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
Does ADHD Medication Cause Weight Loss?
Yes, some ADHD medications can cause weight loss as a side effect. Stimulant medications like methylphenidate and amphetamine-based drugs often reduce appetite and increase metabolism, leading to unintended weight loss in some people. However, weight changes vary significantly between individuals — some people experience no change, while others may gain weight. If you're concerned about weight changes related to ADHD medication, speak to your GP about whether adjustments are needed or whether prescription weight management options like Mounjaro or Wegovy might be suitable for you.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
Which ADHD Medications Can Affect Weight?
Stimulant ADHD medications are most commonly associated with appetite suppression and weight loss. These include methylphenidate (Ritalin, Concerta) and amphetamine-based medications (Adzenys, Vyvanse). Weight loss typically occurs because stimulants increase dopamine and noradrenaline, which suppress hunger signals and can increase energy expenditure.
- Weight loss is more common in the first few weeks or months of treatment
- Some people adapt over time and appetite returns to normal
- Weight changes are often modest — typically 1–3 kg in the first few months
- Non-stimulant ADHD medications (atomoxetine, guanfacine) may have less impact on appetite
It's important to monitor your weight regularly using our free weight converter and BMI calculator to track any changes, and discuss significant weight loss with your GP to ensure it's not causing health concerns.
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.
Weight Management Support in the UK
If you're managing ADHD medication side effects and concerned about weight changes, the NHS offers comprehensive weight management support through specialist tier 3 and tier 4 services. For eligible adults with a BMI of 30 or above (or 27 or above with weight-related health conditions), prescription weight loss medications like Mounjaro (tirzepatide) and Wegovy (semaglutide) are available through NHS specialist services or private online prescribing.
Our GLP-1 weight loss calculator can help you explore potential outcomes with prescription weight management options. Your GP can assess whether you're eligible for prescription weight loss treatment and refer you to appropriate services. Weight management works best alongside lifestyle changes, so combining any medication with a reduced-calorie diet and increased physical activity offers the best results.
- 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.
Can stopping ADHD medication help you gain weight back?
Weight often returns gradually after stopping stimulant ADHD medications, but this varies. Some people regain weight within weeks, others more slowly. The return of appetite is usually the main driver. If you're concerned about weight changes, discuss medication adjustments with your GP rather than stopping treatment abruptly — sudden cessation can cause other health effects.
Are all ADHD medications likely to cause weight loss?
No. Stimulant medications (methylphenidate, amphetamines) are most associated with appetite suppression. Non-stimulant options like atomoxetine or guanfacine may have less impact on weight. Individual responses vary widely — some people experience significant weight loss while others see minimal change. Your GP can discuss options suited to your situation.
Is it safe to take ADHD medication if I'm underweight?
This requires careful GP assessment. If you're already underweight (BMI under 18.5), stimulant ADHD medications carrying weight loss risk may need monitoring or alternative options. Your GP will weigh the benefits of ADHD treatment against nutritional health and may suggest dietary support or non-stimulant alternatives.
Can you take weight loss medication like Mounjaro while on ADHD medication?
This requires GP or prescriber assessment on an individual basis. There are no absolute contraindications, but your prescriber needs to know about all medications you take to check for interactions. Both ADHD and weight loss medications can affect appetite, so combined use requires careful monitoring of nutritional intake and wellbeing.
Should I be worried about weight loss from ADHD medication?
Modest weight loss in the first months is often normal and typically stabilises. However, significant or ongoing weight loss, malnutrition signs, or feeling unwell warrant GP discussion. Your GP can assess whether your weight loss is healthy, suggest dietary adjustments, or explore medication alternatives if weight loss is problematic for your health.
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.