In short. A contour change is bounded by skin quality, how much fat is present and where it sits. Neither option is a weight-loss treatment, and neither one buys a shape.

Key points

  • An assessment can say that an area will change, and roughly in what direction, but it cannot promise an amount or a shape.
  • Any figure quoted before an examination is a sales figure.
  • The honest statement is that the change is bounded by the fat available, the skin over it and how you heal.

Patients rarely ask an assessment what a treatment can do in the abstract. They ask how much it can change, and the honest answer is that the amount is largely set before the choice of route is made. Three things bound it: how much fat is present under the skin, where that fat sits, and what the skin over it does once the fat beneath it is reduced.

How much fat is there, and where

Fat that can be reached is fat between the skin and the muscle. Fat inside the abdomen, around the organs, is not reached by either route and is not affected by either. This is the single most consequential finding in an assessment, because a patient whose fullness is largely internal is a patient for whom neither route changes the shape they dislike, however much fat is taken from the surface.

What the skin will do

Skin that returns quickly when it is released will follow a smaller contour. Skin that has lost that quality will not, and may crease or hang. This is a limit on the result rather than a complication of it, and it applies equally to both routes. A patient whose skin is loose over the area is a patient whose change is smaller than the amount of fat removed would suggest, and no plan can borrow elasticity the skin no longer has.

The answer to how much is a range, not a number

An assessment can say that an area will change, and roughly in what direction, but it cannot promise an amount or a shape. Any figure quoted before an examination is a sales figure. The honest statement is that the change is bounded by the fat available, the skin over it and how you heal.

Neither route is a weight-loss treatment

Both routes change the shape of an area by reducing the fat cells in it. Neither is intended to reduce body weight, and neither improves the health problems associated with excess weight. Body weight may move a little, and that is not the point. A patient whose goal is weight rather than contour is describing a different plan with a different specialist, and the two plans are not interchangeable. That distinction matters more than any other in this comparison, because it decides which plan you are being offered.

When the question is the wrong one

  • The goal is a number on the scale rather than a change in how an area looks.
  • Weight has changed recently, or is expected to change soon.
  • The fullness is central and firm rather than soft and pinchable under the skin.

The question worth asking is not how much can be removed, but how much of what you dislike is reachable and how the skin will behave once it is gone. That answer, given honestly, is worth more than a number, and it is the answer an assessment is arranged to produce.

Related reading

Frequently asked questions

Does the amount of fat removed decide the change in my shape?

Only partly. The change is bounded by how much fat is reachable under the skin, where it sits, and what the skin over it does once the fat is reduced. Fat inside the abdomen is not reachable by either route, so a patient whose fullness is largely internal sees less change than the amount removed would suggest.

Can either option give me a flatter stomach if the fat is inside?

No. Fat inside the abdomen sits behind the muscle wall, and neither an operation nor a device course reaches it. An assessment can tell the difference by examining the area: fat under the skin is soft and pinchable, while fat inside the abdomen gives a firm, central fullness that does not move with the skin. That finding decides whether either route is relevant.

Why can no one tell me exactly how much will change?

Because the result depends on your skin, on how you heal and on how much of the fat is reachable, and none of those can be measured precisely in advance. An assessment can say that an area will change, and in what direction. A specific amount or shape quoted before an examination is a sales figure rather than a clinical one.

Risks & Limitations

  • Neither route tightens skin. Removing fat from skin that has already stretched can leave an area smaller and looser at the same time, and that is the commonest source of disappointment on both sides.
  • Neither route is a weight-loss treatment, and neither improves the health problems associated with excess weight. Weight that is still changing is a reason to wait rather than a reason to remove more fat.
  • An operation carries anaesthetic and surgical risk: bleeding, infection, collections of fluid, delayed healing, and contour irregularities such as a dip or a ridge where fat was taken unevenly.
  • A clot in the leg or the lung is a rare and serious complication of any operation. Compression, early movement and honest patient selection reduce it, and it is a medical emergency rather than a follow-up appointment.
  • Fat inside the abdomen is not reachable by either route, and no cosmetic fat treatment reduces it. A firm, central fullness that does not pinch with the skin is a different problem from the one these routes treat.
  • Numbness over a treated area is common on both routes. It usually settles over weeks to months, and after an operation it may not resolve completely, particularly over a large area.
  • A device course produces a modest change built over several sessions. It is not a smaller version of an operation and it cannot produce the same scale of result, whatever the number of sessions.
  • Revision of a contour is a further operation on tissue that has already been thinned. It carries added risk rather than removing the risk of the first operation.
  • No outcome can be promised on either route, and the result is judged once swelling has settled rather than in the first weeks. How much changes depends on the fat available, the skin over it and how you heal.

When to Seek Care

  • A swollen and painful calf, sudden shortness of breath or chest pain — a clot in the leg or the lung is a medical emergency, so seek emergency care immediately.
  • Fever with spreading redness, warmth or discharge from a wound.
  • Bleeding that does not stop with gentle pressure, or a wound that opens.
  • Pain that is worsening rather than settling, or swelling that increases on one side.
  • Skin over a treated area turning pale, dusky or painful after a device session — contact the treating team the same day.
  • A contour that changes suddenly, or a firm and tender area under the skin.

References & Further Reading

  • American Society of Plastic Surgeons (ASPS) — body contouring and surgical safety guidance
  • International Society of Aesthetic Plastic Surgery (ISAPS) — global standards of practice
  • National Institute for Health and Care Excellence (NICE, UK) — relevant clinical guidance
  • Cochrane Library — systematic reviews in surgery and non-surgical body contouring

Medically reviewed by Tongchun Mao, MD (毛彤春), Deputy Director & Head of Aesthetic Surgery. Last reviewed: 19 September 2026.

This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.