Diet after a sleeve gastrectomy or gastric bypass

Diet after weight loss surgery

After your sleeve gastrectomy or gastric bypass, you must follow a diet plan. You will start with a liquid-only diet and slowly progress to solid food.

Slowly building up to a regular diet avoids putting pressure on your wounds as they heal. It will help you adjust to your new, smaller stomach. You will start with small sips of clear liquid after surgery.

When you are ready, you will move onto the following stages.

At first, you might find that you feel full very quickly and do not feel hungry, so you can only eat very small amounts. You might not manage to eat much food in the few days after surgery, but this is quite normal. Your appetite will get better over the next few weeks.

To avoid problems (such as feeling sick and being sick, or a nutrient deficiency after surgery), it is important that you follow the advice recommended about what to eat and drink.

If you find you are having difficulty tolerating the texture of the foods at any stage, go back to the previous stage for 2 more days, then try again. Everyone heals and progresses at different speeds.

Clear fluids during recovery

After surgery, you should have small sips of clear fluids. Clear fluids include water, black tea or coffee, and diluted no-added-sugar cordial or squash.

It is important to stay well hydrated (drinking plenty).

Try to drink about 2 tablespoons of clear fluids each hour. When you feel full, stop. Drinking too much could cause you to be sick.

Most people only manage a few sips at a time, and it is common to feel some discomfort and wind on the first day.

Once the surgical team have said you are ready, you can move to a liquid diet.

Weeks 1 and 2: Liquid diet

You must have a diet of only liquid for 2 weeks after your surgery.

    For a liquid diet, do:

    • only have liquids that are smooth, runny and with no lumps
    • have 2 litres (3.5 pints) of liquid every day
    • include liquid meals and drinks that are high in protein
    • have 1 to 2 small cups of liquid each hour. Between liquid meals, this can include water, tea, coffee and sugar-free drinks
    • start with sips

    You should drink extra fluids (like water, tea, coffee and diluted sugar free drinks) between your high-protein liquid meals. Try to have 1 to 2 small cups of fluid every hour.

    It is fine to drink fluids like tea, coffee, squash, water but you should make sure these are in addition to high protein liquids, and not instead of them.

    Start with sips. If these feel comfortable, slowly increase the amount you take in one go. Be careful not to gulp your drinks, as this can make you be sick.

    Getting enough protein

    It's important to have 60g to 80g of protein every day. You can do this by having high protein liquid meals and drinks. At least 1 to 1.5 litres of your total liquid should be high in protein.

    You can buy meal replacement shakes that are high in protein, or protein powders that can be added to smoothies or soups. 

    You can also make homemade soups and fruit or vegetable smoothies. These can be blended with milk with added milk powder, high protein yoghurt or protein powder.

    • Shakes and soups by Meritene or Complan (buy in pharmacies or supermarkets).
    • Meal replacement shakes such as by Tesco Slim, Asda Great Shape, Exante or Lighter Life
    • Slimfast powders or drinks (available in supermarkets).
    • Smooth soup (homemade or tinned) with an added 1 to 2 tablespoons of skimmed milk powder, or unflavoured protein powders. Avoid instant cup-a-soups.
    • High protein milkshakes (such as Ufit, Arla, For Goodness Shakes or Urban Active).
    • Protein water (such as, Asda, Vievé, Upbeat or +PW).
    • Whey, soya or pea protein powders, made into a shake (available in health food shops and some pharmacies).

    Milk with added milk powder

    Makes 3 servings (14g protein per serving)

    • 4 tablespoons of skimmed milk powder
    • 1 pint (570ml) of cold skimmed milk
    • Vanilla extract or unsweetened cocoa powder (optional flavouring)

    Mix the milk powder and flavouring with a little of the milk to form a paste. Stir in a pint of cold skimmed milk, and serve.

    Fruit smoothie

    Makes 2 servings (15g protein per serving)

    • Half a pint (285ml) of milk, with added milk powder
    • A quarter of a pint (140ml) of low fat yogurt
    • 100g of fresh soft fruit, such as bananas, berries, peaches

    Blend all the ingredients in a blender until smooth. Add extra milk or water as needed. Serve chilled with ice, or freeze to make an ice lolly.

