Diet instructions after bariatric surgery


This blog provides free information and dietary advice after bariatric surgery, not intended as a medical consult. Please seek appropriate advice from an accredited practising dietician with specialised interest in bariatric surgery, for an individual assessment, personalised advice, individual tailored management and diet plan.

Remember the key to long term weight loss maintenance is a combination of factors:

(Bariatric surgery)


(Improved dietary habits)

(Proper food choices in controlled portions and good eating habits)


(Regular exercises)


(Behavioural change)


Maintained long term excess weight loss

Improve physical health

Other social benefits


The laparoscopic sleeve gastrectomy helps you lose weight because of the restrictive as well as the hormonal (neuro-endocrine brake) effect.

  1. Reducing the size of your stomach, therefore you feel full after eating a smaller meal portion (restrictive effect).
  2. Reducing the stomach hormone (ghrelin) that makes you feel hungry, therefore you are less hungry between meals (reduced hunger sensation effect).
  3. And feel satisfied for longer periods after meals (post prandial satiation effect).


After bariatric surgery adhering to a new healthier diet, learning proper eating habits and performing regular exercise are paramount to long term sustained weight loss and health improvements. This blog focuses mainly on dietary instructions after surgery and introduce the idea that proper diet combined with exercise is necessary in this crucial period.





Nutrition management post op can be divided into 3 different stages:

Stage one: Immediately post op diet:

  • First 2 weeks: liquid diet or puree diet

Stage two: Adaptation phase diet:

  • Week 2 – 4: soft diet
  • After 1 month: full diet

Stage three: Long term adjustment diet:

  • Long term healthy diet plan

Progressing through each stage varies between individuals and depends on your tolerance of food.
In all the stages it is important to:

  • Have small meals
  • Chew your food well
  • Eat slowly
  • Stop eating when you feel full

The long-term goal is to develop and maintain a life-long healthy dietary habit:

  • Select a healthy combination of food (good food choices)
  • Avoid large meals, overeating or regular snacking (correct food portions)
  • Avoid fast eating of large meals (avoid compulsive or binge eating behaviour)





Stage One: Immediately post op

To begin with, the amount of soft food that can be eaten is very small and you may also experience dumping syndrome (eg. abdominal cramps, nausea, diarrhoea, dizzy, faint) after meals especially with high GI index foods (ie. foods with high sugar content).

The nutrition aims at this stage are:

  • Simple fluids for 1-2 weeks (to avoid the undesirable effects described above)
  • Have adequate fluid intake (to avoid dehydration)
  • Have adequate protein intake (to prevent lean body muscle mass loss)
  • Have some vitamin and mineral supplements (usually comes from the VLCD drinks)


Liquid and Puree Diet:

  1. Liquid diet:You may have fluids for the 2 weeks after the operation.
  • These include: water, cordial, soup, jelly, fruit Juice (limited), milk, custard, tea coffee
  • Eat and drink very slowly and stop when you feel full
  1. Puree Diet: If you tolerate the fluid dietprogress to a puree diet.
  • Everything you eat needs to be of a smooth pureed (blended) consistency
  • Some patients continue with puree diet for 2 to 4 weeks

You will need a food processor as all your meals need to be of a smooth pureed consistency

You will not be hungry and you feel full with a small amount of food, thus blend only a small amount to begin with

You will need to have protein foods first and then include other food groups

On a daily basis, it is important to have enough fluids, take a liquid multivitamin and eat small frequent meals that include protein sources (see protein section).

  1. Drink adequate fluids:

Fluids are important in preventing dehydration and also help keep your bowels regular

  • Drink at least 1 – 1.5 L per day
  • Drink small amounts of fluid at a time throughout the day: SIP SIP SIP
  • Avoid using straws and avoid gulping fluids – this will cause pain and discomfort
  • Fluids may include: Water, diet cordial, low fat milk, juice (no added suger) and soup
  1. Vitamins and Minerals:

As you can only take small amounts of food make sure you have good vitamin and mineral replacement as well

  1. Protein: 
  • You need 50-60 grams of protein per day to meet your daily requirements
  • Good sources of protein include: meat, fish, chicken, eggs, legumes and low fat dairy products
  • Eat the protein foods first at each meal
  • Most patients have 1-2 meals replacements (Optifast) as they are high in protein

Puree Diet 

  • You will not be able to drink all the meal replacement/protein drink/Optifast in one go
  • Drink it over a longer period of time, sipping on it slowly and stop when feeling full


  • SIP SIP SIP on water during the day
  • Aim for 1-1½litres of fluid per day
  • Do not eat and drink at the same time – drink your fluid 15 minutes before and 30 minutes after your meals
  • Avoid carbonated “fizzy” drinks, cordials, and juices

