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Ozempic, wegovy, semaglutide — What the Data Actually Shows

  • Writer: SmartReals
    SmartReals
  • Mar 8
  • 3 min read

Updated: Mar 10

The Rise of GLP-1 Medicines

Medications based on GLP-1 receptor agonists, particularly semaglutide, have rapidly become one of the most transformative developments in metabolic medicine.

Originally developed for the treatment of type 2 diabetes, semaglutide is now widely prescribed for obesity management under the brand names Ozempic and Wegovy.

These drugs mimic the natural hormone glucagon-like peptide-1 (GLP-1), which plays a central role in regulating appetite, glucose metabolism, and gastric emptying.

By activating GLP-1 receptors in the hypothalamus, the drug increases satiety signals and reduces hunger.

At the same time, it slows gastric emptying, prolonging the feeling of fullness after eating.

The result is a significant reduction in calorie intake.


Clinical Trial Results

The most influential evidence comes from the STEP clinical trial programme, a series of large randomized trials studying semaglutide for obesity.

One of the most widely cited studies, published in the New England Journal of Medicine, showed that participants receiving semaglutide experienced an average weight loss of approximately 14.9% of body weight after 68 weeks.

This magnitude of weight reduction approaches results previously achievable mainly through bariatric surgery.

However, the response is not universal.

Across trials:

  • Around 14% of participants did not achieve clinically meaningful weight loss

  • Real-world observational studies suggest 20–30% may respond weakly

This variability suggests that genetic factors, metabolic differences, and behavioural patterns influence treatment outcomes.


What Happens When Treatment Stops

Another major question concerns weight regain.

A follow-up study published in JAMA evaluated what happened when semaglutide treatment was discontinued.

Participants who stopped treatment regained roughly two-thirds of the weight they had lost within one year.

This indicates that the medication primarily modulates appetite signalling while it is active, rather than permanently resetting metabolic regulation.

For many patients, this implies that long-term or indefinite treatment may be required to maintain weight loss.



Long-Term Effects Still Under Investigation

Most semaglutide trials currently extend between one and two years.

While results are promising, the long-term metabolic, behavioural, and societal impacts remain uncertain.

Key questions include:

  • How the body adapts to long-term GLP-1 signalling

  • Whether metabolic resistance develops

  • How lifelong treatment affects healthcare systems

  • Whether early use alters long-term obesity risk

Recent research has also examined body composition changes, showing that while most weight lost is fat, some lean mass reduction also occurs.


Cardiovascular Outcomes

Beyond weight loss, new data suggests important cardiovascular benefits.

The SELECT trial demonstrated that semaglutide significantly reduced major adverse cardiovascular events in individuals with obesity and cardiovascular disease.

This suggests the medication may influence systemic metabolic pathways, not only appetite.


Conclusion

Semaglutide represents one of the most significant pharmacological advances in obesity treatment.

However, the available data also highlights important realities:

  • Not everyone responds strongly

  • Weight regain is common after discontinuation

  • Long-term effects remain under investigation

The drug is powerful, but it is not a complete solution to the complex biological and social drivers of obesity.


Key Sources

Wilding JPH et al.Once-Weekly Semaglutide in Adults with Overweight or Obesity

New England Journal of Medicine (2021) https://www.nejm.org/doi/full/10.1056/NEJMoa2032183


Rubino DM et al.Effect of Continued Weekly Semaglutide vs Withdrawal on Weight Maintenance


Rubino D et al.Two-Year Effects of Semaglutide in Adults with Overweight or Obesity (STEP-5)


Lincoff AM et al.Semaglutide and Cardiovascular Outcomes in Obesity – SELECT Trial


Neeland IJ et al.Changes in Body Composition with GLP-1 Receptor Agonists

Diabetes, Obesity and Metabolism https://dom-pubs.onlinelibrary.wiley.com

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