Overview
Carbohydrate loading before surgery – for patients with feeding tubes
This information is for people having surgery who use a feeding tube. There is separate information for patients who eat food and drink orally (by mouth) [ADD LINK].
Important
On this webpage we use the term ‘feed’ when we’re referring to the medicinal products that people receive through their feeding tube.
This is consistent with widely-used clinical terminology, and avoids potential confusion with the term 'food' (usually taken orally) and 'feed' (taken via a feeding tube) which could put people at risk of harm if misunderstood.
Carbohydrate loading
Carbohydrate loading is consuming extra carbohydrates before an event to help your body cope with extra requirements in the short-term. You might have heard that athletes use this before a marathon.
Research has shown that taking carbohydrate-rich nutrition before surgery reduces thirst, hunger and anxiety. It might also help you recover more quickly after your operation.
How to prepare for carbohydrate loading
You will be given 3 sachets of Preload™ at your pre-treatment appointment by your dietitian or clinical nurse specialist.
Hot to mix and take the drinks
Stop your tube feed by midnight on the evening before your surgery. You can continue flushing your tube with cooled boiled or sterile water until 6am on the day of your surgery.
If you’re also taking food or fluids by mouth, you must stop eating by midnight on the evening before your surgery. You can continue drinking water until 6am on the day of your operation.
Using the Preload sachets
You must have followed these steps before midnight on the night before your surgery.
- Mix 2 of the sachets of Preload in 800ml of sterile or cooled boiled water in a jug until fully dissolved.
- If you have a nasogastric tube in place, check the tube tip position using pH strips before administering the Preload solution, as you would normally do before starting a feed.
- Flush your feeding tube with 60ml of cooled boiled or sterile water using a 60ml enteral (purple) syringe.
- Administer the 800ml solution of Preload down your feeding tube using a 60ml enteral (purple) syringe. This can be given over several hours before midnight. The solution can be put in the fridge if giving over several hours but please mix well before administering to dissolve any lumps.
- Flush your feeding tube again with 60mls cooled boiled or sterile water.
If you're also taking fluids orally (by mouth) you can continue drinking water until 6am.
You must have followed these steps by 6am on the morning of your surgery.
- Mix the last sachet of Preload with 400ml of sterile or cooled boiled water in a jug.
- If you have a nasogastric tube in place, check the tube tip position using pH strips before administering the Preload solution, as you would normally do before starting a feed.
- Flush your feeding tube with 60mls cooled boiled or sterile water using a 60ml enteral (purple) syringe.
- Administer the 400ml Preload solution down your feeding tube using a 60ml enteral (purple) syringe.
- Flush your feeding tube again with 60mls cooled boiled or sterile water.
Risks of taking carbohydrate-rich drinks before surgery
There is no evidence of any significant risk from drinking carbohydrate-rich fluids. However, you must make sure that you have:
- stopped eating solid food or taking tube feed 6 hours before your surgery
- stopped flushing your feeding tube with water or drinking water 2 hours before your surgery
As with any general anaesthetic, if there is food or liquid in your stomach during the anaesthetic it could come up to the back of your throat and damage your lungs.
Not having the carbohydrate-rich drinks
If you choose to not have the carbohydrate-rich drinks you must still:
- stop eating solid food 6 hours before your surgery and stop drinking water 2 hours before your surgery.
- stop your tube feed 6 hours before your surgery, and stop flushing your tube with cooled boiled or sterile water 2 hours before your surgery.
What to do if you have a problem
If you cannot administer all of the carbohydrate-rich drinks, take as much as you can and tell the dietitian of the amount that you did deliver via your feeding tube.
Stop administering the carbohydrate-rich drink if:
- you start vomiting
- you have diarrhoea
Make sure you tell the dietitian how much of the drink you have had.
Resource number: 3644/VER5
Last reviewed: October 2026
Next review due: October 2029
