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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Depression and Weight Loss — Understanding Medication Options in the UK
Depression and weight changes often go hand in hand — some people lose appetite and weight during depressive episodes, while others gain weight as a coping mechanism or due to medication side effects. If you're struggling with both depression and excess weight, there are UK-licensed prescription options available that may help with weight management alongside treatment for your mental health. This guide explains what's available through the NHS and private prescribing in the UK, and how to discuss these options with your GP or healthcare provider.
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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.
UK-Licensed Weight Management Medications
Three prescription-only weight management injections are currently licensed in the UK for eligible adults: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 and GIP receptor agonist medications that work by helping regulate appetite and supporting feeling fuller after meals.
Eligibility criteria: Adults with a BMI of 30 kg/m² or above, or 25–29.9 kg/m² with weight-related health conditions, may be eligible. Clinical trials showed average weight loss ranging from approximately 14–21% of body weight depending on the medication and dose used alongside a reduced-calorie diet and increased physical activity. Individual results vary significantly — prescription weight loss medication is not a assured solution, but evidence suggests it may help when combined with lifestyle changes.
All three medications are injectable, once-weekly or daily administration depending on the drug, and require a clinical assessment before prescribing. Use our free GLP-1 weight loss calculator to explore potential weight loss projections at different doses, and our BMI calculator to determine your current weight category.
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 in the UK
NHS route: Weight management medications are available through tier 3 specialist weight management services, typically following referral from your GP. Access varies significantly by region and ICB (Integrated Care Board) — waiting lists can be lengthy in some areas, and availability is not uniform across the UK.
Private route: Prescription weight loss medication is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. This typically offers faster access without waiting for NHS specialist referral, though costs apply (usually £129–£320+ per month depending on dose and provider).
If you're managing depression alongside excess weight, speak to your GP about your options. They can advise whether prescription weight management is appropriate for you, discuss potential interactions with antidepressants or other medications, and signpost you to NHS services or support. Our progress tracker can help you log weight changes as part of your overall health journey.
- 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.
Can weight loss medication help if I'm taking antidepressants?
Some antidepressants can affect weight gain or appetite. Weight loss medication may help, but interactions are possible — certain medications reduce absorption of oral contraceptives and other drugs. Always inform your prescriber of all medications you're taking, including antidepressants, before starting any weight management treatment. Your GP can assess safety and suitability for your individual situation.
Does depression make weight loss harder?
Yes — depression often reduces motivation, energy, and appetite regulation, making sustainable weight loss more challenging. Additionally, some antidepressant medications can increase appetite or cause weight gain as a side effect. Treating depression alongside weight management, rather than attempting weight loss in isolation, tends to be more effective. Your GP can help coordinate both aspects of your care.
How do I access prescription weight loss medication on the NHS?
Speak to your GP, who can refer you to your local tier 3 specialist weight management service if you meet eligibility criteria (BMI ≥30, or BMI 27–29.9 with weight-related health conditions). NHS specialist teams will assess you and prescribe if appropriate. Waiting times vary by region. Private prescribing through online clinics offers faster access but involves costs.
What's the difference between Mounjaro, Wegovy, and Saxenda?
All three are prescription-only weight management injections licensed in the UK. Mounjaro (tirzepatide) is a dual GIP + GLP-1 agonist with doses up to 15mg weekly. Wegovy (semaglutide) is a GLP-1 agonist with doses up to 2.4mg weekly. Saxenda (liraglutide) is a GLP-1 agonist given daily (not weekly). Clinical trials showed varying average weight loss — individual results depend on the medication, dose, adherence, and lifestyle changes.
Can I use weight loss medication if I have a BMI under 30?
Yes — UK eligibility includes adults with a BMI of 27–29.9 kg/m² if you have weight-related health conditions such as type 2 diabetes, prediabetes, high blood pressure, sleep apnoea, or cardiovascular disease. For South Asian, Chinese, Black African, or Black Caribbean adults, lower BMI thresholds may apply due to higher health risks at lower weights. Your prescriber will assess your individual eligibility.
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.