RNY gastric bypass is a powerful surgical procedure that assists you to achieve rapid and permanent weight loss. Of course, your lifelong commitment to active living along with a healthy diet is necessary for a successful outcome. There are certain things you can’t do after gastric bypass. All patients face some dietary constraints and day-to-day living limitations.

Following your doctor’s recommended diet after bariatric surgery is the most important aspect of post-surgery monitoring. Making the right food choices will help you speed up your weight loss process and making poor choices will usually undermine your weight loss progress. A balanced diet and daily physical activity are a must if you want to get rid of obesity forever.

Limitations to Expect After Gastric Bypass

After your weight loss procedure, you must follow a strict postoperative diet and general lifestyle modifications. Typically, these programs follow a structured regime of what you can and can’t eat as well as physical activity. We advise our patients to start an exercise routine, which will start out slow then increase to include more physically-demanding activities.

Many things may vary after bariatric surgery. Some of which are highly advised and others are surely required. Here are five changes you need to take into consideration after gastric bypass surgery:

  1. Dietary Changes: Due to the malabsorptive component of RNY gastric bypass surgery, the food you eat must be healthy and nutrient-rich. The postoperative diet has the biggest impact on what you can and can’t do after bariatric surgery.
  2. Water Intake: Another critical component following gastric bypass is drinking 64 ounces of water every day. Since your stomach pouch is smaller, you may face difficulty consuming enough water and staying hydrated. A famous phrase in the bariatric community is “sip, sip, sip” meaning drink small amounts of fluids constantly throughout the day until you reach or exceed your 64 oz. goal.
  3. Drugs and Alcohol: An increased rate of addiction or dependence is a real risk for RNY patients. Substance misuse is due to our body’s absorption of anything ingested like chemicals, drugs, or alcohol. It’s essential to talk with your primary care physician about any medication you are taking and any related concerns you have. You can learn more about drinking alcohol after gastric bypass here.
  4. Physical Activity: Staying active is a crucial aspect of life after gastric bypass surgery. A big trap for patients is becoming passive and inactive. Exercising, walking, jogging, riding a bicycle are all life-long ways to stay fit and reach your goal weight.
  5. Psychological Changes: Just as your body changes, your mind can too. You can’t weigh yourself every day or look in the mirror for results. Gastric bypass patients don’t notice small changes to their body weight, so try to limit stepping on the scale every day and only weigh yourself once a week at most. Obesity is a psychological battle that you have to keep your head healthy if you’re going to have lasting results.

Dietary Changes

Depending on your bariatric surgery, supplements can be an important aspect of maintaining a nutritious diet. Here are some off-limit foods you can’t have after gastric bypass surgery. Some of the foods that can push you towards failure are listed below.

Things You Can't Eat After Gastric Bypass Surgery

Things You Can’t Eat After Gastric Bypass

  • High-calorie sweets (cake, ice cream, milkshake)
  • High glycemic foods (rice, pasta, bread)
  • Caffeinated, carbonated drinks (soda, sparkling water)
  • Alcoholic beverages (highly recommended)
  • Pizza
  • Milk
  • Hamburger
  • Bacon
  • Chewing gum
  • Sugar alcohols (erythritol, mannitol, sorbitol, glycerol, xylitol, etc.)
  • Red meat that’s tough or dry
  • Greasy, fatty foods
  • Foods reheated in the microwave
  • Spicy foods and heavily seasoned

