How to reduce weight and get in shape in minimum time?

My stomach fat has increased sideways... my under chin fat has also increased... it's been 4 months I am on no oil only vegetarian diet... but I don't see no effect... help me get in shape please. Answers from experienced people would be more appreciated!
Updates
+1 y
Cannot choose a best one... all make enough sense.
How to reduce weight and get in shape in minimum time?
Post Opinion