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 NMN Help With Weight Loss? What the Evidence Shows
NMN (nicotinamide mononucleotide) is a supplement marketed for anti-ageing and metabolism, but there's limited evidence it helps with weight loss in humans. If you're looking to manage your weight in the UK, prescription medications with proven clinical data—like Mounjaro and Wegovy—are available for eligible adults. These GLP-1 and dual-action medications have been studied extensively in clinical trials and are approved by the MHRA for weight management. This guide explains what NMN actually does, why prescription options may be more effective, and how to find out if you're eligible for evidence-based weight loss treatment.
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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.
NMN vs UK-Licensed Weight Management Medications
NMN (nicotinamide mononucleotide) is a supplement that supports cellular NAD+ production, which declines with age. Some animal studies suggest it may improve metabolism, but human evidence for weight loss is extremely limited. NMN is sold over-the-counter and is not regulated as a medicine in the UK.
In contrast, prescription weight loss medications available in the UK have undergone rigorous clinical trials:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 agonist. In the SURMOUNT trial, users lost an average of 15–21% of body weight at the maximum 15mg dose, alongside a reduced-calorie diet and physical activity.
- Wegovy (semaglutide) — a GLP-1 agonist. In the STEP-1 trial, participants lost approximately 15% of body weight at the 2.4mg dose.
- Saxenda (liraglutide) — a daily GLP-1 injection. Approved for weight management but with slightly lower average weight loss than Mounjaro or Wegovy.
If you're considering weight management, checking your BMI with our free BMI calculator can help you understand whether you might be eligible for prescription treatment.
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 Access and Private Options for Weight Loss Treatment
In the UK, prescription weight loss medications are available through two routes:
- NHS specialist services: Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (high blood pressure, type 2 diabetes, heart disease), may be referred to tier 3 specialist weight management services. Availability and waiting times vary significantly by region (ICB).
- Private prescribing: Available through UK-licensed online prescribers following a clinical assessment. No NHS referral needed, but costs vary (typically £150–£350 per month depending on dose).
Your GP can discuss which option suits your situation. Use our GLP-1 weight loss calculator to estimate potential results with different doses, and our weight converter if you need to track progress in different units.
- 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 NMN actually help you lose weight?
Human evidence for NMN and weight loss is very limited. Animal studies show potential for metabolism support, but this hasn't translated to proven weight loss in humans. Prescription medications like Mounjaro and Wegovy have much stronger clinical evidence. If you're interested in weight management, speak to your GP about evidence-based options.
Are NMN supplements safe to use with weight loss medication?
Always inform your prescriber about any supplements you're taking before starting prescription weight loss treatment. Some supplements may interact with medications or slow gastric emptying. Your GP or prescriber can advise whether it's safe to use NMN alongside medications like Mounjaro or Wegovy.
What's the difference between NMN and prescription weight loss injections?
NMN is an over-the-counter supplement with limited weight loss evidence. Prescription injections like Mounjaro and Wegovy are medications with clinical trial data showing 15–21% average body weight loss. They require a prescription and clinical assessment but are MHRA-approved and monitored.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You may be eligible if your BMI is 30 or above, or 27–29.9 with a weight-related health condition. Use our free BMI calculator to check your starting point, then speak to your GP. They can refer you to specialist services or discuss private options if you'd like to explore prescription weight management.
Can I use NMN alongside a reduced-calorie diet for better weight loss?
A reduced-calorie diet is the foundation of sustainable weight loss—that's proven. NMN may support overall health, but it won't significantly boost weight loss on its own. If you need additional support, prescription medications combined with diet and exercise have strong clinical evidence.
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.