The Importance of Proteins: Muscle Mass

Individuals with cystic fibrosis and other chronic diseases often have a “hidden” loss of muscle mass, despite normal body weight and BMI. Increasing your protein intake and exercising regularly are easy ways to preserve muscle mass.

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In this article
  • A lack of protein and fat are the main causes of muscle wasting, which also can be caused by chronic low-grade inflammation, use of oral corticosteroids and hormonal changes.
  • This can be done through a combination of food and exercise. 

Individuals with CF use a lot of energy to breathe and fight infections. But protein and fat digestion problems mean there are fewer nutrients for the body to use. A lack of protein and fat are the main causes of muscle wasting, which also can be caused by chronic low-grade inflammation, use of oral corticosteroids and hormonal changes.

Preserving muscle mass is important in individuals with CF because it:

  • Leads to better survival rates
  • Helps maintain lung function (respiratory muscles)
  • Improves muscle function and exercise performance
  • Lowers the number of exacerbations and hospitalizations each year
  • Decreases the duration of a hospital stay
  • Leads to less bone loss
  • Increases quality of life1,2,3,4,5

How Do I Know Whether I Have Muscle Loss?

Your health care provider or a member of your CF care team can perform several body composition tests to determine your muscle mass. A dual-energy X-ray absorptiometry (DEXA) scan (used mainly for bone mineral density) can show the amount of muscle and fat mass throughout your body.5

How Do I Prevent Muscle Loss?

Quite simply, you need to increase muscle buildup and reduce muscle breakdown. This can be done through a combination of food and exercise. Proteins are the building blocks of muscles, so it is important to eat enough easily digestible protein.

It's also important to do weight-bearing exercises, that work against gravity like walking, hiking, jogging, climbing stairs, tennis or dancing. You can learn more about exercise by watching an archived recording of our Facebook Live event, “Exercise and You,” at the 2016 North American Cystic Fibrosis Conference.

How Much Protein Should I Get?

It is important to note that there are no official recommendations; however, experts recommend that those with a chronic disease should get 1.5 grams of protein per kilogram of body weight per day and more during an exacerbation.5 The recommended dietary allowance for those without CF is 0.8 grams per kilogram of body weight per day.

For example, if you weighed 150 pounds, you would:

  1. Divide your weight in pounds (150) by 2.2 to get your weight in kilograms, which is 68 kg.
  2. Multiply your weight in kilograms (68) by 1.5 to get the amount of protein in grams.

In this example, you would need 102 grams of protein daily.

The amount of protein you need depends on how much your protein digestion is impaired and the efficiency of the enzymes you take to improve your digestion. There is no simple method available to measure the degree of impairment.

Researchers do say that individuals with CF need more protein than those without CF because of the increased work of breathing, chronic inflammation and exacerbations. Consult with your dietitian to find out what is right for you.5


Sharma R, Florea VG, Bolger AP, Wasting as an independent predictor of mortality in patients with cystic fibrosis. Thorax. 2001 Oct;56(10):746-750. doi:10.1136/thorax.56.10.746.

2 Klijn PH, van der Net J, Kimpen JL, Helders PJ, vander Ent CK. Longitudinal determinants of peak aerobic performance in children with cystic fibrosis. Chest 2003 Dec;124(6):2215-9.PMID:14665503

3 Zemel BS, Jawad AF, FitzSimmons S, Stallings VA. Longitudinal relationship among growth, nutritional status, and pulmonary function in children with cystic fibrosis: analysis of the Cystic Fibrosis Foundation National CF Patient Registry. J Pediatr 2000 Sep;137(3):374-80.PMID:10969263.

4 Engelen MPKJ, Com G, Anderson PJ, Deutz NEP. New stable isotope method to measure protein digestibility and response to pancreatic enzyme intake in cystic fibrosis. Clinical nutrition (Edinburgh, Scotland). 2014;33(6):1024-1032. doi:10.1016/j.clnu.2013.11.004.

5 Duetz Nicolaas E and Engelen Marielle P. Lecture presented: Why proteins are so important in cystic fibrosis. Center for Translational Research in Aging & Longevity. Department of Health and Kinesiology, Texas A&M University; September 23, 2014. Retrieved from

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