Scientists discovered how exercise produces Lac-Phe, a molecule that suppresses hunger by acting on brain neurons. The finding could inspire new obesity treatments and explains how workouts naturally curb appetite.
Scientists from Baylor College of Medicine, Stanford University, and partner institutions have discovered how exercise helps curb appetite at the molecular level. Their findings, published in Nature Metabolism (Sept 20, 2025), reveal that a compound called Lac-Phe, produced during intense workouts, directly influences brain cells that regulate hunger.
How Exercise Quietly Controls Appetite
While exercise is well known for burning calories and boosting metabolism, researchers have now shown that it also works through a neural pathway. When the body produces Lac-Phe during workouts, the compound interacts with two sets of brain cells:
- AgRP neurons – which normally trigger hunger signals.
- PVH neurons – which suppress appetite.
- Lac-Phe shuts down AgRP neurons, removing their inhibitory effect on PVH neurons. As a result, PVH neurons become more active and naturally suppress appetite, leading to reduced food intake without unpleasant side effects.
Why This Matters
Previous studies found that giving Lac-Phe to obese mice helped them eat less and lose weight, but scientists didn’t understand the “how.” This study connects the dots, showing that Lac-Phe acts on a protein channel (KATP) in AgRP neurons, directly controlling appetite.
Dr. Yang He, one of the lead researchers, explained:
“Understanding how Lac-Phe works is important for developing future weight-management therapies.”
The discovery could open new doors for safe, natural obesity treatments that mimic the effects of exercise.
Beyond Weight Loss
Researchers note that this breakthrough also deepens our understanding of how the body balances energy and appetite. While the work is currently in mice, future studies will test Lac-Phe in humans under different conditions like obesity or leanness. If proven safe, Lac-Phe or similar compounds could be used in clinical therapies to support healthy weight management.