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Your Pre- and Post-⁠Op Diet

What to expect from your diet before and after gastric sleeve surgery: two weeks to get ready, about seven weeks of stages while your stomach heals, then small, protein-first meals for life. Your dietitian sets your exact plan.

Step through the stages

This page is general information, not medical advice. Always follow the instructions your care team gives you.

Your diet at a glanceAbout 9 weeks
  1. Pre-⁠op diet 2 weeks before
  2. Clear fluids Days 1-2
  3. Full fluids Days 3-13
  4. Puréed Weeks 2-3
  5. Soft foods Weeks 4-6
  6. Regular diet Week 7 on
  • 60-80 gprotein a day
  • 8 cupsof fluid a day (2 L)
  • Every dayvitamins, for life
Protein first · small bites · chew well · no drinks with meals

Two weeks before surgery

Your eating journey starts before surgery. Your dietitian guides you through a short pre-⁠op diet that shrinks your liver and gets your body ready.

  • Why it matters

    Some people have a fatty liver, where fat builds up in and around the liver. A large liver sits over the stomach and makes surgery harder and riskier. The pre-⁠op diet shrinks it, for safer surgery.

  • What it looks like

    Low in calories, sugar and starch, with enough protein. Many people, especially with a higher BMI, use a liquid meal replacement for one to two weeks. If you need it, a two-week supply is included.

The full week-by-week checklist
A typical day on a meal replacementIf your team prescribes it
  • Usually 4 packets a day, each blended with about 1¼ cups (300 mL) of cold water
  • At least 8 cups (2 litres) of fluid a day in total, including the shakes
  • Other drinks: water, decaf coffee or tea without milk or sugar, and sugar-free, non-carbonated drink mixes
  • Up to 2 cups a day of these vegetables only: lettuce, spinach, cabbage, cucumber, celery, broccoli, cauliflower and green peppers
  • No other solid food while you are on a meal replacement
  • The day before surgery: only 2 packets, the last one before 7 pm
If you are not on a meal replacement

Your dietitian gives you a low-calorie, high-protein plan for the two weeks. About two days before surgery, you may switch to clear fluids only: water, broth, black tea or coffee without milk or sugar, and sugar-free gelatin or popsicles.

Five stages after surgery

Your stomach needs time to heal, so textures come back step by step over about seven weeks. Pick a stage to see what it looks like. Your dietitian tells you when to move on.

Days 1-2See-through liquids

Stage 1: Clear fluids

Rest your new stomach and stay hydrated.

Start with small sips of water, then other clear fluids as your team allows. Sip slowly all day, even when you are not thirsty.

Examples

  • Water
  • Low-sodium broth
  • Sugar-free electrolyte drinks
  • Decaf or herbal tea
  • Sugar-free gelatin
  • Sugar-free popsicles

Avoid for now

  • Gulping and straws
  • Carbonated drinks
  • Caffeine
  • Sugary drinks
  • Alcohol

Portion

Sips, about 30 mL (1 oz) at a time

Start Up to

Meals
Small sips through the day
Protein
Not yet. Fluids come first.
Fluids
Start with about 30 mL (1 oz) an hour, and build up as you can

Tip: Keep a log of what you drink. Your nurse asks about it.

Stage 1 of 5

General guidance. Your dietitian sets the stages, amounts and timing that are right for you, and may move you on sooner or later.

Protein and fluids, every day

Two numbers carry you through every stage. Your dietitian may set different targets for you.

60 to 80 gof protein a day

Protein helps your incisions and your new stomach heal, and keeps your muscles strong while you lose weight. Too little can mean slower healing, hair loss and low energy.

Because you eat small amounts, choose protein-rich foods and eat them first, at every meal and snack. Pick lean protein over high-fat choices.

Where it comes from, roughly

  • 1 protein shake20 to 30 g
  • ¾ cup plain Greek yogurtabout 15 g
  • ½ cup cottage cheeseabout 12 g
  • 1 oz (2 tbsp) lean meat, chicken or fish6 to 7 g
  • 1 slice (1 oz) low-fat cheese6 to 7 g
  • ½ cup cooked lentilsabout 9 g
  • 1 cup (250 mL) skim or 1% milkabout 8 g
  • 1 large eggabout 6 g

Approximate amounts. Check food labels.

8 cupsof fluid a day, about 2 litres

Your body used to get much of its water from food. Now you need to sip it on purpose, all day. Water is best. Milk, broth and protein shakes count too.

  • Sip often between meals. Carry a water bottle.
  • No drinks with meals: stop about 30 minutes before you eat, and wait about 30 minutes after.
  • Keep a record of your fluids in the first weeks.
  • Choose decaf coffee and herbal tea. No carbonated drinks.

Signs you need more fluid

  • Dark urine
  • A headache
  • Feeling dizzy or tired
  • Nausea
  • A white coating on your tongue

If you cannot keep fluids down, call us at (416) 360-⁠7360.

Vitamins, every day, for life

You eat much less after a sleeve, so food alone cannot give you everything you need. Supplements fill the gap. Your dietitian names the products and doses for you.

  • MultiA bariatric multivitamin

    Chewable or liquid, 1 to 2 a day. It gives about twice the daily value of most nutrients, including iron, folic acid, thiamine (vitamin B1) and copper.

  • CaCalcium with vitamin D

    Usually calcium citrate, in two or three doses a day. Take it at least 2 hours apart from iron or your multivitamin.

  • B12Vitamin B12 and extra vitamin D

    If your bloodwork or your team says you need more.

