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
Good Diet Plan for Weight Loss in the UK
A good diet plan for weight loss combines sustainable eating habits with realistic calorie targets and lifestyle changes. In the UK, the NHS recommends losing weight at a rate of 0.5 to 1 kg per week for lasting results. This guide covers evidence-based dietary approaches, when prescription weight loss medication may be appropriate, and how to work with your GP to find the right weight management strategy for your 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.
Effective Diet Approaches Backed by Evidence
The best diet plan for weight loss is one you can stick to long-term. Calorie deficit remains the foundation — you need to consume fewer calories than you burn, typically around 500 kcal per day for gradual, sustainable loss of approximately 0.5 kg weekly.
- Mediterranean diet: Strong evidence for cardiovascular health and sustainable weight management through whole grains, lean proteins, healthy fats, and vegetables
- Low carbohydrate approaches: Effective short-term, though long-term outcomes match standard calorie restriction
- Intermittent fasting (16:8, 5:2): Research supports modest weight loss, particularly if it helps maintain a calorie deficit
- Portion control and mindful eating: Key to preventing overeating and maintaining awareness of food intake
The most successful diet plan is one aligned with your lifestyle, food preferences, and ability to maintain it. Calculate your healthy weight range using our free BMI calculator above to establish your personal weight loss target.
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.
Prescription Weight Loss Options in the UK
For adults with significant excess weight, prescription weight loss medication may be appropriate alongside diet and physical activity changes. Three prescription medications are currently licensed for weight management in the UK:
- Mounjaro (tirzepatide): GIP and GLP-1 receptor agonist; once-weekly injection; average weight loss 15–21% of body weight in clinical trials
- Wegovy (semaglutide): GLP-1 receptor agonist; once-weekly injection; average weight loss approximately 14.9% in clinical trials
- Saxenda (liraglutide): GLP-1 receptor agonist; daily injection
Eligibility typically requires BMI ≥30 or BMI 27–29.9 with weight-related health conditions such as type 2 diabetes, hypertension, or sleep apnoea. Try our GLP-1 weight loss calculator to explore potential outcomes with prescription weight management support.
NHS vs Private: Getting Help With Weight Loss- 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 difference between NHS and private weight loss support in the UK?
NHS weight management is available through specialist tier 3 and tier 4 services, though access varies by region and waiting lists can be lengthy. Private routes, including online consultations with registered prescribers, offer faster access without NHS referral. Both require clinical assessment. Your GP can discuss your options and whether you qualify for NHS support or if private options suit your situation.
How do I know if I'm eligible for prescription weight loss medication?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, hypertension, sleep apnoea, or cardiovascular disease. Adults of South Asian, Chinese, Black African, or Black Caribbean heritage may have lower BMI thresholds due to higher health risks at lower weights. Use our BMI calculator to check your BMI, then speak with your GP.
Can I use diet alone, or do I need medication?
Diet and lifestyle changes are the foundation of sustainable weight loss and should always be the primary approach. Prescription weight loss medication is an option for eligible adults when diet alone hasn't achieved sufficient results or when weight-related health conditions require additional support. Your GP can advise whether medication is right for you alongside continued dietary changes.
How quickly can I expect to lose weight with a good diet plan?
The NHS recommends losing 0.5 to 1 kg per week for sustainable results. Very gradual weight management can lead to muscle loss and nutritional deficiencies. A calorie deficit of approximately 500 kcal per day typically results in 0.5 kg weekly loss. Track your progress using our free progress tracker to monitor results over time.
Where should I start if I want to lose weight?
Start by calculating your current BMI and healthy weight range using our free BMI calculator. Then discuss a weight loss plan with your GP, who can assess your health, recommend appropriate dietary approaches, and determine if prescription weight loss support is suitable. The NHS Weight Loss Plan and tier 1 community programmes offer free support, and your GP can refer you to specialist services if needed.
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.