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Before surgery

For three weeks before your surgery you will need to go on the Optifast programme.

Optifast is a total food replacement that:

  • is scientifically formulated and nutritionally complete
  • contains sufficient quantities of proteins, carbohydrates, vitamins and minerals to meet your body's daily needs
  • involves three sachets a day, which we will supply to you.

There are also Optifast soups, bars and desserts, but you will need to buy these if you wish to use them.

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Why do you need to go onto Optifast?

When you are overweight you store fat in your liver, which makes the liver large and firm. For the surgeon to be able to perform your surgery, the liver needs to be moved aside. Optifast helps to shrink and soften the liver, which lessens the time of the operation and lowers post operation risks.

Losing weight before surgery will also lower the anaesthesia risks.

What if I get hungry?

In the first few days on Optifast you will get hungry, but this should ease as your body adjusts. The low calorie Optifast programme forces your body to break down your stored fat. When this happens, ketones are produced, which will reduce your appetite. If you eat other foods that are not recommended, the production of ketones will be interrupted, and your food cravings will increase.

If your hunger is unmanageable, you can increase you intake of clear broth (soup), small portions of diet jelly (within reason), or black tea / diet drinks.

How to use Optifast

  • Each sachet is mixed with 200mls of cold or warm water.
  • Stir, blend, or shake well.
  • You can have a maximum of 2 cups of low starch vegetables each day - see the "foods allowed" list as outlined below.
  • You need to drink at least 2 litres of calorie free fluid a day.
    Water is best but you can also have black tea or herbal tea (ie no milk), diet cordial, mineral water or diet soft drink.
    Coffee is a diuretic, which means it can cause fluid loss from your body. You may then become dehydrated, which will cause low blood pressure, dizziness and tiredness. A small amount of coffee can be included, but this should be black, with NO MILK, and only 1-2 cups per day.
  • You may need to add a fibre source such as Metamucil
    or Benefibre to prevent constipation. You can buy these from a supermarket or Pharmacy without a prescription. Use 1-2 teaspoons a day as required.



  • Use the stock to make a soup with vegetables.
  • Use herbs, spices and sauces for flavour.
  • Try vegetables for dinner and Optifast for supper.
  • Use the shake to make a smoothie, and add the fruit serve to create variety.

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Optifast Meal Plan

The Optifast Meal Plan is designed to replace your usual daily food intake. This is a sample meal plan which consists of three serves of Optifast each day. (One serve is one sachet of Optifast milkshake, soup, dessert, or one bar)



One serve Optifast

Tea or coffee (no milk or sugar)


Clear broth (if desired) One serve Optifast

One cup salad/low starch vegetables (from list) Diet jelly (if desired)

Water/coffee/tea/diet cordial/diet soft drinks


Clear broth (if desired) One serve Optifast

One cup salad/low starch vegetables (from list) Diet jelly (if desired)

Water/coffee/tea/diet cordial/diet soft drinks


Make sure you include at least ten (10) glasses of water each day

In between meals you can also include:

  • Tea (no milk or sugar)
  • Sugar free soft drink
  • Diet cordial
  • Unflavoured mineral water

Drink, Drink, Drink

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Things to be aware of while on Optifast

Diabetics on oral medication

If you are a diabetic on oral medication, you will need to monitor you blood glucose levels more closely, especially in the first few days, as your sugar levels will fall. You may need to reduce your medication while you are on the Optifast programme.

Diabetics on insulin


If you use insulin to control you diabetes, you will need to reduce your insulin dosage while you are on Optifast. You will already have been referred to a Diabetes Nurse Specialist, and they will be able to guide you, helping to monitor your sugar levels and insulin doses.

You should be aware of the signs of hypoglycaemia (low blood glucose levels), and know what to do if this happens.

Gall stones

Gallstones can form when there is rapid weight loss, and if there is no fat in your diet. Adding 1 teaspoon (5ml) of vegetable oil to your daily serve of vegetables may stimulate the gall bladder to empty, and help prevent gallstones from forming.


Rapid weight loss can sometimes lead to high uric acid in the blood, which may bring on an acute attack of gout. If you have previously suffered from gout, make sure you drink at least 2 litres of fluid every day, to help avoid a gout attack.

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After Surgery

After Gastric Sleeve surgery you will need to make changes to your eating patterns. The diet progresses from a liquid diet, to a pureed diet, to a soft diet, and then to a modified diet.

This progression is designed to allow your body to heal. It is very important that you follow the diet progression to improve healing and lesson the risk of complications.

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Fluid diet


For the first few days you will be guided by the nursing staff. You will start with chewing on ice cubes, and then slowly increase from sips of water and clear fluids, to drinking milky drinks, smooth soups, and tea or coffee.

