Would losing a significant amount of weight after BBL reverse the effects?

Hi... thank you for the question... When the fat graft have been integrated, it acts like the rest of your fat tissue, if you loose weight it will shrinks, if you gain weight it will expand. 

Hello dear!
Thanks for the question and provided information as well.
After a BBL, you lose or gain weight in the same way as before. So the answer is yes, if you go back to your previous weight, you should see your previous results, but I encourage you to maintain a clean and healthy diet, along with exercise.
If you have any concerns, I suggest you follow up close with your plastic surgeon.
Good luck :)

Losing weight after a brazilian butt lift may also reduce the overall volume of fat in the buttocks as well.  

This is an excellent question and the answer is as follows:Transplanted fat always behaves as if it were in its ORIGINAL (not transplanted) location.  Thus, if you tend to lose weight from the area where the fat was harvested then you will likely lose the benefit of the enhancement.  Fat transplant is an awesome idea but we have not yet unlocked its secrets. A promising horizon was the concomitant use of stem cells, but this has now been removed from the marketplace,The only reliable way to augment the buttocks is with implants.