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 Shakes Help With Weight Loss?
Meal replacement shakes can be a useful tool for weight loss when used as part of a balanced approach, though results vary significantly between individuals. Many people find shakes helpful for portion control and calorie management as part of a structured weight loss programme. However, shakes work best alongside lifestyle changes like increased physical activity and dietary improvements. For those with a BMI in the overweight or obese range, your GP may recommend shakes as part of a weight management UK strategy, or discuss other evidence-based options including prescription weight loss medication.
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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.
How Shakes Support Weight Loss
Meal replacement shakes can help with weight loss in several ways:
- Portion control — shakes provide measured calories, making it easier to maintain a calorie deficit without guessing portions
- Convenience — quick to prepare, reducing reliance on higher-calorie takeaway meals
- Satiety — many shakes contain protein and fibre, which may help you feel fuller for longer
- Consistency — regular shakes create a predictable eating pattern, supporting adherence to a weight loss plan
However, shakes alone do not clinically studied weight loss. The NHS recommends losing weight at a rate of 0.5 to 1 kg per week for sustainable results. This typically requires a calorie deficit of around 500 kcal per day, which can be achieved through shakes combined with regular meals and increased physical activity. Results depend on overall calorie intake, exercise, metabolism, and individual health factors. Use our free BMI calculator to assess your current weight range, and the weight converter to track your measurements in both metric and imperial units.
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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.
Shakes vs Prescription Weight Loss Options
For adults with a BMI of 30 or above, or 27 or above with weight-related health conditions, the NHS may offer prescription weight loss medication alongside lifestyle support. GLP-1 weight loss injections like Mounjaro and Wegovy have shown significant results in clinical trials, with participants losing an average of 14–21% of body weight when combined with diet and exercise. These are prescription-only medicines requiring clinical assessment through NHS specialist services or private prescribing. Unlike shakes, prescription weight loss medication works on appetite regulation and metabolic pathways. Many people use both approaches together — shakes for meal convenience and prescription medication (if eligible) for additional metabolic support. Try our GLP-1 weight loss calculator to explore potential outcomes with prescription options.
- 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.
Are meal replacement shakes safe for weight loss in the UK?
Yes, commercial meal replacement shakes designed for weight management are generally safe when used as directed. However, very low-calorie shake-only diets (below 800 kcal per day) should only be followed under medical supervision. The NHS recommends combining shakes with regular, balanced meals and consulting your GP before starting any restrictive diet plan.
How many shakes per day should I have for weight loss?
This depends on your individual calorie target and overall diet. Typically, one or two shakes per day as meal replacements, combined with other balanced meals, supports sustainable weight loss. Never rely on shakes alone. Your GP or a dietitian can advise on the right approach for your health goals and BMI.
Can I use shakes if I'm on Mounjaro or Wegovy?
Yes, many people using prescription weight loss injections also use meal replacement shakes for convenience. However, inform your prescriber about all dietary changes. GLP-1 medications slow digestion and may reduce appetite, so combining them with shakes requires careful calorie management to avoid consuming too few calories.
Are liquid shakes better than solid food for weight loss?
Neither is inherently superior. Shakes offer convenience and portion control, whilst solid food provides texture and satiety cues. Evidence suggests that sustainable weight loss comes from whatever approach you can maintain long-term. Many people succeed combining both shakes and regular meals alongside increased physical activity.
Should I see my GP before starting meal replacement shakes?
It's recommended, especially if you have underlying health conditions, take medications, or plan to use shakes as your primary nutrition source. Your GP can assess whether this approach suits your BMI, health profile, and weight loss goals, and discuss whether prescription weight management options might also be appropriate for you.
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.