the right choice or if alternatives like Wegovy might be better suited. A clinical reassessment is standard before restarting any prescription medication.
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