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After gastric sleeve surgery you will need to make changes to your eating patterns. The diet after surgery progresses from a liquid diet to a pureed diet to a soft diet and then a modified diet. This progression is designed to allow your body to heal. It is very important that you follow the diet progression to maximise healing and minimise the risk of complications.

Before Gastric Sleeve Surgery

For two to six weeks before your surgery you are required to follow a low calorie diet. The programme followed is Optifast. Your dietitian and surgeon will advise on the amount of time you will need to follow this diet.

Why is it necessary to lose weight pre-surgery?

  • To lower body fat levels for better access for the surgeon i.e. safer surgery
  • To reduce the size of your liver which would otherwise be in the way
  • Greater ability to adapt to post-operative dietary requirements
  • Reduced operating time and post operative risks
  • Improved physical function and mobility post-surgery

What is Optifast?

  • Very low calorie diet (VLCD) that is < 800kcal per day
  • Nutritionally complete. (All the protein, vitamins and minerals that you need)
  • Involves three “meals” per day, which can be milkshakes soups or bars

How does it work?

  • Each VLCD meal is taken at usual meal times and provides all essential nutrients
  • You need to drink at least 2 litres of the following fluids per day:
    – Water
    – Diet soft drink
    – Black tea or herbal tea without milk or sugar
  • A maximum of 2 cups of low starch vegetables are allowed per day
  • Replacement fibre – 1tsp of psyllium or equivalent per sachet of optifast eg Metamucil or Benefibre
  • Please see attached “foods allowed” lists below for more information

If you are having trouble with this diet or having symptoms such as nausea, please call your dietitian, surgeon or your GP.

Additional Allowances

Allowed Avoid
Fruit one of – 200g strawberries, 1 lychee, 1 apricot, 100g cooked rhubarb, 1 slice of pineapple, 2 passion fruit, 100g grapes, 1 lime, 1 apple, 50g cherries, 1 mango, 1 medium orange, 1 peach, 1 small pear, 120g pear in natural juice, 120g plums, 5 prunes all other fruit, including banana
Low starch and green vegetables
(2 cups per day)
alfalfa sprouts
bok choy
brussel sprouts
mung beans
silver beet
snow peas
green peas
kumara                       taro                                                                 green banana
 soups  stock cubes vegetable soups
(using allowed vegetables)
 miso soup  all others
sauces and condiments lemon juice
worcestershire sauce
soy sauce
(in moderation)
tomato paste
herbs and spices all herbs and spices
miscellaneous artificial sweeteners unsweetened lollies/gum diet jelly essence – e.g. banana, mint, strawberry
calorie free fluids
(at least 2 litres extra per day)
diet soft drink
diet cordial
mineral water
fruit juice

Day Zero (evening of surgery)

  • Ice to suck, sips of water

Day One

  • 1 litre of water (slowly), progressing tobariatric free fluids (room temperature clear/smooth soups, Optifast, tea/coffee, low fat smoothies, low sugar)

Day Two

  • Bariatric free fluid diet, progress to bariatric pureed diet as tolerated (very small amounts of puree/mashed food only half a teacup at a time at most)

Day Three to Week Three

  • Progress tobariatric pureed diet as you are able

Week Four onwards

  • Small meals of soft food that is high in protein and low in fat and sugar

General information

During all of the above stages and when you have recovered fully from surgery it is crucial that you

  • AVOID liquids with meals (do not drink 30 mins pre and post eating)
  • Drink between meals and aim for six to eight glasses fluid per day
  • Follow a general healthy diet, low in fat and sugar


  • Because you are eating less constipation may be a problem. Keeping up with your fluid intake, and occasionally using a gentle laxative will help with this. Most patients will not feel the urge to have bowel movement for several days after surgery. This is because you will be taking very little food and is entirely normal.

Handy hints

  • If you try to eat too much too quickly vomiting or regurgitation may occur.
  • Do not consume liquid calories such as fruit juice, soft drinks, or milkshakes.
  • Eat slowly, chew all food well and take time with your meals.
  • Ensure you have an adequate protein intake. Protein should be eaten before carbohydrates (starchy) foods.
  • As soon as you are home after your surgery start taking a multivitamin daily such as “Centrum”.

Puree diet

  • To be followed until three weeks after your surgery
  • Eating too much can result in complications before healing has occurred.

