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
How a Weight Loss Diary Supports Your Goals
A weight loss diary is one of the most effective tools for tracking progress and staying accountable. Research shows that people who record their weight, food intake, and activity levels are significantly more likely to achieve lasting results. Unlike crash diets, keeping a diary helps you understand your personal patterns, identify triggers, and make informed decisions about your health. Whether you're managing weight through lifestyle changes alone or using prescription weight loss medication as part of a comprehensive approach, a diary keeps you focused on what matters: sustainable progress.
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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.
What to Record in Your Weight Loss Diary
An effective weight loss diary goes beyond just numbers on the scales. Record these key elements:
- Weekly weight: Weigh yourself at the same time each week (ideally same day, same time) rather than daily — this gives a clearer picture of actual progress and avoids fluctuations from water retention, food in your stomach, and hormonal cycles.
- Measurements: Track waist, hip, and chest measurements monthly. You may lose centimetres before the scales shift, especially if building muscle through exercise.
- Food and drink: Note what you eat, portion sizes, and how you felt before and after eating. This reveals patterns — do you snack when stressed? Eat more after certain activities?
- Physical activity: Record type, duration, and how you felt. This supports your weight management UK goals and shows the link between movement and energy levels.
- Mood and sleep: Poor sleep and stress both affect weight loss. Noting these helps you see the bigger picture of what influences your body's ability to lose weight.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Making Your Diary Work for Long-Term Success
Consistency matters more than perfection. Review your diary weekly to spot patterns — do you overeat on certain days? Feel more motivated after exercise? Understanding these patterns lets you plan ahead. Use our free progress tracker to log weight and measurements over time; it creates a visual record that shows genuine progress even on weeks the scales don't move. Remember that weight fluctuates daily due to water, hormones, food timing, and digestion — a diary helps you see the overall trend rather than obsessing over daily changes. If you're considering prescription weight loss medication as part of nhs weight loss services or private options, a diary before and during treatment gives your GP or prescriber valuable information about your baseline habits and how medication affects your relationship with food.
- 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.
Why is a weight loss diary more effective than just weighing myself?
A diary reveals patterns you'd miss otherwise — when you overeat, what triggers cravings, how activity affects your mood and hunger. Research shows people who track are 2–3 times more likely to succeed because they're aware and intentional, not just hoping. Plus, you spot non-scale progress: better sleep, more energy, clothes fitting differently.
How often should I weigh myself if I'm keeping a diary?
Once weekly is ideal — same day, same time. Daily weighing shows normal water and food fluctuations that discourage people. Weekly weighting reveals the actual trend. If you're using glp-1 weight loss medication, weekly tracking shows how your body responds over the weeks and months.
Should I record calories in my weight loss diary?
You don't have to count calories precisely, but noting approximate portions helps. Many people find that simply being aware of what they're eating — writing it down — naturally reduces portions without strict calorie counting. Some prefer counting; others prefer portion awareness. Choose what feels sustainable for you long-term.
Can a weight loss diary help if I'm prescribed Mounjaro or Wegovy?
Yes, absolutely. A diary shows your prescriber how the medication affects your appetite, energy, digestion, and food choices. It helps identify side effects, track weight loss progress against clinical trial averages, and adjust your approach. Many people on GLP-1 medication find a diary especially valuable for understanding how the injection changes their relationship with food.
What if I miss days in my weight loss diary?
Don't abandon it. Diaries aren't about perfection — just resume when you're ready. Even sporadic entries show patterns over weeks and months. The goal is awareness and accountability, not punishment. Consistency builds gradually, and many people find that restarting after a gap is easier because they remember why tracking helped.
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.