Gastric sleeve surgery is a clinically proven method for reducing body weight, involving decreasing stomach size by separating the fundus (upper part of the stomach) from the rest of the organ. The remaining "sleeve" is about 15% of the stomach’s original volume, reducing appetite and aiding in long-term weight control. The effectiveness of this surgery heavily relies on both pre- and post-operative diets, which are essential for recovery, weight loss, and maintaining a healthy lifestyle. To ensure long-term postoperative success, patients must adopt comprehensive lifestyle changes.
Pre-Operative Diet: Preparing for Surgery
The pre-op diet is a food-consumption plan for the period leading up to the gastric sleeve procedure. In many cases, it should begin three weeks before the procedure. It makes the procedure safer and easier and lowers the risk of complications. It also starts you on the habits you’ll need to make a lifelong commitment to weight control. A main, presurgery dietary goal is shrinking your liver. If you’re obese, your liver most likely has an accumulation of fat cells both in and around it. This makes it larger than it should be. Reducing liver volume makes the surgery safer and easier for the doctor. Key components include:
- Reducing Calories: Especially carbohydrates, which are a major source of calories in most diets. Refined sugars, like those in candy and soft drinks, should be eliminated.
- Maximizing Protein Intake: Aim for 60 or more grams of protein daily.
- Focusing on Healthy Fats: Found in foods like fish, nuts, and olives.
- Staying Hydrated: Drink plenty of water in the weeks before the procedure.
Two or three days before surgery, switch to an all-liquid diet of water, broth, gelatins, and low-calorie sports drinks (no sodas). Consumption should be cut out entirely starting at midnight on the day of surgery - even water. Certain medications must also be discontinued prior to surgery.
Post-Operative Diet: A Phased Approach to Recovery and Weight Loss
Following gastric bypass surgery, a staged approach to diet is crucial to help ease back into eating solid foods, with the speed of progression depending on individual healing and adjustment. The post-op diet is essential if you want to realize the benefits of a bariatric procedure. It will also help you avoid potential health complications, including diarrhea, nausea, vomiting, constipation, and gastric leaks.
Phase 1: Clear Liquids (First Week)
For the first day or so after surgery, you'll only be allowed to drink clear liquids, such as water, clear broth, decaffeinated beverages, and sugar-free drink mixes. Sip liquids between meals, not with meals.
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Phase 2: Full Liquids (Second Week)
The second week will see the addition of thicker liquids to your post-op diet. After about a week of tolerating liquids, you can begin to eat strained and blended, or mashed up, foods. Full liquids are foods that are normally liquid and foods that turn into liquid when they are at room temperature. Examples include:
- Sugar-free nutrition shakes
- Instant breakfast drinks
- Shakes made with protein powder
- Thin broth and cream-based soups (no chunks)
- Unsweetened milk
- Sugar-free pudding
- Lite yogurt (no fruit chunks)
- Other blended strained soups
Drink six 8 oz glasses of water each day, taking 5 to 15 minutes to drink 1 oz. Do not wait 30 minutes before or after meal to drink fluids; sip throughout the day. It is important to stop eating when you are full! Start taking vitamin and mineral supplements after your 1 week follow-up visit, as ordered. Follow all of the "Lifestyle Changes."