Your volumes of fluid will also gradually increase, from 30ml every hour, up to 100ml every hour, as you can tolerate. It is important to keep a record of how much you are drinking in these first few days, to ensure you are meeting your body's fluid requirements.

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Puree diet

For the first three weeks after your surgery you will progress from a fluid diet to a puree diet. A puree diet puts less strain on the staples in your stomach, and prevents a leak from the staple line. If a leak from the staples occurs, this is extremely serious.

Puree food does not need chewing; it falls off the spoon slowly but will not pour off. It should be smooth, with no lumps present.

You should only have very small amounts of pureed or mashed food (½ cup at the most). Eating more than this may result in vomiting, or more significant complications, before healing has occurred.

AVOID drinking liquids with meals

(Do not drink 30 minutes before and 30 minutes after eating)


It is important to focus on your protein intake every day, to allow your body to heal well, and to maintain your muscle mass. Try to have protein at every meal, and eat this part of your meal first.

Examples of protein foods include:

  • Pureed meat, fish, chicken, and seafood.
  • Low fat dairy products such as trim milk, low fat yoghurt, grated cheese.
  • Tofu, hummus, and puree baked beans.

Remember these all need to be pureed for the first 3 weeks.

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Preparing a puree diet


You will need a blender or a food processor. A bar mixer is suitable for small amounts. Blend foods separately so you can still enjoy the flavour.

Cut well cooked food into bite size pieces, and just cover with a suitable liquid.

The liquid you use will depend on the food you are processing. Blend until the mixture is smooth and thick, adding liquid until the required consistency is reached.

Some suggestions would be:

  • Red meats: These often lose flavour and colour when pureed. Try adding low fat gravy, stock or sauces such as tomato, BBQ, soy, or Worcestershire. These meats can get stringy and tough when blended. Casserole meat purees easier and has built in flavour.
  • Chicken/Pork/Ham/Veal: These meats are easier to blend. Puree using soups, gravy, or vegetable juices.
  • Fish: Fish combines well with white sauce. You could use packet sauce for a quick, easy alternative.
  • Eggs: As eggs are difficult to puree, try making soft smooth scrambled eggs by adding additional low fat milk.
  • Vegetables: Cook until tender and blend using vegetable water, gravy, or soups. Add a little mashed potato or instant potato flakes to pureed green vegetables, to thicken and improve flavour.

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Storing smooth puree meals

Pureed meals can be kept in the fridge for 12 hours, after which time their nutritional value deteriorates.

Alternatively, you can freeze puree into meal sized portions. These can then be thawed and re-heated thoroughly, adding a little extra liquid if necessary.

Meal Suggestions:

These are a few suggestions for meals. Remember, the size of your meals should fit in ½ a measuring cup (125ml). Start with only 3-4 teaspoons of food at a time.


  • Porridge made up with water, served with trim milk and an artificial sweetener if desired.
  • ½ - 1 scrambled egg. Whisk one egg with trim milk.
  • Fruit and Yoghurt. Puree ¼ banana, a few strawberries, or some tinned peach slices. Serve fruit with a few tablespoons of plain yoghurt.
  • One Weetbix (moistened with hot water) served with trim milk.
  • Smoothie - blend ½ cup trim milk, ¼ cup yoghurt and ¼ cup soft chopped fruit until smooth.


  • Smooth soup such as pumpkin, pureed vegetable, or pureed chicken soup.
  • Creamed Rice. Half a cup of tinned or homemade creamed rice.
  • ½ - 1 scrambled egg.
  • Pureed baked beans.
  • Tinned or bottled baby food.
  • Complan. Make up a glass of Complan using trim milk. Blend with berries or tinned fruit if desired.


  • Steamed fish pureed in a white sauce with mashed potato and pureed vegetables.
  • Pureed macaroni cheese - make the cheese sauce with trim milk and a small amount of cheese.
  • Pureed spaghetti bolognaise.
  • Puree soft lean meat with gravy, or puree casseroles. Add a small serve of mashed potato and pureed vegetables.
  • ½ - 1 scrambled egg or omelette.


  • Custard made with low fat milk.
  • ½ cup of low fat yoghurt or low fat dairy food.
  • Pureed fruit.
  • Mashed banana.
  • Smoothie or milkshake made with low fat milk.

