The big picture concept, and the long-term goal, is to change from "living to eat" to "eating to live”.
Immediately after your surgery, for the first 2 or 3 days, you will be on a sugar-free, clear liquid diet (water, broth, Jell-O, popsicles, unsweetened tea, etc.). Then, you'll advance into sugar-free full liquids (thicker soups without chunks, protein “shakes,” pudding, yogurt, etc.). No carbonation.
For the first two weeks, the most important nutrition goal is hydration. 32 ounces of fluids per day is a minimum. Again, no carbonation.
After two weeks, you gradually introduce solid foods that are low in fat and sugar. Start with softer foods and easy to digest protein sources like tuna, shrimp, egg, deli meats and low-fat dairy. Every person reacts a little differently to the surgery and has to learn by trial and error just how much food and which types of food they can tolerate. Long term, your goal is to eat a variety of healthy foods that are high in nutrition and low in calories. You will strive to have 60-80 grams of protein per day from meat, fish, dairy, vegetarian sources, and/or “protein shakes” or “protein bars,” if they are low-fat, low-sugar. You need to take vitamin and mineral supplements daily. All of your drinks should be non-carbonated and sugar free. You should include fruits, vegetables, and whole-foods, and avoid processed foods with added sugar or fat.