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
Best Vitamin for Weight Loss — What the Evidence Shows
When it comes to weight management in the UK, vitamins alone are unlikely to be the "best" solution for significant weight loss. However, certain vitamins and minerals play important roles in metabolism, energy levels, and overall health during a weight loss journey. This guide explains which nutrients matter most, why they're important, and what prescription weight loss options exist alongside nutritional support. Whether you're exploring vitamin-based approaches or prescription weight loss medication, understanding the full picture helps you make informed decisions about your health.
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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.
Vitamins and Minerals That Support Weight Management
Several vitamins and minerals support healthy weight management in the UK when combined with balanced nutrition and physical activity:
- B vitamins (B6, B12, folate): Support energy metabolism and help your body convert food into fuel efficiently. People following calorie-restricted diets may benefit from B vitamin supplementation, especially if avoiding animal products.
- Vitamin D: Low vitamin D levels are associated with weight gain and metabolic dysfunction. Many UK adults have insufficient vitamin D, particularly in winter. NHS guidance suggests supplementation (10 micrograms daily for adults).
- Iron: Essential for oxygen transport and energy production. Iron deficiency can cause fatigue that makes physical activity harder. Women of reproductive age are at higher risk of deficiency.
- Magnesium: Supports muscle function and may help reduce cravings. Also supports sleep quality, which is important for weight management.
- Calcium: Some research suggests adequate calcium supports bone health during weight loss, though evidence for direct weight loss is limited.
However, vitamins alone cannot create the calorie deficit needed for meaningful weight loss. An evidence-based approach combines good nutrition, physical activity, and where appropriate, prescription weight loss medication or support from NHS weight management services.
Clinically BackedWeight Loss
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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.
Prescription Weight Loss Options Beyond Vitamins
For adults in the UK with a BMI of 30 or above (or 27+ with weight-related health conditions), prescription weight loss medication may be more effective than vitamins alone. Two main options are licensed in the UK: GLP-1 weight loss medications like Wegovy (semaglutide) and Mounjaro (tirzepatide). These prescription injections work differently than vitamins — they help regulate appetite and support feeling fuller after meals.
Clinical trials showed Wegovy helped participants lose an average of approximately 15% of body weight, whilst Mounjaro achieved approximately 20% average weight loss. Both are prescription-only and require clinical assessment. Access in the UK is through NHS specialist weight loss medication NHS services or private online prescribing. Your GP can advise whether you're eligible. Use our free GLP-1 weight loss calculator to estimate potential results at different doses, and our BMI calculator to check your starting point.
- 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 vitamins alone help me lose weight?
Vitamins support metabolism and overall health, but they cannot create the calorie deficit needed for significant weight loss. Weight loss requires eating fewer calories than you burn, alongside physical activity. Vitamins are best viewed as nutritional support alongside diet and exercise, not a primary weight loss tool.
Is vitamin D important for weight loss?
Vitamin D supports bone health, mood, and immune function — all important during weight loss. Some research links low vitamin D to weight gain, though supplementing vitamin D alone won't cause weight loss. The NHS recommends 10 micrograms daily for most UK adults. Discuss your individual needs with your GP.
Should I take a multivitamin while trying to lose weight?
If you're following a very low-calorie diet (under 1200 kcal daily), a multivitamin may help prevent nutritional deficiencies. However, NHS guidance recommends aiming for a balanced diet with whole foods when possible. Speak to your GP or a registered dietitian before starting any supplement regimen.
Are weight loss injections like Wegovy better than vitamins?
Prescription weight loss medications like Wegovy and Mounjaro work through different mechanisms than vitamins. Clinical trials showed these medications help people lose 15–20% body weight on average — significantly more than vitamins alone could achieve. However, they're prescription-only and require clinical assessment. They're used alongside lifestyle changes, not instead of them.
How do I access weight loss support in the UK?
Start by speaking with your GP. They can assess your BMI using our free BMI calculator, discuss your health, and refer you to NHS weight management services if appropriate. For faster access, private online prescribing is available for eligible adults. Your GP can also recommend balanced nutrition and physical activity plans suited to your needs.
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.