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Study breakdown

Second-Generation Obesity Drugs: How Semaglutide, Tirzepatide, and Setmelanotide Compare

ReviewStrong evidence
The takeaway

Second-generation anti-obesity peptide medications achieve average 15% weight loss — far surpassing first-generation drugs — with semaglutide 2.4 mg and tirzepatide also effectively treating concurrent type 2 diabetes.

~15% weight loss

Second-generation anti-obesity peptide drugs achieve about 15% average weight loss with lifestyle modifications, far exceeding first-generation medications

What the researchers found

Second-generation anti-obesity medications achieve ~15% average weight loss with lifestyle modifications. Three approved drugs: setmelanotide (monogenic obesity), semaglutide 2.4 mg, and tirzepatide. Semaglutide and tirzepatide are particularly effective when treating concurrent obesity and T2D.

Why it matters

Obesity affects over 40% of US adults and first-generation medications offered only modest weight loss. The 15% average weight reduction achieved by these peptide drugs is clinically meaningful — enough to significantly reduce cardiovascular risk, improve diabetes control, and reduce the need for bariatric surgery.

The numbers in context

Average weight loss of ~15% with lifestyle modifications. Three approved drugs reviewed: setmelanotide, semaglutide 2.4 mg, and tirzepatide.

How the study worked

Narrative review examining clinical trial data and therapeutic implications of the three approved second-generation anti-obesity medications.

Who was studied

Review covering adults with obesity and concurrent type 2 diabetes

What this study cannot tell us

Short review with limited abstract detail. Doesn't discuss cost, access barriers, or long-term safety. Weight regain upon discontinuation not addressed. Setmelanotide applies only to rare monogenic obesity. Real-world effectiveness may differ from clinical trial results.

How to read the evidence

Rated strong: review synthesizing robust clinical trial evidence for all three approved medications, published in a diabetes specialty journal.

When this study was published

Published in 2024. Covers the current approved landscape of peptide-based anti-obesity medications.

The bigger picture

These peptide-based obesity drugs represent a paradigm shift — for the first time, medications can achieve weight loss approaching that of bariatric surgery. This has transformed obesity from a condition with limited medical options to one with multiple effective pharmacological treatments.

Questions still open

  • How do the next-generation drugs (survodutide, retatrutide) compare to current options?
  • What strategies can maintain weight loss after drug discontinuation?
  • How should clinicians choose between semaglutide and tirzepatide for individual patients?

Common questions

What are the best weight loss medications available now?
The three approved second-generation anti-obesity drugs are semaglutide 2.4 mg (Wegovy), tirzepatide (Zepbound), and setmelanotide (for rare genetic obesity). Semaglutide and tirzepatide achieve about 15% average weight loss and also help with type 2 diabetes.
How much weight can you lose with semaglutide or tirzepatide?
On average, about 15% of body weight when combined with lifestyle changes. Some patients lose more. Both drugs are peptide-based medications that work on gut hormone pathways to reduce appetite and improve metabolism.

Read the original research

Using Second-Generation Anti-Obesity Medications.

Diabetes spectrum : a publication of the American Diabetes Association, 37(4), 303-312

Citation

Schmitz, Sarah H; Aronne, Louis J. (2024). Using Second-Generation Anti-Obesity Medications.. Diabetes spectrum : a publication of the American Diabetes Association, 37(4), 303-312. https://doi.org/10.2337/dsi24-0002