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
Do Vitamins Help With Weight Loss?
Vitamins alone won't cause weight loss, but certain nutrients play an important role in supporting your metabolism, energy levels, and overall health during weight management. If you're trying to lose weight in the UK, understanding which vitamins matter and how they fit into a broader approach—including diet, exercise, and where appropriate, prescription weight loss medication—can help you make informed decisions about your health journey.
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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 Matter for Weight Loss and Metabolism?
Several key vitamins and minerals support metabolic health and weight management:
- Vitamin D: Low levels are linked to increased weight and metabolic dysfunction. Getting adequate vitamin D through sunlight, food, or supplements may support healthy metabolism and mood during weight loss.
- B Vitamins (B6, B12, folate): Essential for energy production and breaking down food. Deficiency can slow metabolism and reduce energy for exercise.
- Iron: Critical for oxygen transport in blood. Low iron causes fatigue, making physical activity harder.
- Zinc: Supports immune function and appetite regulation. Low zinc may affect hunger hormones.
- Magnesium: Helps regulate blood sugar and muscle function, both important during weight loss.
However, taking high-dose supplements won't accelerate weight loss if you're already getting adequate nutrition through food. MyWeightCheck's free BMI calculator can help you understand your current weight status and whether professional advice about nutrition is appropriate for your situation.
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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 Through Nutrition
The foundation of sustainable weight management in the UK is a balanced diet with adequate calories, whole foods, and regular physical activity. Most people get sufficient vitamins and minerals through a varied diet without needing supplements.
If you're considering prescription weight loss medication such as GLP-1 injections like Mounjaro or Wegovy, adequate nutrition becomes even more important—these medications can reduce appetite, so ensuring you eat nutrient-dense foods matters. Our GLP-1 weight loss calculator can help you explore whether prescription weight management might be suitable alongside lifestyle changes. Always consult your GP about your individual nutritional needs, especially if taking medication or following a restricted diet.
- 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.
Will taking vitamin supplements help me lose weight?
Vitamin supplements support overall health and may prevent deficiencies that slow metabolism, but they won't directly cause weight loss. Weight loss requires a calorie deficit through diet and physical activity. Supplements are helpful if you're deficient in a specific nutrient, but not as a weight loss tool on their own.
Should I take vitamins if I'm taking Mounjaro or Wegovy?
Yes, maintaining adequate nutrition is important when taking GLP-1 weight loss medications. These injections reduce appetite, so eating nutrient-dense foods becomes crucial. Discuss your diet and any supplement needs with your prescriber, as reduced food intake may affect nutrient absorption in some cases.
Is vitamin D important for weight management?
Vitamin D deficiency is associated with metabolic issues and weight gain. Getting adequate vitamin D through sunlight exposure, food, or supplementation may support healthy metabolism. UK adults should consider vitamin D intake, especially during winter months when sunlight is limited.
Can I lose weight without taking any vitamins?
Yes, weight loss happens through a calorie deficit from diet and exercise. Vitamins support health during weight loss, but aren't essential for the weight loss itself. However, a deficiency in key nutrients like vitamin D, B12, or iron can make weight loss harder by causing fatigue or metabolic slowdown.
What's the best way to get vitamins for weight loss in the UK?
The NHS recommends trying to get vitamins from food first—lean proteins, whole grains, vegetables, fruits, and dairy. If you're deficient in a specific nutrient, your GP can advise on supplementation. Use MyWeightCheck's BMI calculator to assess your weight status, then discuss nutrition and any weight management options with your healthcare provider.
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.