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
Will Weight Loss Increase Testosterone?
Yes, losing weight can help increase testosterone levels in men, particularly those who are overweight or obese. Research shows that excess body fat lowers testosterone production, so weight management uk through sustainable lifestyle changes or prescription weight loss medication may help restore healthier hormone levels. However, results vary between individuals, and a GP should assess any hormonal concerns. This guide explains the connection between weight and testosterone, and what the evidence shows.
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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 Excess Weight Affects Testosterone Levels
Body fat produces an enzyme called aromatase, which converts testosterone into oestrogen. The more excess fat you carry, the more testosterone is converted away, leading to lower circulating testosterone levels. This is one reason why men with obesity often have lower testosterone than men at a healthy weight.
Additionally, excess weight can increase insulin resistance, which further suppresses testosterone production. Research consistently shows that men with a BMI above 30 have significantly lower testosterone levels compared to men with a healthy BMI of 18.5 to 24.9.
The good news: studies show that losing weight — even a modest 5 to 10% reduction — can help restore testosterone levels. Losing weight through nhs weight loss programmes, dietary changes, increased physical activity, or prescription weight loss uk options like GLP-1 medication may all help. Use our free BMI calculator to check if your weight may be affecting your health.
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.
What Research Shows About Weight Loss and Testosterone
Clinical studies demonstrate that men who lose weight experience measurable improvements in testosterone levels. One study found that men who lost an average of 17kg saw testosterone increase by approximately 15%. The effect is most pronounced in men who are significantly overweight.
Weight loss injections uk like Wegovy (semaglutide) can support sustainable weight management alongside diet and exercise, which may indirectly benefit testosterone. However, GLP-1 weight loss medication itself does not directly increase testosterone — the benefit comes through the weight loss it helps facilitate. If you're concerned about low testosterone, your GP can measure your levels and advise whether weight loss or further investigation is needed.
- 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.
Does weight loss always increase testosterone?
Weight loss typically increases testosterone in overweight and obese men, but results vary. Men already at a healthy weight may see minimal change. Testosterone is also influenced by age, genetics, sleep quality, and stress. If you're concerned about low testosterone, consult your GP for a blood test and personalised advice.
How much weight do I need to lose to see an increase in testosterone?
Research suggests that losing even 5 to 10% of body weight can improve testosterone levels. For a man weighing 100kg, losing 5 to 10kg may produce measurable hormone improvements. Use our free BMI calculator and weight loss calculator to set realistic targets.
Can GLP-1 weight loss injections like Wegovy increase testosterone?
Wegovy (semaglutide) is a prescription-only weight loss medication that helps you lose weight through appetite regulation. It doesn't directly increase testosterone, but the weight loss it supports may indirectly help restore healthier hormone levels. Results vary individually.
What's a healthy BMI for testosterone health?
According to NHS guidelines, a healthy BMI is 18.5 to 24.9 for most adults. Maintaining weight in this range is associated with better testosterone levels. Your GP can advise on your personal healthy weight range based on your health history.
Should I try weight loss medication to increase testosterone?
Prescription weight loss medication like bmi weight loss programmes is only appropriate if you meet NHS eligibility criteria (usually BMI 30 or above, or BMI 27+ with health conditions). Always discuss with your GP whether weight loss medication is right for you and whether your testosterone concerns need investigation.
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.