Your Surgeon will have specific pre and post-op diets that he wants you to stick to for very important reasons.
The pre-op diet typically begins 2-3 weeks before your surgery and includes a low calorie (800-1200 per day), low carb, high protein (60-70 grams per day). Then 2-3 days before your scheduled procedure you will begin a liquid only diet with no soda.
The Post-op diet will start with non-carbonated, sugar free clear liquids only for the first week. The second week you will generally be able to add full liquids back in. Week three you will begin a diet of soft foods. And week four you will be back to a regular diet that focuses on healthy choices and protiens.