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
Free tracker included with every download this week
1 Month Weight Loss Plan: UK Medication and Lifestyle Guide
A realistic 1-month weight loss plan combines sustainable dietary changes, increased physical activity, and where appropriate, prescription support through weight management medication. In the UK, several evidence-based options are available through both NHS and private prescribing. While one month is a relatively short timeframe, setting achievable goals—typically losing 0.5 to 1 kg per week—creates momentum for longer-term success. This guide covers UK-licensed prescription options, eligibility criteria, and how to start a conversation with your GP about the right approach for your individual health needs.
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Calculate Your BMI Instantly
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.
UK-Licensed Prescription Weight Loss Options
For eligible UK adults, three prescription-only weight loss medications are available through NHS specialist services or private prescribing: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide).
Mounjaro is a once-weekly injection using a dual GIP and GLP-1 mechanism. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks alongside lifestyle changes. Wegovy is also a once-weekly GLP-1 injection; trials demonstrated approximately clinically studied weight loss. Saxenda is a daily GLP-1 injection with similar efficacy.
You may be eligible if you have a BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Lower BMI thresholds (27.5+) apply for adults of South Asian, Chinese, Black African, or Black Caribbean heritage. These medications are prescribed following a clinical assessment; they are not assured to work for everyone, and individual results vary significantly.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS vs Private Access and Next Steps
NHS route: Refer yourself or ask your GP for a referral to your local tier 3 specialist weight management service. These services assess you for prescription weight loss medication as part of a comprehensive weight management programme. Availability varies by region and waiting times can be several months.
Private route: Access prescription weight loss treatment through a UK-licensed online prescriber without an NHS referral. You'll complete an online clinical assessment; if approved, a prescription is issued and medication dispensed by a GPhC-registered pharmacy. This typically takes days rather than months.
To get started: book an appointment with your GP to discuss your weight loss goals and whether prescription medication might support your plan. Use our free BMI calculator to establish your current BMI and check eligibility. Our GLP-1 weight loss calculator can help you explore potential outcomes at different doses.
The NHS recommends losing no more than 0.5–1 kg per week for sustainable results. Over one month, realistic weight loss is typically 2–4 kg, depending on your starting weight, calorie deficit, physical activity, and individual metabolism. Prescription weight loss medication is most effective alongside a reduced-calorie diet (approximately 500 kcal daily deficit) and increased physical activity. Track your progress with our free progress tracker to stay motivated throughout the month and beyond. Remember: sustainable weight loss is a marathon, not a sprint. One month is an excellent starting point for building habits that last.
- 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.
How much weight can I lose in one month with prescription weight loss medication?
Individual results vary significantly. In clinical trials, participants lost between 0.5–1.5 kg per week on average when combining medication with lifestyle changes. Over one month, this typically translates to 2–6 kg, though some individuals lose more and others less. Prescription medication is most effective alongside a reduced-calorie diet and increased physical activity—medication alone is not enough.
Am I eligible for Mounjaro or Wegovy on the NHS?
You may be eligible if you have a BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, or cardiovascular disease). Lower thresholds apply for adults of South Asian, Chinese, Black African, or Black Caribbean heritage. NHS access is through specialist tier 3 weight management services. Ask your GP for a referral to your local service.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections licensed for weight loss in the UK. Mounjaro (tirzepatide) uses a dual GIP and GLP-1 mechanism and showed slightly higher average weight loss (15–21%) in trials. Wegovy (semaglutide) is a GLP-1 agonist with average weight loss around 15%. Both require clinical assessment before prescribing; your prescriber will advise which is more suitable for you.
Can I get prescription weight loss medication privately without an NHS referral?
Yes. Private UK-licensed prescribers offer online consultations and prescription services. If you're clinically appropriate, a prescription is issued and medication dispensed by a GPhC-registered pharmacy. Private access is faster than NHS—typically days versus months—but costs vary (roughly £130–£320 per month depending on dose and provider).
Should I follow a specific diet plan with weight loss medication?
Prescription weight loss medication works best alongside a reduced-calorie diet (typically 500 kcal daily deficit) and regular physical activity. You don't need an extreme diet—moderate, sustainable changes are most effective. Your GP or a prescriber can advise on a plan suited to you. Our BMI calculator and progress tracker help you monitor your approach throughout your weight loss journey.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.