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
Collagen At Night For Weight Loss — What The Evidence Shows
Collagen supplements are popular for skin and joint health, but there's limited scientific evidence that taking collagen at night specifically aids weight loss. If you're interested in weight management in the UK, several prescription medications and lifestyle approaches have stronger clinical backing. This guide explores what collagen can and cannot do, and introduces the prescription weight loss options available through the NHS and private prescribing in the UK.
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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 Prescription Weight Loss Options — Evidence-Based Alternatives
If you're looking for proven weight management in the UK, prescription medications offer clinical evidence of effectiveness. Three weight loss medications are currently licensed in the UK and may be suitable if you meet eligibility criteria:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist. Clinical trials showed average weight loss of 15–21% of body weight over 72 weeks, alongside a reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — a GLP-1 receptor agonist. Clinical trials demonstrated average weight loss of approximately 15% of body weight at 68 weeks.
- Saxenda (liraglutide) — a GLP-1 receptor agonist given as a daily injection. Effective for supporting weight loss in eligible adults.
All three are prescription-only medicines requiring clinical assessment before being prescribed. Individual results vary significantly based on diet, exercise, and personal health factors.
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 Prescription Weight Loss — How To Get Started
NHS access: Available through specialist tier 3 weight management services. You'll need a referral from your GP, and availability varies by region. Waiting lists can be lengthy in many areas.
Private access: Available through UK-licensed prescribers following an online clinical assessment. This route doesn't require an NHS referral and can be faster, though there is a cost.
To find out if prescription weight loss medication is suitable for you, calculate your BMI using our free BMI calculator above, then discuss the results with your GP. Your GP can assess whether you meet eligibility criteria (typically BMI 30 or above, or 27–29.9 with weight-related health conditions) and refer you to specialist services 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.
Does collagen help you lose weight at night?
Collagen is primarily used for skin, joint, and connective tissue health. While protein-based supplements can support muscle maintenance during weight loss, there's no scientific evidence that collagen specifically aids weight loss when taken at night. For proven weight loss support, prescription GLP-1 medications like Mounjaro and Wegovy have clinical evidence backing their effectiveness.
What's the difference between collagen supplements and prescription weight loss medication?
Collagen is a food supplement with no licensing requirement and limited weight loss evidence. Prescription weight loss medications like Mounjaro and Wegovy are licensed medicines that have undergone rigorous clinical trials. They work by affecting appetite hormones and are only available with a prescription following clinical assessment.
Can I use collagen alongside weight loss injections like Mounjaro or Wegovy?
Collagen supplements are unlikely to interact with prescription weight loss medications, but always inform your prescriber of all supplements and medications you're taking. Your healthcare provider can advise whether collagen is appropriate for your individual situation.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You're potentially eligible if your BMI is 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or cardiovascular disease. Use our free BMI calculator to check your BMI, then speak to your GP about whether you meet criteria for specialist weight management services.
What's the most effective weight loss approach — collagen, diet, or prescription medication?
Evidence-based weight loss typically combines dietary changes, increased physical activity, and sometimes prescription medication if clinically appropriate. Collagen alone has no proven weight loss benefit. For NHS-approved weight loss support, speak to your GP about referral to tier 3 services or discuss private prescription options with a licensed healthcare provider.
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.