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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Does Collagen Actually Help With Weight Loss?
Collagen supplements are popular for skin and joint health, but can they help with weight loss? The short answer is: collagen alone is unlikely to produce significant weight loss results. However, collagen does have some properties that may support weight management as part of a broader approach. This guide explores what the evidence actually shows, and discusses evidence-based weight management strategies that have proven results in UK clinical practice.
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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.
What Does the Evidence Say About Collagen and Weight Loss?
Research on collagen specifically for weight loss is limited. The main potential benefit is that collagen is a protein, and protein can help with satiety — meaning you may feel fuller for longer after eating. A higher protein intake may also support muscle maintenance during weight loss, which is important because muscle burns more calories at rest than fat tissue.
However, collagen has no special weight loss properties beyond being a protein source. Regular protein from chicken, fish, eggs, or dairy works just as well. Some studies suggest that protein intake of around 1.6–2.2g per kg of body weight can support satiety and muscle preservation during calorie restriction — but this applies to all protein sources, not collagen specifically.
Collagen also lacks certain amino acids (particularly tryptophan and methionine) that complete proteins contain, making it an incomplete protein source on its own. For weight management, you would still need to maintain a calorie deficit — no supplement can overcome this fundamental requirement.
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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.
Evidence-Based Weight Loss Strategies That Actually Work
If you're seeking weight loss support, the NHS recommends starting with lifestyle changes: reduced-calorie diet and increased physical activity. A calorie deficit of approximately 500 kcal per day typically results in weight loss of around 0.5 kg per week — which is a safe, sustainable rate.
For adults with a BMI of 30 or above (or 27 or above with weight-related health conditions), prescription weight loss medication may be available. These include GLP-1 injections like Wegovy, which evidence from the STEP clinical trials showed helped participants lose an average of approximately 15% of body weight alongside lifestyle changes. Check your eligibility using our free BMI calculator, and discuss prescription weight management options 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 collagen supplements replace a weight loss diet?
No. Collagen supplements cannot replace a calorie deficit. Weight loss requires consuming fewer calories than you burn — no supplement can achieve this alone. Collagen may support protein intake and satiety, but it must be part of an overall reduced-calorie approach, not a substitute for diet changes.
Is collagen better for weight loss than other proteins?
No. Collagen is a protein source, but it has no special weight loss advantage over chicken, fish, eggs, or dairy. In fact, collagen is incomplete — it lacks certain amino acids. If you want protein for weight management, whole food sources or complete protein supplements are equally or more effective.
How much protein do I need for weight loss?
Research suggests approximately 1.6–2.2g of protein per kg of body weight supports satiety and muscle preservation during weight loss. This applies to all protein sources. Track your total protein intake across your diet — collagen is just one possible source among many.
What are evidence-based weight loss treatments available in the UK?
The NHS recommends starting with lifestyle changes (calorie deficit and activity). For adults with BMI ≥30 (or ≥27 with health conditions), prescription weight loss medications like Wegovy (semaglutide) are available through specialist services or private prescribing. These have clinical trial evidence of meaningful weight loss.
Should I use our BMI calculator to check my weight management options?
Yes. Our free BMI calculator helps you determine your current BMI category and whether you may be eligible for prescription weight loss support. This information is useful to discuss with your GP when exploring weight management options suited to your individual circumstances.
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.