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
Diet Plans for Weight Loss — What Actually Works
Finding the right diet plan is one of the most important steps in your weight management UK journey. There's no single "best" diet — success depends on what you can sustain long-term. The NHS recommends losing weight at a rate of 0.5 to 1 kg per week through a combination of dietary changes and increased physical activity. This guide covers evidence-based diet approaches, how to create a sustainable calorie deficit, and when additional support like prescription weight loss medication might be appropriate alongside dietary changes.
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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 Diet Approaches for Sustainable Weight Loss
The foundation of any successful weight loss diet is a calorie deficit — consuming fewer calories than you burn. A deficit of around 500 kcal per day typically results in approximately 0.5 kg per week of weight loss. The NHS recommends avoiding very gradual weight management, as it can lead to muscle loss and is harder to maintain long-term.
- Low calorie diet (LCD): 1200–1500 kcal per day — sustainable for many people and doesn't require complex rules
- Mediterranean diet: Strong evidence for cardiovascular health, sustainable eating pattern with whole grains, olive oil, fish, and vegetables
- Low carbohydrate diet: Effective short-term, can help control appetite — though long-term outcomes are similar to standard calorie restriction
- Intermittent fasting: 5:2 diet or 16:8 fasting windows — evidence supports modest weight loss when combined with overall calorie reduction
The best diet plan is one you can follow consistently. Evidence suggests that even a 5% reduction in body weight can have meaningful health benefits, including improved blood pressure and blood sugar control.
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.
Combining Diet with Other Weight Management Strategies
Diet alone is effective, but combining dietary changes with increased physical activity improves results significantly. The NHS emphasises that sustainable weight management involves both eating fewer calories and moving more.
For some people, prescription weight loss medication may be recommended alongside dietary changes. GLP-1 weight loss injections like Mounjaro and Wegovy are prescription-only treatments available in the UK for adults with a BMI of 30 or above, or 27+ with weight-related health conditions. These medications work alongside — not instead of — dietary changes and exercise. Try our free GLP-1 weight loss calculator to explore how medication might support your goals, and use the BMI calculator on this page to check your current weight category.
- 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 best diet plan for weight loss?
There's no single "best" diet. The best plan is one you can stick to long-term. Low calorie diets, Mediterranean approaches, and intermittent fasting all work if they create a calorie deficit. The NHS recommends aiming for 0.5–1 kg per week loss. Consult your GP if you have any underlying health conditions or take medication.
How many calories should I eat to lose weight?
A typical calorie deficit of 500 kcal per day results in approximately 0.5 kg weekly loss. For most adults, this means 1200–1500 kcal per day, though individual needs vary based on height, weight, age, and activity level. Your GP can provide personalised guidance.
Can I lose weight without exercise?
Yes — weight loss is primarily driven by calorie deficit, which diet creates. However, the NHS recommends combining dietary changes with increased physical activity for better health outcomes, improved muscle retention, and sustained results. Exercise also supports cardiovascular health and mental wellbeing.
How long does it take to see results from a diet plan?
Most people see measurable weight loss within 2–4 weeks of maintaining a consistent calorie deficit. However, weight fluctuates daily due to water retention and hormones. Tracking progress weekly using our free progress tracker can help you see trends beyond daily variations.
Should I consider weight loss injections alongside diet?
Prescription weight loss medications like Mounjaro and Wegovy are only prescribed following a clinical assessment by a GP or licensed prescriber. They're used alongside — not instead of — dietary changes and exercise. Eligibility depends on your BMI and health conditions. Discuss with your GP to see if you might be suitable.
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.