Phase 3: Pureed Foods (Weeks 3-4)
After a few weeks of pureed foods, and with your doctor's OK, you can add soft foods to your diet. You can eat 3 to 6 small meals a day, each consisting of 4 to 6 tablespoons of food. Any low-fat, sugar-free food that you can puree, including lean protein sources and nonfibrous vegetables, are acceptable. Examples include:
- Jarred baby foods
- Silken tofu
- Cooked, pureed white fish
- Soft-scrambled or soft-boiled eggs
- Soup
- Cottage cheese
- Canned fruit in juice
- Mashed bananas or very ripe mango
- Hummus
- Pureed or mashed avocado
- Plain Greek yogurt
Phase 4: Soft Foods (Weeks 5-8)
After a few weeks of pureed foods, and with your doctor's OK, you can add soft foods to your diet. You can eat 3 to 5 small meals a day, each meal consisting of one-third to one-half cup of food. Chew foods to a pureed consistency (chew 20 to 30 times before swallowing). Slowly add soft foods to your meals and snacks. Take 30 minutes to eat. Eat 3 milk snacks per day and 3 soft food meals. Drink six 8 oz glasses of water each day, working up to eight 8oz glasses. Stop eating when you are full! Take vitamin and mineral supplements as ordered. Start doing strength-building exercise in your daily routine, such as strength and aerobics for 60 minutes each day. Examples include:
- Chicken (crockpot tender)
- Ground turkey or pork
- 90% lean ground beef
- Salmon, Tilapia, Tuna
- Eggs
- Refried Beans
- Sweet potato
- Carrots
- Cauliflower
- Potato
- Green Beans
- Cream of Wheat
- Black beans
- Peaches
- Broccoli
- Brown Rice
Phase 5: Solid Foods (8 Weeks and Beyond)
After about eight weeks on the gastric bypass diet, you can gradually return to eating firmer foods. Start with eating three meals a day, with each meal consisting of 1 to 1-1/2 cups of food. Depending on how you tolerate solid food, you may be able to vary the number of meals and amount of food at each meal. Try new foods one at a time. At this point most patients are able to eat basically the same stuff that people in their family are eating. It is just asked them to eat healthier and smaller portions. You need to:
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- Chew food to pureed consistency (chew 20 to 30 times before swallowing).
- Eat lean foods, such as baked, broiled, grilled, or steamed foods.
- Drink eight 8-oz glasses of water each day.
- Take vitamin and mineral supplements as ordered.
- Keep doing strength and aerobic exercise for 60 minutes or more each day.
Long-Term Dietary Guidelines: Maintaining Weight Loss and Health
After surgery, it's important to get adequate nourishment while keeping your weight-loss goals on track. Weight loss surgery physically alters the stomach size, reducing the amount of food it can hold. While it may seem that weight loss is automatic after gastric sleeve surgery, it is essential to remember that the stomach is elastic. After having gastric sleeve surgery, the patient’s diet should eventually include all of the items in a balanced meal plan, although it will have fewer calories to encourage weight loss. Initially, the patient will be on a high-protein, very low-calorie diet. Over time, as the stomach heals, calories and variety will increase.
Important Eating Habits
- Eat and drink slowly: To avoid dumping syndrome, take at least 30 minutes to eat your meals and 30 to 60 minutes to drink 1 cup of liquid.
- Keep meals small: Eat several small meals a day. You might start with six small meals a day, then move to four meals and finally, when following a regular diet, three meals a day.
- Drink liquids between meals: To avoid dehydration, you'll need to drink at least 8 cups (1.9 liters) of fluids a day. Do not drink fluids 30 minutes before meals, with meals, or for 30 minutes after meals.
- Chew food thoroughly: The new opening that leads from your stomach into your small intestine is very narrow and can be blocked by larger pieces of food. Blockages prevent food from leaving your stomach and can cause vomiting, nausea and abdominal pain.
- Focus on high-protein foods: Your goal should be a minimum of 65 to 75 grams of protein a day. High-protein foods include eggs, meats, fish, seafood, tuna, poultry, soy milk, tofu, cottage cheese, yogurt and other milk products.
- Avoid foods that are high in fat and sugar: Also avoid processed foods and sugar-added products.
- Take recommended vitamin and mineral supplements: After surgery your body won't be able to absorb enough nutrients from your food. You must take the following supplements on a daily basis to prevent nutrient deficiencies. Please remember that all pills must be crushed or cut into six to eight small pieces. Brands that contain this formula include Trader Joe’s and Centrum Adult chewable multivitamins. Take 1,200 to 2,000 mg of calcium daily to prevent calcium deficiency and bone disease. To enhance absorption, take the calcium in two to three divided doses throughout the day - for example, a 500 to 600 mg supplement taken three times a day. This total amount should be taken in divided doses of 400 to 500 IUs twice a day. Vitamin D should be taken with your calcium supplement. Take 500 mcg of vitamin B daily. Some patients need additional folic acid or iron supplements, particularly women who are still menstruating.
