Real-World Evidence and Observational Data

While randomised clinical trials remain the gold standard for proving safety and efficacy, they do not always reflect what happens in our daily lives.

Real-world studies track how GLP-1 receptor agonists such as semaglutide, tirzepatide, and liraglutide perform among ordinary patients seen in clinics, pharmacies, and weight management programmes.

These studies provide valuable insight into long-term weight loss, adherence, and patient satisfaction, helping both clinicians and patients understand what to expect.

Real-world evidence (RWE) refers to data collected outside of clinical trials. It includes medical records, prescribing databases, pharmacy outcomes, and digital health tracking

Observational studies often involve larger, more diverse populations, reflecting people with coexisting conditions, different ages, and varied lifestyles.

Across international studies, weight loss in real-world use closely mirrors results from clinical trials, though individual outcomes vary. On average, people using GLP-1 medications for at least six months report weight loss of around 10 to 15 percent of their starting body weight. Some achieve more when combined with lifestyle support.

Typical findings:

• Semaglutide users often see steady weight loss over 6 to 12 months.
• Tirzepatide data suggest even greater average reductions in body weight and waist circumference.
• Liraglutide tends to produce slower but consistent results with continued adherence.

Real-world data show that treatment adherence strongly predicts success. Patients who maintain regular dosing and follow clinical advice typically achieve and sustain weight loss for longer periods.

Common reasons for discontinuation include:

• Side effects such as nausea or fatigue
• Limited availability or cost of medication
• Reaching a goal weight and choosing to pause treatment

Structured clinical follow-up and coaching support significantly improve continuation rates compared with self-directed use.

Observational data also demonstrate improvements beyond weight reduction. These include:

• Better blood glucose control, even in people without diabetes
• Reduction in systolic blood pressure and triglyceride
• Improved liver enzyme profiles and markers of inflammation
• Fewer cravings and more stable energy levels

Such outcomes suggest that GLP-1 medications provide metabolic benefits across a broad patient population, reinforcing their role in long-term health management.

Real-world experience has shown that emotional and behavioural adaptation is as important as the biological effect. People who engage in nutrition coaching or behavioural support often report greater satisfaction and more stable results.

 

While outcomes are positive overall, real-world use also highlights challenges:

• Access and cost can limit continuity for some users.
• Side effects may lead to early discontinuation without clinical guidance.
• Misinformation online can lead to incorrect dosing or unrealistic expectations.

Ongoing clinical oversight, clear communication, and patient education are key to maintaining safety and results in real-world settings.

Real-world data confirm that GLP-1 receptor agonists deliver substantial benefits for most patients who stay consistent with treatment and receive ongoing support. The combination of evidence-based prescribing and practical lifestyle coaching produces the best long-term outcomes.

Evidence from real-world practice supports what clinical trials have shown: GLP-1 medications are safe, effective, and transformative when used properly. Most patients experience meaningful and sustained weight loss, particularly when treatment is combined with nutrition, physical activity, and behavioural support. These findings reinforce the importance of comprehensive care and long-term follow-up in achieving lasting results.

You can complete an online health assessment if you would like to explore whether GLP-1 treatment may be clinically appropriate for you – start the assessment.

Dr Abby Hyams completed her medical training in Bristol and has been a GP for 19 years, spending many of those as a partner in an NHS practice in Hemel Hempstead. She has a particular passion for supporting patients with weight loss and promoting positive behaviour change, helping individuals build sustainable habits that improve their long-term health and wellbeing.

This article is for general information only and should not be used for the diagnosis or treatment of medical conditions. Medic Spot Limited has used all reasonable care in compiling the information but makes no warranty as to its accuracy. Consult a doctor or other healthcare professional for diagnosis and treatment of medical conditions. In the event of an emergency, please call 999 for immediate assistance.

There is no guarantee of a specific weight loss medication being prescribed. Clinicians will review your online questionnaire alongside other independently validated medical information about you and will recommend the most appropriate weight loss treatments for you based on your answers. In some cases, the clinicians may contact you for additional information. See Terms of Service for more information.