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
Why Fish Is Good For Weight Loss
Fish is an excellent choice for weight loss because it's high in protein, low in calories, and rich in omega-3 fatty acids. A typical serving of white fish contains around 25g of protein with minimal fat, making it ideal for sustainable weight management in the UK. Protein keeps you feeling fuller for longer, which naturally reduces overall calorie intake. Combined with regular physical activity and a balanced diet, fish can be a cornerstone of an effective weight loss strategy. Whether you're managing your weight independently or supporting a prescription weight loss plan, understanding how different foods support your goals is important.
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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.
The Best Fish Types for Weight Loss
White fish — cod, haddock, and pollock are among the leanest options, containing just 0.7–1.5g of fat per 100g and around 18–20g of protein. These are ideal for reducing calorie intake while maintaining muscle mass.
- Salmon and mackerel contain more fat but are rich in omega-3 fatty acids, which support heart health and may reduce inflammation linked to weight gain
- Tinned fish (in spring water, not oil) offers convenience and similar nutritional benefits to fresh fish
- Portion size matters — aim for 150g servings, roughly the size of your palm, to keep calories controlled
Fish delivers complete protein containing all nine essential amino acids, supporting muscle recovery during weight loss. When grilled, baked, or steamed rather than fried, fish remains a calorie-efficient, nutrient-dense food that fits perfectly into evidence-based weight management strategies.
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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 Fish Fits Into Your Weight Loss Plan
Sustainable weight loss requires a consistent calorie deficit — typically 500 kcal per day leads to approximately 0.5kg weight loss weekly, according to NHS guidance. Fish is an ideal protein source because it satisfies hunger with fewer calories than many other proteins. Aim to include fish 2–3 times weekly as part of a balanced diet including vegetables, wholegrains, and healthy fats.
If you're exploring weight management options — whether through dietary changes, increased physical activity, or prescription weight loss medication — using our free BMI calculator above helps track how your weight relates to your health. For those considering prescription weight loss options like GLP-1 medications, understanding how foods support your goals alongside medication is valuable. Our GLP-1 weight loss calculator can help you estimate potential outcomes when combined with lifestyle changes.
- 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.
How much protein does fish contain per serving?
A typical 150g serving of white fish (cod, haddock, pollock) contains approximately 30–35g of protein with minimal fat. Salmon and mackerel contain similar protein levels (25–30g per 150g) plus beneficial omega-3 fatty acids. This high protein content supports muscle maintenance during weight loss and promotes satiety.
Is tinned fish as good as fresh fish for weight loss?
Yes, tinned fish in spring water is nutritionally similar to fresh fish and offers convenience. Check labels and choose tinned options without added oils or salt. Tinned fish provides the same protein and omega-3 benefits, making it an excellent budget-friendly choice for sustainable weight management.
What's the best way to cook fish for weight loss?
Grill, bake, steam, or poach fish to keep calories minimal. Avoid deep frying or cooking in butter. A simple drizzle of olive oil with lemon and herbs adds flavour without significant calorie increase. Portion control matters more than cooking method — aim for 150g servings.
Can fish alone help me lose weight?
Fish is an excellent protein source but weight loss requires overall calorie deficit alongside physical activity. The NHS recommends losing 0.5–1kg weekly through balanced diet changes. Fish supports this by keeping you fuller longer, but sustainable weight loss involves whole dietary pattern changes, not single foods.
How does fish compare to weight loss medication like Wegovy?
Fish is a fundamental dietary component of any weight loss plan. Prescription weight loss medications (GLP-1 medications) work alongside dietary changes, not instead of them. Using our weight loss calculator can help you understand how medication combines with nutrition for optimal results — always discuss dietary and medication options with your GP.
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.