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
HIIT Training for Weight Loss — How It Works
High-intensity interval training (HIIT) is a form of exercise that alternates between short bursts of intense activity and periods of lower intensity or rest. Many people use HIIT as part of their weight loss strategy because it can increase calorie burn and support cardiovascular fitness. However, weight loss ultimately depends on creating a calorie deficit through diet and exercise combined. Whether you're exploring HIIT or considering other weight management approaches like prescription medication, understanding your options helps you make informed decisions about your health.
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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.
How HIIT Supports Weight Loss
HIIT workouts increase your heart rate rapidly, which can help burn more calories in a shorter time compared to steady-state exercise. A typical HIIT session might last 20–30 minutes but produce significant cardiovascular and metabolic effects. The intensity also triggers what's called the "afterburn effect" (EPOC — excess post-exercise oxygen consumption), where your body continues to burn calories even after you've finished exercising.
- Burns calories efficiently in short timeframes
- May improve insulin sensitivity and metabolic health
- Builds cardiovascular fitness and endurance
- Can be adapted to different fitness levels
- Requires minimal or no equipment
However, HIIT is demanding and not suitable for everyone. Always consult your GP before starting a new exercise programme, especially if you have existing health conditions, joint problems, or are significantly overweight. The NHS recommends combining any exercise with a reduced-calorie diet for sustainable weight 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.
HIIT vs Other Weight Loss Approaches
HIIT is one tool for weight loss, but it works best alongside dietary changes. The NHS recommends losing weight at a rate of 0.5–1 kg per week through a combination of reduced calorie intake and increased physical activity. For some people, prescription weight loss medication alongside lifestyle changes may also be appropriate. Our free BMI calculator can help you understand your current weight category and whether you might benefit from support.
If you're finding weight loss challenging through exercise and diet alone, your GP can discuss all available options with you, including referral to specialist weight management services or prescription treatments approved in the UK.
- 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 HIIT suitable for beginners?
HIIT can be modified for all fitness levels, but it's intense by nature. Beginners should start with lower intensity intervals, longer rest periods, and fewer rounds. Always warm up properly and consult your GP before starting, especially if you're very overweight or have joint problems.
How often should I do HIIT training?
The NHS suggests at least 150 minutes of moderate exercise per week, or 75 minutes of vigorous exercise like HIIT. Most people benefit from 2–3 HIIT sessions weekly, combined with other activity. Rest days are important for recovery and injury prevention.
Can HIIT alone lead to weight loss without diet changes?
HIIT burns calories effectively, but sustainable weight loss requires a calorie deficit. Diet changes are essential — even intense exercise cannot offset a high-calorie diet. Combining HIIT with a healthy, reduced-calorie diet produces the best results for weight loss.
What if I can't do HIIT due to fitness or health reasons?
HIIT isn't mandatory for weight loss. Walking, cycling, swimming, and strength training all support weight loss when combined with dietary changes. Your GP can recommend suitable activities based on your health and fitness level. Weight loss medication may also be an option.
Should I use HIIT if I'm on weight loss medication like GLP-1 injections?
Yes, exercise supports health on GLP-1 medications like Mounjaro or Wegovy. However, start gradually — these medications can affect energy levels and appetite. Always discuss your exercise plan with your prescriber or GP to ensure it suits your individual circumstances.
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.