An Introduction to Diet after Weight Loss Surgery

Patient Experience

  • Reference Number: HEY1028/2018
  • Departments: Nutrition Support
  • Last Updated: 25 October 2023


This diet sheet has been provided by your nurse, doctor or dietitian to provide initial advice for you to follow in the first few days after surgery.  You need to see a dietitian and nurse 6 weeks after your weight loss surgery. An appointment will be sent to you in the post.

Eating after weight loss surgery

The aim of this diet sheet is to give you an introduction to food and drink after weight loss surgery and is suitable for the first few days. This diet sheet is suitable if you have had one of the following operations for the purposes of weight loss:

  • Roux-en-y Gastric Bypass
  • Sleeve Gastrectomy
  • Single Anastomosis Gastric Bypass

It is normal for your portion sizes will be very small to begin with following your surgery. Always stop eating when you feel full, you do not have to finish a full portion.

Foods should be blended until completely smooth; you may need to add extra milk to ensure that the mixture is thin enough.  Aim to eat 3 meals per day.

Choose one of the following foods to have at each meal:

  • Very thin porridge
  • Natural yogurt mixed with fruit juice
  • Smooth soup
  • Sugar free custard
  • Sugar free ground rice / milk pudding or semolina

Do not add any sugar to your meals or drinks. If you plan to purchase pre-made foods, make sure each meal contains no more than 5g of sugar

Drinking after weight loss surgery

You should aim for 2-3 litres (4-5 pints) of still, sugar free fluid every day. Suitable fluids include water, sugar free flavoured water, diluted no added sugar squash and skimmed or semi skimmed milk. Avoid all fizzy drinks. Drinking enough fluid will help you avoid constipation and dehydration.

It is important to remember not to drink around meal times. Stop drinking 30 minutes before a meal and start drinking again one hour after a meal. Your fluid intake should include 200ml of fortified milk, protein water or protein shake 3 times a day, in-between meals.

Fortified milk recipe: whisk 3-4 tablespoon of skimmed milk powder into 600ml of skimmed or semi skimmed milk.

This information does not replace the advice and diet sheets previously given to you.

If you do not have the diet sheets mentioned above, or need further information, please call and ask to speak with a dietitian as soon as you are discharged from hospital. You can contact the dietetic department on 01482 461941

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