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 Smoking Cause Weight Loss?
Smoking can suppress appetite and increase metabolic rate, which may lead to lower body weight in some people. However, smoking causes serious health damage that far outweighs any weight-related effects. If you're interested in weight management in the UK, there are safe, evidence-based approaches including lifestyle changes, NHS weight loss programmes, and prescription weight loss medication when appropriate. This guide explains the relationship between smoking and weight, and why it's not a safe weight loss strategy.
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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 Smoking Affects Weight and Metabolism
Nicotine, the addictive substance in cigarettes, acts as a stimulant that increases metabolic rate by approximately 10–15%. It also suppresses appetite by triggering the release of dopamine and other neurotransmitters in the brain, making smokers feel less hungry. These effects can result in smokers weighing 3–5 kg less on average than non-smokers of similar height and diet.
However, this apparent weight benefit comes with profound health costs. Smoking damages the lungs, cardiovascular system, and increases risk of cancer, heart disease, and stroke. The temporary metabolic boost is far outweighed by the serious medical conditions smoking causes. For anyone focused on weight management in the UK, prescription weight loss medication (like GLP-1 injections) or NHS weight loss programmes are evidence-based alternatives that support health rather than harm it.
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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 Smoking Is Not a Safe Weight Loss Strategy
Relying on smoking for weight control is extremely harmful. Smokers have higher rates of obesity-related diseases despite lower body weight—smoking damages blood vessels, increases inflammation, and raises cancer risk. The weight you might lose from smoking is offset by severe health damage.
Safe weight management approaches include:
- Calorie-controlled diet with balanced nutrition
- Regular physical activity
- NHS weight loss support programmes
- Prescription weight loss injections (for eligible adults)
- Working with a GP or registered dietitian
Use our free BMI calculator above to check your current weight status, and our GLP-1 weight loss calculator to explore evidence-based options if you're considering weight management 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.
Does nicotine speed up your metabolism?
Yes. Nicotine increases metabolic rate by roughly 10–15%, which can suppress appetite and reduce overall calorie intake. However, this metabolic boost is temporary and is not a safe or sustainable weight loss method. The serious health risks of smoking—including lung disease, heart disease, and cancer—far outweigh any metabolic benefit.
Why do smokers often weigh less than non-smokers?
Smokers typically weigh 3–5 kg less due to nicotine's appetite-suppressing and metabolism-boosting effects. Despite lower body weight, smokers have higher rates of cardiovascular disease, cancer, and premature death. Lower weight does not equal better health when it results from smoking.
What happens to weight if you quit smoking?
Many people gain 2–3 kg after quitting smoking because appetite normalises and metabolic rate returns to baseline. This modest weight gain is far outweighed by the health benefits of quitting. NHS smoking cessation services and weight management support are available to help manage weight during and after quitting.
Are there safe alternatives to smoking for weight loss?
Yes. Evidence-based weight management options in the UK include: reduced-calorie diet, physical activity, NHS weight loss programmes, and prescription weight loss medication (for eligible adults with BMI ≥30 or ≥27 with weight-related health conditions). Discuss options with your GP.
Can GLP-1 weight loss injections help if I'm struggling with weight?
GLP-1 medications like Wegovy (semaglutide) are prescription-only injections licensed in the UK for weight management. Clinical trials showed average weight loss of approximately 15% body weight. Eligibility requires clinical assessment. Your GP can discuss whether this medication is suitable for your individual circumstances.
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.