The Brazilian Butt Lift, or BBL, utilizes your own natural fat for the augmentation. One of the keys of the fat transfer is that it is incorporated and becomes your fat just in a better place!
I always tell patients that the fat will act just like fat in any other parts of your body, if you gain weight your butt will get bigger if you lose weight your butt will probably get smaller. However with that said I would encourage you to do butt workout or any type of structured exercise.
The Brazilian Butt Lift has become so popular because it not only enhance your butt, it improves your overall shape.
I would encourage you to do butt workouts or any type of structured exercise. Typically patients that take care of their body and specifically do exercises focused on the buttock tend to enhance their results. These workouts will build your gluteal muscles and thus enhance your natural results.
I hope this helps. Be sure to discuss this with your board certified plastic surgeon.