The early improvement Michelle describes is consistent with the hypothesis that some of tirz's OSA benefit is weight-independent. Fat deposition in the parapharyngeal space (around the throat) may redistribute or reduce earlier than total body weight change would predict, possibly due to GIP-mediated effects on visceral/ectopic fat deposits.
There's also emerging data on GLP-1 receptor expression in the brainstem respiratory centers (nucleus tractus solitarius) that could influence respiratory drive during sleep. This is very preliminary but mechanistically plausible.