Diet after weight loss surgery

Weight loss surgery can also be called bariatric surgery or metabolic surgery. If you have had weight loss surgery, you will need to follow our diet advice after your surgery.

There are different types of weight loss surgery. Our advice about eating and drinking depends on what type of surgery you had.

This guide has been developed by bariatric dietitians. If you have any questions or concerns, please contact the nutrition and dietetics department.

Types of weight loss surgery

Sleeve gastrectomy

The aim of a sleeve gastrectomy is to reduce the amount of food that you can eat.

During surgery, the outside part of the stomach is removed. This leaves a new, smaller stomach pouch.

The volume of the stomach is reduced by about 75 to 80%, which leaves a volume of about 100mls.

The operation might make you less hungry. This is because the part of the stomach that is removed makes a hunger hormone called ghrelin.

Many people are surprised to find that they do not want food as they used to, and some also notice changes to the taste of food and the food they like or do not like.

Although this surgery is a tool to help you lose weight, you are still in control of the food choices you make. While the surgery will help you to eat less, you need to make healthy choices, and exercise regularly, to get the best weight loss result.

Read more about diet after a sleeve gastrectomy.

Gastric bypass

During gastric bypass surgery, we create a small pouch at the top of your stomach. The pouch is connected to the small intestine. This means that food will travel from the pouch straight to the small intestine. The food will miss (or bypass) the rest of the stomach.

The main part of your stomach is left and continues to have a blood supply. There is no food passing through this part of the stomach, but it still makes digestive juices. This part of the stomach is attached further down the small intestine, to allow these juices to mix with your food.

Having this surgery means that:

  1. your stomach cannot hold as much food
  2. it stops nutrients from being absorbed into your body. This is because the food bypasses the first section of the small intestine

The amount of food you can eat is reduced. You will fill up quickly, and stay full for longer, after only a few mouthfuls of food.

Most people find that they do not get the same feeling of hunger that they did before the surgery.

Read more about your diet after a gastric bypass.

Gastric band surgery

A gastric band is a tube of silicone (like rubber) in a loop. We put it at the top of the stomach, just below the point where the food pipe (oesophagus) meets the stomach.

When correctly adjusted, the band creates pressure around the area as food passes through. This causes you to feel fuller earlier, and for longer after eating. 

When you learn to work with your band and eat the right types of foods, you will feel satisfied with only very small portions of food. 

The texture of your food choices is very important if you want to have a good level of weight loss with a gastric band.

When you have your gastric band placed it will have very little or no fluid inside. Once you have fully recovered from surgery you will have your first gastric band adjustment.

An adjustment is a very quick and simple procedure where fluid is added or removed from the band through the port. This makes the band tighter, or looser. You will need a few of these adjustments before your band is tight enough to reduce hunger, make you feel full for a long time, and cause weight loss.

Read more about your diet after gastric band surgery.

Pregnancy after weight loss surgery

You are advised to avoid pregnancy for 12 to 18 months after surgery, until your weight has stabilised. This is because the effects of rapid weight loss on a developing baby are not yet understood.

However, many people do become pregnant during this time, and go on to have a successful pregnancy.

Pregnancy after weight loss (bariatric) surgery is thought to have less risk than pregnancy with morbid obesity.

It's important to remember that as you lose weight your fertility might increase. Make sure that you are taking appropriate contraceptive precautions.

If you become pregnant

If you become pregnant at any point after bariatric surgery you should:

  • tell your midwife you had bariatric surgery
  • contact the bariatric surgery team as soon as possible

You should have nutritional screening every trimester (the 3 stages of pregnancy) and have more regular appointments with your maternity team. This is to monitor the growth of your baby.

You should avoid vitamin and mineral supplements containing vitamin A (retinol form) in the first 12 weeks of pregnancy. 

Your bariatric team can advise you on a multivitamin that is safe to take during pregnancy.

If you have obesity or diabetes, take a higher dose of folic acid than is usually recommended. Please discuss this with your healthcare team.

      Resource number: 5030/VER1
      Last reviewed: August 2020
      Next review: August 2023

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