The pre-operative diet is a mandatory, temporary change in eating habits that patients must follow before gastric sleeve surgery. Adhering strictly to these guidelines helps prepare the body for the physical demands of the operation and the permanent changes to the digestive system that follow. The diet acts as a transition, beginning the process of lifestyle modification necessary for long-term success after the surgery. This article will guide you through the dietary changes you must make in the weeks leading up to your operation.
The Critical Purpose of the Pre-Surgical Diet
The primary goal of the pre-surgical diet is to reduce the size of the liver, which is often enlarged due to fat storage. The low-calorie and low-carbohydrate nature of the diet forces the body to use stored fat and glycogen, leading to a reduction in the liver’s volume and density. This “liver shrinkage” is a safety measure because the liver is located directly over the stomach, and a smaller, softer liver is easier for the surgeon to lift and move. A more accessible surgical site minimizes the risk of complications and makes the laparoscopic procedure technically easier to perform. Failure to adequately reduce the liver size can compromise the surgeon’s visibility and access, potentially leading to the postponement or cancellation of the surgery.
Detailed Nutritional Requirements
The pre-operative diet is high in protein, low in calories, low in carbohydrates, and low in fat. Calorie intake is often restricted to 800 to 1,200 calories per day; reducing carbohydrates and fats triggers the body to deplete its glycogen and fat stores, thereby shrinking the liver. Protein is the central focus, with a typical goal of 60 to 80 grams per day to preserve lean muscle mass, aid in tissue repair, and promote proper wound healing after the operation. Acceptable sources include lean proteins like skinless chicken, turkey, fish, eggs, and specialized protein shakes. Foods to be avoided include sugary items, processed foods, fried items, and simple carbohydrates like bread, pasta, and rice, which would quickly replenish the liver’s glycogen stores.
The Phased Approach to Diet Transition
The pre-surgical diet typically lasts two to four weeks, moving through phases of restriction.
Initial Phase (Whole Foods)
The initial phase, which may begin two to three weeks before surgery, focuses on a modified whole-food diet. Patients are instructed to reduce portion sizes and eliminate simple carbohydrates and high-fat foods, while prioritizing lean protein and non-starchy vegetables.
Full Liquid Diet
The next stage, often starting one to two weeks before the procedure, transitions to a full liquid diet. This phase relies heavily on high-protein, low-carbohydrate meal replacement shakes, along with broth and sugar-free beverages. This accustoms the digestive system to an all-liquid intake.
Clear Liquid Diet
The final stage, usually 24 to 48 hours before surgery, requires a shift to a clear liquid diet. Only transparent liquids are allowed, such as water, clear broth, sugar-free gelatin, and sugar-free popsicles. This limitation ensures the stomach is empty for the procedure, and the exact timing and duration of this phase are determined by the surgical team.
Hydration and Supplementation Guidelines
Proper hydration is necessary during the pre-operative period, with a minimum goal of drinking 64 ounces of fluid daily. Acceptable fluids include water, sugar-free flavored water, and decaffeinated tea, but all carbonated and sugary beverages must be avoided. Protein supplements become the main source of nutrition during the liquid phases, providing the necessary high-protein, low-carb composition. Patients are instructed to begin taking a bariatric-specific multivitamin and calcium supplements in the weeks leading up to surgery to establish a routine for post-operative life. It is also necessary to stop taking certain medications, such as non-steroidal anti-inflammatory drugs (NSAIDs) and blood thinners, before the procedure to minimize the risk of bleeding.