- Eat 3 meals a day.
- Eat protein and a carbohydrate choice at each meal.
- Eat your protein first.
- Take 30 minutes to eat your meal.
- Chew your food to a pureed/mush consistency. This takes 20 to 30 chews.
- Eat nutrient-dense foods such as vegetables, whole grains, fruits, and lean meats.
- Do not eat calorie-dense foods such as chips, cookies, crackers, ice cream, fried food, candy, hot dogs, brats, and bologna.
- Do not eat non-nutrient-dense foods such as pretzels, rice cakes, and animal crackers.
- Eat 3 milk snacks each day.
Foods and Beverages to Avoid
- Sugar-sweetened beverages: Avoid sugar-sweetened beverages, as they are concentrated sources of sugar and calories that pass through the stomach quickly.
- Carbonated beverages: Carbonated drinks should also be avoided because carbonation takes up stomach space, reducing the amount of high-quality, whole foods that can be eaten. Carbonation can cause stomach pain.
- Alcohol: Alcohol is absorbed more quickly into the blood stream after surgery, and bariatric surgery patients will have higher levels of alcohol in their system for a longer period of time after drinking compared to before surgery.
- Citric acid: Do not drink anything with citric acid.
- Tobacco or nicotine products: Do not use tobacco or nicotine products. It slows down healing and can lead to complications.
- Straws: Do not use straws. Air bubbles form in your new pouch and can cause pain.
- Acidic or citrus foods: The first 3 months after surgery, do not eat acidic or citrus foods such as tomatoes, lemon, orange, or lime.
Portion Control
- Measure portions: There are two ways to measure portions or measure food. The second way is to use a food scale and measure the weight of the food.
- Small portions immediately after surgery: Immediately after surgery, the patient should follow the meal plan provided by the surgeon. Usually, this involves starting with a liquid diet, moving to pureed or soft foods, and then advancing to solid foods. After the transition to solid foods has been made and the patient has been cleared to liberalize their diet, portion sizes will still be quite small: 1/4 to 1/2 cup per meal or two to four ounces of food if food is weighed.
- Increasing portions six months post-op: Six months after surgery, food portions increase slightly.
- Long-term portion sizes: One year post-op, the patient’s portion sizes increase to what they will remain for the long term - usually 1 to 1 1/2 cups or 8 to 12 oz of food. The patient will focus on eating adequate protein and including fiber, vegetables, and fruit in their meals.
Importance of Fiber, Carbohydrates, and Fats
- Fiber: Fiber helps the patient’s digestive system work properly and keeps the microbiome healthy. At six months post-op, increased fiber is usually included in the patient’s meal plan.
- Carbohydrates: Carbohydrates provide energy, so it is important to include them in the post-op meal plan. Fruits and vegetables are optimal choices.
- Fats: Fats are essential to assist with the absorption of fat-soluble vitamins, and they are required for the body to make hormones. In general, post-op bariatric surgery meals should be low-fat.
Calorie Intake
The number of calories a patient eats varies depending on how far after surgery it has been. Those who are immediately post-op may eat only a couple of hundred calories daily. As the patient starts eating more solid foods, their intake increases to 300 to 600 calories each day. Once the patient reaches the six-month post-op milestone, calorie intake will increase to approximately 1,000 calories daily.