To avoid gut symptoms at this stage post operatively

  • Eat and drink very slowly
  • Chew your food well to ensure a smooth consistency
  • Do not eat and drink at the same time
  • Stop when you feel full





Stage Two: Adaptation phase

By 4 weeks after surgery you may be able to tolerate soft foods

Only progress to soft food if you tolerated the puree diet

It is still important to eat slowly and chew your food well

Continue to have small meals and eat your protein sources first

You may still include meal replacements such as Optifast at this stage


Soft Diet

Group 1 Breads and Cereals

  • Quick/instant porridge or semolina or Weet-bix™ (soaked in low fat milk)
  • Spaghetti or noodles or rice (well cooked) or Couscous
  • Avoid fresh or soft white bread

Group 2         Fruit and Vegetables

  • Soft ripe, tinned or stewed fruit (with no added sugar)
  • Soft cooked vegetables
  • Avoid stringy fruit, fruit skins and raw vegetables

Group 3 Dairy Products   (3 serves daily)

  • Skim or low fat milk  (maximum 250 ml per day – including tea/coffee)
  • Low fat or calorie reduced yoghurt  (1 tub of 200 grams per day)
  • 1 Slice of low fat cheese
  • Avoid ice cream, milkshakes and flavoured milks

Group 4 Meat, Fish, Poultry, Eggs, Legumes   (2 serves daily, 1 serve = 50 grams)

  • Eggs – try scrambled or poached
  • Lean minced meat (lamb, pork, veal, chicken), add to casseroles and mornays
  • Soft, marinated fish, canned Tuna/Salmon
  • Well cooked beans and legumes – try adding to soups and casseroles
  • Avoid fatty or fried meats

Continue to sip on fluids, do not eat and drink at the same time, eat and drink slowly, chew your food well, and stop when you feel full.





Stage three: Long term dietary plan 

By 6 – 8 weeks after surgery you should be able to eat normal solid foods

It is still important to eat slowly and chew your food well

Continue to have small meals and consume your protein sources first

Losing adequate weight and maintaining this weight loss long term will depend on:

  • Avoid snacking and grazing – aim for 3 meals per day
  • Have a healthy meal plan  (including lean meats and using low fat cooking methods, including fruits and vegetables daily, choosing low fat dairy items and avoiding high calorie dense foods)
  • Last but not least: Regular exercises


Solid Diet

Group 1: Breads and Cereals (2-3 serves/daily)

  • Breakfast cereals – aim for a high fibre, low sugar content
  • Spaghetti or noodles or rice (well cooked), Couscous
  • Multigrain bread – try toasted first

Group 2: Fruit (2 serves/daily) Vegetables (3-4 serves/daily)

  • Fresh fruit or tinned fruit (with no added sugar)
  • Variety of cooked vegetables, slowly introduce salad vegetables

Group 3: Dairy Products   (3 serves/daily)

  • Skim or low fat milk  (maximum 250 ml per day)
  • Low fat and diet yoghurt  (1 tub of 200 grams per day)
  • Low fat cheese slices, cottage or ricotta cheese  (no more than 30 grams/day)
  • Avoid ice cream, milkshakes and flavoured milk

Group 4: Meat, Fish, Chicken, Eggs, Legumes   (2 serve/daily. 1 serve = 50 grams)

  • Lean meat (lamb, pork, veal, beef), fish or chicken, eggs (limit to 2-3 a week), baked beans and legume (chickpeas, lentils etc)

Group 5: Fats, Oils  (maximum 2 teaspoons per day)

  • Use polyunsaturated or monounsaturated margarines and cooking oils





General Recommendations:

Meal Size:

After the surgery you will not be able to eat large amounts of food and fluid at one time. Having small meals will help prevent pain, discomfort, nausea and vomiting. As a general rule stop eating when you feel full or feel any discomfort.



Protein is important in healing and preventing muscle loss while you are losing weight. Not enough protein results in lethargy and hair loss.  We recommend at least 60 grams of protein per day.  You should eat protein foods first at each meal. These include meat, fish, chicken, eggs and low fat or skim dairy products.

