Doctor Gary A. Vela, M.D., encourages a healthy lifestyle at all times. However, you should be extra careful with what you eat before and after cosmetic surgery as the diet can easily make the difference between a successful operation and a failed one. There is always increased demand for nutrients during and after surgery. Ideally, a patient should start preparing for surgery about a month before the big day. If you are planning to undergo cosmetic surgery, the following diet tips can help you.