GLP-1 drug exenatide prevents olanzapine-related weight gain in psychiatric patients | Research

The takeaway

In a double-blind RCT, exenatide prevented olanzapine-associated weight gain (-0.5 kg vs +2.6 kg with placebo over 16 weeks) without affecting mood or psychotic symptoms.

3.1 kg difference in 16 weeks
Exenatide patients lost weight while placebo patients gained, with no worsening of psychiatric symptoms

What the researchers found

Exenatide vs placebo over 16 weeks: -0.5 kg (-0.6%) vs +2.6 kg (+2.8%), both p<0.01. Exenatide was well-tolerated. No clinically meaningful differences in mood or psychotic symptoms between groups.

Why it matters

Olanzapine is one of the most effective antipsychotics but causes severe weight gain that leads to metabolic syndrome, diabetes, and medication discontinuation. An effective, psychiatrically safe weight management option could improve both physical health and medication adherence in this vulnerable population.

The numbers in context

Exenatide: -0.5 kg (-0.6%) vs placebo: +2.6 kg (+2.8%), both P < 0.01. 16-week double-blind trial. Most common side effects: GI symptoms and headaches. No clinically meaningful changes in mood or psychotic symptoms.

How the study worked

Randomized, double-blind, placebo-controlled trial (NCT00845507) in adults with stable major mood or psychotic disorders on olanzapine, treated for 16 weeks.

Who was studied

Overweight or obese adults with stable mood or psychotic disorders on olanzapine

What this study cannot tell us

Relatively small sample size and short 16-week duration. Only studied exenatide (less potent than semaglutide). Only studied olanzapine; results may not generalize to other antipsychotics. Primarily assessed weight prevention rather than weight loss.

How to read the evidence

Randomized, double-blind, placebo-controlled trial—highest quality study design. Moderate sample size and duration. Strong evidence for safety and efficacy in this population.

When this study was published

Published in 2025; addresses a growing clinical need as GLP-1 drug use expands into psychiatric populations.

The bigger picture

Antipsychotic-induced weight gain is a major clinical problem affecting millions of psychiatric patients. This trial demonstrates that GLP-1 drugs can be safely used alongside psychiatric medications, opening a new management strategy for metabolic complications in mental health care.

Questions still open

Would more potent GLP-1 agonists like semaglutide produce greater weight loss in psychiatric patients?
Can GLP-1 drugs improve metabolic syndrome in patients already obese from antipsychotic use?
Should GLP-1 drugs be routinely co-prescribed with weight-gaining antipsychotics?

Common questions

Can GLP-1 drugs be used with psychiatric medications?

This trial shows exenatide is safe and effective alongside olanzapine, with no worsening of mood or psychotic symptoms. It prevented the significant weight gain typically seen with olanzapine, suggesting GLP-1 drugs can be an important tool for managing antipsychotic side effects.

Why do antipsychotics cause weight gain?

Olanzapine and similar antipsychotics affect brain receptors (histamine, serotonin) that regulate appetite and metabolism, leading to increased food intake and metabolic changes. GLP-1 drugs counteract this by reducing appetite and improving metabolic function through a different pathway.

Read the original research

A double-blind, placebo-controlled trial of exenatide for the treatment of olanzapine-related weight gain in obese and overweight adults.

Journal of affective disorders, 382, 116-122

View on PubMed ↗Publisher’s paper ↗

Citation

Patino, Luis R; Strawn, Jeffrey R; Adler, Caleb M; Blom, Thomas J; Welge, Jeffrey A; DelBello, Melissa P. (2025). A double-blind, placebo-controlled trial of exenatide for the treatment of olanzapine-related weight gain in obese and overweight adults.. Journal of affective disorders, 382, 116-122. https://doi.org/10.1016/j.jad.2025.04.046