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
Good Fish for Weight Loss
Fish is one of the best protein sources for weight loss, especially when you're working on sustainable weight management in the UK. Oily and white fish varieties are nutrient-dense, low in calories, and high in protein — making them ideal for supporting a calorie deficit. Whether you're managing your weight through diet changes or alongside prescription weight loss treatment, understanding which fish to choose can make a real difference to your results.
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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.
Best Fish Types for Weight Loss
White fish (cod, haddock, pollock, tilapia) are exceptionally lean, containing as little as 80–90 calories and 18–20g of protein per 100g cooked portion. They are naturally low in fat and mercury, making them ideal for regular consumption.
Oily fish (salmon, mackerel, sardines, trout) are slightly higher in calories due to beneficial omega-3 fats, but remain excellent for weight loss. A 100g portion of salmon contains roughly 206 calories and 22g protein. Omega-3 fatty acids support satiety, reduce inflammation, and promote cardiovascular health — particularly important if you're managing weight-related health conditions like high blood pressure or abnormal blood fats.
- Aim for 2–3 fish portions per week for optimal nutrition
- Grill, bake, or steam fish rather than frying to keep calories low
- Pair with vegetables and whole grains for balanced meals
- Check portion sizes using a food scale or the NHS portion guide
Fish is particularly beneficial alongside a reduced-calorie diet, supporting the weight loss approach recommended by the NHS for sustainable results.
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.
Weight Loss and Nutrition — The Complete Picture
Weight loss requires a sustained calorie deficit of approximately 500 kcal per day to achieve 0.5 kg loss per week — the safe rate recommended by the NHS. Fish supports this by providing high protein content per calorie, which helps you feel fuller for longer and reduces overall food intake. Use our free BMI calculator above to check your current weight status, and our weight loss calculator to estimate realistic outcomes based on your current situation.
If you're exploring weight loss medication options like GLP-1 injections (Mounjaro or Wegovy), a balanced diet rich in fish remains essential. These prescription medications work alongside dietary changes, not instead of them. Your GP or a licensed prescriber can assess whether prescription weight loss treatment is right for you.
Portion control matters as much as food choice. A healthy fish portion is typically 140g cooked weight (about the size of your palm). Track your daily intake using our free progress tracker to monitor both weight changes and dietary consistency. Remember that individual results vary — sustainable weight loss combines appropriate nutrition, increased physical activity, and behaviour change. If you have specific health conditions like high cholesterol or type 2 diabetes, discuss your fish choices with your GP, as some oily fish are particularly beneficial for managing these conditions.
- 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.
Is white fish or oily fish better for weight loss?
Both are excellent. White fish is lower in calories (80–90 per 100g), making it ideal for strict calorie counting. Oily fish contains beneficial omega-3 fats that support satiety and heart health. Aim to include both across the week — white fish 2–3 times weekly and oily fish 1–2 times weekly.
How much fish should I eat per week for weight loss?
The NHS recommends eating fish 2–3 times per week as part of a balanced diet. One portion is approximately 140g cooked weight. Pair each portion with vegetables and whole grains, and aim for a daily calorie deficit of around 500 kcal for sustainable weight loss of 0.5 kg per week.
Can I eat fried fish as part of a weight loss diet?
Fried fish is higher in calories due to added oil during cooking. Grilling, baking, steaming, or poaching fish preserves the protein benefits without adding excess calories. If you do eat fried fish occasionally, account for it in your daily calorie intake.
Does fish help with weight loss medications like Wegovy?
Yes. Prescription weight loss medications like Wegovy (semaglutide) work best alongside a reduced-calorie diet and increased physical activity. Fish provides high-quality protein that supports satiety and helps prevent muscle loss during weight loss — making it an ideal food choice to combine with medication-assisted weight management.
Which fish should I avoid if I'm watching my weight?
All fish varieties are nutritious, but some processed fish products are high in salt and additives. Avoid fish in heavy sauces, breaded fish products, and canned fish in oil. Fresh or frozen plain fish is always the best choice. Canned fish in spring water or brine is acceptable if rinsed before eating.
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.