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
Can Antidepressants Help You Lose Weight?
Some antidepressants are associated with weight loss, but this is not their primary purpose. If you're taking antidepressants and concerned about weight gain—or hoping medication might help with both mental health and weight—it's important to understand what's actually available in the UK. The good news is that prescription weight management uk options exist specifically designed to support weight loss, alongside lifestyle changes. Your GP can help you explore what's right for your situation.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Prescription Weight Loss Options
If you're looking for medication to support weight loss in the UK, there are three prescription-only medicines licensed specifically for weight management:
- Mounjaro (tirzepatide) — a once-weekly injection that activates GLP-1 and GIP pathways. Clinical trials showed an average weight loss of 15–21% of body weight over 72 weeks alongside diet and exercise.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection. Evidence suggests average weight loss of around 15% of body weight.
- Saxenda (liraglutide) — a daily GLP-1 injection. A prescription weight loss medication available through NHS or private prescribing.
These are not antidepressants—they're specifically designed for weight loss and are available to eligible adults with a BMI of 30 or above, or BMI 27+ with weight-related health conditions. Use our GLP-1 weight loss calculator to explore potential outcomes at different doses.
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.
How to Access Weight Loss Medication in the UK
There are two main routes: NHS and private prescribing. NHS weight loss medication is available through specialist tier 3 weight management services—your GP can refer you, though waiting lists vary significantly by region. Private prescribing is faster; you'll have an online consultation with a UK-licensed prescriber who assesses whether treatment is suitable for you.
Both routes require a clinical assessment. Eligibility is based on your BMI, health history, and weight-related conditions. Use our free BMI calculator to check where you fall, and discuss your options with your GP—they can advise on NHS availability in your area or support a private route if appropriate.
- 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.
Do antidepressants actually cause weight loss?
Most antidepressants are associated with weight gain or neutral weight change. A small number—such as some SSRIs—may be associated with modest weight loss in some people, but this is not assured and varies individually. Weight loss is never the primary purpose of antidepressants. If you're concerned about weight changes on your current medication, speak to your GP—never stop antidepressants without professional guidance.
What's the difference between antidepressants and GLP-1 weight loss medication?
Antidepressants treat depression and anxiety by affecting neurotransmitters like serotonin. GLP-1 medications (like Wegovy and Mounjaro) are designed specifically for weight management and work by mimicking a natural gut hormone that regulates appetite and fullness. They have different mechanisms, different purposes, and different side effect profiles.
Can I take antidepressants and weight loss medication together?
In many cases, yes—but this requires careful prescriber assessment. Some medications interact, and your medical history matters. If you're taking antidepressants and considering prescription weight loss treatment, inform the prescriber. Your GP or the prescriber will check for interactions and ensure it's safe for you.
What's the difference between nhs weight loss medication and private?
NHS weight loss medication is prescription-only and delivered through specialist weight management services—free but with variable availability and waiting times depending on your region. Private prescribing is faster and doesn't require NHS referral, but involves a cost (typically £120–£300+ per month depending on dose). Both require a clinical assessment and prescription.
How much weight can I expect to lose with prescription weight loss medication?
Results vary significantly between individuals. Clinical trials showed average weight loss of 15–21% of body weight with GLP-1 medications over several months, alongside reduced-calorie diet and increased physical activity. However, some people lose more, some less. Your GP or prescriber will discuss realistic expectations for your situation.
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.