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 significantly affects your ability to lose weight. Poor sleep disrupts the hormones that regulate hunger and appetite, making weight management much harder. Research shows that people who sleep poorly tend to gain weight more easily and struggle with weight loss programmes. Whether you're managing your weight through diet, exercise, or prescription weight loss medication, adequate sleep is a crucial foundation for success across all UK weight management approaches.
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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 Impacts Weight Loss Success
Sleep affects weight loss through several key biological mechanisms:
- Hunger hormones: Poor sleep increases ghrelin (the "hunger hormone") and decreases leptin (the "fullness hormone"), making you feel hungrier and less satisfied after eating
- Metabolism: Insufficient sleep slows your metabolic rate, meaning your body burns fewer calories at rest
- Blood sugar control: Sleep deprivation impairs insulin sensitivity and glucose regulation, increasing diabetes risk and making weight loss harder
- Fat storage: Lack of sleep shifts your body towards storing more fat, particularly around the abdomen
- Motivation and willpower: Poor sleep reduces impulse control, making unhealthy food choices more likely and exercise adherence lower
Studies show that people sleeping 5–6 hours per night gain approximately twice as much weight as those sleeping 7–9 hours, even with identical calorie intake. This is why sleep is a cornerstone of effective weight management in the UK — whether you're following an NHS weight loss programme or using prescription weight loss medication like Mounjaro or Wegovy.
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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.
Sleep and Weight Loss Medication Effectiveness
If you're considering GLP-1 weight loss injections or other prescription weight loss medication, sleep quality directly affects how well these treatments work. Adequate sleep optimises the hormonal environment your medication is working within, maximising appetite regulation and metabolism support. Our GLP-1 weight loss calculator can help you estimate potential results, but remember that sleep, diet, and exercise are essential for success alongside any medication.
NHS guidance recommends 7–9 hours of quality sleep per night for adults. To support better sleep: maintain a consistent bedtime, avoid screens 30 minutes before bed, keep your bedroom cool and dark, and limit caffeine after 2pm. Weight loss is most sustainable when you combine adequate rest with balanced nutrition, physical activity, and professional support.
- 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?
NHS guidance recommends 7–9 hours per night for adults. Most people need at least 7 hours to maintain healthy hormone levels and metabolic function. Individual needs vary slightly by age and genetics, but consistently sleeping less than 6 hours significantly impairs weight loss efforts.
Can poor sleep prevent weight loss even with a calorie deficit?
Yes. Research shows that people with poor sleep lose less weight than those sleeping adequately, even when eating the same calorie deficit. Sleep deprivation reduces fat loss and increases muscle loss, making your weight loss less healthy. This is why sleep is as important as diet for sustainable weight management.
Does sleep affect appetite hormones?
Absolutely. Just one night of poor sleep increases ghrelin (hunger hormone) and decreases leptin (fullness hormone), making you feel hungrier the next day. After several nights of poor sleep, these hormonal imbalances become significant, leading to increased food intake and difficulty managing portion sizes.
Will improving my sleep help me lose weight without dieting?
Improving sleep alone won't clinically studied weight loss, but it creates the right hormonal environment for weight management to work better. Combined with a balanced diet and physical activity, better sleep dramatically improves weight loss success. If you need additional support, your GP can discuss prescription weight loss medication options.
Does sleep quality matter as much as sleep quantity?
Both matter. You need adequate hours (7–9) and good quality sleep — deep, uninterrupted rest. Waking frequently or spending time in light sleep reduces the hormonal benefits even if total hours seem sufficient. Poor sleep quality is common with sleep apnoea, which also affects weight — your GP can assess this.
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.