    Fruit punch

    (10g protein per serving)

    • 1/3 pint (170ml) sugar-free non-carbonated drink (no–added-sugar squash)
    • 30g of skimmed milk powder
    • 4 ice cubes

    Combine all ingredients in a blender until smooth.

    High protein custard

    (10g protein per serving)

    Make as directed on the packet using milk with added milk powder.

    Homemade and ready-made custards are also suitable, as long as they are thin enough to pass through a straw. Add extra milk if needed.

    Breakfast Milk with added milk powder (200ml)
    Snack Fruit smoothie made with yoghurt (200ml)
    Lunch Homemade or tinned soup blended with 1 to 2 tablespoons of dried skimmed milk powder
    Snack Meal replacement shake (200ml)
    Dinner Complan or Meritene (shake or soup)
    Snack Milk with added milk powder (200ml)

    Weeks 3 and 4: Puree diet

    Your diet of pureed food will last for 2 weeks (weeks 3 and 4 after surgery).

    For a puree diet, do:

    • have smooth food with no lumps (a similar texture to runny yoghurt)
    • eat 4 to 6 small pureed meals every day
    • eat 2 to 3 tablespoons each meal and increase this slowly
    • have 60 to 80g of protein each day
    • drink small glasses between meals (at least 1.5 to 2 litres every day)

    How much to eat and drink

    Eat 4 to 6 small pureed meals every day.

    Start with about 2 to 3 tablespoons each meal. Slowly increase this to about 4 to 6 tablespoons, if and when this feels comfortable.

    If you can only manage very little (less than 4 tablespoons), try to have something every 2 hours (this is at the beginning only).

    Remember to chew well and eat slowly. Stop eating as soon as you feel full or satisfied.

    Drink small glassfuls (100 to 200ml) between meals. This can be water or other low-calorie drinks. Do not drink with your meals.

    How to prepare your meals

    The texture of your foods at this stage should be completely smooth (no lumps) and runny enough to be poured off a spoon (like a thin, smooth yoghurt).

    You can blend foods until smooth using a hand blender or a food processor. You might need to add extra liquid to get the right texture. Try using stock, gravy, cooking water from vegetables or low fat sauces for savoury foods. Use a sieve to remove any seeds or pips after blending.

    You can slowly build up to thicker purees if this feels OK.

    Choose 1 from each group

    Breakfast Low fat, high protein yoghurt
    Weetabix or Ready Brek (add warm milk with added milk powder)
    Homemade fruit smoothie (fruit blended with yoghurt or milk)
    Protein or meal replacement shake
    Snack Low fat, high protein yoghurt (half a pot)
    Fruit puree (a few tablespoons)
    Lunch Thick, smooth, high protein soup (blend lumps into the soup)
    Fish in sauce (pureed) with pureed vegetables and smooth mash
    Bolognese sauce (with pureed minced meat or vegetarian mince)
    Pureed baked beans
    Pureed fish pie with mashed potato
    Pureed scrambled egg
    Snack Milky drink or protein shake (half a serving)
    Low sugar custard
    Dinner Pureed meat stew, with pureed vegetables and smooth mash
    Pureed lentil dhal
    Pureed cauliflower cheese with smooth mash
    Pureed minced beef in gravy, with pureed vegetables and smooth mash
    Pureed shepherd’s or cottage pie
    Pureed chicken casserole, with pureed vegetables and smooth mash
    Chicken or meat and vegetable curry (pureed)

    You should try to balance your meals according to the bariatric plate, with half of your meal being protein, a quarter vegetables and fruit, and a quarter carbohydrate.

    Good high protein meal options

    Serve these with small amounts of pureed vegetables, and carbohydrate (such as smooth mashed potato) to make a complete meal.

    • Pureed minced beef, turkey, Quorn or soya mince with tomato sauce or gravy.
    • Pureed casseroled, stewed or curried meat in a sauce or gravy.
    • Pureed fish in sauce or fish pie.
    • Pureed pulses (such as baked beans).
    • Pureed lentils or dahl.
    • Pureed scrambled egg.
    • Soup from stage one.
    • Light cream cheese, or pureed cottage cheese.
    • Thin high protein yoghurt (Skyr) or mousse (such as, Arla, Isey, Graham, Siggi’s).
    • Low fat custard made with milk with added milk powder.
    • Hummus or bean dips.

