How much does 1200cc of fat weigh? What is the maximum amount of fat that can be taken/ transfer during Brazilian Butt Lift?

Fat cells should be injected into healthy tissues with good blood supply.  Ideally the fat cells are even distributed so that they all have access to oxygen and nutrients.  If you overfill a butt, which is certainly possible, it's no different than overfilling a cup... it just spills out and gets lost.  If you inject too much fat into a butt, most of these cells will just die before your body has a chance to grow new blood vessels into the mass of injected fat.  A bigger butt can handle a larger injection.World authorities on BBL will tell you about 40% of the injected volume survives.  If you inject too much, the % drops down dramatically.

Hello dear!!
Thanks for the question and provided information as well.
Unfortunately, without pictures, it is very difficult to give you a proper answer.
In general, you need to be physically healthy and at a stable weight, have realistic expectations, be a non-smoker and your BMI needs to be 30 or less. l recommend you to make an appointment with a board certified plastic surgeon to talk about your goals and anything you need to know.
Good luck :)

The amount of fat that can be transferred in a BBL depends on how much fat the patient has to harvest and the amount of space there is to move the fat into.