Important points

  • Eat slowly
  • AVOID very hot or very cold foods
  • DO NOT drink within 30 minutes of meal times
  • It is normal to be managing only very small amounts during this phase. Eating with a teaspoon from a small plate is a good idea.
Foods allowed Foods to avoid
high protein, low fat pureed foods:
low fat yoghurt,
cottage cheese,
mashed weetbix,
softly scrambled or poached eggs,
pureed meat/chicken/fish,
pureed/mashed vegetables/potato,
smooth soups,
pureed fruit
raw fruit
raw vegetables
solid food
low fat products butter
cheese (high fat varieties)
ice cream
low sugar products
low calorie drinks
herbal teas
soft drinks


Sample meal plan (initially only 1 -2 tablespoons of food at a time):

Breakfast Weetbix or Optifast
low fat milk or
1 tablespoon low fat yoghurt
1 tablespoon pureed fruit
Lunch smooth vegetable/pumpkin soup
scrambled egg
Dinner pureed chicken and low fat gravy
or mashed fish
pureed potato/pumpkin/vegetables
Snacks (x3/day) puree fruit, mashed banana, low fat yoghurt and milk


Soft diet

  • After your puree diet move to a soft diet for two weeks. This is food you can mash with a fork. Then gradually move to more solid foods
  • Aim to have only three meals per day
  • You should be using a bread and butter size plate
Food group Foods allowed Foods to avoid
meat, chicken and fish Foods allowed
tender chicken, fish and meat in bite sized pieces or minced.
shaved ham, turkey or chicken
tinned salmon and tuna in spring water
hard or stringy meat fat, chicken skin or gristle.
fried meats
milk and milk products low fat milk, cottage/ricotta cheese, low fat yoghurt ice cream, high fat cheeses, cram and full fat milk
Fruit soft fruits: peeled pears, apples, stone fruit, melon pips, skins, pith
Vegetables cooked vegetables:
mashed, stir fried, grilled or boiled
introduce salads slowly
tough or raw vegetables: beans, corn, celery, broccoli stalks etc
breads and cereals low fat crackers e.g. cruskits, rice, pasta, noodles, porridge, weetbix, bran flakes doughy bread, muesli, high fat cereals.
Drinks diluted juice, diet soft drinks and cordials, herbal teas, coffee or tea with low fat milk soft drinks, energy drinks, milkshakes, full fat milk drinks, juice
Miscellaneous artificial sweetener, herbs and spices, marmite, stock, low fat hummus, minimal oil when cooking sugar, chocolate, sweets, syrups, jams, butter, cooking oils, potato chips, high fat crackers, creamy sauces.

Handy hints

  • Introduce more solid foods after a few weeks e.g. salads, red meat
  • AVOID bread and instead have low fat crackers e.g. rice crackers, cruskits
    – Look for <5 g fat per 100g
  • Small amounts of toasted vogels bread can be eaten. AVOID soft white breads
  • Continue to chew food well and take your time eating
  • AVOID fluids with meals
  • Do not over eat as this will make you uncomfortable and may cause vomiting
  • Continue to eat regular meals and select healthy food options to optimise your continued weight loss
  • You will need to make sure that your meals are nutritious and include all the nutrients your body needs
  • Choose foods that you enjoy and take time to savour their flavours

Food to include at each meal

You need to include low fat protein at each meal to ensure you maintain your muscle stores and loose fat stores e.g:

  • Lean red meat 2-3 x per week e.g. lean mince, eye fillet
  • Fish and chicken (no skin)
  • Low fat dairy products e.g. trim milk, low fat yoghurt and cottage cheese
  • Tofu, beans and lentils e.g. baked beans, hummus, kidney beans

Hair loss (temporary) can be a problem if there is inadequate protein in your diet. Using protein powders (muscle building formulas) in fruit smoothies and purees can be a good way to increase your protein intake. Protein helps to keep you feeling satisfied for longer.

Fruit and Vegetables

  • Fresh, frozen or canned vegetables. AVOID hard seeds and pips
  • Fruit that has been peeled and membranes removed.

Carbohydrate/Starchy Food – 2-4 serves per day

  • 1 serve = ½ cup pasta/cereal, 1 slice bread, 1 egg sized potato
  • Potato, bread, rice, pasta and cereals should be eaten in very small amounts only
  • If you are having bread, use wholegrain varieties (e.g. Vogels) and toast it as this will fill you up more
  • Protein foods should take priority


  • 6 – 8 glasses fluid per day (do not include coffee, alcohol or caffeine drinks).
  • AVOID full strength juice, cordials, high calorie fizzy drinks, milkshakes etc


  • Use very minimal margarine or preferably none
  • Vegetables can stir fried with a teaspoon of olive oil
  • Generally avoid oil in cooking. Grill, bake, boil, stir fry or dry roast
  • AVOID fatty meats e.g. sausages, luncheon sausage, salami

Handy hints

  • Order entree size meals when dining out
  • Continue to eat regular meals and select healthy food options to optimise your continued weight loss
  • Aim to exercise 45-50mins five days per week. This should be continuous cardio type of exercise – rather than weights – of enough intensity to “raise a sweat”
    – Brisk walk, cycle, cross-trainer, aqua jogging or swimming
    – Weight-bearing exercise is best for weight loss maintenance


Healthy lifestyle choices →

Gastric bypass surgery requires you to make significant changes to your lifestyle for the rest of your life.