The Gastric Bypass Diet

These dietary guidelines are designed for gastric bypass patients who are preparing before and after surgery. Following these guidelines can help you decide what to eat on each diet stage, lose weight, and keep weight off in the long-term.

Diet plan before gastric bypass surgery

Before the surgery, your surgeon may request you to lose about ten percent of your body weight. Lose weight before surgery may help you reduce the risks involved during the laparoscopic gastric bypass procedure. Be physically active, plan before you eat, and monitor daily food intake can help you keep track with your weight loss goals.

2 Weeks Before Surgery

For about two weeks before surgery, your daily intake may involve fluids only. Follow your doctor’s instructions to maximize your pre-surgical weight loss results.

  • Stay hydrated and drink at least 8 cups (64 oz.) of fluids daily
  • Try to meet your daily protein goal (at least 60 grams/day)
  • You may include protein-enrich beverages, as part of your daily diet. Simple recipe to make protein shake: mix 1 serving of protein powder with 6-8 oz. of water, nonfat milk, or nonfat yogurt. There are many different types of protein powder; some of them are made from whey, egg whites, and vegetables. Choose products that contain high in protein, low in carbohydrate, low in fat, and low in calories
  • Cut back on soda, alcoholic, sugary beverages and foods

Fluid Examples

Water: drinking, spring, no-calorie flavored, and no-calorie vitamin-enrich water

Clear juices without the pulp such as no-sugar added apple juice

Decaffeinated teas and coffees

Crystal light

Sugar-Free gelatin (i.e. Jell-O)

Sugar-free low-calorie popsicles

Sugar-free pudding

Nonfat milk, nonfat yogurt, nonfat lactose-free milk

Protein shakes

Low-calorie vegetable soups without the chunks such as tomato puree soup

Low-sodium chicken, beef, and vegetable stock

Diet plan after gastric bypass surgery

Follow your surgeon’s instructions to reduce risks related to post-operative complications. Consult with your doctor and ask approval before progressing to the next diet stage. Make sure to follow up with your doctor regularly.

Clear Liquid Diet

Weeks 1-2 or until the initial post-operative doctor's visit

After the surgery, your stomach needs to rest and heal. Consume only sugar-free clear fluids for first couple weeks.

  • Follow your doctor’s instructions
  • Stay hydrated. Try to drink at least 64 oz. of fluids daily (about 8 cups)
  • Do not drink sugary, alcoholic, and carbonated beverages
  • Clear protein supplements can help you to meet your daily protein goal
  • Substitute caffeinated teas and coffees with decaf version
  • Drink slowly, in small sips, and rest for a minute before continue (don’t use a straw. Instead, use 1 oz. medicine cup or mini paper cup)

Examples of a Clear Liquid

Water: spring, bottled, no-sugar flavored water, no-sugar electrolyte water

Decaf tea and coffee

Crystal light

Sugar-free low-calorie popsicles

Clear broth without chunks such as low-sodium chicken, vegetables, and beef stock

Clear protein supplement

Full Liquid Diet

Weeks 3-4

On this stage, you have a little more flexibility on what you can consume, but your intake should be liquid to smooth puree consistency. Choose sugar-free, low-fat, low-carbs, low-calorie, high-protein foods and beverages.

  • Sip and eat slowly. Stop if you feel full
  • Do not drink sugary, carbonated, or alcoholic beverages
  • Try to meet your daily protein goal (at least 60 grams daily). Protein helps to build lean muscles and curb your hunger longer
  • Choose protein supplements that are high in protein, low in carbohydrate, low in fat, and low in calories
  • Take vitamins and mineral supplements as directed by your doctor or dietitian

Examples of a Full Liquid

All fluids listed on clear liquid stage

Strained canned tomato soup

Sugar-free and fat-free pudding

No sugar added applesauce – can be diluted with water (50/50 ratio)

Crystal light

Nonfat yogurt

Nonfat milk or nonfat lactose-free milk

Low-calorie soy milk

Whey protein or vegetable-base protein powder mixed with water or nonfat milk

Pureed / Soft Foods

Weeks 5-8

During this stage, soft foods are introduced. While adjusting to soft food, you can blenderize lean meats, seafood, cook vegetables, and any other good protein sources.

