Sometimes a person is at a suitable weight but still has localized areas of excess fat that do not respond to dieting or exercise. This can cause certain parts of the body to appear disproportionate. If this occurs, he or she may choose to have a procedure called liposuction. During liposuction, very small incisions, approximately 1/4 inch long, are made in the problematic areas of the body, and a hollow tube called a cannula is inserted into the fatty tissue. Often the cannula emits ultrasonic waves to break up the fat cells. The ultrasound device in effect liquefies the fat, allowing a larger amount to be removed. During the procedure, a doctor will guide the cannula, moving it around under the skin, while an attached vacuum unit suctions away the liquefied fat. Although liposuction is effective and can be performed on several areas of the body at the same time, it should never be thought of as a substitute for weight loss through diet and exercise. There are several potential complications associated with this procedure that should be discussed with a doctor prior to the surgery.