Your bypass pre-operative diet

It is important that you follow a strict diet before your gastric bypass surgery. By following this diet you reduce the chances of experiencing a complication with your surgery. 

What is the diet?

You need to follow a low calorie diet. The calorie intake should be below 1000 calories a day.

Why do you need to follow the diet?

The purpose of the diet is to shrink your liver in preparation for surgery. The diet reduces the amount of glycogen (storage form of carbohydrate), water and fatty deposits in the liver, which reduces the liver’s overall size. 

Is the diet optional?

The diet is compulsory. This means it is extremely important you follow it. If the diet is not followed the surgeon may refuse to operate on you. A large liver may cause the surgeon to abandon the operation. Do not be tempted to have a large meal the day before surgery as this will reduce the liver reducing effects of the diet.

How long should you follow the diet for?

It can vary depending on your BMI. If this applies to you we will normally apply the following scale.

  • If your BMI is 32-40 follow the pre-op diet for 1 week
  • If your BMI is 40-50 follow the diet for 2 weeks
  • If your BMI is 50-60 follow the diet for 3 weeks
  • If your BMI>60 follow the diet for 4 weeks

Sample Pre-operative Menu

Minimum of 1 week before surgery

Below is an example of what you could be enjoying while you’re preparing for surgery.

Breakfast (150-200 kcal)

Select one from the list below

  • 1 portion of porridge served with a handful of blueberries
  • 1 wholegrain toast with scrambled egg
  • 0.5 Weetabix with 125ml skimmed milk and half a banana/ strawberries
  • 30g oats / bran flakes / All-Bran etc with 125ml skimmed milk and half a banana

Mid-morning snack (80 kcal)

Select one from the list below

  • 1 portion of fruit
  • Low-fat yogurt

Lunch (150-200 kcal)

Select one from the list below

  • 1 bowl of soup served with a side salad
  • Salad with chicken breast / tuna / beans
  • 1 brown toast / 2 crisp breads with deli meat / tuna / low-fat cottage cheese

Mid-afternoon snack (80-100 kcal)

Select one from the list below

  • 1 meal replacement shake chilled into a mousse / iced dessert
  • Raw veg with a low-fat dip
  • Low-fat yogurt

Dinner (300 kcal)

Select one from the list below

  • 1 bowl of soup served with a portion of veg
  • 100g very lean meat (e.g. chicken breast without skin) / grilled white fish / pulses (e.g. lentils & beans) with a portion of veg or a side salad

IMPORTANT: Ensure you drink at least 2 litres of fluid per day

Tips: For extra flavour you can add salt, pepper, herbs, spices, mustard, lemon / lime juice, vinegar, stock cubes, garlic, vanilla etc. Do not add any butter, oil or cream to your veg. A portion of fruit is: one piece of fresh fruit e.g. apple / banana; 2 small fruits e.g. plums / apricots; 1 small glass of fruit juice; 1 tbsp dried fruit; a handful of grapes / cherries.

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