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
Does Sleep Affect Weight Loss?
Yes, sleep quality has a significant impact on weight loss and weight management in the UK. Poor sleep disrupts the hormones that control appetite and metabolism, making it harder to lose weight even with a reduced-calorie diet and increased physical activity. If you're struggling with weight loss despite good lifestyle habits, sleep could be a key factor. For adults considering prescription weight loss medication as part of their weight management journey, addressing sleep quality is equally important alongside medication use.
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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.
How Sleep Affects Weight Loss and Metabolism
Sleep deprivation disrupts two critical hormones that regulate appetite: leptin (which signals fullness) and ghrelin (which triggers hunger). When you don't get enough sleep, leptin drops and ghrelin rises, leading to increased appetite and cravings for high-calorie, sugary foods. This makes it harder to maintain the calorie deficit needed for weight loss.
Poor sleep also affects your metabolic rate. During sleep, your body regulates cortisol (stress hormone) and insulin sensitivity. Chronic sleep deprivation elevates cortisol, which promotes fat storage around the abdomen and increases insulin resistance—both barriers to weight loss. Additionally, when you're tired, your body craves energy-dense foods and you're less likely to exercise. The NHS recognises sleep as a cornerstone of weight management in the UK, alongside diet and physical activity. For those using prescription weight loss medication like Mounjaro or Wegovy, poor sleep can reduce the medication's effectiveness, as it interferes with the hormonal balance these treatments rely on.
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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.
UK Weight Loss Support and Prescription Options
If you're struggling with weight loss despite good sleep habits and lifestyle changes, you may be eligible for prescription weight loss medication available through the NHS or privately. Mounjaro (tirzepatide) and Wegovy (semaglutide) are GLP-1 weight loss injections licensed in the UK for adults with a BMI of 30 or above, or 27 or above with weight-related health conditions. These medications work best when combined with improved sleep, diet, and exercise. Use our free BMI calculator to check your current BMI and eligibility range. If you think prescription treatment might help, speak to your GP about referral to a specialist weight management service, or consult a licensed prescriber through private channels. Track your progress with our free progress tracker once you've started your weight loss journey.
- 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 many hours of sleep do I need for weight loss?
The NHS recommends 7–9 hours per night for most UK adults. Consistent sleep timing is equally important—going to bed and waking at the same time daily helps regulate hunger hormones and metabolism. Even one night of poor sleep can increase appetite and reduce insulin sensitivity.
Can poor sleep prevent weight loss even with a calorie deficit?
Yes, absolutely. Sleep deprivation increases cortisol and disrupts ghrelin and leptin, making your body resistant to weight loss. Studies show that people who sleep poorly lose more muscle and less fat than those sleeping well on the same calorie deficit—making the scale move more slowly despite effort.
Does sleep affect Mounjaro and Wegovy effectiveness?
Yes. These GLP-1 weight loss medications rely on balanced appetite hormones and metabolism. Poor sleep undermines the hormonal signals these medications enhance, reducing their effectiveness. For best results with prescription weight loss treatment, aim for 7–9 hours nightly and maintain consistent sleep patterns.
What can I do to improve sleep for weight loss?
Keep a consistent sleep schedule, limit screens 1 hour before bed, avoid caffeine after 2 PM, keep your bedroom cool and dark, and avoid large meals close to bedtime. Regular physical activity during the day improves sleep—though not within 3 hours of bedtime. If sleep problems persist, discuss with your GP.
Where can I find NHS weight loss support in the UK?
Start by speaking to your GP, who can refer you to a tier 3 specialist weight management service in your area. The NHS also offers free digital tools and the NHS Weight Loss Plan. Use our free BMI calculator and GLP-1 weight loss calculator to understand your starting point and explore options available to you.
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.