Dieting Best Practices: Things You Can’t Do After Gastric Bypass

  • Do Not Eat Quickly: Eat slowly. Take small bites and chew thoroughly – at least 25 times.
  • Avoid Items with Large Amounts of Sugars: Especially those in liquid form. They are filled with non-nutrient calories and slow down weight loss. Consuming high sugar foods can trigger dumping syndrome.
  • Do Not Overeat: Remember the stomach can hold 3-4 oz after surgery. You will probably feel satisfied after 2-3 tablespoons of food. Over time your stomach will stretch. It takes 6-9 months (possibly longer) for your new stomach size to stabilize and allow you to determine your average meal amount.
  • Do Not Eat After You Feel Satisfied: Stop eating when you feel comfortably satisfied. If ignored, vomiting will follow, and you can stretch the size of the stomach. If you cannot keep anything down and have extreme difficulty staying hydrated, sip on Gatorade, which also has electrolytes necessary for normal cell function. Once you feel better, return to non-calorie beverages such as water and flat diet drinks.
  • Do Not Drink Fluids Before/After Meals: Stop drinking liquids 15 minutes before meals and wait 30 minutes after meals.
  • Do Not Introduce New Foods Abruptly: When trying new things, make sure you introduce one at a time to rule out any intolerance. If a food is not tolerated, reintroduce it in 1 week.
  • Do Not Abuse your New Stomach: It’s important to follow diet guidelines and never rush your post-op diet phases by eating solids too soon or overeating!
  • Do Not Drink with a Straw or Chew Gum: The use of straws or chewing gum is not allowed because air gets in your stomach pouch. The risk of painful air pockets in your stomach can cause pain, nausea, and even vomiting. Air also takes up space in your pouch that could be filled with nutrient-rich protein or water.

Things You Can’t Do After Gastric Bypass

The constraints after RNY bypass can be classified into short-term and long-term post-surgery. Short-term consists of immediate limitations up to 6 to 8 weeks following the procedure. Long-term can be anything after 8 weeks that should be incorporated into your new life.

Things You Can’t Do After Gastric Bypass Surgery - Short-Term and Long-Term


  • No carbonated beverages or alcohol for six weeks
  • No heavy lifting or exercise for six weeks (walking is fine and encouraged)
  • No swimming, tub baths, hot tubs, or Jacuzzis for 6 weeks
  • Don’t drive too soon
  • Don’t smoke or use nicotine for at least 30 days post-op


  • No eating unhealthy foods
  • No living sedentary
  • No falling back towards old habits
  • Don’t do too much too soon
  • Follow up with your primary care physician

15 Things I Wish I Knew Before Getting Bariatric Surgery

  1. Your hormones will get out of whack. Men and women. As you lose fat, you release estrogen, creating significant mood swings. It can result in havoc on your system. You might get angry or sad for no reason. You may develop anxiety. You might have depression and/or it might worsen. It WILL get better over time.
  2. Women – your periods will change. If you don’t get them, they may suddenly start. If you were normal before, they might go nuts and happen every two weeks! Some people stop bleeding for a long time. Others never stop. It’s a hormonal thing and yes, it will even out.
  3. Eating will suck at first because you won’t feel satisfied. Feeling full and being satisfied is not the same thing. You will want to eat more but you can’t. It will be hard to adjust, but you WILL adjust.
  4. Taste buds will change. Foods that you loved before will taste different and vice versa.
  5. Hair may or may not fall out. Some people get it badly, others just thin out some. You can take Biotin and other things to help, but you cannot prevent most of the hair loss. It will also even out. Cutting long hair does help because it aids in volume and the new hair blends better.
  6. Relationships may struggle. You will have to take a look at who you are as a person and a couple. You will change and your significant other will have to change as well. Your whole outlook on food and life has to change – and they will either go along with you, or they just won’t be able to take it. Communication is VITAL to keeping love alive and it’s ongoing.
  7. You will lose inches without the pounds. Pay attention to your clothes and not just the scale.
  8. You WILL stall. It happens. Be patient. Drink water.
  9. Some people with loose skin already will only get worse. There is no amount of exercise to prevent it. Some young folks and those with different body types might get lucky. I hope it’s you. If it isn’t, just understand that it isn’t your fault!
  10. Sex will change for you. It might get better (and I hope it does!) It could even hurt due to hormonal changes.
  11. How you see yourself will change. If you have always been the fat one, you will need to get to know yourself again. It’s a process. Accept yourself and these changes.
  12. People will treat you differently – and usually better. This part is hard to take when you realize how real fat shaming is. It should give you a sense of who your real friends are.
  13. You may find yourself judging other fat people for their choices. Stop it.
  14. Find a fitness regimen you love to do and your body will love you for it. Yes, you can lose without a workout, but exercise is vital to maintaining muscle health and toning.
  15. Comparing yourself to others is the best way to fail. You will lose at the pace your body loses and another person’s success does NOT degrade your own. Trust the process and your doctor. Same journey, but different boats, folks.

Most of all – this is not easy. It will NEVER be easy. Nothing worth it ever is.