GLP-1 Weight Loss Treatments: Overview, Comparison, and Guidelines

1. GLP-1 Weight Loss Overview & Comparison

GLP-1 receptor agonists are a breakthrough class of medications originally developed for managing type 2 diabetes. Now approved (or used off-license) for weight loss, these treatments mimic the body's natural GLP-1 hormone, which helps regulate appetite, blood sugar, and digestion. Clinical studies show that GLP-1s can support significant, sustainable weight loss when used alongside lifestyle changes.

Available GLP-1 Treatments:

• Wegovy (Semaglutide) – Licensed for weight loss
• Mounjaro (Tirzepatide) – Licensed for weight loss
• Ozempic (Semaglutide) – Used off-license for weight loss, licensed for diabetes treatment
• Rybelsus (Semaglutide Tablet) – Oral form of semaglutide

Medication	Format	Frequency	Average Weight Loss	Status
Wegovy	Weekly injection	Weekly	~15% body weight	MHRA-approved for weight loss
Mounjaro	Weekly injection	Weekly	~22.5% body weight	MHRA-approved for weight loss
Ozempic	Weekly injection	Weekly	~12–14% (off-license)	Off-license for weight loss, licensed for diabetes
Rybelsus	Daily tablet	Daily	~6–9% body weight	Off-license for weight loss, licensed for diabetes

*average but not guaranteed weight loss*

References: STEP Trials (NEJM, 2021), SURMOUNT Trials (NEJM, 2022), NICE Guidance, MHRA, ADA, GPhC Blue Guide

2. Wegovy: How It Works, Dosage, Side Effects

• What is Wegovy? A once-weekly injection containing up to 2.4mg semaglutide. It reduces appetite and slows digestion.
• Effectiveness: STEP 1 trial showed 14.9% average weight loss over 68 weeks.
• Dose Schedule:
  • Week 1–4: 0.25mg once weekly
  • Week 5–8: 0.5mg
  • Week 9–12: 1mg
  • Week 13–16: 1.7mg
  • Maintenance: 2.4mg
• Common Side Effects: Nausea, vomiting, diarrhoea, constipation, headache, tiredness, injection site reactions
• Red Flags: History of medullary thyroid cancer, pancreatitis, severe GI disease

3. Mounjaro (Tirzepatide): Benefits, Evidence, Who It’s For

• What is Mounjaro? A dual GIP and GLP-1 receptor agonist supporting significant weight loss.
• Effectiveness: SURMOUNT-1: 22.5% average weight loss at 15mg over 72 weeks.
• Dose Schedule: Start at 2.5mg weekly, increase every 4 weeks up to 15mg
• Who Can Use: BMI ≥30, or ≥27 with health conditions. Requires clinical assessment.
• Cautions: Similar red flags as Wegovy

4. Ozempic (Semaglutide): Off-License Use

• Licensed for type 2 diabetes, off-license for weight loss
• Same ingredient as Wegovy, but lower doses (0.25mg–1mg)
• Less expensive, more accessible
• Requires understanding of off-license status

5. Rybelsus (Tablet Semaglutide) Overview

• First oral GLP-1, taken daily on empty stomach
• 6–9% average weight loss
• Alternative for injection-averse patients
• More frequent GI side effects, lower efficacy

6. Side Effects & Safety Monitoring

• Common: Nausea, vomiting, diarrhoea, bloating, fatigue, dizziness
• Rare but Serious: Pancreatitis, gallbladder issues, hypoglycaemia, possible thyroid tumours
• Monitoring: Check-ins via form or teleconsultation, vital signs, adherence tracking

7. Dose Titration Guide

Medication	Initial Dose	Escalation	Maintenance Dose
Wegovy	0.25mg/week	Increase every 4 weeks	2.4mg/week
Mounjaro	2.5mg/week	Increase every 4 weeks	Up to 15mg/week

Why Titration Matters: Helps minimise nausea, allows adaptation, reduces dropout. This is a personalised approach between you and the clinician

8. Eligibility Checker

• Eligible:
  • BMI ≥30
  • BMI ≥27 with comorbidities (e.g. hypertension, prediabetes)
• Not Eligible If:
  • History of thyroid cancer or pancreatitis
  • Eating disorders or unstable mental health
  • Pregnant or breastfeeding
  • Severe GI conditions
• Checked During: Initial consultation, red flag form, GP notification

Guidelines Followed: NICE, GPhC, MHRA, RPS, ADA, EASO, Blue Guide

Last Updated: May 2025

For clinical or regulatory queries, contact our Superintendent Pharmacist or Clinical Lead.