GLP-1 receptor agonists have reshaped obesity treatment, but a persistent question follows them into every exam room: Will this work for me? 

A new systematic review and meta-analysis published in JAMA Internal Medicine, encompassing 41 articles and 64 randomized clinical trials, offers a largely reassuring answer. Trial results showed similar weight loss across age groups, race and ethnicity, BMI levels, and A1c ranges. 

One exception stood out. Among six trials including 19,906 patients, women lost an average of 10.9% of their baseline body weight compared with 6.8% for men.

The sex difference raises more complex clinical questions.

"I find the consistency across age, race, BMI, and glycemic status more clinically exciting than the sex difference," said Jessica Duncan, MD, an obesity medicine physician and chief medical officer at Ivim Health in Atlanta. "That's a strong signal that these medications are doing something real at a biological level."

Why Women May Respond Differently 

The gap was statistically significant, but the mechanism remains unclear, with several competing explanations.

Archana Sadhu, MD, an endocrinologist, director of system diabetes, and associate professor at Houston Methodist Research Institute, said estrogen appears to synergize with GLP-1 signaling to enhance satiety and metabolic effects. Women often have lower baseline body weight, so the same absolute loss in kilograms translates to a higher percentage, she said. 

Subtle pharmacokinetic differences in drug distribution related to body composition and fat-mass distribution may also play a role.

Duncan raised a different possibility. 

"Whether the observed difference is the drug itself or the context around how women and men use it, that question matters before we draw clinical conclusions," she said. 

Women in weight loss studies tend to be greater adherers and more likely to engage in lifestyle modification alongside pharmacotherapy.

The picture is further complicated by how much variation exists within that finding. Chevon Rariy, MD, an endocrinologist and chief clinical innovation officer at Visana Health, Dallas-Fort Worth, Texas, who is board certified in endocrinology, internal medicine, and obesity medicine, said women are not a monolithic group. Response varies across life stages, from reproductive years through menopause. GLP-1 receptor agonists are contraindicated during pregnancy, she noted, making preconception counseling and timing especially important.

What the Consistency Tells Us, and What It Doesn't 

Race, ethnicity, age, BMI, and A1c showed no treatment differences. Clinicians can apply this finding directly. But the subgroup data underpinning it were thin. Sex was evaluated in only six trials, race in nine, ethnicity in seven, age in seven, and baseline A1c in just four trials with fewer than 1900 patients.

Sadhu said seeing comparable weight loss across Black, Asian, Hispanic, and non-Hispanic participants lends support to the universal physiology of central appetite regulation irrespective of race or ethnicity. But the analysis pooled data across semaglutide, liraglutide, dulaglutide, exenatide, and lixisenatide. Trials were dominated by semaglutide (43.8%) and dulaglutide (18.8%), and pooling with less potent agents may have masked drug-specific differences, she said. Tirzepatide was excluded entirely.

"'No significant heterogeneity detected' is not the same as 'equity achieved,'" Rariy said. She called for trials intentionally designed with equity in mind, with populations adequately powered for meaningful subgroup comparison.

What This Means in the Exam Room 

The sex difference has not changed how clinicians in obesity medicine approach prescribing. What it has done is reinforce principles that already guide good practice.

Duncan said she has always been cautious about giving patients a specific number to aim for. 

"When you tell someone 'you'll lose 15%,' they either feel like a failure if they don't hit it or they may think they've reached the end of their journey once they do," she said. 

The consistency finding is more useful in her view because it directly addresses a question she hears constantly: patients who believe they are "too metabolically damaged" for treatment to work.

Sadhu agreed. If a patient meets the criteria for the FDA indications of this drug class, regardless of sex or race and ethnicity, they will benefit, she said.

Where outcomes diverge in practice has less to do with demographics and more to do with engagement. Duncan said the variation she sees is driven more by behavioral and adherence factors than by age or baseline BMI. 

Manikya Kuriti, MD, an endocrinologist at Norton Community Medical Associates – Endocrinology in Louisville, Kentucky, said she uses positive reinforcement to keep patients on track, celebrating milestones and showing patients how their lab values have improved over time. She also emphasized monitoring patients on chronic GLP-1 therapy for vitamin deficiencies and malnourishment and ensuring adequate protein intake.

The broader equity question remains unresolved, but the barrier may not be biology. "The equity gap actually lives in access, not in biology," Duncan said. 

Rariy said equitable care means offering treatment based on clinical need and being honest about data limits without using those limits to withhold treatment.

"Patients need more than a prescription," Rariy said. "They need long-term support, coaching, dose adjustment when needed, and a clinician who helps them interpret what is happening over time."

Beyond the Meta-Analysis 

The sex difference in GLP-1 weight loss is real, but not yet mechanistically understood. Larger trials that are actually powered for sex, race, and ethnic subgroups would help, and none of the sources interviewed expected the sex question to be settled soon. 

But the broader takeaway holds: GLP-1 receptor agonists appear to work across the populations most likely to be prescribed them, and the sex finding is worth watching without changing practice.

"I'd file it under 'watch this space,'" Duncan said.

Duncan, Sadhu, Rariy, and Kuriti reported no relevant financial disclosures.