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
Working Out And No Weight Loss — Why Progress Stalls
It's frustrating to exercise regularly and see no change on the scales. Working out without weight loss is common and usually has a straightforward explanation. Weight loss depends on multiple factors — exercise is important for health, but it's not the only piece of the puzzle. Understanding why you're not seeing results, and what actually drives weight loss, can help you make changes that work. Your GP or a weight management specialist can also assess your individual situation and discuss all available options, including prescription weight loss medication if appropriate.
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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.
Why Exercise Alone May Not Lead To Weight Loss
Weight loss fundamentally requires a calorie deficit — you must consume fewer calories than you burn. Exercise burns calories, but the amount is often less than people expect. A 30-minute gym session might burn 200–300 calories, while a single biscuit or sugary drink adds 100–200 calories back. If your diet hasn't changed, exercise alone rarely creates the deficit needed for weight loss.
- Muscle gain masks fat loss: As you exercise, you build muscle, which weighs more than fat. You may be losing fat whilst gaining muscle, so the scales stay the same — but body composition improves. Use our free BMI calculator to track your overall health metrics alongside the scales.
- Increased appetite: Exercise stimulates hunger hormones. Without conscious dietary control, you may eat more after exercising, offsetting the calorie burn.
- Metabolic adaptation: As you lose weight, your metabolism adjusts and burns fewer calories at rest, making further loss harder.
- Underestimating food intake: Most people underestimate how much they eat — portion sizes creep up, and liquid calories (alcohol, smoothies, juice) are often forgotten.
The NHS weight loss recommendation combines a reduced-calorie diet with physical activity — neither alone is typically sufficient for sustainable 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.
What Actually Works For Weight Loss In The UK
Sustainable weight loss requires a calorie deficit of around 500 kcal per day, which typically results in losing approximately 0.5–1 kg per week. This means both diet and exercise matter. Try tracking your food intake honestly for a week — many people discover they're eating far more than they realised. For some people, particularly those with a BMI over 30 or overweight with weight-related health conditions, prescription weight loss medication alongside lifestyle changes may be appropriate. GLP-1 medications like Wegovy (semaglutide) can help reduce appetite and cravings, making it easier to maintain a calorie deficit. Our GLP-1 weight loss calculator can help you explore potential outcomes. Always discuss options with your GP or a weight management specialist who can assess whether prescription treatment is suitable for you.
- 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 you lose weight just from exercising without changing diet?
It's possible but very difficult. Exercise alone typically burns 200–500 calories per session, while one takeaway meal can be 1000+ calories. Without dietary changes, you're unlikely to create the calorie deficit needed for weight loss. The NHS recommends combining both exercise and a reduced-calorie diet for best results.
Why am I not losing weight despite going to the gym regularly?
Common reasons include: underestimating food intake, increased appetite after exercise, building muscle (which weighs more than fat), or an insufficient calorie deficit. Track your food honestly for a week and consider your overall calorie balance, not just exercise. Your GP can also help identify any underlying health factors.
Does muscle weight count on the scales?
Yes, muscle is denser than fat, so building muscle whilst losing fat means the scales may not change. However, your body composition improves — clothes fit differently and your BMI may improve. Use our free BMI calculator to track your overall health alongside weight.
How much weight should I expect to lose per week?
The NHS recommends losing 0.5–1 kg (1–2 lbs) per week as a safe, sustainable rate. This typically requires a calorie deficit of around 500 kcal per day through diet and exercise combined. Faster weight loss is possible with medical support but may increase muscle loss risk.
What if diet and exercise still don't work?
If you've been consistent for several months with no progress, discuss this with your GP. They can assess whether prescription weight loss medication might help. GLP-1 medications like Wegovy are available in the UK for adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions, and may help when combined with lifestyle changes.
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.