    Weeks 5 to 8: Soft diet

    Your soft diet will last for 4 weeks (weeks 5 to 8 after surgery).

    Foods at this stage should be soft enough that they will fall apart when pressed with a fork or spoon. You should eat the same sorts of foods you were eating during your pureed diet, but they no longer need to be pureed.

    For a soft diet, do:

    • eat 3 to 4 small soft meals or snacks
    • continue to eat 60g to 80g of protein every day
    • continue to drink 1.5 to 2 litres every day
    • start a regular meal pattern and avoid grazing
    • have small mouthfuls and chew well before swallowing
    • listen to your body and stop eating when you feel satisfied

    You should try to balance your meals according to the bariatric plate, where half of your meal should be protein, a quarter should be vegetables or fruit, and a quarter should be carbohydrate.

    Choose a high protein option and add small amounts of soft vegetables and carbohydrate.

    Choose 1 from each group


    Low fat, high protein yoghurt with soft fruit
    Weetabix or other cereal, softened with milk with added milk powder
    Porridge or Ready Brek
    Soft cooked egg (poached, scrambled) with a tinned tomato
    Homemade fruit smoothie (fruit blended with yoghurt or milk)
    Protein or meal replacement shake

    Main meals

    Have 2 main meals a day (lunch and evening meal)

    Crackers or crispbreads with high protein topping (tinned fish, cottage cheese, mashed egg, low fat soft cheese, hummus). Chew crackers to a paste
    Omelette (1 to 2 eggs) with cheese
    Lasagne, ravioli or spaghetti bolognese (soft pasta dishes)
    Shepherd’s or cottage pie
    Fish in sauce or fish pie with soft cooked vegetables
    Tuna pasta bake (with soft cooked pasta)
    Meat or chicken stew with vegetables and boiled or mashed potato, cassava or plantain
    Mince in gravy with vegetables and boiled or mashed potato
    Baked beans with boiled or mashed potato
    Chunky, high protein soup (minestrone, pea and ham, Tuscan bean)
    Lentil dhal
    Meat or chicken and vegetable curry (avoid rice or bread for now)
    Cauliflower cheese or macaroni cheese


    Have 1 to 2 snacks a day

    Soft or tinned fruit
    Protein shake (half a serving)
    Low fat, high protein yoghurt (half a pot)
    Sugar-free jelly

    After 8 weeks: Regular diet

    You are now ready to continue on your long-term eating plan. You should have a regular diet of all textures, but low in fat and sugar.

    Remember, you are not just eating small amounts to reduce your calorie intake and lose weight. You should also be aiming for a healthy, nutritious eating plan.

    The diet we recommend you follow in the long-term is a healthy, balanced diet with plenty of lean protein and fibre.

    Read our information about moving on to a regular diet.

    Foods to avoid after bariatric surgery

    To get the best results and weight loss, have less foods that are high in fats or sugar.

    You should also avoid fizzy drinks of any kind, as much as possible. They can create pressure in the stomach, which causes discomfort and possible stretching. This includes avoiding low calorie versions (such as diet or zero versions) and sparkling water. 

    Foods that are more difficult to eat after bariatric surgery

    Some foods will be more challenging to eat than others, even when you chewing well, and eating slowly.

    Everyone is different, and it is important to take a ‘trial and error’ approach. Some foods that you cannot eat soon after surgery you might be able to tolerate later.

    The most commonly reported problem foods are bread, pasta, rice, red or white meat and certain vegetables and fruit. You can:

    • try toast, pitta breads, wraps or crackerbread
    • try different types of pasta or rice
    • choose tender cuts of meat or moist chicken, or try slow cooking
    • slice or shred vegetables or fruits into small pieces, and remove skins if they are difficult

    Resource number: 5030/VER1
    Last reviewed: August 2020
    Next review: August 2023

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