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
What Is a Weight Loss Plateau and Why Does It Happen?
A weight loss plateau occurs when your body stops losing weight despite continuing your diet and exercise routine. This is a completely normal part of the weight management process and happens to most people trying to lose weight. Understanding why plateaus occur—and how to overcome them—is essential for sustainable, long-term weight loss success in the UK.
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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 Your Body Enters a Weight Loss Plateau
Weight loss plateaus happen for several evidence-based reasons. As you lose weight, your body requires fewer calories to function because there is less mass to sustain. This means the same calorie deficit that worked initially becomes smaller over time. Your metabolic rate adapts to lower calorie intake, a process called metabolic adaptation. Additionally, as you lose weight, your hormones that regulate hunger and fullness—including GLP-1, which naturally controls appetite—may shift, making it harder to maintain the same eating patterns.
- Initial gradual weight management is often water weight, not fat loss
- Your body becomes more efficient at using calories
- Compliance with diet may gradually slip without noticing
- Exercise routines can become less challenging over time
- Hormonal changes affect appetite regulation
For those using GLP-1 weight loss medication like Wegovy or Mounjaro, plateaus can also occur as your body adjusts to the medication's effects. This is normal and does not mean the medication has stopped working.
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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.
Practical Strategies to Break Through a Weight Loss Plateau
The most effective approach is to review your calorie intake and activity level. Often, small increases in daily calories or decreases in activity have accumulated without conscious awareness. Try tracking your food intake for a few days using a food diary or app to confirm your calorie deficit is still present. Alternatively, increase your physical activity—add strength training to build muscle, which raises metabolic rate, or increase the intensity of cardio exercise.
Consider timing changes: eating patterns, meal frequency, or when you exercise can make a difference. Some people find success with short-term dietary changes—like a brief reduction in carbohydrates or a change in meal composition—to restart progress. If you are using weight loss medication, your GP or prescriber can assess whether adjusting your dose may help. Always prioritise sustainable changes over drastic measures, as this supports long-term weight management success across the UK NHS framework.
- 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.
How long does a typical weight loss plateau last?
Plateaus usually last 2–8 weeks, though this varies. If you maintain your calorie deficit and remain patient, your body will typically resume losing weight. If a plateau lasts longer than 2 months despite confirmed calorie deficit, consult your GP for personalised advice.
Should I eat fewer calories to break through a plateau?
Drastically cutting calories is not recommended and often backfires, causing muscle loss and metabolic damage. Instead, review your current intake to ensure your deficit is genuine, increase activity, and consider strength training. Sustainable changes work better than extreme restriction.
Does a weight loss plateau mean my weight loss medication has stopped working?
No. Plateaus are a normal metabolic response, not medication failure. GLP-1 medications like Wegovy work over months, and your prescriber can assess whether a dose adjustment is appropriate if you have plateaued for 8+ weeks.
Can I use the BMI calculator to track plateau progress?
Yes. Use our free BMI calculator regularly to monitor your BMI change even if the scale isn't moving—small weight shifts affect your BMI, and progress in other metrics (waist circumference, energy, fitness) may be happening even during a plateau.
What if I'm eating less but still not losing weight?
Verify your calorie deficit is real—track food for a week using an app. Check for hidden calories in drinks, oils, or portion creep. Ensure you're sleeping well and managing stress, as both affect hunger hormones and weight loss. If confirmed deficit persists without loss for 8+ weeks, ask your GP to rule out medical conditions like thyroid problems.
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.