Silicone breast implants provide the most natural feel. However, Dr. Margoles can achieve a similar consistency with saline implants. She does this by inserting the implants behind the chest muscles and expanding the shell of the implant by filling it with extra saline. Implants will add firmness and strength to your breasts, and this may actually help them resist sagging. However, a large implant’s excess weight may increase the likelihood of sagging as the body ages and the skin loses elasticity.