How to take them

  • Take your multivitamin with a meal, a shake or milk, so it sits well.
  • Keep calcium and iron at least 2 hours apart, so both are absorbed.
  • No gummies: they do not have everything you need, are not well absorbed and can get stuck.
  • Ask your pharmacist before you crush or split a pill. Some, such as extended-release pills, must stay whole.

Checked for you: bloodwork at 6 months and then every year is part of 360 Complete Care, so your team can adjust your supplements.

50%Protein 30%Vegetables 20%Carbs
A 7 to 9 inch plate: half protein, about a third non-starchy vegetables and the rest high-fibre carbs or fruit.

Your portion plate

Once you reach regular food, a small plate makes a small portion look like a full meal. Fill it in this order, and eat it in this order too.

Protein, halfAbout 3 oz

  • Lean cuts of red meat
  • Skinless chicken or turkey
  • Fish and seafood
  • Eggs
  • Tofu
  • Lentils and beans
  • Low-fat dairy

Non-starchy vegetablesAbout ⅓ cup

  • Asparagus
  • Broccoli
  • Brussels sprouts
  • Cabbage
  • Carrots
  • Cauliflower
  • Cucumber
  • Eggplant
  • Green beans
  • Leafy greens
  • Mushrooms
  • Peppers
  • Spinach
  • Tomatoes
  • Zucchini

High-fibre carbs or fruitAbout ¼ cup

  • Quinoa
  • Barley
  • Oats
  • Beans and lentils
  • Potatoes or sweet potatoes
  • Whole grains
  • Fruit

What to avoid, and what to go slow with

Some foods are hard on a healing stomach. Others are worth limiting for good, because they work against your new way of eating.

In the early weeks

Until your dietitian says you are ready.

  • Bread, rice and pasta, until about week 7 or 8
  • Tough, dry or stringy meat
  • Raw vegetables, salad, skins and seeds
  • Nuts, popcorn and chips
  • Spicy, fried or greasy food
  • Caffeine: choose decaf and herbal tea
  • Straws, which bring air into your stomach

Avoid or limit for good

Habits that help your sleeve work for you.

  • Drinking with meals: stop 30 minutes before, wait 30 minutes after
  • Carbonated drinks, which cause gas and discomfort
  • Sugary drinks, sweets and desserts
  • Fried and high-fat food
  • Grazing through the day instead of eating on a schedule
  • Alcohol in the first months. Talk to your team before you drink again: after a sleeve, it hits faster and harder.

Common challenges, and what helps

Most people meet one or two of these in the first months. They are usually easy to manage with your team's help.

Low appetite

It is very common not to feel hungry after surgery. Eat on a schedule, not by hunger, so you still get your protein and fluids.

Nausea or vomiting

Usually from eating too fast or too much, not chewing well, drinking too soon after a meal, or moving to the next stage too early. If it does not settle, or you cannot keep fluids down, call us.

Feeling dehydrated

Dark urine, a headache, dizziness, tiredness or a white coating on the tongue can mean you need more fluid. Sip steadily all day and aim for about 8 cups.

Gas and bloating

Common in the first weeks. Walking helps. Skip straws and carbonated drinks, and eat slowly. Gas from milk can be a sign of lactose intolerance.

Constipation

Less food, less fibre, and iron or calcium can all slow things down. Drink enough, keep walking, and ask your team about a stool softener. Add fibre as your stages allow.

Taste changes

Food may taste different, especially in the first weeks. It often settles. Your dietitian can help you find protein foods you enjoy.

Trouble with dairy

Milk can cause cramps, gas or loose stools for some people after surgery. Lactose-free milk, ultra-filtered milk or a lactase tablet may help.

Hair thinning

Often starts around 3 to 6 months and is usually temporary. Getting enough protein and taking your vitamins every day helps.

Questions about eating after surgery

Short answers to what people ask most. Your dietitian goes through all of it with you.

Still wondering? , or ask the assistant in the corner.

  • 01How much protein do I need after a gastric sleeve?

    Most people aim for 60 to 80 g a day, starting with protein shakes and moving to protein foods as the stages go on. Your dietitian may set a different target for you, based on your size and your health.

  • 02When can I eat solid food again?

    Most people move from fluids to puréed food at about the end of week 2, to soft food at about week 4 and to a regular diet from about week 7. Your dietitian tells you when you are ready for each step.

  • 03Why can't I drink with meals?

    Your new stomach is small. Drinking with a meal fills it with fluid, so you eat less of the protein you need, and it can cause discomfort. Stop drinking about 30 minutes before you eat, and wait about 30 minutes after.

  • 04Can I drink coffee after surgery?

    Not in the first weeks. Caffeine can irritate your healing stomach and make it harder to stay hydrated. Decaf coffee and herbal tea are fine. Ask your dietitian when you can have caffeine again.

  • 05When can I drink alcohol?

    Avoid alcohol in the first months, and talk to your team before you drink again. After a sleeve, alcohol is absorbed faster and has a stronger effect, and it adds calories without nutrition.

  • 06Do I need vitamins for life?

    Yes. You eat much less after a sleeve, so a daily bariatric multivitamin, calcium and vitamin D are part of life after surgery. Bloodwork at 6 months and then every year checks your levels.

  • 07What if a food does not agree with me?

    It is common, especially in the first year. Stop, wait a few weeks and try a small amount again. Call us if you cannot keep fluids down or you vomit often.

The rest of your guide

This page is general information, not medical advice. Always follow the instructions your care team gives you.

Your first step is a conversation

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(416) 360-⁠7360 sleeve@clinic360.com 1131A Leslie St #300, Toronto, ON M3C 3L8

NextWhat to expect after surgeryThe first days and weeks, getting active again, when to call and your follow-⁠ups. Continue