Hello and Great Question. I appreciate the time you are spending researching this procedure. My name is Dr. Matthew J. Nykiel. I am a Board Certified Plastic Surgeon, a Fellowship Trained Cosmetic Surgeon, and a Butt Augmentation Specialist. Weight loss can certainly effect the entire body, so does weight gain. If you happen to lose weight, the effects would be spread throughout your body, affecting the transferred fat too and causing the cells there to shrink. As the buttocks lose volume due to weight loss, it could affect BBL outcomes. On the other hand, weight gain will make all the fat cells in the body expand, including the transferred fat cells. This happens as the calories turn into fat that is stored in the cells. This clearly means you can expect that your butt would gain volume with weight gain. So if you have experienced weight loss after BBL and want to restore the results, you need to gain weight carefully. This can help restore the attractive derriere you achieved through the procedure. I hope that helps! Best of Luck! Matthew J. Nykiel, MD #CoreAesthetic Butt Augmentation Specialist Liposuction Specialist Board Certified Plastic Surgeon