Liposuction, also known as lipoplasty ("fat modeling") or suction lipectomy ("suction-assisted fat removal") is a cosmetic surgery operation which removes fat from many different sites on the human body. Areas affected can range from the abdomen, thighs, buttocks, neck, arms and elsewhere. The fat is usually removed via a cannula and aspirator.

While exercise and dieting may be useful for losing unwanted weight and fat, some fat deposits may not respond to efforts at weight loss. Applying liposuction techniques may be an option in these situations. Liposuction is not a low-effort alternative to exercise and diet. It is a form of body contouring and not a weight loss method. The amount of fat removed varies by doctor, method, and patient, but the average amount is typically less than 10 pounds (5 kg).

There are several factors that limit the amount of fat that can be safely removed in one session. Ultimately, the operating physician and the patient make the decision. There are negative aspects to removing too much fat. Unusual "lumpiness" and/or "dents" in the skin can be seen in those patients "over suctioned".

Reports of people removing 50 pounds (22.7 kg) of fat are exaggerated. However, the contouring possible with liposuction may cause the appearance of weight loss to be greater than the actual amount of fat removed. The procedure may be performed under general or local ("tumescent") anesthesia. The safety of the technique relates to the amount of tissue removed, the choice of anesthetic, and the patient's overall health.