It is well-confirmed that tongue position influences facial structure, particularly during development. Proper tongue posture supports more favorable facial proportions[1]. This relationship has been validated across numerous studies.
Confirmed: Adults Show Measurable Changes
Limited research on adult mewing shows that consistent practice produces measurable changes, though they are subtle and appear over extended timelines. Changes in this adult research typically require 6 months to 2+ years of consistent practice[2].
Unconfirmed: Rapid Transformations
Many before-and-after photos on social media can appear exaggerated, and facial structure remodeling takes significant time; however, mewing also shifts posture and muscle tone and tightens the skin, potentially leading to transformations in a matter of weeks.
Nonetheless, in order to achieve results like this, mewing needs to be part of a system that improves general structural health.