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
Ultra-Processed Food and Weight Loss — What the Research Shows
Ultra-processed foods (UPF) have become a major focus in weight management research. Recent studies show a strong link between UPF consumption and weight gain, making dietary choices a key factor in successful weight loss. Understanding this evidence can help you make informed decisions about your diet, whether you're managing weight naturally or alongside prescription weight loss medication. This guide explains what research tells us about UPF and effective weight management strategies in the UK.
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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.
What Does Research Say About UPF and Weight Gain?
Multiple large-scale studies have found that high ultra-processed food consumption is associated with increased weight gain and obesity. A significant meta-analysis published in the British Medical Journal found that for every 10% increase in ultra-processed food intake, body weight increased by approximately 0.5 kg per year. Ultra-processed foods tend to be high in calories, sugar, salt, and unhealthy fats while being low in fibre and nutrients — making them easy to overeat.
- UPF provides rapid energy delivery that doesn't trigger satiety signals effectively
- These foods often contain additives and emulsifiers that may alter gut bacteria and appetite regulation
- Portion sizes of UPF are typically larger than whole foods, leading to calorie overconsumption
- UPF often replaces whole foods rich in fibre, which support weight management and blood sugar stability
For UK adults aiming for sustainable weight loss, reducing UPF intake alongside increased physical activity is recommended by the NHS as a cornerstone of effective weight management.
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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 Does Diet Fit Into Overall Weight Loss Strategy?
Sustainable weight loss requires a calorie deficit of approximately 500 kcal per day, which typically results in losing 0.5–1 kg per week according to NHS guidance. Cutting ultra-processed foods naturally reduces calorie intake while increasing nutrient density. The NHS weight loss approach emphasises whole foods including vegetables, lean proteins, whole grains, and healthy fats. For those requiring additional support, prescription weight loss medication works best when combined with dietary changes and increased physical activity — not as a replacement for lifestyle modifications. Use our free BMI calculator to assess your current weight status, and our GLP-1 weight loss calculator can help you understand how medication might support your goals alongside improved nutrition and exercise.
- 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.
What exactly are ultra-processed foods?
Ultra-processed foods (UPF) are industrial formulations typically with five or more ingredients, often including hydrogenated oils, high-fructose corn syrup, colourings, and emulsifiers. Examples include mass-produced biscuits, sugary breakfast cereals, instant noodles, many takeaway meals, and shop-bought ready meals. The key difference from processed foods is the extent of industrial processing and the addition of multiple chemical additives designed to enhance taste, texture, and shelf life.
Can I still lose weight while eating some UPF?
Yes, weight loss depends primarily on creating a calorie deficit — you can technically lose weight eating any foods if you consume fewer calories than you burn. However, UPF makes this harder because these foods are calorie-dense, nutrient-poor, and don't trigger fullness signals effectively. Most people find weight loss more sustainable by reducing UPF and choosing whole foods, which are more filling and nutritious at the same calorie level.
Does reducing UPF alone lead to weight loss?
Reducing ultra-processed foods often leads to modest weight loss for many people, partly because whole foods are naturally lower in calories and higher in fibre. However, sustainable weight loss typically requires a deliberate calorie deficit alongside regular physical activity. Your GP or a weight management specialist can advise on the best approach for your individual circumstances.
Are prescription weight loss medications like Mounjaro or Wegovy used with diet changes?
Yes, absolutely. Prescription weight loss medications like Mounjaro (tirzepatide) and Wegovy (semaglutide) are always used alongside reduced-calorie diet and increased physical activity — they're not a replacement for lifestyle changes. These medications may help reduce appetite and support feeling fuller, making it easier to maintain a healthier diet including fewer ultra-processed foods. Access in the UK is through NHS specialist services or private prescribing following clinical assessment.
What's the fastest safe rate of weight loss in the UK?
The NHS recommends losing 0.5–1 kg (1–2 lbs) per week as a safe, sustainable rate. Faster weight loss is possible with medical supervision but increases the risk of muscle loss and nutritional deficiency. Very gradual weight management should only be attempted under professional healthcare guidance. Use our free progress tracker to monitor your weight loss journey safely over time.
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.