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
Vitamins That Help With Weight Loss
While no vitamin alone causes weight loss, certain nutrients play important roles in supporting weight management by boosting metabolism, reducing appetite, and helping your body use food efficiently. The evidence suggests that addressing nutritional deficiencies — particularly vitamin D, B vitamins, and minerals like iron and magnesium — can help support weight loss efforts. However, vitamins work best alongside a reduced-calorie diet, physical activity, and healthy lifestyle changes. If you're managing your weight in the UK, your GP can advise whether you have any nutritional gaps worth addressing.
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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.
Which Vitamins Support Weight Management?
Several vitamins and minerals have evidence supporting their role in weight management when nutritional deficiencies are corrected:
- Vitamin D: Low levels are linked to weight gain and difficulty losing weight. NHS guidance recommends vitamin D supplementation for many UK adults, particularly in winter months. Studies suggest adequate vitamin D may support metabolism and appetite regulation.
- B vitamins (B6, B12, folate): These support energy production and metabolism. B12 deficiency is associated with slower metabolism and fatigue, making exercise harder.
- Iron: Essential for oxygen transport and energy. Low iron causes fatigue and reduced exercise capacity, hindering weight loss efforts.
- Magnesium: Supports muscle function, energy production, and blood sugar control. Deficiency is common in the UK and may affect metabolism.
- Calcium: Some research suggests adequate calcium intake supports healthy weight management, though the effect is modest.
The key point: these vitamins help when you're deficient. If your nutrition is adequate, additional supplements are unlikely to cause weight loss alone.
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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.
How to Support Weight Loss Effectively
Vitamins work best as part of a comprehensive weight management approach. For sustainable weight loss in the UK, focus on a reduced-calorie diet (typically 500 kcal deficit for 0.5 kg per week), regular physical activity, and adequate sleep. If you have a BMI over 25 or weight-related health conditions, your GP can refer you to specialist weight management services. For many adults, prescription weight loss medication — such as GLP-1 injections — combined with lifestyle changes and vitamin adequacy, offers more effective support than vitamins alone. Use our free BMI calculator to check your current health status, and discuss any nutritional concerns with your GP before starting supplements.
- 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?
No. Vitamins alone do not cause weight loss. However, correcting deficiencies in vitamin D, B12, iron, or magnesium can support metabolism and energy levels, making it easier to follow a reduced-calorie diet and exercise programme. Weight loss requires a calorie deficit, physical activity, and lifestyle changes — vitamins are supportive, not primary drivers.
Is vitamin D really important for weight loss in the UK?
Yes. UK adults often have low vitamin D, especially October to April. Low vitamin D is associated with weight gain, depression, and reduced activity levels. The NHS recommends vitamin D supplementation (10 micrograms daily) for most UK adults, particularly those with limited sun exposure. Adequate vitamin D may help support weight loss efforts and overall health.
Should I take vitamin supplements before starting a weight loss programme?
It's sensible to discuss this with your GP, particularly if you have any symptoms of deficiency (fatigue, poor mood, muscle weakness). Your GP can test for deficiencies and advise whether supplementation is needed. For most people eating a reasonably varied diet, targeted supplementation of vitamin D is the main priority in the UK.
Are there vitamins that suppress appetite?
Not specifically. However, B vitamins support energy and metabolism, which can help you feel more energetic during exercise and calorie restriction. Some minerals like magnesium and chromium have been studied, but evidence for direct appetite suppression is weak. A reduced-calorie diet, adequate protein, and regular activity are far more effective at managing appetite.
Can vitamins replace prescription weight loss medication?
No. Prescription weight loss medications like GLP-1 injections (Mounjaro, Wegovy) work through specific hormonal pathways to reduce appetite and support weight loss — vitamins cannot replicate this. If you're eligible for weight loss medication following clinical assessment, it will be far more effective than vitamins alone. Vitamins and medication can work together as part of a comprehensive approach to weight management.
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.