Dear SAS80:If you have a treatment that eliminates fat cells, those cells will die and not return. When you gain weight, all the fat cells of your body get larger because they need to store more fat, and when you lose weight, they all get smaller. Without any treatment, you have a given number of fat cells at birth, and that number does not change throughout your lifetime (with the exception of someone who is severely obese, in which case the cells can increase in number), but with treatment, the number of cells in the treated area is permanently reduced. Those cells will not be replaced with new cells, and you will reduce the volume of fat in the area you treat. And you will put less fat on in the treated area with weight gain than you would have had you never had the treatment. Relative to the rest of your body, you will always have less fat in the treated area than you did before. Now, it can appear that the fat has returned even when it hasn't, since there are factors that influence the amount of fat that will be stored in the fat cells in different areas of the body. For example, cortisol and insulin allow more fat to be stored in the fat cells around the waistline. So if you are severely stressed chronically, and/or eat foods that are digested very quickly often (foods with a high glycemic index, such as sugary desserts, white bread, rice, and potatoes), over time more fat may be stored around the organs in your midsection (visceral fat). If this happens, even though the layer of subcutaneous fat has fewer cells because of CoolSculpting, your tummy can protrude from deposition of fat much deeper, within the abdominal cavity.This of course assumes that you have a treatment that allows the cells to enter apoptosis and die. There are treatments out there that only injure the cells or empty them of their fat, but when they recover they will take on fat again, and the fat reduction will only be temporary. CoolSculpting does kill the fat cells, as does liposuction and #Kybella. I do hope this answers your questions.All the best, Dr. Clark