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
Quick Weight Loss Diet Plan — What Actually Works
If you're looking for a quick weight loss diet plan, it's important to understand what "quick" realistically means for sustainable results. The NHS recommends losing weight at a rate of 0.5 to 1 kg per week — this is the safest and most sustainable pace. Crash diets or extreme calorie restriction rarely work long-term and can harm your health. This guide covers evidence-based approaches to weight management in the UK, from dietary changes to when prescription support might help. Use our free BMI calculator above to establish your starting point and understand your individual weight management needs.
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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.
Evidence-Based Quick Weight Loss Approaches
Safe weight loss requires a calorie deficit, but "quick" doesn't mean unsafe. A realistic target is losing 0.5–1 kg per week, which typically requires a deficit of around 500 kcal per day. This can be achieved through diet alone, exercise alone, or — most effectively — a combination of both.
Proven dietary approaches for weight loss in the UK include:
- Calorie-controlled eating — track intake using apps or food diaries; the NHS Weight Loss Plan offers free guidance
- Mediterranean diet — strong evidence for cardiovascular health and sustainable weight management alongside weight loss
- Intermittent fasting (16:8 or 5:2) — can support weight loss and improve metabolic markers
- Low-carbohydrate diets — effective short-term, though long-term outcomes are similar to standard calorie restriction
- Increased protein intake — supports satiety and preserves muscle during weight loss
Very gradual weight management (more than 1.5 kg per week) is not recommended without medical supervision, as it increases muscle loss and nutrient deficiency risk. Try our free weight loss calculator to see realistic projections over time.
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.
When Prescription Weight Loss Support May Help
If diet and lifestyle changes alone aren't delivering results, prescription weight loss medication may be considered for UK adults with:
- BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions
- Commitment to ongoing dietary and lifestyle changes
- Medical assessment confirming suitability
GLP-1 weight loss injections (including Mounjaro and Wegovy) are prescription-only medications available through NHS specialist services or private prescribing. In clinical trials, these medications helped participants lose an average of 15–21% of body weight — though individual results vary significantly. Weight loss medication works alongside diet and exercise, not instead of them. Your GP can refer you to specialist weight management services, or you can access private prescribing following an online assessment.
- 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.
What's the fastest safe weight loss rate?
The NHS recommends losing 0.5–1 kg per week for sustainable, healthy results. This typically requires a calorie deficit of around 500 kcal daily. Faster loss is possible with medical support but increases risks including muscle loss and nutrient deficiency. Aim for steady progress rather than rapid drops.
Can I lose weight quickly without dieting?
Exercise alone can support weight loss but is less effective than combining diet and activity. A calorie deficit is essential — you can create this through reduced food intake, increased physical activity, or both. Most successful weight loss combines dietary changes with regular movement.
Are crash diets effective for quick weight loss?
Crash diets typically fail long-term. They're unsustainable, can harm metabolism, and usually result in rapid weight regain once normal eating resumes. The NHS recommends evidence-based approaches like gradual calorie reduction, behaviour change, and increased activity — these deliver lasting results.
When should I consider prescription weight loss medication?
Prescription weight loss treatment (available on NHS or privately) may be appropriate for adults with BMI 30+, or BMI 27–29.9 with weight-related health conditions. Discuss options with your GP or a licensed prescriber to assess suitability. Medication works best alongside diet and lifestyle changes.
How does the NHS support quick weight loss?
The NHS offers free support through the Weight Loss Plan, tier 1 community programmes, and referral to specialist tier 3 services for eligible adults. Specialist services may prescribe weight loss medication if appropriate. Your GP can discuss which support pathway suits you best based on your BMI and health needs.
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.