Fitness problem ............pls.help.?

hi, i am 5 ft. 2 inches tall, & age: 32+. i was 74 kg. 1 & half yrs. back. so i joined gym, now i am 63 kgs. now the problem is due to my new job i can't adjust the time of my gym & i want to continue in the same gym institution. they have yoga too & it's time suits me. so if i switch to yoga from gym, will i become fat again (o.k i know i am still fat but my query is am i going to gain weight)?pls. help.