Maigrir belong to the 2nd
group. Maigrir is a common french verb.
Maigrir is conjugated the same way that verbs that end in : -ir
Maigrir is conjugated with the two auxiliaries être
Maigrir verb is
direct transitive, intransitive.
verb is a direct transitive verb, so passive voice can be used.
Attention: passive voice can only be used when maigrir verb is conjugated with auxiliary avoir.