Maintaining a good body weight

eatingwell-big.jpgBy the time you get to be an adult with CF, the need to maintain a good body weight is something you will have heard over and over again.

Diet definitely does matter. Achieving and maintaining a good weight helps to maintain good lung function, which can result in less time in hospital.

A healthy body mass index (BMI) for someone with CF is between 22-25.

Dietary requirements

A person with CF may need up to 120%-150% of the calories needed by someone without CF. This is due to an increased energy expenditure and a number of different reasons.

  • They may have difficulty absorbing the nutrients from food and so need to eat more

  • When infection is present the amount of energy someone with CF needs increases even more 

  • When you are sick you may not feel like eating or have a reduced appetite, and will be more likely to loose weight

  • The lower a persons lung function is, the higher their body’s energy requirements become due to the increased work of breathing

High calorie diet

Why can a high calorie diet be hard to achieve? 

  • Many people with CF experience reduced appetite, especially during infection

  • Forgetting or taking too few enzymes will result in some fat (energy) being wasted  in your stools. 

  •  Even if you are taking your enzymes appropriately you will continue to lose some fat in your stools and this contributes to your increased energy requirements.

In the case of maintaining a good body weight, the answer is very simple. If you want to stay well for longer and you want to stay out of hospital, then work at keeping up your weight so that your body can fight off the infections that are bound to hit you from time to time.

Gastrostomy Tube

What is a PEG?

A gastrostomy tube (PEG) is used by people with CF (PWCF) to supplement their food intake. This can help to maintain or improve your weight and achieve good nutrition.  

Maintaining or gaining weight to reach a healthy BMI.

Some people find it difficult to maintain or gain weight to reach a healthy BMI. If this is the case, meeting with the dietitian can:

  • Give you tips on maximising the amount of calories in your diet

  • Review your enzyme use so you get the most out of the food you are eating

  • Advise you on high energy supplement drinks

Reaching an ideal weight

If you are still unable to reach an ideal weight then having a PEG inserted can take the pressure off and help you take in the extra energy you need. A PEG might be a good idea if:

  • You are unable to gain weight by improving your diet and using oral nutritional supplements

  • You find your appetite is low

  • You often vomit from coughing

  • You are unable to regain weight that was lost when you were sick

  • You are trying to put on weight for lung transplant

A PEG can be used during the day or for overnight feeding while you sleep. It is used to supplement your food intake, not to replace what you usually eat.

How are PEG tubes put in?


PEG tubes are usually put in by a specialist team in the Gastroscopy Day Unit. While you are sedated, the tube is placed into your stomach through the abdominal wall. Initially you will have a longer tube in place until the incision site (stoma/tract) has healed completely (6-8 weeks).

The long tube is then replaced with a low profile “button” as shown in the picture. Using a connecting tube, supplement drinks/feeds can go straight into your stomach.

Most people will use their PEG tube on a daily basis, or several times a week, however some people who have achieved their target weight may only use it as a back up if they get sick or lose weight.

If you think a PEG may be helpful for you, or are interested in finding out more, please ask one of the CF team for more information.

More information on CF and nutrition

If you would like to find out more about CF and nutrition, the websites below have some useful information.

CF Canada - Nutrition

Nutrition information from Cystic Fibrosis Foundation

Nutrition: A guide for adults with cystic fibrosis

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Page last reviewed: 03 October 2013