GLP-1 Weight Loss Drugs Show Consistent Results Across Most Demographic Groups

The leverage of prescription weight-loss medications, particularly glucagon-like peptide-1 receptor agonists (GLP-1 RAs), has increased significantly in recent years. Originally developed to treat type 2 diabetes, these drugs have demonstrated substantial and sustained weight reduction in clinical trials, leading to expanded regulatory approvals and growing demand.

Do Weight Loss Drugs Work the Same for Everyone?

As GLP-1 RAs become a mainstream option for obesity care, a key question arises: do these medications work equally well for different people, or do factors like age, race, or starting weight influence the results? A new review led by researchers at the Johns Hopkins Bloomberg School of Public Health offers reassuring insights.

Study Findings: Broadly Similar Weight Loss

The review, which analyzed 64 clinical trials of GLP-1 RAs – including semaglutide (Ozempic), dulaglutide (Trulicity), and others in the same class – suggests that these medications produce broadly similar weight loss across a wide range of participants. The trials collectively involved tens of thousands of patients. The findings were recently published in JAMA Internal Medicine.

When researchers pooled the results, women experienced an average weight loss of approximately 11% of their starting weight, compared to about 7% for men. But, overall effectiveness appeared similar when participants were grouped by age (under 65 versus 65 and older), race, ethnicity, starting body mass index (BMI), and starting HbA1c levels (a measure of average blood sugar).

Why the Difference Between Men and Women?

Researchers propose several potential reasons for the stronger average response in women. These include possible interactions between the drugs and estrogen, differences in how women metabolize the medications, and generally lower median body weight among women.

How GLP-1 Receptor Agonists Work

GLP-1 is a hormone naturally released by cells in the gut after eating. It works by reducing appetite and signaling the pancreas to release insulin, which helps regulate blood glucose levels. Because the natural hormone breaks down quickly, scientists have developed longer-lasting compounds that mimic its effects. Today, GLP-1 RAs are prescribed for obesity, type 2 diabetes, and to lower the risk of cardiovascular events. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, is one such example.

What About Tirzepatide (Zepbound)?

The researchers did not include tirzepatide (Zepbound) in their analysis. Tirzepatide differs from other studied medications as it targets both GLP-1 and another hormone called GIP.

The Need for Further Research

“These results should give clinicians and their patients more confidence that GLP-1-RAs work similarly well across different racial and ethnic populations, and different ages and weights, though they appear to have modestly greater effectiveness among women compared to men,” says study senior author Hemal Mehta, PhD, an associate professor in the Bloomberg School’s Department of Epidemiology.

Study corresponding author G. Caleb Alexander, MD, a professor in the Bloomberg School’s Department of Epidemiology, emphasizes the need for continued research. “The popularity and the cost of GLP-1 RAs are such that we need more studies like this to better understand the benefits of these products in clinical practice, especially for individuals that might be under-represented in clinical trials.”

Key Takeaways

• GLP-1 receptor agonists demonstrate consistent weight loss results across most demographic groups.
• Women, on average, experience greater weight loss with GLP-1 RAs compared to men.
• Age, race, ethnicity, BMI, and HbA1c levels do not appear to significantly impact the effectiveness of these medications.
• Further research is needed to understand the nuances of GLP-1 RA effectiveness in diverse populations.

Reference: Alexander, G. C., et al. “Heterogeneity of Treatment Effects of Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss in Adults: A Systematic Review and Meta-Analysis.” JAMA Internal Medicine, 2 March 2026, https://jamanetwork.com/journals/jamainternalmedicine. DOI: 10.1001/jamainternmed.2025.8222