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!
The key is how do we maximize the amount of fat that is going “take” or survive for the augmentation. One of the things that can help increase the amount of fat that stays after the transfer is preventing any trauma to the buttock area, that includes sitting. The pressure of sitting can be harmful to the fat for the first couple of weeks after the transfer.
I typically have patients avoid sitting for two weeks after the surgery. They can walk and sleep on their belly, just no sitting. After the first two weeks they can sit for an hour with a 10 minute break in between sitting sessions. After six weeks they can return to all of their normal routines.
The second important part of the Brazilian Butt Lift is the compression garment as you are asking. I do think it is important that you have a specialized garment after your procedure. I have tried various garments, with and without material over the buttock area. From a patient comfort standpoint I have found that the garments with a very soft mesh over the buttock has been best. However this is personal decision between you and your surgeon.
There are special pillows that patients can purchase that avoids any pressure on the buttock in the post-operative period so that they can sit at work and still protect their fat transfer procedure.
I hope this helps, be sure to discuss this with your board certified plastic surgeon.