Bariatric Diet Progression
- Today: Low-calorie general diet
- 10 days before surgery: Pre-surgery blended liquid diet (dietitian will tell you what day to start)
- Day of surgery: No food or drink
- Day 1 (in the hospital): Clear liquid diet
- Days 2 to 14 (2 weeks): Full liquid diet
- Days 15 to 30 (until 1 month visit): Pureed diet (very smooth)
- Days 31 to 60 (after 1 month visit): Soft diet
- Days 61 to forever: General diet
Bariatric Surgery Full Liquid Diet
You will be on a full liquid diet days 2 to 14 after your surgery. Full liquids are foods that are normally liquid and foods that turn into liquid when they are at room temperature.
- Drink six 8 oz glasses of water each day. Take 5 to 15 minutes to drink 1 oz.
- Do not wait 30 minutes before or after meal to drink fluids. Sip throughout the day. Stop eating when you are full!
- Start taking vitamin and mineral supplements after your 1 week follow-up visit, as ordered.
- Follow all of the "Lifestyle Changes."
Double Milk Snack Choices - choose 3 per day
- 1 cup fat free Fairlife milk
- 5 to 6 oz Greek yogurt (100 kcal or less)
- 1 cup fat free Fairlife or regular skim milk + 2 tbsp Peanut Butter powder
- 1/2 cup Cottage cheese (fat free or 1%)
- 1 cup skim milk + 1/3 cup non-fat dry milk powder
- 1 cup skim milk + Carnation Instant Breakfast (Light Start or No-Sugar-Added)
- 1/2 protein shake (see table on following page for choices) *can flavor milks with Peanut Butter Powder, sugar-free chocolate syrup or sugar-free hot coco mix
Meal Portion Size:
- Protein:1/4 to 1/3 cup or 2 to 3 oz
- Carbohydrate: 1/4 cup
Full liquid food ideas:
- Sugar- free pudding (make with Fairlife or add collagen protein powder or non-fat dry milk powder for extra protein)
- Cream soups (celery, mushroom, chicken, broccoli, ect.)
- Homemade blended liquid soups (ex. Butternut squash soup, Carrot ginger soup)
- Sugar-free popsicle (limit 1 per day)
- Lite yogurt (no fruit chunks)
- Other blended strained soups
Bariatric Surgery Pureed Diet
You will be on a pureed diet days 15 to 30 after your surgery.
Bariatric Surgery Soft Diet
You will be on a soft diet days 31 to 60 after your surgery. You will start this diet after your 1 month follow-up visit.
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- Chew foods to a pureed consistency (chew 20 to 30 times before swallowing).
- Slowly add soft foods to your meals and snacks.
- Take 30 minutes to eat.
- Eat 3 milk snacks per day and 3 soft food meals.
- Drink six 8 oz glasses of water each day, working up to eight 8oz glasses.
- Stop eating when you are full!
- Take vitamin and mineral supplements as ordered.
- Start doing strength-building exercise in your daily routine, such as strength and aerobics for 60 minutes each day.
Milk Snack Choices - choose 3 per day
- 1 cup skim Fairlife milk
- 5 to 6 oz Greek Yogurt (100 kcal or less)
- 1 cup skim milk
- 1/2 cup Cottage cheese (fat free or 1%)
- 1 lite mozzarella string cheese stick
- 1 cup unsweetened soy milk (or high protein pant-based milk)
- 1/2 cup Fat Free Chocolate Milk (mixed with 1/2 cup skim white milk)
- 1/2 protein shake (see previous page for choices)*Can flavor milks with Peanut Butter Powder, sugar-free chocolate syrup or sugar-free hot coco mix
Meal Portion Size:
- Protein:1/4 to 1/3 cup or 2 to 3 oz
- Vegetable:1 to 2 bites
- Carbohydrate (fruit & starches):1 to 2 bites
Soft Food (Looking for crockpot tender):
- Chicken
- Ground turkey or pork
- 90% lean ground beef
- Salmon, Tilapia, Tuna
- Eggs
- Refried Beans
- Sweet potato
- Carrots
- Cauliflower
- Potato
- Green Beans
- Cream of Wheat
- Black beans
- Peaches
- Broccoli
- Brown Rice
Soft Food Menu Items:
- Breakfast: 1/2 slice of toast with low sugar fruit spread, 2 scrambled eggs, 1 to 2 bites of fruit
- Lunch: 2 to 3 ounces shredded chicken, 1/4 cup green beans, 1 to 2 ounces ground turkey, 1-ounce light cheese, 1/4 cup black beans
- Dinner: 1-ounce light cheese, 1/2 tortilla (6 inch), 2 to 3 ounces salmon, 1/4 cup mixed vegetables, 2 to 3 ounces baked fish, 1/4 cup cooked carrots, 1-2 bites of fruit
Bariatric Surgery General Diet
You will be on a general bariatric diet for the rest of your life starting day 61 after your surgery.
