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Getting Started With Your Gastric Bypass Pre-Op Diet

Getting Started With Your Gastric Bypass Pre-Op Diet

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      Every year, over 200,000 bariatric surgery procedures are performed across the United States. Bariatric procedures are considered the most effective long-term solutions to severe obesity and related conditions.

      Although getting approved for gastric bypass surgery can be exciting, it can be a bit scary at the same time. Even before your surgery is completed, you will need to start following a gastric bypass pre-op diet to help better prepare you for surgery.

      Currently, the gastric bypass is the second-most commonly performed bariatric operation in the U.S and in the world. Let’s learn a little about gastric bypass surgery and the changes you will need to make in your eating before surgery.

      What is gastric bypass surgery?

      Gastric bypass surgery, also known as Roux-en-Y, is a procedure that helps produce weight loss in several ways. First, the stomach is formed into a smaller pouch which will ultimately hold less food. Along with this smaller pouch, a portion of the small intestine is split, and a portion of it is connected to the smaller stomach.

      Together, these two alterations in the digestive system allow for digestion of less food and less absorption of calories and nutrients. Your new stomach pouch will only be able to hold about an ounce of food at a time. Not to mention that this rerouting also changes levels of gut hormones that are responsible for hunger and fullness, which ultimately aids in weight loss.

      Why do I have to change my diet before surgery?

      In the months prior to your gastric bypass surgery, some insurance companies will require you to lose a certain amount of weight based on the assumption that pre-op weight loss can help improve blood glucose levels. Some experts have found a connection between hyperglycemia -  high blood glucose levels - before surgery and an increased risk of surgical complications.

      Explaining Gastric Bypass Pre-Op Diet
      Your doctor and bariatric dietitian can support you during your pre-op diet.

      In the weeks leading up to surgery, most people undergoing a gastric bypass may be placed on a pre-op diet focused on reducing the size of the liver and reducing fat in the abdomen. By reducing the size of the liver, you will give your surgeon better access to your stomach and in turn will help reduce complications during surgery.

      In what ways do I have to change my diet before gastric bypass surgery?

      For the pre-op diet months before surgery, this will be a time to learn from health professionals about basic healthy eating guidelines. You will learn how you can make changes in your current eating habits to provide your body with the most nutrients at each meal.

      At the same time, you may learn about ways you can prepare yourself for life after surgery by adopting certain behaviors now such as eating smaller portions at each meal or eating smaller bites.

      For the pre-op diet in the weeks before surgery, you will be asked to reduce calories and carbohydrates in your diet. The low carbohydrate diet seems to be more effective than the low-fat diet in short-term weight loss, improvement in insulin sensitivity, and reducing lipids in the blood before bariatric surgery.

      Depending on your height, weight, and health status, your doctor may recommend different calorie levels for your pre-op diet. On average, you may see recommendations of around 1000 calories a day.

      An example of a meal plan day for the pre-op diet may look like the following:

      Breakfast:  Protein shake (200 calories or less, 20-30 grams protein, less than 5 grams of sugar)

      Morning Snack: 6 ounces of low-sugar, high protein Greek yogurt

      Carrot for pre-op diet
      During the pre-op diet, be sure to consume enough protein.

      Lunch: Protein shake (200 calories or less, 20-30 grams protein, less than 5 grams of sugar)

      Afternoon Snack: 1 cup low-carbohydrate fruit like strawberries or low-carbohydrate vegetables like sliced cucumber or 10-12 baby carrots

      Dinner: 3 to 6 ounces of lean protein like baked or grilled chicken breast or fish with 1 cup non-starchy vegetables or 2 cups garden salad with 2 tablespoons

      Veggies for pre-op diet
      You should only eat non-starchy vegetables on your pre-op diet.

      Evening snack (optional): Protein shake (200 calories or less, 20-30 grams protein, less than 5 grams of sugar)

      If you’re not sure what a non-starchy vegetable is, then just remember that for the most part, it’s any vegetable that is not corn, peas, beans, or potatoes. Here is a short list of some common non-starchy vegetables that you can eat on your pre-op diet before the gastric bypass surgery.

      • Artichoke
      • Asparagus
      • Green beans
      • Brussels sprouts
      • Broccoli
      • Cabbage
      • Carrots
      • Cauliflower
      • Cucumber
      • Collard greens
      • Kale
      • Mushrooms
      • Peppers
      • Radishes
      • Spinach
      • Tomatoes
      Protein shake for pre-op diet
      Protein shakes can help you meet protein needs during your pre-op diet.

      Also, when it comes to lean protein sources, any lean beef, chicken, fish, or other seafood will do. And when it comes to snack options, if you don’t care for yogurt, you can try an ounce or two of cheese, a couple hard-boiled eggs, or a low-sugar, high protein snack bar instead.

      Other gastric bypass pre-op diet tips

      Along with making sure that you’re eating the right foods in appropriate portions on your gastric bypass pre-op diet, there are several other things you should keep in mind.

      Drink plenty of water each day: During the time of your pre-op diet, be sure to drink at least 64 ounces of water each day. This will ensure that you stay hydrated before surgery. Besides water, you can also drink other sugar-free beverages like unsweetened tea, flavored sugar-free water or other beverages, or water infused with low-carbohydrate fruit like lemon slices.

      Practice chewing more per bite: By chewing more per bite, you will slow your pace of eating. Not only is this good for your digestion, but can help you feel fuller with smaller portions of food. This will help you after surgery since you will not be able to tolerate a lot of food at each mealtime.

      Start taking a complete multivitamin:  When you start the pre-op diet before your gastric bypass surgery, you may also be asked to start a daily multivitamin if you haven’t already started. This is important to do since you will eating much smaller portions of food each day after surgery, and in turn you may have trouble consuming enough of the daily recommended vitamins and nutrients in your diet.

      Start taking a complete multivitamin before surgery.

      Not to mention that your body will absorb vitamins and nutrients differently after surgery. Therefore, a daily complete multivitamin will help you fill in any nutritional gaps in your diet and lower your risk of nutrient deficiencies after surgery. And if you’re wondering why you should start taking this vitamin before surgery, the answer is that it will help you become used to taking it in the morning after surgery.

      Start your journey on the right foot by sticking to your pre-op diet

      Gastric bypass surgery is a life-changing procedure that can help many people lose weight and lower their risk of chronic diseases like heart disease and diabetes. It can be exciting to receive approval for this surgery from your doctor, but at the same time it comes with some new responsibilities to keep in mind.

      Along with having a smaller stomach, you will have to make several lifestyle changes after surgery to stay your healthiest. Not to mention, that before surgery you will have to go on a pre-op diet to help shrink your liver and in turn make surgery a safer experience.

      This preparation can ensure that both you and your body is ready for the new life you are about to experience after your gastric bypass surgery.

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        Staci Gulbin, MS, MEd, RD


        Staci has been a registered dietitian with the Commission on Dietetic Registration since 2010 and has over a decade of experience in the nutrition and dietetics industry.

        Gintas Antanavicius, MD, FACS, FASMBS

        Medical Reviewer

        Dr. G is a co-founder of BariBuilder. A US-based expert surgeon with over 10 years of bariatric experience, he regularly publishes research in medical journals like SOARD, Obesity Surgery, etc.