  • Eat small meals three times daily
  • Drink at least 64 oz. (about 8 cups) of water daily
  • Do not eat raw food on this stage
  • Cook the foods thoroughly until tender
  • Choose low-fat and low-carb meals
  • Prioritize on food that are rich in protein, including fish and soy products
  • Your protein goal is at least 60 grams/day
  • Try to cook with as little oil as possible. You can boil, steam, bake, or grill
  • Limit on starchy food such as potatoes
  • Do not eat fried foods
  • Eat slowly, chew thoroughly, and stop eating once you feel full
  • Take vitamins and mineral supplements as directed by your doctor or dietitian
  • Self-monitor your intake by creating weekly food logs/diary

Examples of Pureed / Soft Food

Blenderized cooked chicken, turkey, fish, beef, beans, fruits, and vegetables

97% fat-free ground beef

Low-fat cottage cheese

Mashed potatoes

Baked beans

Scrambled egg

Canned tuna in water

Canned chicken breast in water

Cooked spinach

Slow-cooked chicken stew

Meat stew

Chopped/blenderized soft mushrooms (cooked)

Regular Foods

Week 9+

Serve food in a mini bite size, chew thoroughly and swallow your food slowly. Do not drink at least 30 minutes before and after you eat. Now you can introduce new low-fat, low-carb, low-sugar, and high-protein foods, one at a time.

  • Stop eating right away once you feel full. Overeating can cause severe gastric pain
  • Consume high protein foods such as lean meat, fish, and soy products
  • Your daily protein goal is at least 60 grams daily
  • Take vitamins and mineral supplements as directed by your physician
  • Avoid sugary food, fried food, and empty calorie food (high in calorie but has no nutritional value such as sugary cookies)
  • Eat bread, pasta, rice, or any source of starches in moderation
  • Avoid, chips, pretzels, popcorn, crunchy cereal
  • Raw vegetables and nuts sometimes can lead to gastric discomfort. If you are planning to eat raw vegetables, choose low fiber (i.e. beets, eggplants, zucchini) and chopped vegetables
  • Cooking the vegetables and chew thoroughly can help to ease the digestion
  • Record and monitor your daily food intake in a journal/diary

Examples of Regular Foods

Grilled, baked, or steamed fish

Grilled, baked, or steamed chicken

Cucumber slices

Apple slices

Cooked baby carrots

Cooked spinach

Lean ground beef

Chicken breast sandwich

Grilled eggplant (cut in cubes)

Lean beefsteak

Cooked beet cubes

Boiled egg

Salad with low-calorie mayo or vinaigrette

Behavioral modification for gastric bypass diet

Below are few tips to healthier eating habits. Consult with your doctor about the appropriate exercise plan that can boost your weight loss results and stay fit in the long run.

  • Eat meals slowly and chew thoroughly. Chew food at least 25 times for each bite. Swallowing food too early can block the opening pouch that may lead to severe gastric discomfort.
  • Use small plates to hold your meals
  • Take small bites. Use a baby spoon or chopsticks to help you portion control your food intake.
  • Eat sitting down at the table. Do not do other activities while eating such as watching TV, running, or reading a book.
  • Measure your food in 1 oz. medicine cup.
  • Drink no-calorie or low-calorie fluids throughout the day. Your daily fluid goal is at least 64 oz. or about 8 glasses (in 8 oz. cup) of fluids.
  • Introduce healthy new foods one at a time.
  • Food intolerance may vary with each patient. Foods that may be difficult to tolerate are beef, chicken, turkey, corn, celery, bread, lettuce, spicy foods, and fried foods.
  • Monitor and record your food intake in a food diary can help to track your weight loss progress.
Frequently Asked Bariatric Questions Icon

Frequently Asked Questions About Gastric Bypass Diet

After surgery, a portion of your small intestine is bypassed. Thus, your body may not be able to absorb sufficient nutrients from your meals. Follow your doctor’s vitamins and mineral supplements recommendations to lower the chance of nutrient deficiency.

Dumping syndrome is one of the symptoms occur after the gastric surgery. Unlike protein, foods that are high in sugar, carbs, and fat, travel rapidly to your stomach. However, your new stomach is smaller than before. Thus, the foods dump too quickly into the small intestine. Some indications of the symptom include nausea, vomiting, dizziness, and diarrhea.

Your physician or dietitian will assist you on exactly how much calories you are allowed to eat.

“Empty” calorie food refers to food that is high in calorie (high in sugar, fat, and carbs) content but does not give beneficial nutrient values. Some examples are sugary cookies, sodas, caramel sauce, and frosting.

It is recommended to eat only at the dinner table without doing other activities such as reading, texting, or watching TV.

Water helps to maintain the appropriate levels of fluid in your body and replace the losses from weight loss and daily activities. Drinking not enough water can lead to a headache, muscle cramps, dehydration, organ failure, and constipation.