Is lipo or cosmetic fat removal bad?

I'm 20lbs overweight.

Yes it is. The body is made to function properly on its own. By having yourself cut open and the fat cut out of your body presents a huge shock to your system. Granted people have it done all the time and survive without any complications, that doesn't make it good. Furthermore, as I am always constantly reminding people of here, muscle weighs 2.94 times as much as fat. If you want to become thinner, work out and convert that fat to muscle. If you want to become lighter, then simply eat properly and do only very light exercises (like a light jog instead of a run, or shadow boxing instead of bench pressing). Also, cut out all snacking.