The Science Behind GLP-1 Weight Loss: How Mounjaro & Wegovy Are Changing Lives

In the past two years, weight management has witnessed a revolution. No longer limited to diets or willpower alone, clinically proven medications like Mounjaro (tirzepatide) and Wegovy (semaglutide) are delivering sustainable weight loss for people struggling with obesity or weight-related health risks. Here’s what the latest science says about these groundbreaking treatments and why Redwood Pharmacy stands at the forefront of this new era in weight management.

What Are GLP-1 Weight Loss Medications?

GLP-1 receptor agonists are medicines that mimic glucagon-like peptide-1, a natural hormone that helps control appetite and blood sugar. Semaglutide (Wegovy) and tirzepatide (Mounjaro) are among the leading GLP-1 agents now approved for chronic weight management—and recent research continues to affirm their powerful benefits.www.gov.uk+2

Dual Action for Greater Results

• Mounjaro (tirzepatide) uniquely targets both GLP-1 and GIP receptors, amplifying appetite suppression and metabolic improvements beyond GLP-1 alone.nature.com+2

• Wegovy (semaglutide) focuses on the GLP-1 pathway and consistently delivers significant, lasting weight loss across diverse populations, including those without diabetes.nature.com+2

Latest Clinical Results: How Much Weight Loss Can You Expect?

• Mounjaro (Tirzepatide): People using tirzepatide for 72 weeks lost up to 21% of their starting body weight according to data from phase III SURMOUNT trials. The latest three-year studies report average losses of 23.1%, with most people maintaining results over the long term.easo.org+3

  • Tirzepatide outperformed semaglutide by about 50% in head-to-head studies: average loss of 20.2% for tirzepatide vs. 13.7% for semaglutide in people without diabetes.easo.org

• Wegovy (Semaglutide): High-quality trials show up to 15% average body weight reduction at standard doses, and even greater losses—up to 21%—with investigational higher doses. Results are durable, with benefits maintained for up to four years in recent studies.nature.com+1

Beyond the Scales: Added Health Benefits

GLP-1 medications aren’t just about weight loss. The latest science shows they can deliver compelling health improvements:

• Blood sugar and insulin improvements: Proven benefit for people at risk of or living with type 2 diabetes.www.gov.uk+1

• Reduced risk of major cardiovascular events (such as heart attack and stroke): Semaglutide delivered a 20% reduction in major events in a landmark trial.nature.com+1

• Lower fat in the liver and reduced cardiovascular risk factors—even for people without diabetes.nature.com

Muscle Matters: Quality of Weight Loss

A hot topic in 2025 research is “quality” of weight loss. It’s now recognized that, although GLP-1 treatments greatly reduce fat mass, they can also lead to some reduction in muscle mass—sometimes accounting for 15–40% of the total weight lost. That’s why experts recommend:diabetes.org+1

• Prioritizing protein intake (1.2–1.6g/kg/day)

• Including resistance training (2–3 times weekly)

• Considering healthy supplements (e.g., magnesium, vitamin D, creatine) for overall wellbeingdiabetes.org+1

The Patient Journey: What to Expect

1. Consultation: A medical assessment matches you to the right treatment, dose, and support plan.

2. Weekly Treatment: Both Mounjaro and Wegovy are administered once weekly via a simple injection.

3. Gradual, Sustainable Results: Most patients experience steady weight loss of 0.5–1kg per week, significant appetite reduction, and improved energy.nature.com+2

4. Support for Lifestyle Change: Medications work best when paired with healthy eating, sufficient protein, exercise, and good sleep.

Side Effects and Safety

• Mild digestive issues (nausea, diarrhoea, constipation) are common, especially early or during dose increases.

• Rare risks: pancreatitis, severe allergic reactions, and, for Mounjaro, a slight increase in discontinuations at higher doses, usually due to gastrointestinal effects.www.gov.uk+1

• Not for everyone: Not suitable for under-18s, pregnant or breastfeeding women, or those with specific health issues such as severe digestive disease or certain cancers.www.gov.uk

What Happens If You Stop Treatment?

Recent research confirms a risk of weight regain if medication is stopped, often emerging within weeks. Maintaining healthy lifestyle habits and regular check-ins helps minimize this effect.independent.co.uk

Looking Forward: Innovations on the Horizon

The pipeline for new and more convenient weight loss drugs is robust.

• New combination therapies (targeting additional hormones) are showing early promise for even greater and more sustainable results.oxfordonlinepharmacy.co.uk+2

• Oral GLP-1 drugs are being developed, offering the convenience of pills with similar efficacy.nature.com

Real-World Demand & Access

Demand for these breakthrough injections is unprecedented, with more people seeking medical weight management than ever before. At Redwood Pharmacy, we offer medically supervised access, education, and ongoing support—helping you achieve not just weight loss, but a healthier, more vibrant life.bbc.co.uk

Ready to start your journey or want to discover if GLP-1 therapy is right for you?
Book your expert pharmacist consultation today at Redwood Pharmacy.