How can i reduce the size of my labia major without major surgery?

Probably cant: Labiaplasty sounds awful but the recovery & pain is usually not awful. It takes 8 weeks to fully recover & resume intercourse. I can't think of any other way to reduce labial size. Are you sure you're not talking about labia minora? I've not really had to reduce the size of the labia majora.

Weight loss: There are a few treatable causes that may relate to hernia or vascular malformations but these are extremely rare. The vast majority of the labia majora is fat and nonsurgical reduction can be accomplished with weight loss. Other alternatives include liposuction as a relatively minor procedure. Debunking with surgical excision is the last definitive procedure.

Not really: You might decrease the size a little bit with weight loss but it really depends upon what exactly is the source of the enlargement. It is not always fat.