Semaglutide Reduced Exercise Motivation in Mice by Altering Brain Dopamine Signaling | Research

The takeaway

A mouse study found that semaglutide reduces voluntary exercise and motivation to run by altering dopamine signaling in the brain's reward center, independent of its appetite-suppressing effects.

Motivation reduced independent of eating
Semaglutide-treated mice showed decreased effort to access exercise even when controlling for reduced food intake, pointing to a direct effect on reward circuitry

What the researchers found

Semaglutide suppressed voluntary wheel running in both lean and obese mice — and this wasn't just because the mice were eating less. In a progressive ratio task (where mice had to work harder and harder to access the running wheel), semaglutide-treated mice showed reduced motivation to exert effort for exercise.

Real-time dopamine measurements using fiber photometry revealed that semaglutide amplified dopamine dynamics in the nucleus accumbens (the brain's reward center) at the start and end of running bouts. This suggests semaglutide doesn't just suppress appetite — it alters the brain's reward circuitry in ways that reduce motivation for non-food activities like exercise.

Why it matters

One of the biggest concerns about GLP-1 weight loss drugs is whether they cause muscle loss, and exercise is the primary tool patients use to counteract this. If semaglutide directly reduces exercise motivation through dopamine pathways — independent of its appetite effects — that's a clinically important finding. It could help explain why some patients on these drugs report reduced drive to exercise and has implications for how weight loss is maintained.

How the study worked

Animal study using lean and diet-induced obese mice. Voluntary wheel running was measured to assess activity levels. Motivation was tested using a progressive ratio task where mice pressed a lever with increasing effort requirements to access a running wheel. Real-time dopamine dynamics in the nucleus accumbens were measured using fiber photometry during running bouts.

Who was studied

Lean and diet-induced obese mice

What this study cannot tell us

Mouse study — dopamine dynamics and exercise motivation may not directly translate to human behavior. The study used a preprint server (bioRxiv), meaning it hasn't completed peer review. Wheel running is an innate rodent behavior that may not perfectly model human exercise motivation. The doses and pharmacokinetics of semaglutide in mice differ from human use.

How to read the evidence

This is a preliminary-grade animal study published as a preprint (bioRxiv), meaning it has not yet been peer-reviewed. While the experimental methods (fiber photometry, progressive ratio tasks) are rigorous, the findings are in mice and cannot be directly applied to humans.

When this study was published

Published in 2025 as a bioRxiv preprint, this represents cutting-edge research that has not yet completed peer review. The findings should be considered preliminary until published in a peer-reviewed journal.

The bigger picture

This study adds to a growing body of research suggesting GLP-1 drugs affect the brain's reward system beyond just food. Other studies have found reduced alcohol consumption, gambling urges, and compulsive behaviors in GLP-1 drug users. The dopamine mechanism identified here could be the common thread — and it raises important questions about whether these broad motivational effects are beneficial (reducing addictions) or harmful (reducing healthy exercise motivation).

Questions still open

Do humans on semaglutide show measurably reduced exercise motivation, and if so, can targeted interventions counteract this?
Is the dopamine-mediated reduction in motivation specific to certain activities or does it broadly dampen drive across all rewarding behaviors?
Could lower doses of semaglutide preserve appetite suppression while minimizing effects on exercise motivation?

Common questions

Does Ozempic reduce your motivation to exercise?

This mouse study suggests it might — semaglutide reduced both voluntary exercise and the willingness to work for exercise access, and this was linked to changes in dopamine signaling in the brain's reward center. Some human patients have anecdotally reported reduced exercise motivation on GLP-1 drugs, but controlled human studies are still needed to confirm this finding.

How does semaglutide affect dopamine in the brain?

The study found that semaglutide amplified dopamine dynamics in the nucleus accumbens — the brain's reward center — specifically at the beginning and end of exercise bouts. This altered dopamine pattern was associated with reduced motivation to exercise. It suggests semaglutide doesn't just work on appetite circuits but broadly influences the brain's reward and motivation systems.

Read the original research

The GLP-1R Agonist Semaglutide Reduces Motivated Running and Alters Dopamine Dynamics in the Nucleus Accumbens.

bioRxiv : the preprint server for biology

View on PubMed ↗Publisher’s paper ↗

Citation

Foscue, Ethan P; Trinko, Joseph R; Jiménez, Jaysen Lara; Kong, Edward; Thompson, Summer L; Stankewich, Kiera; Corstens, Anouk M; Serlie, Mireille J; Taylor, Jane R; DiLeone, Ralph J. (2025). The GLP-1R Agonist Semaglutide Reduces Motivated Running and Alters Dopamine Dynamics in the Nucleus Accumbens.. bioRxiv : the preprint server for biology. https://doi.org/10.1101/2025.10.08.681212