As has been mentioned different hospital have different pre-op diets (I am surprised by the variation in advise for both pre and post op diets at different hospitals). To give you a few examples at Royal Berkshire they advise
http://www.royalberkshire.nhs.uk/pdf/Gastric band_diet_jul11.pdf
And my dietician advised:-
'Pre -op diet for Bariatric (weight loss) surgery'
You need to follow this diet for the two weeks immediately before your operation. It will reduce the fat and glycogen stored in your liver and make the operation easier for the surgeon.
If the surgeon finds your liver is too big your operation will not be able to go ahead.
This diet is ONLY recommended for 14 days before surgery and should NOT be followed at any other time as it is too restrictive.
• Have three meals a day and use the ‘extra’ fruit or yoghurts as deserts or as snacks.
• Try to vary the foods as much as possible during the fortnight to help make sure you are getting a good range of nutrients. It may be a good idea to start having the multi-vitamin and iron supplement (that you are recommended to take for the first six months after your band/bypass) while you are on this restricted diet.
• Do not guess weights – use scales to measure portions accurately.
• No sugar, cooking oils, margarine, butter, low fat spread, mayonnaise or sauces are allowed.
• The following drinks and flavourings are allowed freely:
Water, tea and coffee (using milk from allowance), low calorie squash.
A small amount of the following can be added to food if needed: salt, lemon juice, vinegar, balsamic vinegar, garlic, herbs and spices, pepper, artificial sweeteners
• Include at least 2 litres (4-5 pints) of fluid a day.
Breakfast
30g non sugar-coated and nut-free cereal eg. porridge oats, ready brek, branflakes, rice crispies, special K, cornflakes, shreddies, sultana bran
or
1½ weetabix or shredded wheat
or
1 portion of fruit
or
1 diet yoghurt
or
1 small slice bread or roll
Lunch and Dinner
1 small slice bread or small roll
or
2 crispbreads
or
100g potato (uncooked weight) – jacket, boiled or mashed with milk from allowance.
or
30g (uncooked weight) of rice, couscous, pasta or noodles
With
100g of vegetables
or
cereal bowl of salad with 1 teaspoon of low calorie dressing (no salad cream or mayonnaise)
With
Choose one of the following - all are cooked weights:
150g steamed or poached fish. No batter or breadcrumb coatings
or
50g lean meat. Trim off all fat before cooking
or
1 large egg eg poached, boiled or scrambled with milk
or
110g Quorn or Tofu
or
25g cheese eg. cheddar, brie, stilton etc.
or
50g low fat soft cheese eg. Philadelphia light, Laughing cow light etc.
or
75g chicken or turkey
or
100g tinned tuna/pilchards (not in oil)
or
50g tinned salmon/sardines (not in oil)
Each day also have:
260ml (½ pint) of skimmed or semi-skimmed milk
2 portions of fruit (one of which could be swapped for a small (150ml) glass of fruit juice)
1 diet/light/virtually fat-free yoghurt or fromage frais
A portion of fruit is:
1 large fruit eg. banana, apple, pear, orange, grapefruit
or
2 small fruits eg. kiwi, plum, satsuma
or
200g strawberries, raspberries, blueberries, blackberries, rhubarb or gooseberries
or
10 grapes or cherries
or
100g tinned fruit in juice