Getting a surgery like that, teaches you nothing about how to LIVE a healthy lifestyle. Meaning, you're going to get the surgery, but not know how to eat and live healthy. Which means you're just going to put the weight back on.
Depending on the surgeon's professional ability and experience, some negative effects of liposuction are that your body may not look symmetrical in some of the areas where the fat cells were removed, after recovery when everything has healed. If you are really planning on getting any type of fat-reduction surgery, you must start now on changing your lifestyle. You must have a healthy routine situated so that the transition after surgery will not be too drastic and will help keep you looking and feeling beautiful.
The negative medical effects could include infection, shock, scarring, aesthetic abnormalities, extended recovery time, numbness, nerve damage and difficulty with wound healing to name a few. It's a personal choice that works well for some and not so great for others.