The Short Version
The only rigorous study showing facial stretching improves symmetry involved Bell's palsy patients recovering from nerve paralysis — not healthy individuals. Other peer-reviewed research on facial exercises measured muscle tone, elasticity, or cheek fullness, not symmetry directly. Harvard Health and other credible sources explicitly note that evidence for stretching routines improving facial symmetry in the general population is lacking. The claim overgeneralizes clinical rehabilitation findings to everyday use, creating a misleading impression.