This question comes up because of the appearance of new technologies that reportedly can eliminate stubborn fat deposits without surgery. They use various forms of energy, such as ultrasonic energy, delivered to the tissues through the skin in an effort to dissolve or melt fat. The claim is then made that the body ‘naturally’ then eliminates the liquefied fat.
Normal Fat Metabolism
So, what is this mechanism by which our bodies can ‘naturally’ eliminate fat? First we must look at what our body normally does with fat. Obviously, fat enters our bodies through our intestinal tract. After fat is consumed, it is broken down into smaller molecules by enzymes created by our pancreas so that it can be absorbed into the blood stream. From there, fat is deposited into fat cells wherever it chooses to; this is mostly determined by genetics. Unfortunately, where we tend to put fat on first is where we tend to break it down last.
Fat is mobilized from these deposits when it is needed as an energy source; either during times of starvation or diet and exercise when our stores of carbohydrates in our muscles and liver are getting depleted. In neither if these situations, is it eliminated, it is utilized. As much as we don’t like it, our bodies cherish its fat deposits as a survival mechanism. In addition, muscles do not reach out and grab the fat that is next to it for energy metabolism; genetics and hormones determine how our bodies utilize fat stores for energy. Therefore, exercising your arms does not work fat off of your arms and doing sit-ups does not work fat off of your stomach.
Let’s say that some of these techniques can liquefy fat. What would then happen is that the fat would be absorbed by the blood stream and be deposited just like fat absorbed from the intestine. Large volumes of fat absorbed into the blood can get trapped in the lungs; known as a fat embolism syndrome, which can be very serious.
The kidneys cannot eliminate fat because it is not water-soluble. It cannot go from the blood stream back into the intestines because there is no physiologic mechanism for fat to move in that direction. It is not a system that can go in reverse. Fat cannot be eliminated like carbon dioxide from the lungs because it does not exist as a gas. And you cannot sweat out fat.
True Fat Removal
So, the true answer is: It doesn’t! Liposuction is the procedure that eliminates unwanted pockets of fat by actually removing the excess fat and fat cells. Fortunately, when these fat cells are removed, they are permanently eliminated unlike the so-called nonsurgical fat ‘removal’ procedures where, even if some fat was eliminated, all of the cells would still be present to take on future fat. When fat cells are removed through surgical liposuction, new cells do not grow back unless one gains a tremendous amount of weight.