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 Depression Cause Weight Loss?
Yes, depression can cause weight loss, though weight gain is more common. Depression affects appetite, sleep, motivation, and metabolism in different ways for different people. Some individuals lose their appetite and stop eating regularly, whilst others turn to comfort eating. If you've noticed unexplained weight changes alongside low mood, fatigue, or loss of interest in activities, it's important to speak with your GP. They can assess both your mental health and physical wellbeing together.
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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 Depression Affects Weight and Appetite
Depression influences weight through several interconnected pathways. The condition can suppress appetite by affecting neurotransmitters like serotonin and norepinephrine, which regulate hunger signals. Some people with depression lose interest in eating or forget to eat altogether. Others experience reduced motivation and energy (anhedonia), making cooking, shopping, or self-care feel impossible. Sleep disturbances — a hallmark of depression — can also disrupt metabolic regulation and hunger hormones like leptin and ghrelin.
Additionally, slowed metabolism and reduced physical activity often accompany depression, meaning some people gain weight despite eating less. Conversely, severe depression can lead to significant weight loss through appetite suppression alone. Individual responses vary widely based on depression severity, personal biology, and whether medication is being taken. If you're experiencing unexplained weight loss alongside depression symptoms, your GP should assess both your mental and physical health as part of your overall care plan.
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.
When to Seek GP Support
Contact your GP if you notice sudden or unexplained weight changes combined with depression symptoms such as persistent low mood, loss of interest in activities, sleep problems, or fatigue lasting more than two weeks. Weight loss can sometimes signal more serious health conditions beyond depression — including thyroid disorders, diabetes, or nutritional deficiencies — which your GP needs to rule out.
Your GP can offer holistic support including talking therapies (CBT, counselling), medication if appropriate, lifestyle changes, and referral to specialist mental health services. They'll also monitor your weight as part of your overall health picture. If you're struggling with motivation around eating or self-care, be honest with your GP — they're there to help, not judge. Use our free BMI calculator above to track your weight baseline, and consider keeping a simple food and mood diary to share with your GP.
- 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 depression medication cause weight loss?
Antidepressants can affect weight differently depending on the medication. Some SSRIs may cause initial weight loss, whilst others may increase appetite. Your GP will discuss potential side effects before prescribing and can adjust treatment if weight changes become problematic. Never stop medication without medical guidance.
Is weight loss from depression dangerous?
Significant unintentional weight loss can lead to malnutrition, weakened immunity, muscle loss, and low energy — all of which worsen depression. gradual weight management is a red flag requiring urgent GP assessment. Your GP can assess whether the weight loss poses health risks and recommend appropriate support.
How much weight loss is normal with depression?
There's no "normal" amount — depression affects people differently. However, any sudden, unexplained weight change warrants GP evaluation. Gradual loss over weeks or months combined with depression symptoms should be discussed with your healthcare provider to rule out other causes.
Can I lose weight whilst managing depression?
Yes, sustainable weight loss is possible alongside mental health treatment. In fact, physical activity and improved nutrition often support both mental and physical health. Your GP or a counsellor can help you set realistic, compassionate goals that don't worsen depression or create unhealthy restriction.
Should I use weight loss medication if I have depression?
GLP-1 weight loss medications like Wegovy are prescription-only and require clinical assessment. Your prescriber needs to know about any mental health conditions, as some medications interact with antidepressants or may affect mood. Always disclose your full medical history before any prescription is issued.
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.