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
Does Sertraline Cause Weight Loss? Reviews and Facts
Sertraline is an antidepressant medication, not a weight loss drug, but many people wonder whether it affects their weight. Some reviews report weight loss whilst taking sertraline, whilst others describe weight gain. The reality is that sertraline affects weight differently for different people — and the reasons are more complex than the medication alone. If you're looking for prescription weight management in the UK, your GP can discuss evidence-based options, and our free BMI calculator can help you understand your current health status and weight management goals.
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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.
How Sertraline Affects Weight
Sertraline (brand name Lustral) is a selective serotonin reuptake inhibitor (SSRI) used primarily to treat depression, anxiety, and obsessive-compulsive disorder. It works by increasing serotonin levels in the brain, which affects mood, but also has effects on appetite and metabolism.
Why weight changes occur:
- Appetite suppression early on: Some people report reduced appetite in the first few weeks of sertraline treatment, which can lead to weight loss
- Weight gain later: Over months, some people experience increased appetite or changes in metabolism, leading to weight gain
- Depression itself: Untreated depression often causes weight loss due to reduced appetite; as sertraline improves mood, appetite may return to normal or increase
- Individual variation: Genetic factors, dosage, other medications, and lifestyle all influence whether someone loses or gains weight
Clinical reviews show that sertraline is not prescribed as a weight loss medication — any weight changes are side effects, not the primary therapeutic goal. For evidence-based weight loss injections uk options, prescription medications like GLP-1 agonists are specifically designed and licensed for weight management.
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.
Weight Loss Medication vs Sertraline
If weight management is your primary goal, sertraline is not the right tool. Instead, the NHS offers specialist nhs weight loss services and prescription medications specifically designed to help lose weight uk. These include GLP-1 receptor agonists like Wegovy (semaglutide) and Mounjaro (tirzepatide), which are licensed for weight management when combined with lifestyle changes.
If you're taking sertraline for depression or anxiety and experiencing unwanted weight changes, speak to your GP before stopping the medication — suddenly stopping can cause withdrawal symptoms. Your GP can discuss adjusting your dose, switching to a different antidepressant, or adding lifestyle strategies. Use our free weight converter to track your weight in stone and lbs, and our progress tracker to log changes over time. Your bmi weight loss goals should be addressed separately through specialist weight management referral if needed.
- 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.
Does sertraline cause weight loss or weight gain?
Both occur in different people. Early in treatment, some experience appetite suppression and lose weight. Later, some gain weight due to increased appetite or metabolic changes. It depends on individual response, depression severity (untreated depression causes weight loss), and other factors. Reviews vary widely because sertraline is not a weight loss medication — any weight change is a side effect.
Is sertraline a weight loss medication?
No. Sertraline is an antidepressant (SSRI) used to treat depression, anxiety, and OCD. It is not prescribed for weight loss, and weight changes are side effects only. If you need prescription weight loss medication, your GP can refer you to NHS specialist services or discuss GLP-1 weight loss options.
Can I use sertraline instead of a weight loss injection like Wegovy?
No. Sertraline and Wegovy work completely differently. Sertraline treats mental health conditions; Wegovy is licensed specifically for weight management in eligible adults. Wegovy is a GLP-1 receptor agonist with clinical trial evidence for weight loss. Never replace antidepressant treatment with weight loss medication without GP guidance.
What should I do if sertraline is causing weight gain?
Contact your GP. Do not stop sertraline suddenly — withdrawal can occur. Your GP can discuss adjusting your dose, switching to a different antidepressant with different weight effects, or adding structured lifestyle support. NHS weight management services are available if weight is a concern alongside your mental health treatment.
What are the best evidence-based weight loss options in the UK?
The NHS tier 3 specialist weight management services offer behavioural support, dietary guidance, and prescription medications. GLP-1 medications (Wegovy, Mounjaro) are now licensed for eligible adults with a BMI of 30+ or 27+ with weight-related health conditions. Calculate your BMI using our free BMI calculator to understand if you're eligible for specialist referral.
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.