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Handy Hints in the first 3 weeks

  • Eat three small meals and three snacks for the first three weeks.
  • It is normal to be managing only very small amounts at this stage. This may be as little as 3-4 teaspoons each serving.
  • Eat slowly! Rest for two minutes between each mouthful. Your meal should take 20-30 minutes to eat.
  • Continue with scheduled meal times. Don't be tempted to skip meals, as this can lead to nutritional deficiencies.
  • You should have 5-6 very small meals every day.
  • You can use a high protein drink, (such as a milkshake, smoothie or Optifast) as a snack. This will give you a source of energy, as well as help to meet your fluid needs.
  • Avoid fizzy drinks, including diet coke cola and diet lemonade, as the bubbles in your stomach may cause bloating and discomfort.
  • Eat your protein foods first to avoid you getting too full to finish your meal.
  • Baby foods are useful when travelling or visiting. There are some tasty flavours available. Make enough puree for a number of meals, which can then be frozen. This will provide you with a variety of choices, and be more convenient.


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Soft Diet

At the end of the third week after your surgery, you can gradually add soft foods to your diet, as you progress towards a normal diet.

Continue to have small meals, ½ cup per serving, and choose foods that are high in protein, and low in fat and sugar.

You can start to introduce more solid foods, such as salads and red meat, after a few weeks on the soft diet.

AVOID drinking liquids with meals. (Do not drink 30 minutes before and 30 minutes after eating.)

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Foods to include at each meal



It is important to include low fat protein at each meal to ensure you maintain your muscle mass, whilst still losing fat stores. Remember to eat the protein part of your meal first.

If there is inadequate protein in your diet, hair loss can become a problem. However, this is usually temporary once corrected.


  • Low fat dairy products, such as trim milk, low fat yoghurt. Serve with cereal, or make into a smoothie.
  • Scrambled egg or omelet.


  • Low fat cottage cheese.
  • Tofu, beans (baked beans; kidney beans; chickpeas made into hummus) and lentils.
  • Fish, tinned tuna/salmon, or chicken (with skin removed).
  • Lean red meat, well cooked and soft (casseroled is ideal).
  • Quiche or frittata made with well cooked vegetables.
  • Savoury mince.

Fruit and Vegetables

  • Avoid hard seeds and pips.


  • Fresh fruit that has been peeled and skins removed.

  • Frozen fruit (eg berries).


  • Fresh, frozen or canned vegetables.


Aim for in between 2-4 serves of carbohydrates every day.

One serve is equal to ½ cup pasta or cereal, one slice of bread, or one egg sized potato.

You may not tolerate eating white bread, however you may find toast is manageable.


  • ½ cup of bran based cereal, or cooked porridge.

  • One slice of toast using whole grain bread.


  • Whole grain crackers or cruskits .

  • Potato, rice, and pasta - should be eaten in very small amounts only.

  • Legumes, such as beans, lentils or chickpeas.


Aim for 6 - 8 glasses of fluid per day. Minimise the amount of coffee, alcohol, or caffeine drinks.

Avoid drinking full strength fruit juices, cordials, and high calorie fizzy drinks, as these contain a high level of sugar.

Fluids include soups, smoothies and milkshakes. Although a good source of protein initially, avoid excessive milkshakes in the longer term.

Know the signs of dehydration - dry mouth, reduced urine output, dizziness. Sip regularly throughout the day to avoid this.


Use very minimal amounts of margarine and butter.

Avoid cooking foods in oil. Grill, bake, boil, stir fry, or dry roast when possible.

Avoid fatty meats such as sausages, luncheon sausage, and salami.

For more information and healthy eating recipe ideas:

Check out these websites:

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Handy Hints

  • Eat slowly, chew all food well, and take you time with your meals. If you try to eat too quickly, or too much, pain and vomit- ing may occur.
  • Avoid drinking liquids with meals. Do not drink 30 minutes before and 30 minutes after eating, or vomiting may occur.
  • Between meals, sip liquids slowly, drinking at least ½ cup every hour to avoid dehydration.
  • Remember to focus on an adequate protein intake. Protein foods should be eaten before carbohydrate (starchy) foods.
  • Avoid high calorie liquids such as fruit juice, soft drinks, cordial, or milkshakes.
  • Continue to eat regular meals. You may not feel hungry, but you should still eat 3 meals each day.
  • It is important to select nutritious, healthy food options that are low in fat and sugar. This will optimize your continued weight loss, while still providing all the nutrients your body needs.
  • After your surgery, you will need to start taking a multivitamin every day, for the rest of your life. You will leave the hospital with a prescribed multivitamin, but you may choose to buy a higher quality supplement, such as "Centrum".
  • Because you are eating less, constipation may become a problem. Keeping up with your fluid intake, and occasionally using a gentle laxative will help with this.
  • Small amounts of toasted vogels bread can be eaten. Avoid soft white breads, and instead have low fat crackers such as rice crackers or cruskits. These should have less than 5gms of fat per 100gms.
  • Order entrée size meals when dining out at restaurants.
  • Minimise alcohol intake as it is high in calories, may cause an ulcer, and the effects may be felt much more quickly.

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Last updated: March 21, 2019