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 Lack of Sleep Cause Weight Loss?
The short answer is no — lack of sleep typically does not cause weight loss. In fact, poor sleep often leads to weight gain. When you don't sleep enough, your body experiences hormonal changes that increase hunger, boost cravings for high-calorie foods, and slow your metabolism. Sleep deprivation affects the hormones that regulate appetite, making sustainable weight management UK much harder. Understanding this connection is important if you're considering your overall health strategy, whether through lifestyle changes or prescribed weight management options.
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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 Poor Sleep Affects Your Weight
Sleep deprivation disrupts two key hunger hormones: ghrelin (the appetite-stimulating hormone) and leptin (the satiety hormone that signals fullness). When you lack sleep, ghrelin levels rise while leptin levels drop, creating a biological urge to eat more — especially foods high in sugar and fat. Additionally, poor sleep reduces insulin sensitivity, meaning your body struggles to regulate blood sugar effectively. This metabolic slowdown, combined with increased fatigue, often leads to reduced physical activity and weight gain rather than loss. Research shows that adults sleeping fewer than 6 hours per night are significantly more likely to be overweight or obese. Sleep is therefore as important as diet and exercise in any weight management strategy.
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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.
Why Weight Loss Requires Quality Sleep
If you're pursuing sustainable weight loss, prioritising sleep is essential. During sleep, your body repairs muscle tissue, regulates hormones, and processes the energy expenditure from your day. Poor sleep increases cortisol (stress hormone), which promotes fat storage — particularly around the abdomen. The NHS recommends 7–9 hours of quality sleep per night for adults. When combined with a reduced-calorie diet and increased physical activity, adequate sleep significantly improves weight loss outcomes. Try using our free progress tracker to monitor both your sleep patterns and weight changes together. If you're exploring prescription weight loss medication through NHS weight loss services or other weight loss medication options, establishing a consistent sleep routine will enhance your results.
- 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.
Can lack of sleep actually cause you to lose weight?
No. Sleep deprivation typically causes weight gain, not loss. Poor sleep increases hunger hormones and reduces metabolic rate, making you more likely to eat more and move less. Even if calorie intake drops, the hormonal and metabolic disruptions usually lead to net weight gain over time.
How many hours of sleep do I need for weight management?
The NHS recommends 7–9 hours of quality sleep per night for adults. Consistency matters too — irregular sleep patterns disrupt appetite hormones even if total hours are adequate. Poor sleep quality, even with sufficient hours, can still impair weight management efforts.
Does lack of sleep slow your metabolism?
Yes. Sleep deprivation reduces metabolic rate and insulin sensitivity, meaning your body burns fewer calories and processes glucose less effectively. This metabolic slowdown, combined with increased hunger, makes weight gain more likely during periods of poor sleep.
Can I lose weight if I'm not sleeping well?
Weight loss is possible with poor sleep, but it's significantly harder and less sustainable. You may lose weight initially through a strict diet, but hormonal disruptions make it difficult to maintain. Better sleep quality consistently improves weight loss outcomes and helps prevent regaining lost weight.
Should I improve my sleep before trying weight loss medication?
Yes. If you're considering prescription weight loss options, establishing good sleep habits first creates a better foundation. Quality sleep enhances the effectiveness of lifestyle changes and any medication. Your GP can advise on the best approach for your individual circumstances during a weight loss consultation.
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.