This might seem silly to ask but I better be sure now. Is it common to compliment someone who’s lost weight in Haiti? How would you say “you’ve lost some weight”?

I guess if the person was dieting it would be a compliment to notice his/her loss of weight.  Haitians often use the word “seksi” – “W’ap fè seksi.” or “Ou pèdi pwa”.

You’ve lost some weight
Ou mèg
Ou megri / Ou fè yon ti megri.
Ou kase/ Ou fè yon ti kase.
Ou desann
 
You look good.
Ou anfòm
Ou byen kanpe
Ou seksi
 
Ou vin sèch.
You look emaciated.

 

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words