  • Buy lean meat
  • Remove all visible fat from meats and the skin from chicken before cooking
  • Avoid processed meats (eg. salami, ham)
  • Use low fat cooking methods such as grilling, steaming, microwaving or boiling instead of frying

Meats and alternatives 

  • Source of protein, iron, zinc and Vitamin B12
  • Low fat varieties
  • Buy lean meat
  • Avoid processed meat
  • Remove all visible fats

(Aim for 2 serves)

  • 50 g of meat, chicken, fish
  • 1/2 cup of lean mince
  • 1/2 cup of cooked beans, lentils, chick peas, split peas or canned beans
  • 1 small eggs (limit 2-3 /week)


Dairy products

  • Source of protein, calcium and zinc
  • Low fat / diet varieties

(Aim for 3 serves)

  • 250 ml of low fat milk -1 cup
  • 200 g yoghurt (1 small carton)
  • 20 g cheese (1 slice)
  • 250 ml custard (1 cup)

You can also use meal replacements with protein such as: Optifast, Tony Ferguson, Dr. MacLeods, etc. There are other commercial supplements available at pharmacies. Your dietitian will recommend these if necessary.



Protein counter

This protein counter table is based on foods that we consider good sources of protein. It is designed to help you get enough protein during your post op period.

Food item Portion Protein (grams)
Baked beans, kidney beans, chick peas, lentils ½ cup 7
Egg 1 6
Meat/ Chicken/ Seafood
Beef, Lamb, Pork, Veal 30 grams 8
Chicken, No skin 30 grams 8
Fish 30 grams 8
Prawns 5 pieces 7
Lobster, Crab 30 grams 5
Milk. Skim 1 cup 8
Cheese, Cottage 1/2 cup 14
Cheese,Parmesan,grated ¼ cup 12
Cheese, Ricotta ½ cup 14
Cheese, Mozzarella 30 grams 8
Soy items
Soybean ½ cup 14
Tofu ½ cup 10
Textured Soy protein ½ cup 11
Soy milk, plain 1 cup 6.6
Soy nuts ½ cup 15
Yoghurt, low fat 200 mls 8
Meal replacements
Optifast™ 1 sachet 17
Tony Ferguson™ 1 sachet 17
Kicstart™ 1 sachet 17

Note: 1 Standard cup =  250 mls Minerals and Multivitamins:



As the amount of food you can eat is very small, you will not be able to get all the nutrition from food alone. This could result in vitamin and mineral deficiencies.  To prevent this we recommended that you:

  1. Take the following recommended vitamin and mineral supplementations
  2. Initially: Berroca Performance (let it go flat before taking it).
  3. One month post op (or as tolerated): Blakemore’s
  4. Ensure that the multivitamin you take contains 400 µg folate
  5. Have routine blood tests if you are vitamin deficient
  6. Adequate replacement is needed for any vitamin or mineral deficiencies






Fluids are important in preventing dehydration and also help keep your bowels regular

  • It is important to drink plenty of water (6-8 glasses per day)
  • Avoid large amounts of fluids with meals
  • Drink 30 minutes before meals and wait for 30-45 minutes after meals
  • Avoid calorie liquids, these are fluids that have calories and add to your total energy intake without giving you any feeling of fullness
  • Drinking these on a regular basis is often one of the reasons that patients do not get good weight loss (eg. non diet soft drinks, cordials, juices, milkshakes or sports drinks)


Alcoholic beverages:

You will be affected by alcohol much more quickly after the surgery. Therefore it is important to start with small amounts first and as per recommendations: DO NOT DRINK AND DRIVE. 

Alcoholic drinks such as wine, beer, spirits, sherry and port have no nutritional benefits and are also very high in calorie. It is best to limit these beverages.


Fibre is important to keep your bowels regular. Initially your diet lacks fibre and therefore you may need to take a fibre supplement (such as Benefibre™) with plenty of water. This increases bulk and should help with regular bowel activity.

As your diet progresses you should include breads and cereals, fruits and vegetables as well as adequate fluids daily. Daily exercise is also important in preventing constipation. If constipation is a problem discuss this with your doctor.





Long term weight loss maintenance:

As mentioned earlier your success post surgery will depend on your life long efforts to change your lifestyle. This includes making some radical changes to your eating as well as exercise habits.

Some of the key factors in achieving optimal weight loss and maintaining it are:

Monitor your weight closely 

You need to weigh yourself weekly to give yourself feedback on your progress.

If you are putting on weight again, your diet needs to be reviewed and increase your activity level.


Protect the new stomach pouch 

The aim of the sleeve is to help you feel full after eating a small meal. However you still need to protect the stomach pouch to prevent over stretching it resulting in loss of satiety and weight regain.

  • Eat  a healthy and balanced meals: including lean meats, fruits and vegetables, choosing low fat dairy items and avoiding high calorie dense foods
  • Avoid snacking and grazing – aim for 3 meals per day
  • Avoid liquid calories
  • Do not drink 30 minutes before and 45 minutes after eating

Regular exercise

  • Choose an exercise that you enjoy and do it daily (eg. start with walking  20  minutes a day)
  • Increase the activity level in your routine day