- Chew food to pureed consistency (chew 20 to 30 times before swallowing).
- Eat lean foods, such as baked, broiled, grilled, or steamed foods.
- Drink eight 8-oz glasses of water each day.
- Take vitamin and mineral supplements as ordered.
- Keep doing strength and aerobic exercise for 60 minutes or more each day.
Milk Snack Choices - choose 3 per day
- 1 cup skim Fairlife milk
- 5 to 6 oz Greek yogurt (100 kcal or less)
- 1 cup skim milk
- 1/2 cup Cottage cheese (fat free or 1%)
- 1 lite mozzarella string cheese stick
- 1 cup unsweetened soy milk (or high protein plant-based milk)
- 1/2 cup Fat Free Chocolate milk (mixed with 1/2 cup skim white milk)
- 1/2 protein shake (see previous page for options)* can flavor milk with Peanut Butter Powder.
Potential Complications and How to Avoid Them
The greatest risks of the gastric bypass diet come from not following the diet properly. If you eat too much or eat food that you shouldn't, you could have complications.
- Dumping syndrome: If too much food enters your small intestine quickly, you are likely to experience nausea, vomiting, dizziness, sweating and diarrhea.
- Dehydration: Because you're not supposed to drink fluids with your meals, some people become dehydrated.
- Constipation.
- Blocked opening of your stomach pouch: Food can become lodged at the opening of your stomach pouch, even if you carefully follow the diet. Symptoms of a blocked stomach opening include ongoing nausea, vomiting and abdominal pain.
- Weight gain or failure to lose weight.
The Role of Dietitians
Dietitians play a vital role in the multidisciplinary team before and after bariatric surgery. They can provide guidance on appropriate shake selection, serving size, and thickness determination. The consistency of the liquids will determine how much can comfortably be consumed. Previous studies have shown that adherence to a regular nutritional follow-up contributes to weight reduction postsurgery and prevents weight regain.
Additional Lifestyle Changes
- Exercise: Exercise 30 minutes or more a day. Walking frequently, starting within just a few hours after surgery, can help patients recover faster.
- Keep detailed food and activity records: Keep detailed food and activity records (bubble sheets). Bring them to each dietitian appointment.
- Quit smoking: Patients who have chosen to undergo a major surgical procedure to make themselves healthier need to quit smoking for the rest of their life.
Medication Adjustments
After surgery, patient will often be able to be taken off certain medications or their dosages will be decreased. These decisions will be made with the patient’s primary doctor and their surgeon. Some patients will need different forms of medications if they are taking extended-release drugs, and some will need adjustments in dosages very early after surgery. Changes such as liquid or chewable medications may be needed, and these should be done under the direction of a doctor or pharmacist.
Pregnancy
Female patient should have a birth control plan before surgery and avoid pregnancy for 12 to 18 months after surgery. In order to reach their lowest possible weight and ensure that they have adequate nutrition should they want to become pregnant. In addition, bariatric surgery patients who had problems getting pregnant before can find that they have a much easier time after surgery.
Long-Term Follow-Up
Early after surgery, patients will follow up every few months for the first year. They should have yearly visits with a bariatric specialist for life. These are important visits, since obesity is a chronic disease, and can continue or even return after surgery.