There are some patients who seek out plastic surgery as a desperate attempt to look better without having to address the fact that they need to lose weight. While I do not believe that you need to be at your ideal weight for a cosmetic procedure, you do need to be reasonably close to it.
Not everyone wants to be skinny, and in fact the height and weight charts that are out there are often unrealistic and difficult to apply to everyone. Some people are naturally thicker, and look well at higher weights. My general rule of thumb is that if you are within 20lbs of your desired weight, it is reasonable to consider plastic surgery. There are, however, limits.
The BMI, or Body Mass Index, is a quick calculation based upon your height and weight ((weight in pounds / height in inches x height in inches)x 703). In my office, we do not offer surgery if your BMI is over 35. This is due to an increased risk of complications from surgery at this higher number, as well as a less than optimal cosmetic result.
Patients are often disappointed when I tell them to lose weight before plastic surgery. When I explain to them that it is for their own safety and long term cosmetic benefit, some of them realize that I am trying to help. I obviously do not make money by saying no. Unfortunately, some doctors here, and many overseas, do not care about your weight and will do whatever you like if you have the money. I urge you to not let this happen. Please ask them if your weight adds any additional risk, or if losing weight after surgery will alter your result. If they say no, run.